6695 lines
222 KiB
C
6695 lines
222 KiB
C
/*
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** 2004 May 22
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This file contains the VFS implementation for unix-like operating systems
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** include Linux, MacOSX, *BSD, QNX, VxWorks, AIX, HPUX, and others.
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**
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** There are actually several different VFS implementations in this file.
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** The differences are in the way that file locking is done. The default
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** implementation uses Posix Advisory Locks. Alternative implementations
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** use flock(), dot-files, various proprietary locking schemas, or simply
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** skip locking all together.
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**
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** This source file is organized into divisions where the logic for various
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** subfunctions is contained within the appropriate division. PLEASE
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** KEEP THE STRUCTURE OF THIS FILE INTACT. New code should be placed
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** in the correct division and should be clearly labeled.
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**
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** The layout of divisions is as follows:
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**
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** * General-purpose declarations and utility functions.
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** * Unique file ID logic used by VxWorks.
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** * Various locking primitive implementations (all except proxy locking):
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** + for Posix Advisory Locks
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** + for no-op locks
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** + for dot-file locks
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** + for flock() locking
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** + for named semaphore locks (VxWorks only)
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** + for AFP filesystem locks (MacOSX only)
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** * sqlite3_file methods not associated with locking.
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** * Definitions of sqlite3_io_methods objects for all locking
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** methods plus "finder" functions for each locking method.
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** * sqlite3_vfs method implementations.
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** * Locking primitives for the proxy uber-locking-method. (MacOSX only)
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** * Definitions of sqlite3_vfs objects for all locking methods
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** plus implementations of sqlite3_os_init() and sqlite3_os_end().
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*/
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#include "sqliteInt.h"
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#if SQLITE_OS_UNIX /* This file is used on unix only */
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/*
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** There are various methods for file locking used for concurrency
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** control:
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**
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** 1. POSIX locking (the default),
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** 2. No locking,
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** 3. Dot-file locking,
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** 4. flock() locking,
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** 5. AFP locking (OSX only),
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** 6. Named POSIX semaphores (VXWorks only),
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** 7. proxy locking. (OSX only)
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**
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** Styles 4, 5, and 7 are only available of SQLITE_ENABLE_LOCKING_STYLE
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** is defined to 1. The SQLITE_ENABLE_LOCKING_STYLE also enables automatic
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** selection of the appropriate locking style based on the filesystem
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** where the database is located.
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*/
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#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
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# if defined(__APPLE__)
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# define SQLITE_ENABLE_LOCKING_STYLE 1
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# else
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# define SQLITE_ENABLE_LOCKING_STYLE 0
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# endif
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#endif
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/*
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** Define the OS_VXWORKS pre-processor macro to 1 if building on
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** vxworks, or 0 otherwise.
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*/
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#ifndef OS_VXWORKS
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# if defined(__RTP__) || defined(_WRS_KERNEL)
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# define OS_VXWORKS 1
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# else
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# define OS_VXWORKS 0
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# endif
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#endif
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/*
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** These #defines should enable >2GB file support on Posix if the
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** underlying operating system supports it. If the OS lacks
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** large file support, these should be no-ops.
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**
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** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
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** on the compiler command line. This is necessary if you are compiling
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** on a recent machine (ex: RedHat 7.2) but you want your code to work
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** on an older machine (ex: RedHat 6.0). If you compile on RedHat 7.2
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** without this option, LFS is enable. But LFS does not exist in the kernel
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** in RedHat 6.0, so the code won't work. Hence, for maximum binary
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** portability you should omit LFS.
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**
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** The previous paragraph was written in 2005. (This paragraph is written
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** on 2008-11-28.) These days, all Linux kernels support large files, so
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** you should probably leave LFS enabled. But some embedded platforms might
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** lack LFS in which case the SQLITE_DISABLE_LFS macro might still be useful.
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*/
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#ifndef SQLITE_DISABLE_LFS
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# define _LARGE_FILE 1
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# ifndef _FILE_OFFSET_BITS
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# define _FILE_OFFSET_BITS 64
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# endif
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# define _LARGEFILE_SOURCE 1
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#endif
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/*
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** standard include files.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <time.h>
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#include <sys/time.h>
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#include <errno.h>
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#ifndef SQLITE_OMIT_WAL
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#include <sys/mman.h>
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#endif
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#if SQLITE_ENABLE_LOCKING_STYLE
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# include <sys/ioctl.h>
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# if OS_VXWORKS
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# include <semaphore.h>
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# include <limits.h>
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# else
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# include <sys/file.h>
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# include <sys/param.h>
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# endif
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#endif /* SQLITE_ENABLE_LOCKING_STYLE */
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#if defined(__APPLE__) || (SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS)
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# include <sys/mount.h>
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#endif
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/*
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** Allowed values of unixFile.fsFlags
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*/
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#define SQLITE_FSFLAGS_IS_MSDOS 0x1
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/*
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** If we are to be thread-safe, include the pthreads header and define
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** the SQLITE_UNIX_THREADS macro.
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*/
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#if SQLITE_THREADSAFE
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# include <pthread.h>
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# define SQLITE_UNIX_THREADS 1
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#endif
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/*
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** Default permissions when creating a new file
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*/
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#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
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# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
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#endif
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/*
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** Default permissions when creating auto proxy dir
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*/
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#ifndef SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
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# define SQLITE_DEFAULT_PROXYDIR_PERMISSIONS 0755
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#endif
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/*
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** Maximum supported path-length.
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*/
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#define MAX_PATHNAME 512
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/*
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** Only set the lastErrno if the error code is a real error and not
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** a normal expected return code of SQLITE_BUSY or SQLITE_OK
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*/
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#define IS_LOCK_ERROR(x) ((x != SQLITE_OK) && (x != SQLITE_BUSY))
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/* Forward references */
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typedef struct unixShm unixShm; /* Connection shared memory */
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typedef struct unixShmNode unixShmNode; /* Shared memory instance */
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typedef struct unixInodeInfo unixInodeInfo; /* An i-node */
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typedef struct UnixUnusedFd UnixUnusedFd; /* An unused file descriptor */
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/*
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** Sometimes, after a file handle is closed by SQLite, the file descriptor
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** cannot be closed immediately. In these cases, instances of the following
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** structure are used to store the file descriptor while waiting for an
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** opportunity to either close or reuse it.
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*/
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struct UnixUnusedFd {
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int fd; /* File descriptor to close */
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int flags; /* Flags this file descriptor was opened with */
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UnixUnusedFd *pNext; /* Next unused file descriptor on same file */
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};
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/*
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** The unixFile structure is subclass of sqlite3_file specific to the unix
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** VFS implementations.
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*/
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typedef struct unixFile unixFile;
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struct unixFile {
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sqlite3_io_methods const *pMethod; /* Always the first entry */
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unixInodeInfo *pInode; /* Info about locks on this inode */
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int h; /* The file descriptor */
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int dirfd; /* File descriptor for the directory */
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unsigned char eFileLock; /* The type of lock held on this fd */
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unsigned char ctrlFlags; /* Behavioral bits. UNIXFILE_* flags */
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int lastErrno; /* The unix errno from last I/O error */
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void *lockingContext; /* Locking style specific state */
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UnixUnusedFd *pUnused; /* Pre-allocated UnixUnusedFd */
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const char *zPath; /* Name of the file */
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unixShm *pShm; /* Shared memory segment information */
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int szChunk; /* Configured by FCNTL_CHUNK_SIZE */
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#if SQLITE_ENABLE_LOCKING_STYLE
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int openFlags; /* The flags specified at open() */
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#endif
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#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
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unsigned fsFlags; /* cached details from statfs() */
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#endif
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#if OS_VXWORKS
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int isDelete; /* Delete on close if true */
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struct vxworksFileId *pId; /* Unique file ID */
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#endif
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#ifndef NDEBUG
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/* The next group of variables are used to track whether or not the
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** transaction counter in bytes 24-27 of database files are updated
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** whenever any part of the database changes. An assertion fault will
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** occur if a file is updated without also updating the transaction
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** counter. This test is made to avoid new problems similar to the
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** one described by ticket #3584.
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*/
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unsigned char transCntrChng; /* True if the transaction counter changed */
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unsigned char dbUpdate; /* True if any part of database file changed */
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unsigned char inNormalWrite; /* True if in a normal write operation */
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#endif
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#ifdef SQLITE_TEST
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/* In test mode, increase the size of this structure a bit so that
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** it is larger than the struct CrashFile defined in test6.c.
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*/
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char aPadding[32];
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#endif
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};
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/*
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** Allowed values for the unixFile.ctrlFlags bitmask:
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*/
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#define UNIXFILE_EXCL 0x01 /* Connections from one process only */
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#define UNIXFILE_RDONLY 0x02 /* Connection is read only */
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/*
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** Include code that is common to all os_*.c files
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*/
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#include "os_common.h"
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/*
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** Define various macros that are missing from some systems.
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*/
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#ifndef O_LARGEFILE
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# define O_LARGEFILE 0
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#endif
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#ifdef SQLITE_DISABLE_LFS
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# undef O_LARGEFILE
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# define O_LARGEFILE 0
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#endif
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#ifndef O_NOFOLLOW
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# define O_NOFOLLOW 0
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#endif
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#ifndef O_BINARY
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# define O_BINARY 0
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#endif
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/*
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** The threadid macro resolves to the thread-id or to 0. Used for
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** testing and debugging only.
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*/
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#if SQLITE_THREADSAFE
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#define threadid pthread_self()
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#else
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#define threadid 0
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#endif
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/*
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** Many system calls are accessed through pointer-to-functions so that
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** they may be overridden at runtime to facilitate fault injection during
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** testing and sandboxing. The following array holds the names and pointers
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** to all overrideable system calls.
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*/
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static struct unix_syscall {
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const char *zName; /* Name of the sytem call */
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sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
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sqlite3_syscall_ptr pDefault; /* Default value */
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} aSyscall[] = {
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{ "open", (sqlite3_syscall_ptr)open, 0 },
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#define osOpen ((int(*)(const char*,int,int))aSyscall[0].pCurrent)
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{ "close", (sqlite3_syscall_ptr)close, 0 },
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#define osClose ((int(*)(int))aSyscall[1].pCurrent)
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{ "access", (sqlite3_syscall_ptr)access, 0 },
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#define osAccess ((int(*)(const char*,int))aSyscall[2].pCurrent)
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{ "getcwd", (sqlite3_syscall_ptr)getcwd, 0 },
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#define osGetcwd ((char*(*)(char*,size_t))aSyscall[3].pCurrent)
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{ "stat", (sqlite3_syscall_ptr)stat, 0 },
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#define osStat ((int(*)(const char*,struct stat*))aSyscall[4].pCurrent)
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/*
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** The DJGPP compiler environment looks mostly like Unix, but it
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** lacks the fcntl() system call. So redefine fcntl() to be something
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** that always succeeds. This means that locking does not occur under
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** DJGPP. But it is DOS - what did you expect?
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*/
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#ifdef __DJGPP__
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{ "fstat", 0, 0 },
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#define osFstat(a,b,c) 0
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#else
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{ "fstat", (sqlite3_syscall_ptr)fstat, 0 },
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#define osFstat ((int(*)(int,struct stat*))aSyscall[5].pCurrent)
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#endif
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{ "ftruncate", (sqlite3_syscall_ptr)ftruncate, 0 },
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#define osFtruncate ((int(*)(int,off_t))aSyscall[6].pCurrent)
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{ "fcntl", (sqlite3_syscall_ptr)fcntl, 0 },
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#define osFcntl ((int(*)(int,int,...))aSyscall[7].pCurrent)
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{ "read", (sqlite3_syscall_ptr)read, 0 },
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#define osRead ((ssize_t(*)(int,void*,size_t))aSyscall[8].pCurrent)
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#if defined(USE_PREAD) || defined(SQLITE_ENABLE_LOCKING_STYLE)
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{ "pread", (sqlite3_syscall_ptr)pread, 0 },
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#else
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{ "pread", (sqlite3_syscall_ptr)0, 0 },
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#endif
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#define osPread ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[9].pCurrent)
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#if defined(USE_PREAD64)
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{ "pread64", (sqlite3_syscall_ptr)pread64, 0 },
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#else
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{ "pread64", (sqlite3_syscall_ptr)0, 0 },
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#endif
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#define osPread64 ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[10].pCurrent)
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{ "write", (sqlite3_syscall_ptr)write, 0 },
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#define osWrite ((ssize_t(*)(int,const void*,size_t))aSyscall[11].pCurrent)
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#if defined(USE_PREAD) || defined(SQLITE_ENABLE_LOCKING_STYLE)
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{ "pwrite", (sqlite3_syscall_ptr)pwrite, 0 },
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#else
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{ "pwrite", (sqlite3_syscall_ptr)0, 0 },
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#endif
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#define osPwrite ((ssize_t(*)(int,const void*,size_t,off_t))\
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aSyscall[12].pCurrent)
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#if defined(USE_PREAD64)
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{ "pwrite64", (sqlite3_syscall_ptr)pwrite64, 0 },
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#else
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{ "pwrite64", (sqlite3_syscall_ptr)0, 0 },
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#endif
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#define osPwrite64 ((ssize_t(*)(int,const void*,size_t,off_t))\
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aSyscall[13].pCurrent)
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{ "fchmod", (sqlite3_syscall_ptr)fchmod, 0 },
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#define osFchmod ((int(*)(int,mode_t))aSyscall[14].pCurrent)
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#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
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{ "fallocate", (sqlite3_syscall_ptr)posix_fallocate, 0 },
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#else
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{ "fallocate", (sqlite3_syscall_ptr)0, 0 },
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#endif
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#define osFallocate ((int(*)(int,off_t,off_t))aSyscall[15].pCurrent)
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}; /* End of the overrideable system calls */
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/*
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** This is the xSetSystemCall() method of sqlite3_vfs for all of the
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** "unix" VFSes. Return SQLITE_OK opon successfully updating the
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** system call pointer, or SQLITE_NOTFOUND if there is no configurable
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** system call named zName.
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*/
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static int unixSetSystemCall(
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sqlite3_vfs *pNotUsed, /* The VFS pointer. Not used */
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const char *zName, /* Name of system call to override */
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sqlite3_syscall_ptr pNewFunc /* Pointer to new system call value */
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|
){
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unsigned int i;
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int rc = SQLITE_NOTFOUND;
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UNUSED_PARAMETER(pNotUsed);
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|
if( zName==0 ){
|
|
/* If no zName is given, restore all system calls to their default
|
|
** settings and return NULL
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*/
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for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
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if( aSyscall[i].pDefault ){
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aSyscall[i].pCurrent = aSyscall[i].pDefault;
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rc = SQLITE_OK;
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}
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}
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}else{
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/* If zName is specified, operate on only the one system call
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** specified.
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*/
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for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
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if( strcmp(zName, aSyscall[i].zName)==0 ){
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if( aSyscall[i].pDefault==0 ){
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aSyscall[i].pDefault = aSyscall[i].pCurrent;
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}
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rc = SQLITE_OK;
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if( pNewFunc==0 ) pNewFunc = aSyscall[i].pDefault;
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aSyscall[i].pCurrent = pNewFunc;
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break;
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}
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}
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}
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return rc;
|
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}
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|
|
/*
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|
** Return the value of a system call. Return NULL if zName is not a
|
|
** recognized system call name. NULL is also returned if the system call
|
|
** is currently undefined.
|
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*/
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|
static sqlite3_syscall_ptr unixGetSystemCall(
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sqlite3_vfs *pNotUsed,
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const char *zName
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){
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unsigned int i;
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UNUSED_PARAMETER(pNotUsed);
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for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
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if( strcmp(zName, aSyscall[i].zName)==0 ) return aSyscall[i].pCurrent;
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|
}
|
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return 0;
|
|
}
|
|
|
|
/*
|
|
** Return the name of the first system call after zName. If zName==NULL
|
|
** then return the name of the first system call. Return NULL if zName
|
|
** is the last system call or if zName is not the name of a valid
|
|
** system call.
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*/
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static const char *unixNextSystemCall(sqlite3_vfs *p, const char *zName){
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int i = -1;
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UNUSED_PARAMETER(p);
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if( zName ){
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for(i=0; i<ArraySize(aSyscall)-1; i++){
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if( strcmp(zName, aSyscall[i].zName)==0 ) break;
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}
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}
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for(i++; i<ArraySize(aSyscall); i++){
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if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
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}
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return 0;
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}
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|
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/*
|
|
** Retry open() calls that fail due to EINTR
|
|
*/
|
|
static int robust_open(const char *z, int f, int m){
|
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int rc;
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do{ rc = osOpen(z,f,m); }while( rc<0 && errno==EINTR );
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return rc;
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}
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|
|
/*
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|
** Helper functions to obtain and relinquish the global mutex. The
|
|
** global mutex is used to protect the unixInodeInfo and
|
|
** vxworksFileId objects used by this file, all of which may be
|
|
** shared by multiple threads.
|
|
**
|
|
** Function unixMutexHeld() is used to assert() that the global mutex
|
|
** is held when required. This function is only used as part of assert()
|
|
** statements. e.g.
|
|
**
|
|
** unixEnterMutex()
|
|
** assert( unixMutexHeld() );
|
|
** unixEnterLeave()
|
|
*/
|
|
static void unixEnterMutex(void){
|
|
sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
|
|
}
|
|
static void unixLeaveMutex(void){
|
|
sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
|
|
}
|
|
#ifdef SQLITE_DEBUG
|
|
static int unixMutexHeld(void) {
|
|
return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
|
|
}
|
|
#endif
|
|
|
|
|
|
#ifdef SQLITE_DEBUG
|
|
/*
|
|
** Helper function for printing out trace information from debugging
|
|
** binaries. This returns the string represetation of the supplied
|
|
** integer lock-type.
|
|
*/
|
|
static const char *azFileLock(int eFileLock){
|
|
switch( eFileLock ){
|
|
case NO_LOCK: return "NONE";
|
|
case SHARED_LOCK: return "SHARED";
|
|
case RESERVED_LOCK: return "RESERVED";
|
|
case PENDING_LOCK: return "PENDING";
|
|
case EXCLUSIVE_LOCK: return "EXCLUSIVE";
|
|
}
|
|
return "ERROR";
|
|
}
|
|
#endif
|
|
|
|
#ifdef SQLITE_LOCK_TRACE
|
|
/*
|
|
** Print out information about all locking operations.
|
|
**
|
|
** This routine is used for troubleshooting locks on multithreaded
|
|
** platforms. Enable by compiling with the -DSQLITE_LOCK_TRACE
|
|
** command-line option on the compiler. This code is normally
|
|
** turned off.
|
|
*/
|
|
static int lockTrace(int fd, int op, struct flock *p){
|
|
char *zOpName, *zType;
|
|
int s;
|
|
int savedErrno;
|
|
if( op==F_GETLK ){
|
|
zOpName = "GETLK";
|
|
}else if( op==F_SETLK ){
|
|
zOpName = "SETLK";
|
|
}else{
|
|
s = osFcntl(fd, op, p);
|
|
sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
|
|
return s;
|
|
}
|
|
if( p->l_type==F_RDLCK ){
|
|
zType = "RDLCK";
|
|
}else if( p->l_type==F_WRLCK ){
|
|
zType = "WRLCK";
|
|
}else if( p->l_type==F_UNLCK ){
|
|
zType = "UNLCK";
|
|
}else{
|
|
assert( 0 );
|
|
}
|
|
assert( p->l_whence==SEEK_SET );
|
|
s = osFcntl(fd, op, p);
|
|
savedErrno = errno;
|
|
sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
|
|
threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
|
|
(int)p->l_pid, s);
|
|
if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
|
|
struct flock l2;
|
|
l2 = *p;
|
|
osFcntl(fd, F_GETLK, &l2);
|
|
if( l2.l_type==F_RDLCK ){
|
|
zType = "RDLCK";
|
|
}else if( l2.l_type==F_WRLCK ){
|
|
zType = "WRLCK";
|
|
}else if( l2.l_type==F_UNLCK ){
|
|
zType = "UNLCK";
|
|
}else{
|
|
assert( 0 );
|
|
}
|
|
sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
|
|
zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
|
|
}
|
|
errno = savedErrno;
|
|
return s;
|
|
}
|
|
#undef osFcntl
|
|
#define osFcntl lockTrace
|
|
#endif /* SQLITE_LOCK_TRACE */
|
|
|
|
/*
|
|
** Retry ftruncate() calls that fail due to EINTR
|
|
*/
|
|
static int robust_ftruncate(int h, sqlite3_int64 sz){
|
|
int rc;
|
|
do{ rc = osFtruncate(h,sz); }while( rc<0 && errno==EINTR );
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** This routine translates a standard POSIX errno code into something
|
|
** useful to the clients of the sqlite3 functions. Specifically, it is
|
|
** intended to translate a variety of "try again" errors into SQLITE_BUSY
|
|
** and a variety of "please close the file descriptor NOW" errors into
|
|
** SQLITE_IOERR
|
|
**
|
|
** Errors during initialization of locks, or file system support for locks,
|
|
** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
|
|
*/
|
|
static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
|
|
switch (posixError) {
|
|
case 0:
|
|
return SQLITE_OK;
|
|
|
|
case EAGAIN:
|
|
case ETIMEDOUT:
|
|
case EBUSY:
|
|
case EINTR:
|
|
case ENOLCK:
|
|
/* random NFS retry error, unless during file system support
|
|
* introspection, in which it actually means what it says */
|
|
return SQLITE_BUSY;
|
|
|
|
case EACCES:
|
|
/* EACCES is like EAGAIN during locking operations, but not any other time*/
|
|
if( (sqliteIOErr == SQLITE_IOERR_LOCK) ||
|
|
(sqliteIOErr == SQLITE_IOERR_UNLOCK) ||
|
|
(sqliteIOErr == SQLITE_IOERR_RDLOCK) ||
|
|
(sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
|
|
return SQLITE_BUSY;
|
|
}
|
|
/* else fall through */
|
|
case EPERM:
|
|
return SQLITE_PERM;
|
|
|
|
case EDEADLK:
|
|
return SQLITE_IOERR_BLOCKED;
|
|
|
|
#if EOPNOTSUPP!=ENOTSUP
|
|
case EOPNOTSUPP:
|
|
/* something went terribly awry, unless during file system support
|
|
* introspection, in which it actually means what it says */
|
|
#endif
|
|
#ifdef ENOTSUP
|
|
case ENOTSUP:
|
|
/* invalid fd, unless during file system support introspection, in which
|
|
* it actually means what it says */
|
|
#endif
|
|
case EIO:
|
|
case EBADF:
|
|
case EINVAL:
|
|
case ENOTCONN:
|
|
case ENODEV:
|
|
case ENXIO:
|
|
case ENOENT:
|
|
case ESTALE:
|
|
case ENOSYS:
|
|
/* these should force the client to close the file and reconnect */
|
|
|
|
default:
|
|
return sqliteIOErr;
|
|
}
|
|
}
|
|
|
|
|
|
|
|
/******************************************************************************
|
|
****************** Begin Unique File ID Utility Used By VxWorks ***************
|
|
**
|
|
** On most versions of unix, we can get a unique ID for a file by concatenating
|
|
** the device number and the inode number. But this does not work on VxWorks.
|
|
** On VxWorks, a unique file id must be based on the canonical filename.
|
|
**
|
|
** A pointer to an instance of the following structure can be used as a
|
|
** unique file ID in VxWorks. Each instance of this structure contains
|
|
** a copy of the canonical filename. There is also a reference count.
|
|
** The structure is reclaimed when the number of pointers to it drops to
|
|
** zero.
|
|
**
|
|
** There are never very many files open at one time and lookups are not
|
|
** a performance-critical path, so it is sufficient to put these
|
|
** structures on a linked list.
|
|
*/
|
|
struct vxworksFileId {
|
|
struct vxworksFileId *pNext; /* Next in a list of them all */
|
|
int nRef; /* Number of references to this one */
|
|
int nName; /* Length of the zCanonicalName[] string */
|
|
char *zCanonicalName; /* Canonical filename */
|
|
};
|
|
|
|
#if OS_VXWORKS
|
|
/*
|
|
** All unique filenames are held on a linked list headed by this
|
|
** variable:
|
|
*/
|
|
static struct vxworksFileId *vxworksFileList = 0;
|
|
|
|
/*
|
|
** Simplify a filename into its canonical form
|
|
** by making the following changes:
|
|
**
|
|
** * removing any trailing and duplicate /
|
|
** * convert /./ into just /
|
|
** * convert /A/../ where A is any simple name into just /
|
|
**
|
|
** Changes are made in-place. Return the new name length.
|
|
**
|
|
** The original filename is in z[0..n-1]. Return the number of
|
|
** characters in the simplified name.
|
|
*/
|
|
static int vxworksSimplifyName(char *z, int n){
|
|
int i, j;
|
|
while( n>1 && z[n-1]=='/' ){ n--; }
|
|
for(i=j=0; i<n; i++){
|
|
if( z[i]=='/' ){
|
|
if( z[i+1]=='/' ) continue;
|
|
if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){
|
|
i += 1;
|
|
continue;
|
|
}
|
|
if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){
|
|
while( j>0 && z[j-1]!='/' ){ j--; }
|
|
if( j>0 ){ j--; }
|
|
i += 2;
|
|
continue;
|
|
}
|
|
}
|
|
z[j++] = z[i];
|
|
}
|
|
z[j] = 0;
|
|
return j;
|
|
}
|
|
|
|
/*
|
|
** Find a unique file ID for the given absolute pathname. Return
|
|
** a pointer to the vxworksFileId object. This pointer is the unique
|
|
** file ID.
|
|
**
|
|
** The nRef field of the vxworksFileId object is incremented before
|
|
** the object is returned. A new vxworksFileId object is created
|
|
** and added to the global list if necessary.
|
|
**
|
|
** If a memory allocation error occurs, return NULL.
|
|
*/
|
|
static struct vxworksFileId *vxworksFindFileId(const char *zAbsoluteName){
|
|
struct vxworksFileId *pNew; /* search key and new file ID */
|
|
struct vxworksFileId *pCandidate; /* For looping over existing file IDs */
|
|
int n; /* Length of zAbsoluteName string */
|
|
|
|
assert( zAbsoluteName[0]=='/' );
|
|
n = (int)strlen(zAbsoluteName);
|
|
pNew = sqlite3_malloc( sizeof(*pNew) + (n+1) );
|
|
if( pNew==0 ) return 0;
|
|
pNew->zCanonicalName = (char*)&pNew[1];
|
|
memcpy(pNew->zCanonicalName, zAbsoluteName, n+1);
|
|
n = vxworksSimplifyName(pNew->zCanonicalName, n);
|
|
|
|
/* Search for an existing entry that matching the canonical name.
|
|
** If found, increment the reference count and return a pointer to
|
|
** the existing file ID.
|
|
*/
|
|
unixEnterMutex();
|
|
for(pCandidate=vxworksFileList; pCandidate; pCandidate=pCandidate->pNext){
|
|
if( pCandidate->nName==n
|
|
&& memcmp(pCandidate->zCanonicalName, pNew->zCanonicalName, n)==0
|
|
){
|
|
sqlite3_free(pNew);
|
|
pCandidate->nRef++;
|
|
unixLeaveMutex();
|
|
return pCandidate;
|
|
}
|
|
}
|
|
|
|
/* No match was found. We will make a new file ID */
|
|
pNew->nRef = 1;
|
|
pNew->nName = n;
|
|
pNew->pNext = vxworksFileList;
|
|
vxworksFileList = pNew;
|
|
unixLeaveMutex();
|
|
return pNew;
|
|
}
|
|
|
|
/*
|
|
** Decrement the reference count on a vxworksFileId object. Free
|
|
** the object when the reference count reaches zero.
|
|
*/
|
|
static void vxworksReleaseFileId(struct vxworksFileId *pId){
|
|
unixEnterMutex();
|
|
assert( pId->nRef>0 );
|
|
pId->nRef--;
|
|
if( pId->nRef==0 ){
|
|
struct vxworksFileId **pp;
|
|
for(pp=&vxworksFileList; *pp && *pp!=pId; pp = &((*pp)->pNext)){}
|
|
assert( *pp==pId );
|
|
*pp = pId->pNext;
|
|
sqlite3_free(pId);
|
|
}
|
|
unixLeaveMutex();
|
|
}
|
|
#endif /* OS_VXWORKS */
|
|
/*************** End of Unique File ID Utility Used By VxWorks ****************
|
|
******************************************************************************/
|
|
|
|
|
|
/******************************************************************************
|
|
*************************** Posix Advisory Locking ****************************
|
|
**
|
|
** POSIX advisory locks are broken by design. ANSI STD 1003.1 (1996)
|
|
** section 6.5.2.2 lines 483 through 490 specify that when a process
|
|
** sets or clears a lock, that operation overrides any prior locks set
|
|
** by the same process. It does not explicitly say so, but this implies
|
|
** that it overrides locks set by the same process using a different
|
|
** file descriptor. Consider this test case:
|
|
**
|
|
** int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
|
|
** int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
|
|
**
|
|
** Suppose ./file1 and ./file2 are really the same file (because
|
|
** one is a hard or symbolic link to the other) then if you set
|
|
** an exclusive lock on fd1, then try to get an exclusive lock
|
|
** on fd2, it works. I would have expected the second lock to
|
|
** fail since there was already a lock on the file due to fd1.
|
|
** But not so. Since both locks came from the same process, the
|
|
** second overrides the first, even though they were on different
|
|
** file descriptors opened on different file names.
|
|
**
|
|
** This means that we cannot use POSIX locks to synchronize file access
|
|
** among competing threads of the same process. POSIX locks will work fine
|
|
** to synchronize access for threads in separate processes, but not
|
|
** threads within the same process.
|
|
**
|
|
** To work around the problem, SQLite has to manage file locks internally
|
|
** on its own. Whenever a new database is opened, we have to find the
|
|
** specific inode of the database file (the inode is determined by the
|
|
** st_dev and st_ino fields of the stat structure that fstat() fills in)
|
|
** and check for locks already existing on that inode. When locks are
|
|
** created or removed, we have to look at our own internal record of the
|
|
** locks to see if another thread has previously set a lock on that same
|
|
** inode.
|
|
**
|
|
** (Aside: The use of inode numbers as unique IDs does not work on VxWorks.
|
|
** For VxWorks, we have to use the alternative unique ID system based on
|
|
** canonical filename and implemented in the previous division.)
|
|
**
|
|
** The sqlite3_file structure for POSIX is no longer just an integer file
|
|
** descriptor. It is now a structure that holds the integer file
|
|
** descriptor and a pointer to a structure that describes the internal
|
|
** locks on the corresponding inode. There is one locking structure
|
|
** per inode, so if the same inode is opened twice, both unixFile structures
|
|
** point to the same locking structure. The locking structure keeps
|
|
** a reference count (so we will know when to delete it) and a "cnt"
|
|
** field that tells us its internal lock status. cnt==0 means the
|
|
** file is unlocked. cnt==-1 means the file has an exclusive lock.
|
|
** cnt>0 means there are cnt shared locks on the file.
|
|
**
|
|
** Any attempt to lock or unlock a file first checks the locking
|
|
** structure. The fcntl() system call is only invoked to set a
|
|
** POSIX lock if the internal lock structure transitions between
|
|
** a locked and an unlocked state.
|
|
**
|
|
** But wait: there are yet more problems with POSIX advisory locks.
|
|
**
|
|
** If you close a file descriptor that points to a file that has locks,
|
|
** all locks on that file that are owned by the current process are
|
|
** released. To work around this problem, each unixInodeInfo object
|
|
** maintains a count of the number of pending locks on tha inode.
|
|
** When an attempt is made to close an unixFile, if there are
|
|
** other unixFile open on the same inode that are holding locks, the call
|
|
** to close() the file descriptor is deferred until all of the locks clear.
|
|
** The unixInodeInfo structure keeps a list of file descriptors that need to
|
|
** be closed and that list is walked (and cleared) when the last lock
|
|
** clears.
|
|
**
|
|
** Yet another problem: LinuxThreads do not play well with posix locks.
|
|
**
|
|
** Many older versions of linux use the LinuxThreads library which is
|
|
** not posix compliant. Under LinuxThreads, a lock created by thread
|
|
** A cannot be modified or overridden by a different thread B.
|
|
** Only thread A can modify the lock. Locking behavior is correct
|
|
** if the appliation uses the newer Native Posix Thread Library (NPTL)
|
|
** on linux - with NPTL a lock created by thread A can override locks
|
|
** in thread B. But there is no way to know at compile-time which
|
|
** threading library is being used. So there is no way to know at
|
|
** compile-time whether or not thread A can override locks on thread B.
|
|
** One has to do a run-time check to discover the behavior of the
|
|
** current process.
|
|
**
|
|
** SQLite used to support LinuxThreads. But support for LinuxThreads
|
|
** was dropped beginning with version 3.7.0. SQLite will still work with
|
|
** LinuxThreads provided that (1) there is no more than one connection
|
|
** per database file in the same process and (2) database connections
|
|
** do not move across threads.
|
|
*/
|
|
|
|
/*
|
|
** An instance of the following structure serves as the key used
|
|
** to locate a particular unixInodeInfo object.
|
|
*/
|
|
struct unixFileId {
|
|
dev_t dev; /* Device number */
|
|
#if OS_VXWORKS
|
|
struct vxworksFileId *pId; /* Unique file ID for vxworks. */
|
|
#else
|
|
ino_t ino; /* Inode number */
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
** An instance of the following structure is allocated for each open
|
|
** inode. Or, on LinuxThreads, there is one of these structures for
|
|
** each inode opened by each thread.
|
|
**
|
|
** A single inode can have multiple file descriptors, so each unixFile
|
|
** structure contains a pointer to an instance of this object and this
|
|
** object keeps a count of the number of unixFile pointing to it.
|
|
*/
|
|
struct unixInodeInfo {
|
|
struct unixFileId fileId; /* The lookup key */
|
|
int nShared; /* Number of SHARED locks held */
|
|
unsigned char eFileLock; /* One of SHARED_LOCK, RESERVED_LOCK etc. */
|
|
unsigned char bProcessLock; /* An exclusive process lock is held */
|
|
int nRef; /* Number of pointers to this structure */
|
|
unixShmNode *pShmNode; /* Shared memory associated with this inode */
|
|
int nLock; /* Number of outstanding file locks */
|
|
UnixUnusedFd *pUnused; /* Unused file descriptors to close */
|
|
unixInodeInfo *pNext; /* List of all unixInodeInfo objects */
|
|
unixInodeInfo *pPrev; /* .... doubly linked */
|
|
#if defined(SQLITE_ENABLE_LOCKING_STYLE)
|
|
unsigned long long sharedByte; /* for AFP simulated shared lock */
|
|
#endif
|
|
#if OS_VXWORKS
|
|
sem_t *pSem; /* Named POSIX semaphore */
|
|
char aSemName[MAX_PATHNAME+2]; /* Name of that semaphore */
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
** A lists of all unixInodeInfo objects.
|
|
*/
|
|
static unixInodeInfo *inodeList = 0;
|
|
|
|
/*
|
|
**
|
|
** This function - unixLogError_x(), is only ever called via the macro
|
|
** unixLogError().
|
|
**
|
|
** It is invoked after an error occurs in an OS function and errno has been
|
|
** set. It logs a message using sqlite3_log() containing the current value of
|
|
** errno and, if possible, the human-readable equivalent from strerror() or
|
|
** strerror_r().
|
|
**
|
|
** The first argument passed to the macro should be the error code that
|
|
** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN).
|
|
** The two subsequent arguments should be the name of the OS function that
|
|
** failed (e.g. "unlink", "open") and the the associated file-system path,
|
|
** if any.
|
|
*/
|
|
#define unixLogError(a,b,c) unixLogErrorAtLine(a,b,c,__LINE__)
|
|
static int unixLogErrorAtLine(
|
|
int errcode, /* SQLite error code */
|
|
const char *zFunc, /* Name of OS function that failed */
|
|
const char *zPath, /* File path associated with error */
|
|
int iLine /* Source line number where error occurred */
|
|
){
|
|
char *zErr; /* Message from strerror() or equivalent */
|
|
int iErrno = errno; /* Saved syscall error number */
|
|
|
|
/* If this is not a threadsafe build (SQLITE_THREADSAFE==0), then use
|
|
** the strerror() function to obtain the human-readable error message
|
|
** equivalent to errno. Otherwise, use strerror_r().
|
|
*/
|
|
#if SQLITE_THREADSAFE && defined(HAVE_STRERROR_R)
|
|
char aErr[80];
|
|
memset(aErr, 0, sizeof(aErr));
|
|
zErr = aErr;
|
|
|
|
/* If STRERROR_R_CHAR_P (set by autoconf scripts) or __USE_GNU is defined,
|
|
** assume that the system provides the the GNU version of strerror_r() that
|
|
** returns a pointer to a buffer containing the error message. That pointer
|
|
** may point to aErr[], or it may point to some static storage somewhere.
|
|
** Otherwise, assume that the system provides the POSIX version of
|
|
** strerror_r(), which always writes an error message into aErr[].
|
|
**
|
|
** If the code incorrectly assumes that it is the POSIX version that is
|
|
** available, the error message will often be an empty string. Not a
|
|
** huge problem. Incorrectly concluding that the GNU version is available
|
|
** could lead to a segfault though.
|
|
*/
|
|
#if defined(STRERROR_R_CHAR_P) || defined(__USE_GNU)
|
|
zErr =
|
|
# endif
|
|
strerror_r(iErrno, aErr, sizeof(aErr)-1);
|
|
|
|
#elif SQLITE_THREADSAFE
|
|
/* This is a threadsafe build, but strerror_r() is not available. */
|
|
zErr = "";
|
|
#else
|
|
/* Non-threadsafe build, use strerror(). */
|
|
zErr = strerror(iErrno);
|
|
#endif
|
|
|
|
assert( errcode!=SQLITE_OK );
|
|
if( zPath==0 ) zPath = "";
|
|
sqlite3_log(errcode,
|
|
"os_unix.c:%d: (%d) %s(%s) - %s",
|
|
iLine, iErrno, zFunc, zPath, zErr
|
|
);
|
|
|
|
return errcode;
|
|
}
|
|
|
|
/*
|
|
** Close a file descriptor.
|
|
**
|
|
** We assume that close() almost always works, since it is only in a
|
|
** very sick application or on a very sick platform that it might fail.
|
|
** If it does fail, simply leak the file descriptor, but do log the
|
|
** error.
|
|
**
|
|
** Note that it is not safe to retry close() after EINTR since the
|
|
** file descriptor might have already been reused by another thread.
|
|
** So we don't even try to recover from an EINTR. Just log the error
|
|
** and move on.
|
|
*/
|
|
static void robust_close(unixFile *pFile, int h, int lineno){
|
|
if( osClose(h) ){
|
|
unixLogErrorAtLine(SQLITE_IOERR_CLOSE, "close",
|
|
pFile ? pFile->zPath : 0, lineno);
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Close all file descriptors accumuated in the unixInodeInfo->pUnused list.
|
|
*/
|
|
static void closePendingFds(unixFile *pFile){
|
|
unixInodeInfo *pInode = pFile->pInode;
|
|
UnixUnusedFd *p;
|
|
UnixUnusedFd *pNext;
|
|
for(p=pInode->pUnused; p; p=pNext){
|
|
pNext = p->pNext;
|
|
robust_close(pFile, p->fd, __LINE__);
|
|
sqlite3_free(p);
|
|
}
|
|
pInode->pUnused = 0;
|
|
}
|
|
|
|
/*
|
|
** Release a unixInodeInfo structure previously allocated by findInodeInfo().
|
|
**
|
|
** The mutex entered using the unixEnterMutex() function must be held
|
|
** when this function is called.
|
|
*/
|
|
static void releaseInodeInfo(unixFile *pFile){
|
|
unixInodeInfo *pInode = pFile->pInode;
|
|
assert( unixMutexHeld() );
|
|
if( pInode ){
|
|
pInode->nRef--;
|
|
if( pInode->nRef==0 ){
|
|
assert( pInode->pShmNode==0 );
|
|
closePendingFds(pFile);
|
|
if( pInode->pPrev ){
|
|
assert( pInode->pPrev->pNext==pInode );
|
|
pInode->pPrev->pNext = pInode->pNext;
|
|
}else{
|
|
assert( inodeList==pInode );
|
|
inodeList = pInode->pNext;
|
|
}
|
|
if( pInode->pNext ){
|
|
assert( pInode->pNext->pPrev==pInode );
|
|
pInode->pNext->pPrev = pInode->pPrev;
|
|
}
|
|
sqlite3_free(pInode);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Given a file descriptor, locate the unixInodeInfo object that
|
|
** describes that file descriptor. Create a new one if necessary. The
|
|
** return value might be uninitialized if an error occurs.
|
|
**
|
|
** The mutex entered using the unixEnterMutex() function must be held
|
|
** when this function is called.
|
|
**
|
|
** Return an appropriate error code.
|
|
*/
|
|
static int findInodeInfo(
|
|
unixFile *pFile, /* Unix file with file desc used in the key */
|
|
unixInodeInfo **ppInode /* Return the unixInodeInfo object here */
|
|
){
|
|
int rc; /* System call return code */
|
|
int fd; /* The file descriptor for pFile */
|
|
struct unixFileId fileId; /* Lookup key for the unixInodeInfo */
|
|
struct stat statbuf; /* Low-level file information */
|
|
unixInodeInfo *pInode = 0; /* Candidate unixInodeInfo object */
|
|
|
|
assert( unixMutexHeld() );
|
|
|
|
/* Get low-level information about the file that we can used to
|
|
** create a unique name for the file.
|
|
*/
|
|
fd = pFile->h;
|
|
rc = osFstat(fd, &statbuf);
|
|
if( rc!=0 ){
|
|
pFile->lastErrno = errno;
|
|
#ifdef EOVERFLOW
|
|
if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS;
|
|
#endif
|
|
return SQLITE_IOERR;
|
|
}
|
|
|
|
#ifdef __APPLE__
|
|
/* On OS X on an msdos filesystem, the inode number is reported
|
|
** incorrectly for zero-size files. See ticket #3260. To work
|
|
** around this problem (we consider it a bug in OS X, not SQLite)
|
|
** we always increase the file size to 1 by writing a single byte
|
|
** prior to accessing the inode number. The one byte written is
|
|
** an ASCII 'S' character which also happens to be the first byte
|
|
** in the header of every SQLite database. In this way, if there
|
|
** is a race condition such that another thread has already populated
|
|
** the first page of the database, no damage is done.
|
|
*/
|
|
if( statbuf.st_size==0 && (pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS)!=0 ){
|
|
do{ rc = osWrite(fd, "S", 1); }while( rc<0 && errno==EINTR );
|
|
if( rc!=1 ){
|
|
pFile->lastErrno = errno;
|
|
return SQLITE_IOERR;
|
|
}
|
|
rc = osFstat(fd, &statbuf);
|
|
if( rc!=0 ){
|
|
pFile->lastErrno = errno;
|
|
return SQLITE_IOERR;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
memset(&fileId, 0, sizeof(fileId));
|
|
fileId.dev = statbuf.st_dev;
|
|
#if OS_VXWORKS
|
|
fileId.pId = pFile->pId;
|
|
#else
|
|
fileId.ino = statbuf.st_ino;
|
|
#endif
|
|
pInode = inodeList;
|
|
while( pInode && memcmp(&fileId, &pInode->fileId, sizeof(fileId)) ){
|
|
pInode = pInode->pNext;
|
|
}
|
|
if( pInode==0 ){
|
|
pInode = sqlite3_malloc( sizeof(*pInode) );
|
|
if( pInode==0 ){
|
|
return SQLITE_NOMEM;
|
|
}
|
|
memset(pInode, 0, sizeof(*pInode));
|
|
memcpy(&pInode->fileId, &fileId, sizeof(fileId));
|
|
pInode->nRef = 1;
|
|
pInode->pNext = inodeList;
|
|
pInode->pPrev = 0;
|
|
if( inodeList ) inodeList->pPrev = pInode;
|
|
inodeList = pInode;
|
|
}else{
|
|
pInode->nRef++;
|
|
}
|
|
*ppInode = pInode;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
/*
|
|
** This routine checks if there is a RESERVED lock held on the specified
|
|
** file by this or any other process. If such a lock is held, set *pResOut
|
|
** to a non-zero value otherwise *pResOut is set to zero. The return value
|
|
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
|
|
*/
|
|
static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
|
|
int rc = SQLITE_OK;
|
|
int reserved = 0;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
|
|
|
|
assert( pFile );
|
|
unixEnterMutex(); /* Because pFile->pInode is shared across threads */
|
|
|
|
/* Check if a thread in this process holds such a lock */
|
|
if( pFile->pInode->eFileLock>SHARED_LOCK ){
|
|
reserved = 1;
|
|
}
|
|
|
|
/* Otherwise see if some other process holds it.
|
|
*/
|
|
#ifndef __DJGPP__
|
|
if( !reserved && !pFile->pInode->bProcessLock ){
|
|
struct flock lock;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = RESERVED_BYTE;
|
|
lock.l_len = 1;
|
|
lock.l_type = F_WRLCK;
|
|
if (-1 == osFcntl(pFile->h, F_GETLK, &lock)) {
|
|
int tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
|
|
pFile->lastErrno = tErrno;
|
|
} else if( lock.l_type!=F_UNLCK ){
|
|
reserved = 1;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
unixLeaveMutex();
|
|
OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));
|
|
|
|
*pResOut = reserved;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Attempt to set a system-lock on the file pFile. The lock is
|
|
** described by pLock.
|
|
**
|
|
** If the pFile was opened read/write from unix-excl, then the only lock
|
|
** ever obtained is an exclusive lock, and it is obtained exactly once
|
|
** the first time any lock is attempted. All subsequent system locking
|
|
** operations become no-ops. Locking operations still happen internally,
|
|
** in order to coordinate access between separate database connections
|
|
** within this process, but all of that is handled in memory and the
|
|
** operating system does not participate.
|
|
**
|
|
** This function is a pass-through to fcntl(F_SETLK) if pFile is using
|
|
** any VFS other than "unix-excl" or if pFile is opened on "unix-excl"
|
|
** and is read-only.
|
|
*/
|
|
static int unixFileLock(unixFile *pFile, struct flock *pLock){
|
|
int rc;
|
|
unixInodeInfo *pInode = pFile->pInode;
|
|
assert( unixMutexHeld() );
|
|
assert( pInode!=0 );
|
|
if( ((pFile->ctrlFlags & UNIXFILE_EXCL)!=0 || pInode->bProcessLock)
|
|
&& ((pFile->ctrlFlags & UNIXFILE_RDONLY)==0)
|
|
){
|
|
if( pInode->bProcessLock==0 ){
|
|
struct flock lock;
|
|
assert( pInode->nLock==0 );
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = SHARED_FIRST;
|
|
lock.l_len = SHARED_SIZE;
|
|
lock.l_type = F_WRLCK;
|
|
rc = osFcntl(pFile->h, F_SETLK, &lock);
|
|
if( rc<0 ) return rc;
|
|
pInode->bProcessLock = 1;
|
|
pInode->nLock++;
|
|
}else{
|
|
rc = 0;
|
|
}
|
|
}else{
|
|
rc = osFcntl(pFile->h, F_SETLK, pLock);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lock the file with the lock specified by parameter eFileLock - one
|
|
** of the following:
|
|
**
|
|
** (1) SHARED_LOCK
|
|
** (2) RESERVED_LOCK
|
|
** (3) PENDING_LOCK
|
|
** (4) EXCLUSIVE_LOCK
|
|
**
|
|
** Sometimes when requesting one lock state, additional lock states
|
|
** are inserted in between. The locking might fail on one of the later
|
|
** transitions leaving the lock state different from what it started but
|
|
** still short of its goal. The following chart shows the allowed
|
|
** transitions and the inserted intermediate states:
|
|
**
|
|
** UNLOCKED -> SHARED
|
|
** SHARED -> RESERVED
|
|
** SHARED -> (PENDING) -> EXCLUSIVE
|
|
** RESERVED -> (PENDING) -> EXCLUSIVE
|
|
** PENDING -> EXCLUSIVE
|
|
**
|
|
** This routine will only increase a lock. Use the sqlite3OsUnlock()
|
|
** routine to lower a locking level.
|
|
*/
|
|
static int unixLock(sqlite3_file *id, int eFileLock){
|
|
/* The following describes the implementation of the various locks and
|
|
** lock transitions in terms of the POSIX advisory shared and exclusive
|
|
** lock primitives (called read-locks and write-locks below, to avoid
|
|
** confusion with SQLite lock names). The algorithms are complicated
|
|
** slightly in order to be compatible with windows systems simultaneously
|
|
** accessing the same database file, in case that is ever required.
|
|
**
|
|
** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
|
|
** byte', each single bytes at well known offsets, and the 'shared byte
|
|
** range', a range of 510 bytes at a well known offset.
|
|
**
|
|
** To obtain a SHARED lock, a read-lock is obtained on the 'pending
|
|
** byte'. If this is successful, a random byte from the 'shared byte
|
|
** range' is read-locked and the lock on the 'pending byte' released.
|
|
**
|
|
** A process may only obtain a RESERVED lock after it has a SHARED lock.
|
|
** A RESERVED lock is implemented by grabbing a write-lock on the
|
|
** 'reserved byte'.
|
|
**
|
|
** A process may only obtain a PENDING lock after it has obtained a
|
|
** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
|
|
** on the 'pending byte'. This ensures that no new SHARED locks can be
|
|
** obtained, but existing SHARED locks are allowed to persist. A process
|
|
** does not have to obtain a RESERVED lock on the way to a PENDING lock.
|
|
** This property is used by the algorithm for rolling back a journal file
|
|
** after a crash.
|
|
**
|
|
** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
|
|
** implemented by obtaining a write-lock on the entire 'shared byte
|
|
** range'. Since all other locks require a read-lock on one of the bytes
|
|
** within this range, this ensures that no other locks are held on the
|
|
** database.
|
|
**
|
|
** The reason a single byte cannot be used instead of the 'shared byte
|
|
** range' is that some versions of windows do not support read-locks. By
|
|
** locking a random byte from a range, concurrent SHARED locks may exist
|
|
** even if the locking primitive used is always a write-lock.
|
|
*/
|
|
int rc = SQLITE_OK;
|
|
unixFile *pFile = (unixFile*)id;
|
|
unixInodeInfo *pInode = pFile->pInode;
|
|
struct flock lock;
|
|
int s = 0;
|
|
int tErrno = 0;
|
|
|
|
assert( pFile );
|
|
OSTRACE(("LOCK %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
|
|
azFileLock(eFileLock), azFileLock(pFile->eFileLock),
|
|
azFileLock(pInode->eFileLock), pInode->nShared , getpid()));
|
|
|
|
/* If there is already a lock of this type or more restrictive on the
|
|
** unixFile, do nothing. Don't use the end_lock: exit path, as
|
|
** unixEnterMutex() hasn't been called yet.
|
|
*/
|
|
if( pFile->eFileLock>=eFileLock ){
|
|
OSTRACE(("LOCK %d %s ok (already held) (unix)\n", pFile->h,
|
|
azFileLock(eFileLock)));
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* Make sure the locking sequence is correct.
|
|
** (1) We never move from unlocked to anything higher than shared lock.
|
|
** (2) SQLite never explicitly requests a pendig lock.
|
|
** (3) A shared lock is always held when a reserve lock is requested.
|
|
*/
|
|
assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
|
|
assert( eFileLock!=PENDING_LOCK );
|
|
assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
|
|
|
|
/* This mutex is needed because pFile->pInode is shared across threads
|
|
*/
|
|
unixEnterMutex();
|
|
pInode = pFile->pInode;
|
|
|
|
/* If some thread using this PID has a lock via a different unixFile*
|
|
** handle that precludes the requested lock, return BUSY.
|
|
*/
|
|
if( (pFile->eFileLock!=pInode->eFileLock &&
|
|
(pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
|
|
){
|
|
rc = SQLITE_BUSY;
|
|
goto end_lock;
|
|
}
|
|
|
|
/* If a SHARED lock is requested, and some thread using this PID already
|
|
** has a SHARED or RESERVED lock, then increment reference counts and
|
|
** return SQLITE_OK.
|
|
*/
|
|
if( eFileLock==SHARED_LOCK &&
|
|
(pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
|
|
assert( eFileLock==SHARED_LOCK );
|
|
assert( pFile->eFileLock==0 );
|
|
assert( pInode->nShared>0 );
|
|
pFile->eFileLock = SHARED_LOCK;
|
|
pInode->nShared++;
|
|
pInode->nLock++;
|
|
goto end_lock;
|
|
}
|
|
|
|
|
|
/* A PENDING lock is needed before acquiring a SHARED lock and before
|
|
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
|
|
** be released.
|
|
*/
|
|
lock.l_len = 1L;
|
|
lock.l_whence = SEEK_SET;
|
|
if( eFileLock==SHARED_LOCK
|
|
|| (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
|
|
){
|
|
lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
|
|
lock.l_start = PENDING_BYTE;
|
|
s = unixFileLock(pFile, &lock);
|
|
if( s==(-1) ){
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_lock;
|
|
}
|
|
}
|
|
|
|
|
|
/* If control gets to this point, then actually go ahead and make
|
|
** operating system calls for the specified lock.
|
|
*/
|
|
if( eFileLock==SHARED_LOCK ){
|
|
assert( pInode->nShared==0 );
|
|
assert( pInode->eFileLock==0 );
|
|
|
|
/* Now get the read-lock */
|
|
lock.l_start = SHARED_FIRST;
|
|
lock.l_len = SHARED_SIZE;
|
|
if( (s = unixFileLock(pFile, &lock))==(-1) ){
|
|
tErrno = errno;
|
|
}
|
|
/* Drop the temporary PENDING lock */
|
|
lock.l_start = PENDING_BYTE;
|
|
lock.l_len = 1L;
|
|
lock.l_type = F_UNLCK;
|
|
if( unixFileLock(pFile, &lock)!=0 ){
|
|
if( s != -1 ){
|
|
/* This could happen with a network mount */
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_lock;
|
|
}
|
|
}
|
|
if( s==(-1) ){
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
}else{
|
|
pFile->eFileLock = SHARED_LOCK;
|
|
pInode->nLock++;
|
|
pInode->nShared = 1;
|
|
}
|
|
}else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
|
|
/* We are trying for an exclusive lock but another thread in this
|
|
** same process is still holding a shared lock. */
|
|
rc = SQLITE_BUSY;
|
|
}else{
|
|
/* The request was for a RESERVED or EXCLUSIVE lock. It is
|
|
** assumed that there is a SHARED or greater lock on the file
|
|
** already.
|
|
*/
|
|
assert( 0!=pFile->eFileLock );
|
|
lock.l_type = F_WRLCK;
|
|
switch( eFileLock ){
|
|
case RESERVED_LOCK:
|
|
lock.l_start = RESERVED_BYTE;
|
|
break;
|
|
case EXCLUSIVE_LOCK:
|
|
lock.l_start = SHARED_FIRST;
|
|
lock.l_len = SHARED_SIZE;
|
|
break;
|
|
default:
|
|
assert(0);
|
|
}
|
|
s = unixFileLock(pFile, &lock);
|
|
if( s==(-1) ){
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
#ifndef NDEBUG
|
|
/* Set up the transaction-counter change checking flags when
|
|
** transitioning from a SHARED to a RESERVED lock. The change
|
|
** from SHARED to RESERVED marks the beginning of a normal
|
|
** write operation (not a hot journal rollback).
|
|
*/
|
|
if( rc==SQLITE_OK
|
|
&& pFile->eFileLock<=SHARED_LOCK
|
|
&& eFileLock==RESERVED_LOCK
|
|
){
|
|
pFile->transCntrChng = 0;
|
|
pFile->dbUpdate = 0;
|
|
pFile->inNormalWrite = 1;
|
|
}
|
|
#endif
|
|
|
|
|
|
if( rc==SQLITE_OK ){
|
|
pFile->eFileLock = eFileLock;
|
|
pInode->eFileLock = eFileLock;
|
|
}else if( eFileLock==EXCLUSIVE_LOCK ){
|
|
pFile->eFileLock = PENDING_LOCK;
|
|
pInode->eFileLock = PENDING_LOCK;
|
|
}
|
|
|
|
end_lock:
|
|
unixLeaveMutex();
|
|
OSTRACE(("LOCK %d %s %s (unix)\n", pFile->h, azFileLock(eFileLock),
|
|
rc==SQLITE_OK ? "ok" : "failed"));
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Add the file descriptor used by file handle pFile to the corresponding
|
|
** pUnused list.
|
|
*/
|
|
static void setPendingFd(unixFile *pFile){
|
|
unixInodeInfo *pInode = pFile->pInode;
|
|
UnixUnusedFd *p = pFile->pUnused;
|
|
p->pNext = pInode->pUnused;
|
|
pInode->pUnused = p;
|
|
pFile->h = -1;
|
|
pFile->pUnused = 0;
|
|
}
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
**
|
|
** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
|
|
** the byte range is divided into 2 parts and the first part is unlocked then
|
|
** set to a read lock, then the other part is simply unlocked. This works
|
|
** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to
|
|
** remove the write lock on a region when a read lock is set.
|
|
*/
|
|
static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
|
|
unixFile *pFile = (unixFile*)id;
|
|
unixInodeInfo *pInode;
|
|
struct flock lock;
|
|
int rc = SQLITE_OK;
|
|
int h;
|
|
int tErrno; /* Error code from system call errors */
|
|
|
|
assert( pFile );
|
|
OSTRACE(("UNLOCK %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
|
|
pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
|
|
getpid()));
|
|
|
|
assert( eFileLock<=SHARED_LOCK );
|
|
if( pFile->eFileLock<=eFileLock ){
|
|
return SQLITE_OK;
|
|
}
|
|
unixEnterMutex();
|
|
h = pFile->h;
|
|
pInode = pFile->pInode;
|
|
assert( pInode->nShared!=0 );
|
|
if( pFile->eFileLock>SHARED_LOCK ){
|
|
assert( pInode->eFileLock==pFile->eFileLock );
|
|
SimulateIOErrorBenign(1);
|
|
SimulateIOError( h=(-1) )
|
|
SimulateIOErrorBenign(0);
|
|
|
|
#ifndef NDEBUG
|
|
/* When reducing a lock such that other processes can start
|
|
** reading the database file again, make sure that the
|
|
** transaction counter was updated if any part of the database
|
|
** file changed. If the transaction counter is not updated,
|
|
** other connections to the same file might not realize that
|
|
** the file has changed and hence might not know to flush their
|
|
** cache. The use of a stale cache can lead to database corruption.
|
|
*/
|
|
#if 0
|
|
assert( pFile->inNormalWrite==0
|
|
|| pFile->dbUpdate==0
|
|
|| pFile->transCntrChng==1 );
|
|
#endif
|
|
pFile->inNormalWrite = 0;
|
|
#endif
|
|
|
|
/* downgrading to a shared lock on NFS involves clearing the write lock
|
|
** before establishing the readlock - to avoid a race condition we downgrade
|
|
** the lock in 2 blocks, so that part of the range will be covered by a
|
|
** write lock until the rest is covered by a read lock:
|
|
** 1: [WWWWW]
|
|
** 2: [....W]
|
|
** 3: [RRRRW]
|
|
** 4: [RRRR.]
|
|
*/
|
|
if( eFileLock==SHARED_LOCK ){
|
|
|
|
#if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
|
|
(void)handleNFSUnlock;
|
|
assert( handleNFSUnlock==0 );
|
|
#endif
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
if( handleNFSUnlock ){
|
|
off_t divSize = SHARED_SIZE - 1;
|
|
|
|
lock.l_type = F_UNLCK;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = SHARED_FIRST;
|
|
lock.l_len = divSize;
|
|
if( unixFileLock(pFile,, &lock)==(-1) ){
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_unlock;
|
|
}
|
|
lock.l_type = F_RDLCK;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = SHARED_FIRST;
|
|
lock.l_len = divSize;
|
|
if( unixFileLock(pFile, &lock)==(-1) ){
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_unlock;
|
|
}
|
|
lock.l_type = F_UNLCK;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = SHARED_FIRST+divSize;
|
|
lock.l_len = SHARED_SIZE-divSize;
|
|
if( unixFileLock(pFile, &lock)==(-1) ){
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_unlock;
|
|
}
|
|
}else
|
|
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
|
|
{
|
|
lock.l_type = F_RDLCK;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = SHARED_FIRST;
|
|
lock.l_len = SHARED_SIZE;
|
|
if( unixFileLock(pFile, &lock)==(-1) ){
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_unlock;
|
|
}
|
|
}
|
|
}
|
|
lock.l_type = F_UNLCK;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = PENDING_BYTE;
|
|
lock.l_len = 2L; assert( PENDING_BYTE+1==RESERVED_BYTE );
|
|
if( unixFileLock(pFile, &lock)!=(-1) ){
|
|
pInode->eFileLock = SHARED_LOCK;
|
|
}else{
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
goto end_unlock;
|
|
}
|
|
}
|
|
if( eFileLock==NO_LOCK ){
|
|
/* Decrement the shared lock counter. Release the lock using an
|
|
** OS call only when all threads in this same process have released
|
|
** the lock.
|
|
*/
|
|
pInode->nShared--;
|
|
if( pInode->nShared==0 ){
|
|
lock.l_type = F_UNLCK;
|
|
lock.l_whence = SEEK_SET;
|
|
lock.l_start = lock.l_len = 0L;
|
|
SimulateIOErrorBenign(1);
|
|
SimulateIOError( h=(-1) )
|
|
SimulateIOErrorBenign(0);
|
|
if( unixFileLock(pFile, &lock)!=(-1) ){
|
|
pInode->eFileLock = NO_LOCK;
|
|
}else{
|
|
tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
pInode->eFileLock = NO_LOCK;
|
|
pFile->eFileLock = NO_LOCK;
|
|
}
|
|
}
|
|
|
|
/* Decrement the count of locks against this same file. When the
|
|
** count reaches zero, close any other file descriptors whose close
|
|
** was deferred because of outstanding locks.
|
|
*/
|
|
pInode->nLock--;
|
|
assert( pInode->nLock>=0 );
|
|
if( pInode->nLock==0 ){
|
|
closePendingFds(pFile);
|
|
}
|
|
}
|
|
|
|
end_unlock:
|
|
unixLeaveMutex();
|
|
if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
*/
|
|
static int unixUnlock(sqlite3_file *id, int eFileLock){
|
|
return posixUnlock(id, eFileLock, 0);
|
|
}
|
|
|
|
/*
|
|
** This function performs the parts of the "close file" operation
|
|
** common to all locking schemes. It closes the directory and file
|
|
** handles, if they are valid, and sets all fields of the unixFile
|
|
** structure to 0.
|
|
**
|
|
** It is *not* necessary to hold the mutex when this routine is called,
|
|
** even on VxWorks. A mutex will be acquired on VxWorks by the
|
|
** vxworksReleaseFileId() routine.
|
|
*/
|
|
static int closeUnixFile(sqlite3_file *id){
|
|
unixFile *pFile = (unixFile*)id;
|
|
if( pFile ){
|
|
if( pFile->dirfd>=0 ){
|
|
robust_close(pFile, pFile->dirfd, __LINE__);
|
|
pFile->dirfd=-1;
|
|
}
|
|
if( pFile->h>=0 ){
|
|
robust_close(pFile, pFile->h, __LINE__);
|
|
pFile->h = -1;
|
|
}
|
|
#if OS_VXWORKS
|
|
if( pFile->pId ){
|
|
if( pFile->isDelete ){
|
|
unlink(pFile->pId->zCanonicalName);
|
|
}
|
|
vxworksReleaseFileId(pFile->pId);
|
|
pFile->pId = 0;
|
|
}
|
|
#endif
|
|
OSTRACE(("CLOSE %-3d\n", pFile->h));
|
|
OpenCounter(-1);
|
|
sqlite3_free(pFile->pUnused);
|
|
memset(pFile, 0, sizeof(unixFile));
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Close a file.
|
|
*/
|
|
static int unixClose(sqlite3_file *id){
|
|
int rc = SQLITE_OK;
|
|
if( id ){
|
|
unixFile *pFile = (unixFile *)id;
|
|
unixUnlock(id, NO_LOCK);
|
|
unixEnterMutex();
|
|
assert( pFile->pInode==0 || pFile->pInode->nLock>0
|
|
|| pFile->pInode->bProcessLock==0 );
|
|
if( pFile->pInode && pFile->pInode->nLock ){
|
|
/* If there are outstanding locks, do not actually close the file just
|
|
** yet because that would clear those locks. Instead, add the file
|
|
** descriptor to pInode->pUnused list. It will be automatically closed
|
|
** when the last lock is cleared.
|
|
*/
|
|
setPendingFd(pFile);
|
|
}
|
|
releaseInodeInfo(pFile);
|
|
rc = closeUnixFile(id);
|
|
unixLeaveMutex();
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/************** End of the posix advisory lock implementation *****************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
****************************** No-op Locking **********************************
|
|
**
|
|
** Of the various locking implementations available, this is by far the
|
|
** simplest: locking is ignored. No attempt is made to lock the database
|
|
** file for reading or writing.
|
|
**
|
|
** This locking mode is appropriate for use on read-only databases
|
|
** (ex: databases that are burned into CD-ROM, for example.) It can
|
|
** also be used if the application employs some external mechanism to
|
|
** prevent simultaneous access of the same database by two or more
|
|
** database connections. But there is a serious risk of database
|
|
** corruption if this locking mode is used in situations where multiple
|
|
** database connections are accessing the same database file at the same
|
|
** time and one or more of those connections are writing.
|
|
*/
|
|
|
|
static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
*pResOut = 0;
|
|
return SQLITE_OK;
|
|
}
|
|
static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){
|
|
UNUSED_PARAMETER2(NotUsed, NotUsed2);
|
|
return SQLITE_OK;
|
|
}
|
|
static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
|
|
UNUSED_PARAMETER2(NotUsed, NotUsed2);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Close the file.
|
|
*/
|
|
static int nolockClose(sqlite3_file *id) {
|
|
return closeUnixFile(id);
|
|
}
|
|
|
|
/******************* End of the no-op lock implementation *********************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
************************* Begin dot-file Locking ******************************
|
|
**
|
|
** The dotfile locking implementation uses the existance of separate lock
|
|
** files in order to control access to the database. This works on just
|
|
** about every filesystem imaginable. But there are serious downsides:
|
|
**
|
|
** (1) There is zero concurrency. A single reader blocks all other
|
|
** connections from reading or writing the database.
|
|
**
|
|
** (2) An application crash or power loss can leave stale lock files
|
|
** sitting around that need to be cleared manually.
|
|
**
|
|
** Nevertheless, a dotlock is an appropriate locking mode for use if no
|
|
** other locking strategy is available.
|
|
**
|
|
** Dotfile locking works by creating a file in the same directory as the
|
|
** database and with the same name but with a ".lock" extension added.
|
|
** The existance of a lock file implies an EXCLUSIVE lock. All other lock
|
|
** types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
|
|
*/
|
|
|
|
/*
|
|
** The file suffix added to the data base filename in order to create the
|
|
** lock file.
|
|
*/
|
|
#define DOTLOCK_SUFFIX ".lock"
|
|
|
|
/*
|
|
** This routine checks if there is a RESERVED lock held on the specified
|
|
** file by this or any other process. If such a lock is held, set *pResOut
|
|
** to a non-zero value otherwise *pResOut is set to zero. The return value
|
|
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
|
|
**
|
|
** In dotfile locking, either a lock exists or it does not. So in this
|
|
** variation of CheckReservedLock(), *pResOut is set to true if any lock
|
|
** is held on the file and false if the file is unlocked.
|
|
*/
|
|
static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
|
|
int rc = SQLITE_OK;
|
|
int reserved = 0;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
|
|
|
|
assert( pFile );
|
|
|
|
/* Check if a thread in this process holds such a lock */
|
|
if( pFile->eFileLock>SHARED_LOCK ){
|
|
/* Either this connection or some other connection in the same process
|
|
** holds a lock on the file. No need to check further. */
|
|
reserved = 1;
|
|
}else{
|
|
/* The lock is held if and only if the lockfile exists */
|
|
const char *zLockFile = (const char*)pFile->lockingContext;
|
|
reserved = osAccess(zLockFile, 0)==0;
|
|
}
|
|
OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved));
|
|
*pResOut = reserved;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lock the file with the lock specified by parameter eFileLock - one
|
|
** of the following:
|
|
**
|
|
** (1) SHARED_LOCK
|
|
** (2) RESERVED_LOCK
|
|
** (3) PENDING_LOCK
|
|
** (4) EXCLUSIVE_LOCK
|
|
**
|
|
** Sometimes when requesting one lock state, additional lock states
|
|
** are inserted in between. The locking might fail on one of the later
|
|
** transitions leaving the lock state different from what it started but
|
|
** still short of its goal. The following chart shows the allowed
|
|
** transitions and the inserted intermediate states:
|
|
**
|
|
** UNLOCKED -> SHARED
|
|
** SHARED -> RESERVED
|
|
** SHARED -> (PENDING) -> EXCLUSIVE
|
|
** RESERVED -> (PENDING) -> EXCLUSIVE
|
|
** PENDING -> EXCLUSIVE
|
|
**
|
|
** This routine will only increase a lock. Use the sqlite3OsUnlock()
|
|
** routine to lower a locking level.
|
|
**
|
|
** With dotfile locking, we really only support state (4): EXCLUSIVE.
|
|
** But we track the other locking levels internally.
|
|
*/
|
|
static int dotlockLock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
int fd;
|
|
char *zLockFile = (char *)pFile->lockingContext;
|
|
int rc = SQLITE_OK;
|
|
|
|
|
|
/* If we have any lock, then the lock file already exists. All we have
|
|
** to do is adjust our internal record of the lock level.
|
|
*/
|
|
if( pFile->eFileLock > NO_LOCK ){
|
|
pFile->eFileLock = eFileLock;
|
|
#if !OS_VXWORKS
|
|
/* Always update the timestamp on the old file */
|
|
utimes(zLockFile, NULL);
|
|
#endif
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* grab an exclusive lock */
|
|
fd = robust_open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
|
|
if( fd<0 ){
|
|
/* failed to open/create the file, someone else may have stolen the lock */
|
|
int tErrno = errno;
|
|
if( EEXIST == tErrno ){
|
|
rc = SQLITE_BUSY;
|
|
} else {
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
}
|
|
return rc;
|
|
}
|
|
robust_close(pFile, fd, __LINE__);
|
|
|
|
/* got it, set the type and return ok */
|
|
pFile->eFileLock = eFileLock;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
**
|
|
** When the locking level reaches NO_LOCK, delete the lock file.
|
|
*/
|
|
static int dotlockUnlock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
char *zLockFile = (char *)pFile->lockingContext;
|
|
|
|
assert( pFile );
|
|
OSTRACE(("UNLOCK %d %d was %d pid=%d (dotlock)\n", pFile->h, eFileLock,
|
|
pFile->eFileLock, getpid()));
|
|
assert( eFileLock<=SHARED_LOCK );
|
|
|
|
/* no-op if possible */
|
|
if( pFile->eFileLock==eFileLock ){
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* To downgrade to shared, simply update our internal notion of the
|
|
** lock state. No need to mess with the file on disk.
|
|
*/
|
|
if( eFileLock==SHARED_LOCK ){
|
|
pFile->eFileLock = SHARED_LOCK;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* To fully unlock the database, delete the lock file */
|
|
assert( eFileLock==NO_LOCK );
|
|
if( unlink(zLockFile) ){
|
|
int rc = 0;
|
|
int tErrno = errno;
|
|
if( ENOENT != tErrno ){
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
}
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
return rc;
|
|
}
|
|
pFile->eFileLock = NO_LOCK;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Close a file. Make sure the lock has been released before closing.
|
|
*/
|
|
static int dotlockClose(sqlite3_file *id) {
|
|
int rc;
|
|
if( id ){
|
|
unixFile *pFile = (unixFile*)id;
|
|
dotlockUnlock(id, NO_LOCK);
|
|
sqlite3_free(pFile->lockingContext);
|
|
}
|
|
rc = closeUnixFile(id);
|
|
return rc;
|
|
}
|
|
/****************** End of the dot-file lock implementation *******************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
************************** Begin flock Locking ********************************
|
|
**
|
|
** Use the flock() system call to do file locking.
|
|
**
|
|
** flock() locking is like dot-file locking in that the various
|
|
** fine-grain locking levels supported by SQLite are collapsed into
|
|
** a single exclusive lock. In other words, SHARED, RESERVED, and
|
|
** PENDING locks are the same thing as an EXCLUSIVE lock. SQLite
|
|
** still works when you do this, but concurrency is reduced since
|
|
** only a single process can be reading the database at a time.
|
|
**
|
|
** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
|
|
** compiling for VXWORKS.
|
|
*/
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS
|
|
|
|
/*
|
|
** Retry flock() calls that fail with EINTR
|
|
*/
|
|
#ifdef EINTR
|
|
static int robust_flock(int fd, int op){
|
|
int rc;
|
|
do{ rc = flock(fd,op); }while( rc<0 && errno==EINTR );
|
|
return rc;
|
|
}
|
|
#else
|
|
# define robust_flock(a,b) flock(a,b)
|
|
#endif
|
|
|
|
|
|
/*
|
|
** This routine checks if there is a RESERVED lock held on the specified
|
|
** file by this or any other process. If such a lock is held, set *pResOut
|
|
** to a non-zero value otherwise *pResOut is set to zero. The return value
|
|
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
|
|
*/
|
|
static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
|
|
int rc = SQLITE_OK;
|
|
int reserved = 0;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
|
|
|
|
assert( pFile );
|
|
|
|
/* Check if a thread in this process holds such a lock */
|
|
if( pFile->eFileLock>SHARED_LOCK ){
|
|
reserved = 1;
|
|
}
|
|
|
|
/* Otherwise see if some other process holds it. */
|
|
if( !reserved ){
|
|
/* attempt to get the lock */
|
|
int lrc = robust_flock(pFile->h, LOCK_EX | LOCK_NB);
|
|
if( !lrc ){
|
|
/* got the lock, unlock it */
|
|
lrc = robust_flock(pFile->h, LOCK_UN);
|
|
if ( lrc ) {
|
|
int tErrno = errno;
|
|
/* unlock failed with an error */
|
|
lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(lrc) ){
|
|
pFile->lastErrno = tErrno;
|
|
rc = lrc;
|
|
}
|
|
}
|
|
} else {
|
|
int tErrno = errno;
|
|
reserved = 1;
|
|
/* someone else might have it reserved */
|
|
lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
|
|
if( IS_LOCK_ERROR(lrc) ){
|
|
pFile->lastErrno = tErrno;
|
|
rc = lrc;
|
|
}
|
|
}
|
|
}
|
|
OSTRACE(("TEST WR-LOCK %d %d %d (flock)\n", pFile->h, rc, reserved));
|
|
|
|
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
|
|
if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
|
|
rc = SQLITE_OK;
|
|
reserved=1;
|
|
}
|
|
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
|
|
*pResOut = reserved;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lock the file with the lock specified by parameter eFileLock - one
|
|
** of the following:
|
|
**
|
|
** (1) SHARED_LOCK
|
|
** (2) RESERVED_LOCK
|
|
** (3) PENDING_LOCK
|
|
** (4) EXCLUSIVE_LOCK
|
|
**
|
|
** Sometimes when requesting one lock state, additional lock states
|
|
** are inserted in between. The locking might fail on one of the later
|
|
** transitions leaving the lock state different from what it started but
|
|
** still short of its goal. The following chart shows the allowed
|
|
** transitions and the inserted intermediate states:
|
|
**
|
|
** UNLOCKED -> SHARED
|
|
** SHARED -> RESERVED
|
|
** SHARED -> (PENDING) -> EXCLUSIVE
|
|
** RESERVED -> (PENDING) -> EXCLUSIVE
|
|
** PENDING -> EXCLUSIVE
|
|
**
|
|
** flock() only really support EXCLUSIVE locks. We track intermediate
|
|
** lock states in the sqlite3_file structure, but all locks SHARED or
|
|
** above are really EXCLUSIVE locks and exclude all other processes from
|
|
** access the file.
|
|
**
|
|
** This routine will only increase a lock. Use the sqlite3OsUnlock()
|
|
** routine to lower a locking level.
|
|
*/
|
|
static int flockLock(sqlite3_file *id, int eFileLock) {
|
|
int rc = SQLITE_OK;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
assert( pFile );
|
|
|
|
/* if we already have a lock, it is exclusive.
|
|
** Just adjust level and punt on outta here. */
|
|
if (pFile->eFileLock > NO_LOCK) {
|
|
pFile->eFileLock = eFileLock;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* grab an exclusive lock */
|
|
|
|
if (robust_flock(pFile->h, LOCK_EX | LOCK_NB)) {
|
|
int tErrno = errno;
|
|
/* didn't get, must be busy */
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
} else {
|
|
/* got it, set the type and return ok */
|
|
pFile->eFileLock = eFileLock;
|
|
}
|
|
OSTRACE(("LOCK %d %s %s (flock)\n", pFile->h, azFileLock(eFileLock),
|
|
rc==SQLITE_OK ? "ok" : "failed"));
|
|
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
|
|
if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
|
|
rc = SQLITE_BUSY;
|
|
}
|
|
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
|
|
return rc;
|
|
}
|
|
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
*/
|
|
static int flockUnlock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
assert( pFile );
|
|
OSTRACE(("UNLOCK %d %d was %d pid=%d (flock)\n", pFile->h, eFileLock,
|
|
pFile->eFileLock, getpid()));
|
|
assert( eFileLock<=SHARED_LOCK );
|
|
|
|
/* no-op if possible */
|
|
if( pFile->eFileLock==eFileLock ){
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* shared can just be set because we always have an exclusive */
|
|
if (eFileLock==SHARED_LOCK) {
|
|
pFile->eFileLock = eFileLock;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* no, really, unlock. */
|
|
int rc = robust_flock(pFile->h, LOCK_UN);
|
|
if (rc) {
|
|
int r, tErrno = errno;
|
|
r = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(r) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
|
|
if( (r & SQLITE_IOERR) == SQLITE_IOERR ){
|
|
r = SQLITE_BUSY;
|
|
}
|
|
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
|
|
|
|
return r;
|
|
} else {
|
|
pFile->eFileLock = NO_LOCK;
|
|
return SQLITE_OK;
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Close a file.
|
|
*/
|
|
static int flockClose(sqlite3_file *id) {
|
|
if( id ){
|
|
flockUnlock(id, NO_LOCK);
|
|
}
|
|
return closeUnixFile(id);
|
|
}
|
|
|
|
#endif /* SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORK */
|
|
|
|
/******************* End of the flock lock implementation *********************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
************************ Begin Named Semaphore Locking ************************
|
|
**
|
|
** Named semaphore locking is only supported on VxWorks.
|
|
**
|
|
** Semaphore locking is like dot-lock and flock in that it really only
|
|
** supports EXCLUSIVE locking. Only a single process can read or write
|
|
** the database file at a time. This reduces potential concurrency, but
|
|
** makes the lock implementation much easier.
|
|
*/
|
|
#if OS_VXWORKS
|
|
|
|
/*
|
|
** This routine checks if there is a RESERVED lock held on the specified
|
|
** file by this or any other process. If such a lock is held, set *pResOut
|
|
** to a non-zero value otherwise *pResOut is set to zero. The return value
|
|
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
|
|
*/
|
|
static int semCheckReservedLock(sqlite3_file *id, int *pResOut) {
|
|
int rc = SQLITE_OK;
|
|
int reserved = 0;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
|
|
|
|
assert( pFile );
|
|
|
|
/* Check if a thread in this process holds such a lock */
|
|
if( pFile->eFileLock>SHARED_LOCK ){
|
|
reserved = 1;
|
|
}
|
|
|
|
/* Otherwise see if some other process holds it. */
|
|
if( !reserved ){
|
|
sem_t *pSem = pFile->pInode->pSem;
|
|
struct stat statBuf;
|
|
|
|
if( sem_trywait(pSem)==-1 ){
|
|
int tErrno = errno;
|
|
if( EAGAIN != tErrno ){
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
|
|
pFile->lastErrno = tErrno;
|
|
} else {
|
|
/* someone else has the lock when we are in NO_LOCK */
|
|
reserved = (pFile->eFileLock < SHARED_LOCK);
|
|
}
|
|
}else{
|
|
/* we could have it if we want it */
|
|
sem_post(pSem);
|
|
}
|
|
}
|
|
OSTRACE(("TEST WR-LOCK %d %d %d (sem)\n", pFile->h, rc, reserved));
|
|
|
|
*pResOut = reserved;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lock the file with the lock specified by parameter eFileLock - one
|
|
** of the following:
|
|
**
|
|
** (1) SHARED_LOCK
|
|
** (2) RESERVED_LOCK
|
|
** (3) PENDING_LOCK
|
|
** (4) EXCLUSIVE_LOCK
|
|
**
|
|
** Sometimes when requesting one lock state, additional lock states
|
|
** are inserted in between. The locking might fail on one of the later
|
|
** transitions leaving the lock state different from what it started but
|
|
** still short of its goal. The following chart shows the allowed
|
|
** transitions and the inserted intermediate states:
|
|
**
|
|
** UNLOCKED -> SHARED
|
|
** SHARED -> RESERVED
|
|
** SHARED -> (PENDING) -> EXCLUSIVE
|
|
** RESERVED -> (PENDING) -> EXCLUSIVE
|
|
** PENDING -> EXCLUSIVE
|
|
**
|
|
** Semaphore locks only really support EXCLUSIVE locks. We track intermediate
|
|
** lock states in the sqlite3_file structure, but all locks SHARED or
|
|
** above are really EXCLUSIVE locks and exclude all other processes from
|
|
** access the file.
|
|
**
|
|
** This routine will only increase a lock. Use the sqlite3OsUnlock()
|
|
** routine to lower a locking level.
|
|
*/
|
|
static int semLock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
int fd;
|
|
sem_t *pSem = pFile->pInode->pSem;
|
|
int rc = SQLITE_OK;
|
|
|
|
/* if we already have a lock, it is exclusive.
|
|
** Just adjust level and punt on outta here. */
|
|
if (pFile->eFileLock > NO_LOCK) {
|
|
pFile->eFileLock = eFileLock;
|
|
rc = SQLITE_OK;
|
|
goto sem_end_lock;
|
|
}
|
|
|
|
/* lock semaphore now but bail out when already locked. */
|
|
if( sem_trywait(pSem)==-1 ){
|
|
rc = SQLITE_BUSY;
|
|
goto sem_end_lock;
|
|
}
|
|
|
|
/* got it, set the type and return ok */
|
|
pFile->eFileLock = eFileLock;
|
|
|
|
sem_end_lock:
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
*/
|
|
static int semUnlock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
sem_t *pSem = pFile->pInode->pSem;
|
|
|
|
assert( pFile );
|
|
assert( pSem );
|
|
OSTRACE(("UNLOCK %d %d was %d pid=%d (sem)\n", pFile->h, eFileLock,
|
|
pFile->eFileLock, getpid()));
|
|
assert( eFileLock<=SHARED_LOCK );
|
|
|
|
/* no-op if possible */
|
|
if( pFile->eFileLock==eFileLock ){
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* shared can just be set because we always have an exclusive */
|
|
if (eFileLock==SHARED_LOCK) {
|
|
pFile->eFileLock = eFileLock;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* no, really unlock. */
|
|
if ( sem_post(pSem)==-1 ) {
|
|
int rc, tErrno = errno;
|
|
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
return rc;
|
|
}
|
|
pFile->eFileLock = NO_LOCK;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Close a file.
|
|
*/
|
|
static int semClose(sqlite3_file *id) {
|
|
if( id ){
|
|
unixFile *pFile = (unixFile*)id;
|
|
semUnlock(id, NO_LOCK);
|
|
assert( pFile );
|
|
unixEnterMutex();
|
|
releaseInodeInfo(pFile);
|
|
unixLeaveMutex();
|
|
closeUnixFile(id);
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
#endif /* OS_VXWORKS */
|
|
/*
|
|
** Named semaphore locking is only available on VxWorks.
|
|
**
|
|
*************** End of the named semaphore lock implementation ****************
|
|
******************************************************************************/
|
|
|
|
|
|
/******************************************************************************
|
|
*************************** Begin AFP Locking *********************************
|
|
**
|
|
** AFP is the Apple Filing Protocol. AFP is a network filesystem found
|
|
** on Apple Macintosh computers - both OS9 and OSX.
|
|
**
|
|
** Third-party implementations of AFP are available. But this code here
|
|
** only works on OSX.
|
|
*/
|
|
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
/*
|
|
** The afpLockingContext structure contains all afp lock specific state
|
|
*/
|
|
typedef struct afpLockingContext afpLockingContext;
|
|
struct afpLockingContext {
|
|
int reserved;
|
|
const char *dbPath; /* Name of the open file */
|
|
};
|
|
|
|
struct ByteRangeLockPB2
|
|
{
|
|
unsigned long long offset; /* offset to first byte to lock */
|
|
unsigned long long length; /* nbr of bytes to lock */
|
|
unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */
|
|
unsigned char unLockFlag; /* 1 = unlock, 0 = lock */
|
|
unsigned char startEndFlag; /* 1=rel to end of fork, 0=rel to start */
|
|
int fd; /* file desc to assoc this lock with */
|
|
};
|
|
|
|
#define afpfsByteRangeLock2FSCTL _IOWR('z', 23, struct ByteRangeLockPB2)
|
|
|
|
/*
|
|
** This is a utility for setting or clearing a bit-range lock on an
|
|
** AFP filesystem.
|
|
**
|
|
** Return SQLITE_OK on success, SQLITE_BUSY on failure.
|
|
*/
|
|
static int afpSetLock(
|
|
const char *path, /* Name of the file to be locked or unlocked */
|
|
unixFile *pFile, /* Open file descriptor on path */
|
|
unsigned long long offset, /* First byte to be locked */
|
|
unsigned long long length, /* Number of bytes to lock */
|
|
int setLockFlag /* True to set lock. False to clear lock */
|
|
){
|
|
struct ByteRangeLockPB2 pb;
|
|
int err;
|
|
|
|
pb.unLockFlag = setLockFlag ? 0 : 1;
|
|
pb.startEndFlag = 0;
|
|
pb.offset = offset;
|
|
pb.length = length;
|
|
pb.fd = pFile->h;
|
|
|
|
OSTRACE(("AFPSETLOCK [%s] for %d%s in range %llx:%llx\n",
|
|
(setLockFlag?"ON":"OFF"), pFile->h, (pb.fd==-1?"[testval-1]":""),
|
|
offset, length));
|
|
err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
|
|
if ( err==-1 ) {
|
|
int rc;
|
|
int tErrno = errno;
|
|
OSTRACE(("AFPSETLOCK failed to fsctl() '%s' %d %s\n",
|
|
path, tErrno, strerror(tErrno)));
|
|
#ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS
|
|
rc = SQLITE_BUSY;
|
|
#else
|
|
rc = sqliteErrorFromPosixError(tErrno,
|
|
setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK);
|
|
#endif /* SQLITE_IGNORE_AFP_LOCK_ERRORS */
|
|
if( IS_LOCK_ERROR(rc) ){
|
|
pFile->lastErrno = tErrno;
|
|
}
|
|
return rc;
|
|
} else {
|
|
return SQLITE_OK;
|
|
}
|
|
}
|
|
|
|
/*
|
|
** This routine checks if there is a RESERVED lock held on the specified
|
|
** file by this or any other process. If such a lock is held, set *pResOut
|
|
** to a non-zero value otherwise *pResOut is set to zero. The return value
|
|
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
|
|
*/
|
|
static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){
|
|
int rc = SQLITE_OK;
|
|
int reserved = 0;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
|
|
|
|
assert( pFile );
|
|
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
|
|
if( context->reserved ){
|
|
*pResOut = 1;
|
|
return SQLITE_OK;
|
|
}
|
|
unixEnterMutex(); /* Because pFile->pInode is shared across threads */
|
|
|
|
/* Check if a thread in this process holds such a lock */
|
|
if( pFile->pInode->eFileLock>SHARED_LOCK ){
|
|
reserved = 1;
|
|
}
|
|
|
|
/* Otherwise see if some other process holds it.
|
|
*/
|
|
if( !reserved ){
|
|
/* lock the RESERVED byte */
|
|
int lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);
|
|
if( SQLITE_OK==lrc ){
|
|
/* if we succeeded in taking the reserved lock, unlock it to restore
|
|
** the original state */
|
|
lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
|
|
} else {
|
|
/* if we failed to get the lock then someone else must have it */
|
|
reserved = 1;
|
|
}
|
|
if( IS_LOCK_ERROR(lrc) ){
|
|
rc=lrc;
|
|
}
|
|
}
|
|
|
|
unixLeaveMutex();
|
|
OSTRACE(("TEST WR-LOCK %d %d %d (afp)\n", pFile->h, rc, reserved));
|
|
|
|
*pResOut = reserved;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lock the file with the lock specified by parameter eFileLock - one
|
|
** of the following:
|
|
**
|
|
** (1) SHARED_LOCK
|
|
** (2) RESERVED_LOCK
|
|
** (3) PENDING_LOCK
|
|
** (4) EXCLUSIVE_LOCK
|
|
**
|
|
** Sometimes when requesting one lock state, additional lock states
|
|
** are inserted in between. The locking might fail on one of the later
|
|
** transitions leaving the lock state different from what it started but
|
|
** still short of its goal. The following chart shows the allowed
|
|
** transitions and the inserted intermediate states:
|
|
**
|
|
** UNLOCKED -> SHARED
|
|
** SHARED -> RESERVED
|
|
** SHARED -> (PENDING) -> EXCLUSIVE
|
|
** RESERVED -> (PENDING) -> EXCLUSIVE
|
|
** PENDING -> EXCLUSIVE
|
|
**
|
|
** This routine will only increase a lock. Use the sqlite3OsUnlock()
|
|
** routine to lower a locking level.
|
|
*/
|
|
static int afpLock(sqlite3_file *id, int eFileLock){
|
|
int rc = SQLITE_OK;
|
|
unixFile *pFile = (unixFile*)id;
|
|
unixInodeInfo *pInode = pFile->pInode;
|
|
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
|
|
|
|
assert( pFile );
|
|
OSTRACE(("LOCK %d %s was %s(%s,%d) pid=%d (afp)\n", pFile->h,
|
|
azFileLock(eFileLock), azFileLock(pFile->eFileLock),
|
|
azFileLock(pInode->eFileLock), pInode->nShared , getpid()));
|
|
|
|
/* If there is already a lock of this type or more restrictive on the
|
|
** unixFile, do nothing. Don't use the afp_end_lock: exit path, as
|
|
** unixEnterMutex() hasn't been called yet.
|
|
*/
|
|
if( pFile->eFileLock>=eFileLock ){
|
|
OSTRACE(("LOCK %d %s ok (already held) (afp)\n", pFile->h,
|
|
azFileLock(eFileLock)));
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* Make sure the locking sequence is correct
|
|
** (1) We never move from unlocked to anything higher than shared lock.
|
|
** (2) SQLite never explicitly requests a pendig lock.
|
|
** (3) A shared lock is always held when a reserve lock is requested.
|
|
*/
|
|
assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
|
|
assert( eFileLock!=PENDING_LOCK );
|
|
assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
|
|
|
|
/* This mutex is needed because pFile->pInode is shared across threads
|
|
*/
|
|
unixEnterMutex();
|
|
pInode = pFile->pInode;
|
|
|
|
/* If some thread using this PID has a lock via a different unixFile*
|
|
** handle that precludes the requested lock, return BUSY.
|
|
*/
|
|
if( (pFile->eFileLock!=pInode->eFileLock &&
|
|
(pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
|
|
){
|
|
rc = SQLITE_BUSY;
|
|
goto afp_end_lock;
|
|
}
|
|
|
|
/* If a SHARED lock is requested, and some thread using this PID already
|
|
** has a SHARED or RESERVED lock, then increment reference counts and
|
|
** return SQLITE_OK.
|
|
*/
|
|
if( eFileLock==SHARED_LOCK &&
|
|
(pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
|
|
assert( eFileLock==SHARED_LOCK );
|
|
assert( pFile->eFileLock==0 );
|
|
assert( pInode->nShared>0 );
|
|
pFile->eFileLock = SHARED_LOCK;
|
|
pInode->nShared++;
|
|
pInode->nLock++;
|
|
goto afp_end_lock;
|
|
}
|
|
|
|
/* A PENDING lock is needed before acquiring a SHARED lock and before
|
|
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
|
|
** be released.
|
|
*/
|
|
if( eFileLock==SHARED_LOCK
|
|
|| (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
|
|
){
|
|
int failed;
|
|
failed = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 1);
|
|
if (failed) {
|
|
rc = failed;
|
|
goto afp_end_lock;
|
|
}
|
|
}
|
|
|
|
/* If control gets to this point, then actually go ahead and make
|
|
** operating system calls for the specified lock.
|
|
*/
|
|
if( eFileLock==SHARED_LOCK ){
|
|
int lrc1, lrc2, lrc1Errno;
|
|
long lk, mask;
|
|
|
|
assert( pInode->nShared==0 );
|
|
assert( pInode->eFileLock==0 );
|
|
|
|
mask = (sizeof(long)==8) ? LARGEST_INT64 : 0x7fffffff;
|
|
/* Now get the read-lock SHARED_LOCK */
|
|
/* note that the quality of the randomness doesn't matter that much */
|
|
lk = random();
|
|
pInode->sharedByte = (lk & mask)%(SHARED_SIZE - 1);
|
|
lrc1 = afpSetLock(context->dbPath, pFile,
|
|
SHARED_FIRST+pInode->sharedByte, 1, 1);
|
|
if( IS_LOCK_ERROR(lrc1) ){
|
|
lrc1Errno = pFile->lastErrno;
|
|
}
|
|
/* Drop the temporary PENDING lock */
|
|
lrc2 = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);
|
|
|
|
if( IS_LOCK_ERROR(lrc1) ) {
|
|
pFile->lastErrno = lrc1Errno;
|
|
rc = lrc1;
|
|
goto afp_end_lock;
|
|
} else if( IS_LOCK_ERROR(lrc2) ){
|
|
rc = lrc2;
|
|
goto afp_end_lock;
|
|
} else if( lrc1 != SQLITE_OK ) {
|
|
rc = lrc1;
|
|
} else {
|
|
pFile->eFileLock = SHARED_LOCK;
|
|
pInode->nLock++;
|
|
pInode->nShared = 1;
|
|
}
|
|
}else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
|
|
/* We are trying for an exclusive lock but another thread in this
|
|
** same process is still holding a shared lock. */
|
|
rc = SQLITE_BUSY;
|
|
}else{
|
|
/* The request was for a RESERVED or EXCLUSIVE lock. It is
|
|
** assumed that there is a SHARED or greater lock on the file
|
|
** already.
|
|
*/
|
|
int failed = 0;
|
|
assert( 0!=pFile->eFileLock );
|
|
if (eFileLock >= RESERVED_LOCK && pFile->eFileLock < RESERVED_LOCK) {
|
|
/* Acquire a RESERVED lock */
|
|
failed = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);
|
|
if( !failed ){
|
|
context->reserved = 1;
|
|
}
|
|
}
|
|
if (!failed && eFileLock == EXCLUSIVE_LOCK) {
|
|
/* Acquire an EXCLUSIVE lock */
|
|
|
|
/* Remove the shared lock before trying the range. we'll need to
|
|
** reestablish the shared lock if we can't get the afpUnlock
|
|
*/
|
|
if( !(failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST +
|
|
pInode->sharedByte, 1, 0)) ){
|
|
int failed2 = SQLITE_OK;
|
|
/* now attemmpt to get the exclusive lock range */
|
|
failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST,
|
|
SHARED_SIZE, 1);
|
|
if( failed && (failed2 = afpSetLock(context->dbPath, pFile,
|
|
SHARED_FIRST + pInode->sharedByte, 1, 1)) ){
|
|
/* Can't reestablish the shared lock. Sqlite can't deal, this is
|
|
** a critical I/O error
|
|
*/
|
|
rc = ((failed & SQLITE_IOERR) == SQLITE_IOERR) ? failed2 :
|
|
SQLITE_IOERR_LOCK;
|
|
goto afp_end_lock;
|
|
}
|
|
}else{
|
|
rc = failed;
|
|
}
|
|
}
|
|
if( failed ){
|
|
rc = failed;
|
|
}
|
|
}
|
|
|
|
if( rc==SQLITE_OK ){
|
|
pFile->eFileLock = eFileLock;
|
|
pInode->eFileLock = eFileLock;
|
|
}else if( eFileLock==EXCLUSIVE_LOCK ){
|
|
pFile->eFileLock = PENDING_LOCK;
|
|
pInode->eFileLock = PENDING_LOCK;
|
|
}
|
|
|
|
afp_end_lock:
|
|
unixLeaveMutex();
|
|
OSTRACE(("LOCK %d %s %s (afp)\n", pFile->h, azFileLock(eFileLock),
|
|
rc==SQLITE_OK ? "ok" : "failed"));
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
*/
|
|
static int afpUnlock(sqlite3_file *id, int eFileLock) {
|
|
int rc = SQLITE_OK;
|
|
unixFile *pFile = (unixFile*)id;
|
|
unixInodeInfo *pInode;
|
|
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
|
|
int skipShared = 0;
|
|
#ifdef SQLITE_TEST
|
|
int h = pFile->h;
|
|
#endif
|
|
|
|
assert( pFile );
|
|
OSTRACE(("UNLOCK %d %d was %d(%d,%d) pid=%d (afp)\n", pFile->h, eFileLock,
|
|
pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
|
|
getpid()));
|
|
|
|
assert( eFileLock<=SHARED_LOCK );
|
|
if( pFile->eFileLock<=eFileLock ){
|
|
return SQLITE_OK;
|
|
}
|
|
unixEnterMutex();
|
|
pInode = pFile->pInode;
|
|
assert( pInode->nShared!=0 );
|
|
if( pFile->eFileLock>SHARED_LOCK ){
|
|
assert( pInode->eFileLock==pFile->eFileLock );
|
|
SimulateIOErrorBenign(1);
|
|
SimulateIOError( h=(-1) )
|
|
SimulateIOErrorBenign(0);
|
|
|
|
#ifndef NDEBUG
|
|
/* When reducing a lock such that other processes can start
|
|
** reading the database file again, make sure that the
|
|
** transaction counter was updated if any part of the database
|
|
** file changed. If the transaction counter is not updated,
|
|
** other connections to the same file might not realize that
|
|
** the file has changed and hence might not know to flush their
|
|
** cache. The use of a stale cache can lead to database corruption.
|
|
*/
|
|
assert( pFile->inNormalWrite==0
|
|
|| pFile->dbUpdate==0
|
|
|| pFile->transCntrChng==1 );
|
|
pFile->inNormalWrite = 0;
|
|
#endif
|
|
|
|
if( pFile->eFileLock==EXCLUSIVE_LOCK ){
|
|
rc = afpSetLock(context->dbPath, pFile, SHARED_FIRST, SHARED_SIZE, 0);
|
|
if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1) ){
|
|
/* only re-establish the shared lock if necessary */
|
|
int sharedLockByte = SHARED_FIRST+pInode->sharedByte;
|
|
rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 1);
|
|
} else {
|
|
skipShared = 1;
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK && pFile->eFileLock>=PENDING_LOCK ){
|
|
rc = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);
|
|
}
|
|
if( rc==SQLITE_OK && pFile->eFileLock>=RESERVED_LOCK && context->reserved ){
|
|
rc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
|
|
if( !rc ){
|
|
context->reserved = 0;
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1)){
|
|
pInode->eFileLock = SHARED_LOCK;
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK && eFileLock==NO_LOCK ){
|
|
|
|
/* Decrement the shared lock counter. Release the lock using an
|
|
** OS call only when all threads in this same process have released
|
|
** the lock.
|
|
*/
|
|
unsigned long long sharedLockByte = SHARED_FIRST+pInode->sharedByte;
|
|
pInode->nShared--;
|
|
if( pInode->nShared==0 ){
|
|
SimulateIOErrorBenign(1);
|
|
SimulateIOError( h=(-1) )
|
|
SimulateIOErrorBenign(0);
|
|
if( !skipShared ){
|
|
rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 0);
|
|
}
|
|
if( !rc ){
|
|
pInode->eFileLock = NO_LOCK;
|
|
pFile->eFileLock = NO_LOCK;
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
pInode->nLock--;
|
|
assert( pInode->nLock>=0 );
|
|
if( pInode->nLock==0 ){
|
|
closePendingFds(pFile);
|
|
}
|
|
}
|
|
}
|
|
|
|
unixLeaveMutex();
|
|
if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Close a file & cleanup AFP specific locking context
|
|
*/
|
|
static int afpClose(sqlite3_file *id) {
|
|
int rc = SQLITE_OK;
|
|
if( id ){
|
|
unixFile *pFile = (unixFile*)id;
|
|
afpUnlock(id, NO_LOCK);
|
|
unixEnterMutex();
|
|
if( pFile->pInode && pFile->pInode->nLock ){
|
|
/* If there are outstanding locks, do not actually close the file just
|
|
** yet because that would clear those locks. Instead, add the file
|
|
** descriptor to pInode->aPending. It will be automatically closed when
|
|
** the last lock is cleared.
|
|
*/
|
|
setPendingFd(pFile);
|
|
}
|
|
releaseInodeInfo(pFile);
|
|
sqlite3_free(pFile->lockingContext);
|
|
rc = closeUnixFile(id);
|
|
unixLeaveMutex();
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
|
|
/*
|
|
** The code above is the AFP lock implementation. The code is specific
|
|
** to MacOSX and does not work on other unix platforms. No alternative
|
|
** is available. If you don't compile for a mac, then the "unix-afp"
|
|
** VFS is not available.
|
|
**
|
|
********************* End of the AFP lock implementation **********************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
*************************** Begin NFS Locking ********************************/
|
|
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
*/
|
|
static int nfsUnlock(sqlite3_file *id, int eFileLock){
|
|
return posixUnlock(id, eFileLock, 1);
|
|
}
|
|
|
|
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
|
|
/*
|
|
** The code above is the NFS lock implementation. The code is specific
|
|
** to MacOSX and does not work on other unix platforms. No alternative
|
|
** is available.
|
|
**
|
|
********************* End of the NFS lock implementation **********************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
**************** Non-locking sqlite3_file methods *****************************
|
|
**
|
|
** The next division contains implementations for all methods of the
|
|
** sqlite3_file object other than the locking methods. The locking
|
|
** methods were defined in divisions above (one locking method per
|
|
** division). Those methods that are common to all locking modes
|
|
** are gather together into this division.
|
|
*/
|
|
|
|
/*
|
|
** Seek to the offset passed as the second argument, then read cnt
|
|
** bytes into pBuf. Return the number of bytes actually read.
|
|
**
|
|
** NB: If you define USE_PREAD or USE_PREAD64, then it might also
|
|
** be necessary to define _XOPEN_SOURCE to be 500. This varies from
|
|
** one system to another. Since SQLite does not define USE_PREAD
|
|
** any any form by default, we will not attempt to define _XOPEN_SOURCE.
|
|
** See tickets #2741 and #2681.
|
|
**
|
|
** To avoid stomping the errno value on a failed read the lastErrno value
|
|
** is set before returning.
|
|
*/
|
|
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
|
|
int got;
|
|
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
|
|
i64 newOffset;
|
|
#endif
|
|
TIMER_START;
|
|
#if defined(USE_PREAD)
|
|
do{ got = osPread(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
|
|
SimulateIOError( got = -1 );
|
|
#elif defined(USE_PREAD64)
|
|
do{ got = osPread64(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR);
|
|
SimulateIOError( got = -1 );
|
|
#else
|
|
newOffset = lseek(id->h, offset, SEEK_SET);
|
|
SimulateIOError( newOffset-- );
|
|
if( newOffset!=offset ){
|
|
if( newOffset == -1 ){
|
|
((unixFile*)id)->lastErrno = errno;
|
|
}else{
|
|
((unixFile*)id)->lastErrno = 0;
|
|
}
|
|
return -1;
|
|
}
|
|
do{ got = osRead(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
|
|
#endif
|
|
TIMER_END;
|
|
if( got<0 ){
|
|
((unixFile*)id)->lastErrno = errno;
|
|
}
|
|
OSTRACE(("READ %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
|
|
return got;
|
|
}
|
|
|
|
/*
|
|
** Read data from a file into a buffer. Return SQLITE_OK if all
|
|
** bytes were read successfully and SQLITE_IOERR if anything goes
|
|
** wrong.
|
|
*/
|
|
static int unixRead(
|
|
sqlite3_file *id,
|
|
void *pBuf,
|
|
int amt,
|
|
sqlite3_int64 offset
|
|
){
|
|
unixFile *pFile = (unixFile *)id;
|
|
int got;
|
|
assert( id );
|
|
|
|
/* If this is a database file (not a journal, master-journal or temp
|
|
** file), the bytes in the locking range should never be read or written. */
|
|
#if 0
|
|
assert( pFile->pUnused==0
|
|
|| offset>=PENDING_BYTE+512
|
|
|| offset+amt<=PENDING_BYTE
|
|
);
|
|
#endif
|
|
|
|
got = seekAndRead(pFile, offset, pBuf, amt);
|
|
if( got==amt ){
|
|
return SQLITE_OK;
|
|
}else if( got<0 ){
|
|
/* lastErrno set by seekAndRead */
|
|
return SQLITE_IOERR_READ;
|
|
}else{
|
|
pFile->lastErrno = 0; /* not a system error */
|
|
/* Unread parts of the buffer must be zero-filled */
|
|
memset(&((char*)pBuf)[got], 0, amt-got);
|
|
return SQLITE_IOERR_SHORT_READ;
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Seek to the offset in id->offset then read cnt bytes into pBuf.
|
|
** Return the number of bytes actually read. Update the offset.
|
|
**
|
|
** To avoid stomping the errno value on a failed write the lastErrno value
|
|
** is set before returning.
|
|
*/
|
|
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
|
|
int got;
|
|
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
|
|
i64 newOffset;
|
|
#endif
|
|
TIMER_START;
|
|
#if defined(USE_PREAD)
|
|
do{ got = osPwrite(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
|
|
#elif defined(USE_PREAD64)
|
|
do{ got = osPwrite64(id->h, pBuf, cnt, offset);}while( got<0 && errno==EINTR);
|
|
#else
|
|
newOffset = lseek(id->h, offset, SEEK_SET);
|
|
if( newOffset!=offset ){
|
|
if( newOffset == -1 ){
|
|
((unixFile*)id)->lastErrno = errno;
|
|
}else{
|
|
((unixFile*)id)->lastErrno = 0;
|
|
}
|
|
return -1;
|
|
}
|
|
do{ got = osWrite(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
|
|
#endif
|
|
TIMER_END;
|
|
if( got<0 ){
|
|
((unixFile*)id)->lastErrno = errno;
|
|
}
|
|
|
|
OSTRACE(("WRITE %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
|
|
return got;
|
|
}
|
|
|
|
|
|
/*
|
|
** Write data from a buffer into a file. Return SQLITE_OK on success
|
|
** or some other error code on failure.
|
|
*/
|
|
static int unixWrite(
|
|
sqlite3_file *id,
|
|
const void *pBuf,
|
|
int amt,
|
|
sqlite3_int64 offset
|
|
){
|
|
unixFile *pFile = (unixFile*)id;
|
|
int wrote = 0;
|
|
assert( id );
|
|
assert( amt>0 );
|
|
|
|
/* If this is a database file (not a journal, master-journal or temp
|
|
** file), the bytes in the locking range should never be read or written. */
|
|
#if 0
|
|
assert( pFile->pUnused==0
|
|
|| offset>=PENDING_BYTE+512
|
|
|| offset+amt<=PENDING_BYTE
|
|
);
|
|
#endif
|
|
|
|
#ifndef NDEBUG
|
|
/* If we are doing a normal write to a database file (as opposed to
|
|
** doing a hot-journal rollback or a write to some file other than a
|
|
** normal database file) then record the fact that the database
|
|
** has changed. If the transaction counter is modified, record that
|
|
** fact too.
|
|
*/
|
|
if( pFile->inNormalWrite ){
|
|
pFile->dbUpdate = 1; /* The database has been modified */
|
|
if( offset<=24 && offset+amt>=27 ){
|
|
int rc;
|
|
char oldCntr[4];
|
|
SimulateIOErrorBenign(1);
|
|
rc = seekAndRead(pFile, 24, oldCntr, 4);
|
|
SimulateIOErrorBenign(0);
|
|
if( rc!=4 || memcmp(oldCntr, &((char*)pBuf)[24-offset], 4)!=0 ){
|
|
pFile->transCntrChng = 1; /* The transaction counter has changed */
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
while( amt>0 && (wrote = seekAndWrite(pFile, offset, pBuf, amt))>0 ){
|
|
amt -= wrote;
|
|
offset += wrote;
|
|
pBuf = &((char*)pBuf)[wrote];
|
|
}
|
|
SimulateIOError(( wrote=(-1), amt=1 ));
|
|
SimulateDiskfullError(( wrote=0, amt=1 ));
|
|
|
|
if( amt>0 ){
|
|
if( wrote<0 ){
|
|
/* lastErrno set by seekAndWrite */
|
|
return SQLITE_IOERR_WRITE;
|
|
}else{
|
|
pFile->lastErrno = 0; /* not a system error */
|
|
return SQLITE_FULL;
|
|
}
|
|
}
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
#ifdef SQLITE_TEST
|
|
/*
|
|
** Count the number of fullsyncs and normal syncs. This is used to test
|
|
** that syncs and fullsyncs are occurring at the right times.
|
|
*/
|
|
int sqlite3_sync_count = 0;
|
|
int sqlite3_fullsync_count = 0;
|
|
#endif
|
|
|
|
/*
|
|
** We do not trust systems to provide a working fdatasync(). Some do.
|
|
** Others do no. To be safe, we will stick with the (slower) fsync().
|
|
** If you know that your system does support fdatasync() correctly,
|
|
** then simply compile with -Dfdatasync=fdatasync
|
|
*/
|
|
#if !defined(fdatasync) && !defined(__linux__)
|
|
# define fdatasync fsync
|
|
#endif
|
|
|
|
/*
|
|
** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not
|
|
** the F_FULLFSYNC macro is defined. F_FULLFSYNC is currently
|
|
** only available on Mac OS X. But that could change.
|
|
*/
|
|
#ifdef F_FULLFSYNC
|
|
# define HAVE_FULLFSYNC 1
|
|
#else
|
|
# define HAVE_FULLFSYNC 0
|
|
#endif
|
|
|
|
|
|
/*
|
|
** The fsync() system call does not work as advertised on many
|
|
** unix systems. The following procedure is an attempt to make
|
|
** it work better.
|
|
**
|
|
** The SQLITE_NO_SYNC macro disables all fsync()s. This is useful
|
|
** for testing when we want to run through the test suite quickly.
|
|
** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
|
|
** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
|
|
** or power failure will likely corrupt the database file.
|
|
**
|
|
** SQLite sets the dataOnly flag if the size of the file is unchanged.
|
|
** The idea behind dataOnly is that it should only write the file content
|
|
** to disk, not the inode. We only set dataOnly if the file size is
|
|
** unchanged since the file size is part of the inode. However,
|
|
** Ted Ts'o tells us that fdatasync() will also write the inode if the
|
|
** file size has changed. The only real difference between fdatasync()
|
|
** and fsync(), Ted tells us, is that fdatasync() will not flush the
|
|
** inode if the mtime or owner or other inode attributes have changed.
|
|
** We only care about the file size, not the other file attributes, so
|
|
** as far as SQLite is concerned, an fdatasync() is always adequate.
|
|
** So, we always use fdatasync() if it is available, regardless of
|
|
** the value of the dataOnly flag.
|
|
*/
|
|
static int full_fsync(int fd, int fullSync, int dataOnly){
|
|
int rc;
|
|
|
|
/* The following "ifdef/elif/else/" block has the same structure as
|
|
** the one below. It is replicated here solely to avoid cluttering
|
|
** up the real code with the UNUSED_PARAMETER() macros.
|
|
*/
|
|
#ifdef SQLITE_NO_SYNC
|
|
UNUSED_PARAMETER(fd);
|
|
UNUSED_PARAMETER(fullSync);
|
|
UNUSED_PARAMETER(dataOnly);
|
|
#elif HAVE_FULLFSYNC
|
|
UNUSED_PARAMETER(dataOnly);
|
|
#else
|
|
UNUSED_PARAMETER(fullSync);
|
|
UNUSED_PARAMETER(dataOnly);
|
|
#endif
|
|
|
|
/* Record the number of times that we do a normal fsync() and
|
|
** FULLSYNC. This is used during testing to verify that this procedure
|
|
** gets called with the correct arguments.
|
|
*/
|
|
#ifdef SQLITE_TEST
|
|
if( fullSync ) sqlite3_fullsync_count++;
|
|
sqlite3_sync_count++;
|
|
#endif
|
|
|
|
/* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
|
|
** no-op
|
|
*/
|
|
#ifdef SQLITE_NO_SYNC
|
|
rc = SQLITE_OK;
|
|
#elif HAVE_FULLFSYNC
|
|
if( fullSync ){
|
|
rc = osFcntl(fd, F_FULLFSYNC, 0);
|
|
}else{
|
|
rc = 1;
|
|
}
|
|
/* If the FULLFSYNC failed, fall back to attempting an fsync().
|
|
** It shouldn't be possible for fullfsync to fail on the local
|
|
** file system (on OSX), so failure indicates that FULLFSYNC
|
|
** isn't supported for this file system. So, attempt an fsync
|
|
** and (for now) ignore the overhead of a superfluous fcntl call.
|
|
** It'd be better to detect fullfsync support once and avoid
|
|
** the fcntl call every time sync is called.
|
|
*/
|
|
if( rc ) rc = fsync(fd);
|
|
|
|
#elif defined(__APPLE__)
|
|
/* fdatasync() on HFS+ doesn't yet flush the file size if it changed correctly
|
|
** so currently we default to the macro that redefines fdatasync to fsync
|
|
*/
|
|
rc = fsync(fd);
|
|
#else
|
|
rc = fdatasync(fd);
|
|
#if OS_VXWORKS
|
|
if( rc==-1 && errno==ENOTSUP ){
|
|
rc = fsync(fd);
|
|
}
|
|
#endif /* OS_VXWORKS */
|
|
#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */
|
|
|
|
if( OS_VXWORKS && rc!= -1 ){
|
|
rc = 0;
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Make sure all writes to a particular file are committed to disk.
|
|
**
|
|
** If dataOnly==0 then both the file itself and its metadata (file
|
|
** size, access time, etc) are synced. If dataOnly!=0 then only the
|
|
** file data is synced.
|
|
**
|
|
** Under Unix, also make sure that the directory entry for the file
|
|
** has been created by fsync-ing the directory that contains the file.
|
|
** If we do not do this and we encounter a power failure, the directory
|
|
** entry for the journal might not exist after we reboot. The next
|
|
** SQLite to access the file will not know that the journal exists (because
|
|
** the directory entry for the journal was never created) and the transaction
|
|
** will not roll back - possibly leading to database corruption.
|
|
*/
|
|
static int unixSync(sqlite3_file *id, int flags){
|
|
int rc;
|
|
unixFile *pFile = (unixFile*)id;
|
|
|
|
int isDataOnly = (flags&SQLITE_SYNC_DATAONLY);
|
|
int isFullsync = (flags&0x0F)==SQLITE_SYNC_FULL;
|
|
|
|
/* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
|
|
assert((flags&0x0F)==SQLITE_SYNC_NORMAL
|
|
|| (flags&0x0F)==SQLITE_SYNC_FULL
|
|
);
|
|
|
|
/* Unix cannot, but some systems may return SQLITE_FULL from here. This
|
|
** line is to test that doing so does not cause any problems.
|
|
*/
|
|
SimulateDiskfullError( return SQLITE_FULL );
|
|
|
|
assert( pFile );
|
|
OSTRACE(("SYNC %-3d\n", pFile->h));
|
|
rc = full_fsync(pFile->h, isFullsync, isDataOnly);
|
|
SimulateIOError( rc=1 );
|
|
if( rc ){
|
|
pFile->lastErrno = errno;
|
|
return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
|
|
}
|
|
if( pFile->dirfd>=0 ){
|
|
OSTRACE(("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
|
|
HAVE_FULLFSYNC, isFullsync));
|
|
#ifndef SQLITE_DISABLE_DIRSYNC
|
|
/* The directory sync is only attempted if full_fsync is
|
|
** turned off or unavailable. If a full_fsync occurred above,
|
|
** then the directory sync is superfluous.
|
|
*/
|
|
if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){
|
|
/*
|
|
** We have received multiple reports of fsync() returning
|
|
** errors when applied to directories on certain file systems.
|
|
** A failed directory sync is not a big deal. So it seems
|
|
** better to ignore the error. Ticket #1657
|
|
*/
|
|
/* pFile->lastErrno = errno; */
|
|
/* return SQLITE_IOERR; */
|
|
}
|
|
#endif
|
|
/* Only need to sync once, so close the directory when we are done */
|
|
robust_close(pFile, pFile->dirfd, __LINE__);
|
|
pFile->dirfd = -1;
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Truncate an open file to a specified size
|
|
*/
|
|
static int unixTruncate(sqlite3_file *id, i64 nByte){
|
|
unixFile *pFile = (unixFile *)id;
|
|
int rc;
|
|
assert( pFile );
|
|
SimulateIOError( return SQLITE_IOERR_TRUNCATE );
|
|
|
|
/* If the user has configured a chunk-size for this file, truncate the
|
|
** file so that it consists of an integer number of chunks (i.e. the
|
|
** actual file size after the operation may be larger than the requested
|
|
** size).
|
|
*/
|
|
if( pFile->szChunk ){
|
|
nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
|
|
}
|
|
|
|
rc = robust_ftruncate(pFile->h, (off_t)nByte);
|
|
if( rc ){
|
|
pFile->lastErrno = errno;
|
|
return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
|
|
}else{
|
|
#ifndef NDEBUG
|
|
/* If we are doing a normal write to a database file (as opposed to
|
|
** doing a hot-journal rollback or a write to some file other than a
|
|
** normal database file) and we truncate the file to zero length,
|
|
** that effectively updates the change counter. This might happen
|
|
** when restoring a database using the backup API from a zero-length
|
|
** source.
|
|
*/
|
|
if( pFile->inNormalWrite && nByte==0 ){
|
|
pFile->transCntrChng = 1;
|
|
}
|
|
#endif
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Determine the current size of a file in bytes
|
|
*/
|
|
static int unixFileSize(sqlite3_file *id, i64 *pSize){
|
|
int rc;
|
|
struct stat buf;
|
|
assert( id );
|
|
rc = osFstat(((unixFile*)id)->h, &buf);
|
|
SimulateIOError( rc=1 );
|
|
if( rc!=0 ){
|
|
((unixFile*)id)->lastErrno = errno;
|
|
return SQLITE_IOERR_FSTAT;
|
|
}
|
|
*pSize = buf.st_size;
|
|
|
|
/* When opening a zero-size database, the findInodeInfo() procedure
|
|
** writes a single byte into that file in order to work around a bug
|
|
** in the OS-X msdos filesystem. In order to avoid problems with upper
|
|
** layers, we need to report this file size as zero even though it is
|
|
** really 1. Ticket #3260.
|
|
*/
|
|
if( *pSize==1 ) *pSize = 0;
|
|
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
|
|
/*
|
|
** Handler for proxy-locking file-control verbs. Defined below in the
|
|
** proxying locking division.
|
|
*/
|
|
static int proxyFileControl(sqlite3_file*,int,void*);
|
|
#endif
|
|
|
|
/*
|
|
** This function is called to handle the SQLITE_FCNTL_SIZE_HINT
|
|
** file-control operation.
|
|
**
|
|
** If the user has configured a chunk-size for this file, it could be
|
|
** that the file needs to be extended at this point. Otherwise, the
|
|
** SQLITE_FCNTL_SIZE_HINT operation is a no-op for Unix.
|
|
*/
|
|
static int fcntlSizeHint(unixFile *pFile, i64 nByte){
|
|
if( pFile->szChunk ){
|
|
i64 nSize; /* Required file size */
|
|
struct stat buf; /* Used to hold return values of fstat() */
|
|
|
|
if( osFstat(pFile->h, &buf) ) return SQLITE_IOERR_FSTAT;
|
|
|
|
nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
|
|
if( nSize>(i64)buf.st_size ){
|
|
#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
|
|
int rc;
|
|
do{
|
|
rc = osFallocate(pFile->h, buf.st_size, nSize-buf.st_size);
|
|
}while( rc<0 && errno==EINTR );
|
|
if( rc ) return SQLITE_IOERR_WRITE;
|
|
#else
|
|
/* If the OS does not have posix_fallocate(), fake it. First use
|
|
** ftruncate() to set the file size, then write a single byte to
|
|
** the last byte in each block within the extended region. This
|
|
** is the same technique used by glibc to implement posix_fallocate()
|
|
** on systems that do not have a real fallocate() system call.
|
|
*/
|
|
int nBlk = buf.st_blksize; /* File-system block size */
|
|
i64 iWrite; /* Next offset to write to */
|
|
int nWrite; /* Return value from seekAndWrite() */
|
|
|
|
if( robust_ftruncate(pFile->h, nSize) ){
|
|
pFile->lastErrno = errno;
|
|
return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
|
|
}
|
|
iWrite = ((buf.st_size + 2*nBlk - 1)/nBlk)*nBlk-1;
|
|
do {
|
|
nWrite = seekAndWrite(pFile, iWrite, "", 1);
|
|
iWrite += nBlk;
|
|
} while( nWrite==1 && iWrite<nSize );
|
|
if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
|
|
#endif
|
|
}
|
|
}
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Information and control of an open file handle.
|
|
*/
|
|
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
|
|
switch( op ){
|
|
case SQLITE_FCNTL_LOCKSTATE: {
|
|
*(int*)pArg = ((unixFile*)id)->eFileLock;
|
|
return SQLITE_OK;
|
|
}
|
|
case SQLITE_LAST_ERRNO: {
|
|
*(int*)pArg = ((unixFile*)id)->lastErrno;
|
|
return SQLITE_OK;
|
|
}
|
|
case SQLITE_FCNTL_CHUNK_SIZE: {
|
|
((unixFile*)id)->szChunk = *(int *)pArg;
|
|
return SQLITE_OK;
|
|
}
|
|
case SQLITE_FCNTL_SIZE_HINT: {
|
|
return fcntlSizeHint((unixFile *)id, *(i64 *)pArg);
|
|
}
|
|
#ifndef NDEBUG
|
|
/* The pager calls this method to signal that it has done
|
|
** a rollback and that the database is therefore unchanged and
|
|
** it hence it is OK for the transaction change counter to be
|
|
** unchanged.
|
|
*/
|
|
case SQLITE_FCNTL_DB_UNCHANGED: {
|
|
((unixFile*)id)->dbUpdate = 0;
|
|
return SQLITE_OK;
|
|
}
|
|
#endif
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
|
|
case SQLITE_SET_LOCKPROXYFILE:
|
|
case SQLITE_GET_LOCKPROXYFILE: {
|
|
return proxyFileControl(id,op,pArg);
|
|
}
|
|
#endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */
|
|
case SQLITE_FCNTL_SYNC_OMITTED: {
|
|
return SQLITE_OK; /* A no-op */
|
|
}
|
|
}
|
|
return SQLITE_NOTFOUND;
|
|
}
|
|
|
|
/*
|
|
** Return the sector size in bytes of the underlying block device for
|
|
** the specified file. This is almost always 512 bytes, but may be
|
|
** larger for some devices.
|
|
**
|
|
** SQLite code assumes this function cannot fail. It also assumes that
|
|
** if two files are created in the same file-system directory (i.e.
|
|
** a database and its journal file) that the sector size will be the
|
|
** same for both.
|
|
*/
|
|
static int unixSectorSize(sqlite3_file *NotUsed){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return SQLITE_DEFAULT_SECTOR_SIZE;
|
|
}
|
|
|
|
/*
|
|
** Return the device characteristics for the file. This is always 0 for unix.
|
|
*/
|
|
static int unixDeviceCharacteristics(sqlite3_file *NotUsed){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return 0;
|
|
}
|
|
|
|
#ifndef SQLITE_OMIT_WAL
|
|
|
|
|
|
/*
|
|
** Object used to represent an shared memory buffer.
|
|
**
|
|
** When multiple threads all reference the same wal-index, each thread
|
|
** has its own unixShm object, but they all point to a single instance
|
|
** of this unixShmNode object. In other words, each wal-index is opened
|
|
** only once per process.
|
|
**
|
|
** Each unixShmNode object is connected to a single unixInodeInfo object.
|
|
** We could coalesce this object into unixInodeInfo, but that would mean
|
|
** every open file that does not use shared memory (in other words, most
|
|
** open files) would have to carry around this extra information. So
|
|
** the unixInodeInfo object contains a pointer to this unixShmNode object
|
|
** and the unixShmNode object is created only when needed.
|
|
**
|
|
** unixMutexHeld() must be true when creating or destroying
|
|
** this object or while reading or writing the following fields:
|
|
**
|
|
** nRef
|
|
**
|
|
** The following fields are read-only after the object is created:
|
|
**
|
|
** fid
|
|
** zFilename
|
|
**
|
|
** Either unixShmNode.mutex must be held or unixShmNode.nRef==0 and
|
|
** unixMutexHeld() is true when reading or writing any other field
|
|
** in this structure.
|
|
*/
|
|
struct unixShmNode {
|
|
unixInodeInfo *pInode; /* unixInodeInfo that owns this SHM node */
|
|
sqlite3_mutex *mutex; /* Mutex to access this object */
|
|
char *zFilename; /* Name of the mmapped file */
|
|
int h; /* Open file descriptor */
|
|
int szRegion; /* Size of shared-memory regions */
|
|
int nRegion; /* Size of array apRegion */
|
|
char **apRegion; /* Array of mapped shared-memory regions */
|
|
int nRef; /* Number of unixShm objects pointing to this */
|
|
unixShm *pFirst; /* All unixShm objects pointing to this */
|
|
#ifdef SQLITE_DEBUG
|
|
u8 exclMask; /* Mask of exclusive locks held */
|
|
u8 sharedMask; /* Mask of shared locks held */
|
|
u8 nextShmId; /* Next available unixShm.id value */
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
** Structure used internally by this VFS to record the state of an
|
|
** open shared memory connection.
|
|
**
|
|
** The following fields are initialized when this object is created and
|
|
** are read-only thereafter:
|
|
**
|
|
** unixShm.pFile
|
|
** unixShm.id
|
|
**
|
|
** All other fields are read/write. The unixShm.pFile->mutex must be held
|
|
** while accessing any read/write fields.
|
|
*/
|
|
struct unixShm {
|
|
unixShmNode *pShmNode; /* The underlying unixShmNode object */
|
|
unixShm *pNext; /* Next unixShm with the same unixShmNode */
|
|
u8 hasMutex; /* True if holding the unixShmNode mutex */
|
|
u16 sharedMask; /* Mask of shared locks held */
|
|
u16 exclMask; /* Mask of exclusive locks held */
|
|
#ifdef SQLITE_DEBUG
|
|
u8 id; /* Id of this connection within its unixShmNode */
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
** Constants used for locking
|
|
*/
|
|
#define UNIX_SHM_BASE ((22+SQLITE_SHM_NLOCK)*4) /* first lock byte */
|
|
#define UNIX_SHM_DMS (UNIX_SHM_BASE+SQLITE_SHM_NLOCK) /* deadman switch */
|
|
|
|
/*
|
|
** Apply posix advisory locks for all bytes from ofst through ofst+n-1.
|
|
**
|
|
** Locks block if the mask is exactly UNIX_SHM_C and are non-blocking
|
|
** otherwise.
|
|
*/
|
|
static int unixShmSystemLock(
|
|
unixShmNode *pShmNode, /* Apply locks to this open shared-memory segment */
|
|
int lockType, /* F_UNLCK, F_RDLCK, or F_WRLCK */
|
|
int ofst, /* First byte of the locking range */
|
|
int n /* Number of bytes to lock */
|
|
){
|
|
struct flock f; /* The posix advisory locking structure */
|
|
int rc = SQLITE_OK; /* Result code form fcntl() */
|
|
|
|
/* Access to the unixShmNode object is serialized by the caller */
|
|
assert( sqlite3_mutex_held(pShmNode->mutex) || pShmNode->nRef==0 );
|
|
|
|
/* Shared locks never span more than one byte */
|
|
assert( n==1 || lockType!=F_RDLCK );
|
|
|
|
/* Locks are within range */
|
|
assert( n>=1 && n<SQLITE_SHM_NLOCK );
|
|
|
|
if( pShmNode->h>=0 ){
|
|
/* Initialize the locking parameters */
|
|
memset(&f, 0, sizeof(f));
|
|
f.l_type = lockType;
|
|
f.l_whence = SEEK_SET;
|
|
f.l_start = ofst;
|
|
f.l_len = n;
|
|
|
|
rc = osFcntl(pShmNode->h, F_SETLK, &f);
|
|
rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;
|
|
}
|
|
|
|
/* Update the global lock state and do debug tracing */
|
|
#ifdef SQLITE_DEBUG
|
|
{ u16 mask;
|
|
OSTRACE(("SHM-LOCK "));
|
|
mask = (1<<(ofst+n)) - (1<<ofst);
|
|
if( rc==SQLITE_OK ){
|
|
if( lockType==F_UNLCK ){
|
|
OSTRACE(("unlock %d ok", ofst));
|
|
pShmNode->exclMask &= ~mask;
|
|
pShmNode->sharedMask &= ~mask;
|
|
}else if( lockType==F_RDLCK ){
|
|
OSTRACE(("read-lock %d ok", ofst));
|
|
pShmNode->exclMask &= ~mask;
|
|
pShmNode->sharedMask |= mask;
|
|
}else{
|
|
assert( lockType==F_WRLCK );
|
|
OSTRACE(("write-lock %d ok", ofst));
|
|
pShmNode->exclMask |= mask;
|
|
pShmNode->sharedMask &= ~mask;
|
|
}
|
|
}else{
|
|
if( lockType==F_UNLCK ){
|
|
OSTRACE(("unlock %d failed", ofst));
|
|
}else if( lockType==F_RDLCK ){
|
|
OSTRACE(("read-lock failed"));
|
|
}else{
|
|
assert( lockType==F_WRLCK );
|
|
OSTRACE(("write-lock %d failed", ofst));
|
|
}
|
|
}
|
|
OSTRACE((" - afterwards %03x,%03x\n",
|
|
pShmNode->sharedMask, pShmNode->exclMask));
|
|
}
|
|
#endif
|
|
|
|
return rc;
|
|
}
|
|
|
|
|
|
/*
|
|
** Purge the unixShmNodeList list of all entries with unixShmNode.nRef==0.
|
|
**
|
|
** This is not a VFS shared-memory method; it is a utility function called
|
|
** by VFS shared-memory methods.
|
|
*/
|
|
static void unixShmPurge(unixFile *pFd){
|
|
unixShmNode *p = pFd->pInode->pShmNode;
|
|
assert( unixMutexHeld() );
|
|
if( p && p->nRef==0 ){
|
|
int i;
|
|
assert( p->pInode==pFd->pInode );
|
|
if( p->mutex ) sqlite3_mutex_free(p->mutex);
|
|
for(i=0; i<p->nRegion; i++){
|
|
if( p->h>=0 ){
|
|
munmap(p->apRegion[i], p->szRegion);
|
|
}else{
|
|
sqlite3_free(p->apRegion[i]);
|
|
}
|
|
}
|
|
sqlite3_free(p->apRegion);
|
|
if( p->h>=0 ){
|
|
robust_close(pFd, p->h, __LINE__);
|
|
p->h = -1;
|
|
}
|
|
p->pInode->pShmNode = 0;
|
|
sqlite3_free(p);
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Open a shared-memory area associated with open database file pDbFd.
|
|
** This particular implementation uses mmapped files.
|
|
**
|
|
** The file used to implement shared-memory is in the same directory
|
|
** as the open database file and has the same name as the open database
|
|
** file with the "-shm" suffix added. For example, if the database file
|
|
** is "/home/user1/config.db" then the file that is created and mmapped
|
|
** for shared memory will be called "/home/user1/config.db-shm".
|
|
**
|
|
** Another approach to is to use files in /dev/shm or /dev/tmp or an
|
|
** some other tmpfs mount. But if a file in a different directory
|
|
** from the database file is used, then differing access permissions
|
|
** or a chroot() might cause two different processes on the same
|
|
** database to end up using different files for shared memory -
|
|
** meaning that their memory would not really be shared - resulting
|
|
** in database corruption. Nevertheless, this tmpfs file usage
|
|
** can be enabled at compile-time using -DSQLITE_SHM_DIRECTORY="/dev/shm"
|
|
** or the equivalent. The use of the SQLITE_SHM_DIRECTORY compile-time
|
|
** option results in an incompatible build of SQLite; builds of SQLite
|
|
** that with differing SQLITE_SHM_DIRECTORY settings attempt to use the
|
|
** same database file at the same time, database corruption will likely
|
|
** result. The SQLITE_SHM_DIRECTORY compile-time option is considered
|
|
** "unsupported" and may go away in a future SQLite release.
|
|
**
|
|
** When opening a new shared-memory file, if no other instances of that
|
|
** file are currently open, in this process or in other processes, then
|
|
** the file must be truncated to zero length or have its header cleared.
|
|
**
|
|
** If the original database file (pDbFd) is using the "unix-excl" VFS
|
|
** that means that an exclusive lock is held on the database file and
|
|
** that no other processes are able to read or write the database. In
|
|
** that case, we do not really need shared memory. No shared memory
|
|
** file is created. The shared memory will be simulated with heap memory.
|
|
*/
|
|
static int unixOpenSharedMemory(unixFile *pDbFd){
|
|
struct unixShm *p = 0; /* The connection to be opened */
|
|
struct unixShmNode *pShmNode; /* The underlying mmapped file */
|
|
int rc; /* Result code */
|
|
unixInodeInfo *pInode; /* The inode of fd */
|
|
char *zShmFilename; /* Name of the file used for SHM */
|
|
int nShmFilename; /* Size of the SHM filename in bytes */
|
|
|
|
/* Allocate space for the new unixShm object. */
|
|
p = sqlite3_malloc( sizeof(*p) );
|
|
if( p==0 ) return SQLITE_NOMEM;
|
|
memset(p, 0, sizeof(*p));
|
|
assert( pDbFd->pShm==0 );
|
|
|
|
/* Check to see if a unixShmNode object already exists. Reuse an existing
|
|
** one if present. Create a new one if necessary.
|
|
*/
|
|
unixEnterMutex();
|
|
pInode = pDbFd->pInode;
|
|
pShmNode = pInode->pShmNode;
|
|
if( pShmNode==0 ){
|
|
struct stat sStat; /* fstat() info for database file */
|
|
|
|
/* Call fstat() to figure out the permissions on the database file. If
|
|
** a new *-shm file is created, an attempt will be made to create it
|
|
** with the same permissions. The actual permissions the file is created
|
|
** with are subject to the current umask setting.
|
|
*/
|
|
if( osFstat(pDbFd->h, &sStat) && pInode->bProcessLock==0 ){
|
|
rc = SQLITE_IOERR_FSTAT;
|
|
goto shm_open_err;
|
|
}
|
|
|
|
#ifdef SQLITE_SHM_DIRECTORY
|
|
nShmFilename = sizeof(SQLITE_SHM_DIRECTORY) + 30;
|
|
#else
|
|
nShmFilename = 5 + (int)strlen(pDbFd->zPath);
|
|
#endif
|
|
pShmNode = sqlite3_malloc( sizeof(*pShmNode) + nShmFilename );
|
|
if( pShmNode==0 ){
|
|
rc = SQLITE_NOMEM;
|
|
goto shm_open_err;
|
|
}
|
|
memset(pShmNode, 0, sizeof(*pShmNode));
|
|
zShmFilename = pShmNode->zFilename = (char*)&pShmNode[1];
|
|
#ifdef SQLITE_SHM_DIRECTORY
|
|
sqlite3_snprintf(nShmFilename, zShmFilename,
|
|
SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x",
|
|
(u32)sStat.st_ino, (u32)sStat.st_dev);
|
|
#else
|
|
sqlite3_snprintf(nShmFilename, zShmFilename, "%s-shm", pDbFd->zPath);
|
|
#endif
|
|
pShmNode->h = -1;
|
|
pDbFd->pInode->pShmNode = pShmNode;
|
|
pShmNode->pInode = pDbFd->pInode;
|
|
pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
|
|
if( pShmNode->mutex==0 ){
|
|
rc = SQLITE_NOMEM;
|
|
goto shm_open_err;
|
|
}
|
|
|
|
if( pInode->bProcessLock==0 ){
|
|
pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
|
|
(sStat.st_mode & 0777));
|
|
if( pShmNode->h<0 ){
|
|
rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
|
|
goto shm_open_err;
|
|
}
|
|
|
|
/* Check to see if another process is holding the dead-man switch.
|
|
** If not, truncate the file to zero length.
|
|
*/
|
|
rc = SQLITE_OK;
|
|
if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
|
|
if( robust_ftruncate(pShmNode->h, 0) ){
|
|
rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename);
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
rc = unixShmSystemLock(pShmNode, F_RDLCK, UNIX_SHM_DMS, 1);
|
|
}
|
|
if( rc ) goto shm_open_err;
|
|
}
|
|
}
|
|
|
|
/* Make the new connection a child of the unixShmNode */
|
|
p->pShmNode = pShmNode;
|
|
#ifdef SQLITE_DEBUG
|
|
p->id = pShmNode->nextShmId++;
|
|
#endif
|
|
pShmNode->nRef++;
|
|
pDbFd->pShm = p;
|
|
unixLeaveMutex();
|
|
|
|
/* The reference count on pShmNode has already been incremented under
|
|
** the cover of the unixEnterMutex() mutex and the pointer from the
|
|
** new (struct unixShm) object to the pShmNode has been set. All that is
|
|
** left to do is to link the new object into the linked list starting
|
|
** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex
|
|
** mutex.
|
|
*/
|
|
sqlite3_mutex_enter(pShmNode->mutex);
|
|
p->pNext = pShmNode->pFirst;
|
|
pShmNode->pFirst = p;
|
|
sqlite3_mutex_leave(pShmNode->mutex);
|
|
return SQLITE_OK;
|
|
|
|
/* Jump here on any error */
|
|
shm_open_err:
|
|
unixShmPurge(pDbFd); /* This call frees pShmNode if required */
|
|
sqlite3_free(p);
|
|
unixLeaveMutex();
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** This function is called to obtain a pointer to region iRegion of the
|
|
** shared-memory associated with the database file fd. Shared-memory regions
|
|
** are numbered starting from zero. Each shared-memory region is szRegion
|
|
** bytes in size.
|
|
**
|
|
** If an error occurs, an error code is returned and *pp is set to NULL.
|
|
**
|
|
** Otherwise, if the bExtend parameter is 0 and the requested shared-memory
|
|
** region has not been allocated (by any client, including one running in a
|
|
** separate process), then *pp is set to NULL and SQLITE_OK returned. If
|
|
** bExtend is non-zero and the requested shared-memory region has not yet
|
|
** been allocated, it is allocated by this function.
|
|
**
|
|
** If the shared-memory region has already been allocated or is allocated by
|
|
** this call as described above, then it is mapped into this processes
|
|
** address space (if it is not already), *pp is set to point to the mapped
|
|
** memory and SQLITE_OK returned.
|
|
*/
|
|
static int unixShmMap(
|
|
sqlite3_file *fd, /* Handle open on database file */
|
|
int iRegion, /* Region to retrieve */
|
|
int szRegion, /* Size of regions */
|
|
int bExtend, /* True to extend file if necessary */
|
|
void volatile **pp /* OUT: Mapped memory */
|
|
){
|
|
unixFile *pDbFd = (unixFile*)fd;
|
|
unixShm *p;
|
|
unixShmNode *pShmNode;
|
|
int rc = SQLITE_OK;
|
|
|
|
/* If the shared-memory file has not yet been opened, open it now. */
|
|
if( pDbFd->pShm==0 ){
|
|
rc = unixOpenSharedMemory(pDbFd);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
}
|
|
|
|
p = pDbFd->pShm;
|
|
pShmNode = p->pShmNode;
|
|
sqlite3_mutex_enter(pShmNode->mutex);
|
|
assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
|
|
assert( pShmNode->pInode==pDbFd->pInode );
|
|
assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
|
|
assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
|
|
|
|
if( pShmNode->nRegion<=iRegion ){
|
|
char **apNew; /* New apRegion[] array */
|
|
int nByte = (iRegion+1)*szRegion; /* Minimum required file size */
|
|
struct stat sStat; /* Used by fstat() */
|
|
|
|
pShmNode->szRegion = szRegion;
|
|
|
|
if( pShmNode->h>=0 ){
|
|
/* The requested region is not mapped into this processes address space.
|
|
** Check to see if it has been allocated (i.e. if the wal-index file is
|
|
** large enough to contain the requested region).
|
|
*/
|
|
if( osFstat(pShmNode->h, &sStat) ){
|
|
rc = SQLITE_IOERR_SHMSIZE;
|
|
goto shmpage_out;
|
|
}
|
|
|
|
if( sStat.st_size<nByte ){
|
|
/* The requested memory region does not exist. If bExtend is set to
|
|
** false, exit early. *pp will be set to NULL and SQLITE_OK returned.
|
|
**
|
|
** Alternatively, if bExtend is true, use ftruncate() to allocate
|
|
** the requested memory region.
|
|
*/
|
|
if( !bExtend ) goto shmpage_out;
|
|
if( robust_ftruncate(pShmNode->h, nByte) ){
|
|
rc = unixLogError(SQLITE_IOERR_SHMSIZE, "ftruncate",
|
|
pShmNode->zFilename);
|
|
goto shmpage_out;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Map the requested memory region into this processes address space. */
|
|
apNew = (char **)sqlite3_realloc(
|
|
pShmNode->apRegion, (iRegion+1)*sizeof(char *)
|
|
);
|
|
if( !apNew ){
|
|
rc = SQLITE_IOERR_NOMEM;
|
|
goto shmpage_out;
|
|
}
|
|
pShmNode->apRegion = apNew;
|
|
while(pShmNode->nRegion<=iRegion){
|
|
void *pMem;
|
|
if( pShmNode->h>=0 ){
|
|
pMem = mmap(0, szRegion, PROT_READ|PROT_WRITE,
|
|
MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion
|
|
);
|
|
if( pMem==MAP_FAILED ){
|
|
rc = SQLITE_IOERR;
|
|
goto shmpage_out;
|
|
}
|
|
}else{
|
|
pMem = sqlite3_malloc(szRegion);
|
|
if( pMem==0 ){
|
|
rc = SQLITE_NOMEM;
|
|
goto shmpage_out;
|
|
}
|
|
memset(pMem, 0, szRegion);
|
|
}
|
|
pShmNode->apRegion[pShmNode->nRegion] = pMem;
|
|
pShmNode->nRegion++;
|
|
}
|
|
}
|
|
|
|
shmpage_out:
|
|
if( pShmNode->nRegion>iRegion ){
|
|
*pp = pShmNode->apRegion[iRegion];
|
|
}else{
|
|
*pp = 0;
|
|
}
|
|
sqlite3_mutex_leave(pShmNode->mutex);
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Change the lock state for a shared-memory segment.
|
|
**
|
|
** Note that the relationship between SHAREd and EXCLUSIVE locks is a little
|
|
** different here than in posix. In xShmLock(), one can go from unlocked
|
|
** to shared and back or from unlocked to exclusive and back. But one may
|
|
** not go from shared to exclusive or from exclusive to shared.
|
|
*/
|
|
static int unixShmLock(
|
|
sqlite3_file *fd, /* Database file holding the shared memory */
|
|
int ofst, /* First lock to acquire or release */
|
|
int n, /* Number of locks to acquire or release */
|
|
int flags /* What to do with the lock */
|
|
){
|
|
unixFile *pDbFd = (unixFile*)fd; /* Connection holding shared memory */
|
|
unixShm *p = pDbFd->pShm; /* The shared memory being locked */
|
|
unixShm *pX; /* For looping over all siblings */
|
|
unixShmNode *pShmNode = p->pShmNode; /* The underlying file iNode */
|
|
int rc = SQLITE_OK; /* Result code */
|
|
u16 mask; /* Mask of locks to take or release */
|
|
|
|
assert( pShmNode==pDbFd->pInode->pShmNode );
|
|
assert( pShmNode->pInode==pDbFd->pInode );
|
|
assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
|
|
assert( n>=1 );
|
|
assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
|
|
|| flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
|
|
|| flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
|
|
|| flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
|
|
assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
|
|
assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
|
|
assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
|
|
|
|
mask = (1<<(ofst+n)) - (1<<ofst);
|
|
assert( n>1 || mask==(1<<ofst) );
|
|
sqlite3_mutex_enter(pShmNode->mutex);
|
|
if( flags & SQLITE_SHM_UNLOCK ){
|
|
u16 allMask = 0; /* Mask of locks held by siblings */
|
|
|
|
/* See if any siblings hold this same lock */
|
|
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
|
|
if( pX==p ) continue;
|
|
assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
|
|
allMask |= pX->sharedMask;
|
|
}
|
|
|
|
/* Unlock the system-level locks */
|
|
if( (mask & allMask)==0 ){
|
|
rc = unixShmSystemLock(pShmNode, F_UNLCK, ofst+UNIX_SHM_BASE, n);
|
|
}else{
|
|
rc = SQLITE_OK;
|
|
}
|
|
|
|
/* Undo the local locks */
|
|
if( rc==SQLITE_OK ){
|
|
p->exclMask &= ~mask;
|
|
p->sharedMask &= ~mask;
|
|
}
|
|
}else if( flags & SQLITE_SHM_SHARED ){
|
|
u16 allShared = 0; /* Union of locks held by connections other than "p" */
|
|
|
|
/* Find out which shared locks are already held by sibling connections.
|
|
** If any sibling already holds an exclusive lock, go ahead and return
|
|
** SQLITE_BUSY.
|
|
*/
|
|
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
|
|
if( (pX->exclMask & mask)!=0 ){
|
|
rc = SQLITE_BUSY;
|
|
break;
|
|
}
|
|
allShared |= pX->sharedMask;
|
|
}
|
|
|
|
/* Get shared locks at the system level, if necessary */
|
|
if( rc==SQLITE_OK ){
|
|
if( (allShared & mask)==0 ){
|
|
rc = unixShmSystemLock(pShmNode, F_RDLCK, ofst+UNIX_SHM_BASE, n);
|
|
}else{
|
|
rc = SQLITE_OK;
|
|
}
|
|
}
|
|
|
|
/* Get the local shared locks */
|
|
if( rc==SQLITE_OK ){
|
|
p->sharedMask |= mask;
|
|
}
|
|
}else{
|
|
/* Make sure no sibling connections hold locks that will block this
|
|
** lock. If any do, return SQLITE_BUSY right away.
|
|
*/
|
|
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
|
|
if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
|
|
rc = SQLITE_BUSY;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Get the exclusive locks at the system level. Then if successful
|
|
** also mark the local connection as being locked.
|
|
*/
|
|
if( rc==SQLITE_OK ){
|
|
rc = unixShmSystemLock(pShmNode, F_WRLCK, ofst+UNIX_SHM_BASE, n);
|
|
if( rc==SQLITE_OK ){
|
|
assert( (p->sharedMask & mask)==0 );
|
|
p->exclMask |= mask;
|
|
}
|
|
}
|
|
}
|
|
sqlite3_mutex_leave(pShmNode->mutex);
|
|
OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n",
|
|
p->id, getpid(), p->sharedMask, p->exclMask));
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Implement a memory barrier or memory fence on shared memory.
|
|
**
|
|
** All loads and stores begun before the barrier must complete before
|
|
** any load or store begun after the barrier.
|
|
*/
|
|
static void unixShmBarrier(
|
|
sqlite3_file *fd /* Database file holding the shared memory */
|
|
){
|
|
UNUSED_PARAMETER(fd);
|
|
unixEnterMutex();
|
|
unixLeaveMutex();
|
|
}
|
|
|
|
/*
|
|
** Close a connection to shared-memory. Delete the underlying
|
|
** storage if deleteFlag is true.
|
|
**
|
|
** If there is no shared memory associated with the connection then this
|
|
** routine is a harmless no-op.
|
|
*/
|
|
static int unixShmUnmap(
|
|
sqlite3_file *fd, /* The underlying database file */
|
|
int deleteFlag /* Delete shared-memory if true */
|
|
){
|
|
unixShm *p; /* The connection to be closed */
|
|
unixShmNode *pShmNode; /* The underlying shared-memory file */
|
|
unixShm **pp; /* For looping over sibling connections */
|
|
unixFile *pDbFd; /* The underlying database file */
|
|
|
|
pDbFd = (unixFile*)fd;
|
|
p = pDbFd->pShm;
|
|
if( p==0 ) return SQLITE_OK;
|
|
pShmNode = p->pShmNode;
|
|
|
|
assert( pShmNode==pDbFd->pInode->pShmNode );
|
|
assert( pShmNode->pInode==pDbFd->pInode );
|
|
|
|
/* Remove connection p from the set of connections associated
|
|
** with pShmNode */
|
|
sqlite3_mutex_enter(pShmNode->mutex);
|
|
for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
|
|
*pp = p->pNext;
|
|
|
|
/* Free the connection p */
|
|
sqlite3_free(p);
|
|
pDbFd->pShm = 0;
|
|
sqlite3_mutex_leave(pShmNode->mutex);
|
|
|
|
/* If pShmNode->nRef has reached 0, then close the underlying
|
|
** shared-memory file, too */
|
|
unixEnterMutex();
|
|
assert( pShmNode->nRef>0 );
|
|
pShmNode->nRef--;
|
|
if( pShmNode->nRef==0 ){
|
|
if( deleteFlag && pShmNode->h>=0 ) unlink(pShmNode->zFilename);
|
|
unixShmPurge(pDbFd);
|
|
}
|
|
unixLeaveMutex();
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
#else
|
|
# define unixShmMap 0
|
|
# define unixShmLock 0
|
|
# define unixShmBarrier 0
|
|
# define unixShmUnmap 0
|
|
#endif /* #ifndef SQLITE_OMIT_WAL */
|
|
|
|
/*
|
|
** Here ends the implementation of all sqlite3_file methods.
|
|
**
|
|
********************** End sqlite3_file Methods *******************************
|
|
******************************************************************************/
|
|
|
|
/*
|
|
** This division contains definitions of sqlite3_io_methods objects that
|
|
** implement various file locking strategies. It also contains definitions
|
|
** of "finder" functions. A finder-function is used to locate the appropriate
|
|
** sqlite3_io_methods object for a particular database file. The pAppData
|
|
** field of the sqlite3_vfs VFS objects are initialized to be pointers to
|
|
** the correct finder-function for that VFS.
|
|
**
|
|
** Most finder functions return a pointer to a fixed sqlite3_io_methods
|
|
** object. The only interesting finder-function is autolockIoFinder, which
|
|
** looks at the filesystem type and tries to guess the best locking
|
|
** strategy from that.
|
|
**
|
|
** For finder-funtion F, two objects are created:
|
|
**
|
|
** (1) The real finder-function named "FImpt()".
|
|
**
|
|
** (2) A constant pointer to this function named just "F".
|
|
**
|
|
**
|
|
** A pointer to the F pointer is used as the pAppData value for VFS
|
|
** objects. We have to do this instead of letting pAppData point
|
|
** directly at the finder-function since C90 rules prevent a void*
|
|
** from be cast into a function pointer.
|
|
**
|
|
**
|
|
** Each instance of this macro generates two objects:
|
|
**
|
|
** * A constant sqlite3_io_methods object call METHOD that has locking
|
|
** methods CLOSE, LOCK, UNLOCK, CKRESLOCK.
|
|
**
|
|
** * An I/O method finder function called FINDER that returns a pointer
|
|
** to the METHOD object in the previous bullet.
|
|
*/
|
|
#define IOMETHODS(FINDER, METHOD, VERSION, CLOSE, LOCK, UNLOCK, CKLOCK) \
|
|
static const sqlite3_io_methods METHOD = { \
|
|
VERSION, /* iVersion */ \
|
|
CLOSE, /* xClose */ \
|
|
unixRead, /* xRead */ \
|
|
unixWrite, /* xWrite */ \
|
|
unixTruncate, /* xTruncate */ \
|
|
unixSync, /* xSync */ \
|
|
unixFileSize, /* xFileSize */ \
|
|
LOCK, /* xLock */ \
|
|
UNLOCK, /* xUnlock */ \
|
|
CKLOCK, /* xCheckReservedLock */ \
|
|
unixFileControl, /* xFileControl */ \
|
|
unixSectorSize, /* xSectorSize */ \
|
|
unixDeviceCharacteristics, /* xDeviceCapabilities */ \
|
|
unixShmMap, /* xShmMap */ \
|
|
unixShmLock, /* xShmLock */ \
|
|
unixShmBarrier, /* xShmBarrier */ \
|
|
unixShmUnmap /* xShmUnmap */ \
|
|
}; \
|
|
static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){ \
|
|
UNUSED_PARAMETER(z); UNUSED_PARAMETER(p); \
|
|
return &METHOD; \
|
|
} \
|
|
static const sqlite3_io_methods *(*const FINDER)(const char*,unixFile *p) \
|
|
= FINDER##Impl;
|
|
|
|
/*
|
|
** Here are all of the sqlite3_io_methods objects for each of the
|
|
** locking strategies. Functions that return pointers to these methods
|
|
** are also created.
|
|
*/
|
|
IOMETHODS(
|
|
posixIoFinder, /* Finder function name */
|
|
posixIoMethods, /* sqlite3_io_methods object name */
|
|
2, /* shared memory is enabled */
|
|
unixClose, /* xClose method */
|
|
unixLock, /* xLock method */
|
|
unixUnlock, /* xUnlock method */
|
|
unixCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
IOMETHODS(
|
|
nolockIoFinder, /* Finder function name */
|
|
nolockIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
nolockClose, /* xClose method */
|
|
nolockLock, /* xLock method */
|
|
nolockUnlock, /* xUnlock method */
|
|
nolockCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
IOMETHODS(
|
|
dotlockIoFinder, /* Finder function name */
|
|
dotlockIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
dotlockClose, /* xClose method */
|
|
dotlockLock, /* xLock method */
|
|
dotlockUnlock, /* xUnlock method */
|
|
dotlockCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS
|
|
IOMETHODS(
|
|
flockIoFinder, /* Finder function name */
|
|
flockIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
flockClose, /* xClose method */
|
|
flockLock, /* xLock method */
|
|
flockUnlock, /* xUnlock method */
|
|
flockCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
#endif
|
|
|
|
#if OS_VXWORKS
|
|
IOMETHODS(
|
|
semIoFinder, /* Finder function name */
|
|
semIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
semClose, /* xClose method */
|
|
semLock, /* xLock method */
|
|
semUnlock, /* xUnlock method */
|
|
semCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
#endif
|
|
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
IOMETHODS(
|
|
afpIoFinder, /* Finder function name */
|
|
afpIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
afpClose, /* xClose method */
|
|
afpLock, /* xLock method */
|
|
afpUnlock, /* xUnlock method */
|
|
afpCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
#endif
|
|
|
|
/*
|
|
** The proxy locking method is a "super-method" in the sense that it
|
|
** opens secondary file descriptors for the conch and lock files and
|
|
** it uses proxy, dot-file, AFP, and flock() locking methods on those
|
|
** secondary files. For this reason, the division that implements
|
|
** proxy locking is located much further down in the file. But we need
|
|
** to go ahead and define the sqlite3_io_methods and finder function
|
|
** for proxy locking here. So we forward declare the I/O methods.
|
|
*/
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
static int proxyClose(sqlite3_file*);
|
|
static int proxyLock(sqlite3_file*, int);
|
|
static int proxyUnlock(sqlite3_file*, int);
|
|
static int proxyCheckReservedLock(sqlite3_file*, int*);
|
|
IOMETHODS(
|
|
proxyIoFinder, /* Finder function name */
|
|
proxyIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
proxyClose, /* xClose method */
|
|
proxyLock, /* xLock method */
|
|
proxyUnlock, /* xUnlock method */
|
|
proxyCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
#endif
|
|
|
|
/* nfs lockd on OSX 10.3+ doesn't clear write locks when a read lock is set */
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
IOMETHODS(
|
|
nfsIoFinder, /* Finder function name */
|
|
nfsIoMethods, /* sqlite3_io_methods object name */
|
|
1, /* shared memory is disabled */
|
|
unixClose, /* xClose method */
|
|
unixLock, /* xLock method */
|
|
nfsUnlock, /* xUnlock method */
|
|
unixCheckReservedLock /* xCheckReservedLock method */
|
|
)
|
|
#endif
|
|
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
/*
|
|
** This "finder" function attempts to determine the best locking strategy
|
|
** for the database file "filePath". It then returns the sqlite3_io_methods
|
|
** object that implements that strategy.
|
|
**
|
|
** This is for MacOSX only.
|
|
*/
|
|
static const sqlite3_io_methods *autolockIoFinderImpl(
|
|
const char *filePath, /* name of the database file */
|
|
unixFile *pNew /* open file object for the database file */
|
|
){
|
|
static const struct Mapping {
|
|
const char *zFilesystem; /* Filesystem type name */
|
|
const sqlite3_io_methods *pMethods; /* Appropriate locking method */
|
|
} aMap[] = {
|
|
{ "hfs", &posixIoMethods },
|
|
{ "ufs", &posixIoMethods },
|
|
{ "afpfs", &afpIoMethods },
|
|
{ "smbfs", &afpIoMethods },
|
|
{ "webdav", &nolockIoMethods },
|
|
{ 0, 0 }
|
|
};
|
|
int i;
|
|
struct statfs fsInfo;
|
|
struct flock lockInfo;
|
|
|
|
if( !filePath ){
|
|
/* If filePath==NULL that means we are dealing with a transient file
|
|
** that does not need to be locked. */
|
|
return &nolockIoMethods;
|
|
}
|
|
if( statfs(filePath, &fsInfo) != -1 ){
|
|
if( fsInfo.f_flags & MNT_RDONLY ){
|
|
return &nolockIoMethods;
|
|
}
|
|
for(i=0; aMap[i].zFilesystem; i++){
|
|
if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
|
|
return aMap[i].pMethods;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Default case. Handles, amongst others, "nfs".
|
|
** Test byte-range lock using fcntl(). If the call succeeds,
|
|
** assume that the file-system supports POSIX style locks.
|
|
*/
|
|
lockInfo.l_len = 1;
|
|
lockInfo.l_start = 0;
|
|
lockInfo.l_whence = SEEK_SET;
|
|
lockInfo.l_type = F_RDLCK;
|
|
if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
|
|
if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){
|
|
return &nfsIoMethods;
|
|
} else {
|
|
return &posixIoMethods;
|
|
}
|
|
}else{
|
|
return &dotlockIoMethods;
|
|
}
|
|
}
|
|
static const sqlite3_io_methods
|
|
*(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
|
|
|
|
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
|
|
|
|
#if OS_VXWORKS && SQLITE_ENABLE_LOCKING_STYLE
|
|
/*
|
|
** This "finder" function attempts to determine the best locking strategy
|
|
** for the database file "filePath". It then returns the sqlite3_io_methods
|
|
** object that implements that strategy.
|
|
**
|
|
** This is for VXWorks only.
|
|
*/
|
|
static const sqlite3_io_methods *autolockIoFinderImpl(
|
|
const char *filePath, /* name of the database file */
|
|
unixFile *pNew /* the open file object */
|
|
){
|
|
struct flock lockInfo;
|
|
|
|
if( !filePath ){
|
|
/* If filePath==NULL that means we are dealing with a transient file
|
|
** that does not need to be locked. */
|
|
return &nolockIoMethods;
|
|
}
|
|
|
|
/* Test if fcntl() is supported and use POSIX style locks.
|
|
** Otherwise fall back to the named semaphore method.
|
|
*/
|
|
lockInfo.l_len = 1;
|
|
lockInfo.l_start = 0;
|
|
lockInfo.l_whence = SEEK_SET;
|
|
lockInfo.l_type = F_RDLCK;
|
|
if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
|
|
return &posixIoMethods;
|
|
}else{
|
|
return &semIoMethods;
|
|
}
|
|
}
|
|
static const sqlite3_io_methods
|
|
*(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
|
|
|
|
#endif /* OS_VXWORKS && SQLITE_ENABLE_LOCKING_STYLE */
|
|
|
|
/*
|
|
** An abstract type for a pointer to a IO method finder function:
|
|
*/
|
|
typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);
|
|
|
|
|
|
/****************************************************************************
|
|
**************************** sqlite3_vfs methods ****************************
|
|
**
|
|
** This division contains the implementation of methods on the
|
|
** sqlite3_vfs object.
|
|
*/
|
|
|
|
/*
|
|
** Initialize the contents of the unixFile structure pointed to by pId.
|
|
*/
|
|
static int fillInUnixFile(
|
|
sqlite3_vfs *pVfs, /* Pointer to vfs object */
|
|
int h, /* Open file descriptor of file being opened */
|
|
int dirfd, /* Directory file descriptor */
|
|
sqlite3_file *pId, /* Write to the unixFile structure here */
|
|
const char *zFilename, /* Name of the file being opened */
|
|
int noLock, /* Omit locking if true */
|
|
int isDelete, /* Delete on close if true */
|
|
int isReadOnly /* True if the file is opened read-only */
|
|
){
|
|
const sqlite3_io_methods *pLockingStyle;
|
|
unixFile *pNew = (unixFile *)pId;
|
|
int rc = SQLITE_OK;
|
|
|
|
assert( pNew->pInode==NULL );
|
|
|
|
/* Parameter isDelete is only used on vxworks. Express this explicitly
|
|
** here to prevent compiler warnings about unused parameters.
|
|
*/
|
|
UNUSED_PARAMETER(isDelete);
|
|
|
|
/* Usually the path zFilename should not be a relative pathname. The
|
|
** exception is when opening the proxy "conch" file in builds that
|
|
** include the special Apple locking styles.
|
|
*/
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
assert( zFilename==0 || zFilename[0]=='/'
|
|
|| pVfs->pAppData==(void*)&autolockIoFinder );
|
|
#else
|
|
assert( zFilename==0 || zFilename[0]=='/' );
|
|
#endif
|
|
|
|
OSTRACE(("OPEN %-3d %s\n", h, zFilename));
|
|
pNew->h = h;
|
|
pNew->dirfd = dirfd;
|
|
pNew->zPath = zFilename;
|
|
if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
|
|
pNew->ctrlFlags = UNIXFILE_EXCL;
|
|
}else{
|
|
pNew->ctrlFlags = 0;
|
|
}
|
|
if( isReadOnly ){
|
|
pNew->ctrlFlags |= UNIXFILE_RDONLY;
|
|
}
|
|
|
|
#if OS_VXWORKS
|
|
pNew->pId = vxworksFindFileId(zFilename);
|
|
if( pNew->pId==0 ){
|
|
noLock = 1;
|
|
rc = SQLITE_NOMEM;
|
|
}
|
|
#endif
|
|
|
|
if( noLock ){
|
|
pLockingStyle = &nolockIoMethods;
|
|
}else{
|
|
pLockingStyle = (**(finder_type*)pVfs->pAppData)(zFilename, pNew);
|
|
#if SQLITE_ENABLE_LOCKING_STYLE
|
|
/* Cache zFilename in the locking context (AFP and dotlock override) for
|
|
** proxyLock activation is possible (remote proxy is based on db name)
|
|
** zFilename remains valid until file is closed, to support */
|
|
pNew->lockingContext = (void*)zFilename;
|
|
#endif
|
|
}
|
|
|
|
if( pLockingStyle == &posixIoMethods
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
|| pLockingStyle == &nfsIoMethods
|
|
#endif
|
|
){
|
|
unixEnterMutex();
|
|
rc = findInodeInfo(pNew, &pNew->pInode);
|
|
if( rc!=SQLITE_OK ){
|
|
/* If an error occured in findInodeInfo(), close the file descriptor
|
|
** immediately, before releasing the mutex. findInodeInfo() may fail
|
|
** in two scenarios:
|
|
**
|
|
** (a) A call to fstat() failed.
|
|
** (b) A malloc failed.
|
|
**
|
|
** Scenario (b) may only occur if the process is holding no other
|
|
** file descriptors open on the same file. If there were other file
|
|
** descriptors on this file, then no malloc would be required by
|
|
** findInodeInfo(). If this is the case, it is quite safe to close
|
|
** handle h - as it is guaranteed that no posix locks will be released
|
|
** by doing so.
|
|
**
|
|
** If scenario (a) caused the error then things are not so safe. The
|
|
** implicit assumption here is that if fstat() fails, things are in
|
|
** such bad shape that dropping a lock or two doesn't matter much.
|
|
*/
|
|
robust_close(pNew, h, __LINE__);
|
|
h = -1;
|
|
}
|
|
unixLeaveMutex();
|
|
}
|
|
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
|
|
else if( pLockingStyle == &afpIoMethods ){
|
|
/* AFP locking uses the file path so it needs to be included in
|
|
** the afpLockingContext.
|
|
*/
|
|
afpLockingContext *pCtx;
|
|
pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) );
|
|
if( pCtx==0 ){
|
|
rc = SQLITE_NOMEM;
|
|
}else{
|
|
/* NB: zFilename exists and remains valid until the file is closed
|
|
** according to requirement F11141. So we do not need to make a
|
|
** copy of the filename. */
|
|
pCtx->dbPath = zFilename;
|
|
pCtx->reserved = 0;
|
|
srandomdev();
|
|
unixEnterMutex();
|
|
rc = findInodeInfo(pNew, &pNew->pInode);
|
|
if( rc!=SQLITE_OK ){
|
|
sqlite3_free(pNew->lockingContext);
|
|
robust_close(pNew, h, __LINE__);
|
|
h = -1;
|
|
}
|
|
unixLeaveMutex();
|
|
}
|
|
}
|
|
#endif
|
|
|
|
else if( pLockingStyle == &dotlockIoMethods ){
|
|
/* Dotfile locking uses the file path so it needs to be included in
|
|
** the dotlockLockingContext
|
|
*/
|
|
char *zLockFile;
|
|
int nFilename;
|
|
nFilename = (int)strlen(zFilename) + 6;
|
|
zLockFile = (char *)sqlite3_malloc(nFilename);
|
|
if( zLockFile==0 ){
|
|
rc = SQLITE_NOMEM;
|
|
}else{
|
|
sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
|
|
}
|
|
pNew->lockingContext = zLockFile;
|
|
}
|
|
|
|
#if OS_VXWORKS
|
|
else if( pLockingStyle == &semIoMethods ){
|
|
/* Named semaphore locking uses the file path so it needs to be
|
|
** included in the semLockingContext
|
|
*/
|
|
unixEnterMutex();
|
|
rc = findInodeInfo(pNew, &pNew->pInode);
|
|
if( (rc==SQLITE_OK) && (pNew->pInode->pSem==NULL) ){
|
|
char *zSemName = pNew->pInode->aSemName;
|
|
int n;
|
|
sqlite3_snprintf(MAX_PATHNAME, zSemName, "/%s.sem",
|
|
pNew->pId->zCanonicalName);
|
|
for( n=1; zSemName[n]; n++ )
|
|
if( zSemName[n]=='/' ) zSemName[n] = '_';
|
|
pNew->pInode->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
|
|
if( pNew->pInode->pSem == SEM_FAILED ){
|
|
rc = SQLITE_NOMEM;
|
|
pNew->pInode->aSemName[0] = '\0';
|
|
}
|
|
}
|
|
unixLeaveMutex();
|
|
}
|
|
#endif
|
|
|
|
pNew->lastErrno = 0;
|
|
#if OS_VXWORKS
|
|
if( rc!=SQLITE_OK ){
|
|
if( h>=0 ) robust_close(pNew, h, __LINE__);
|
|
h = -1;
|
|
unlink(zFilename);
|
|
isDelete = 0;
|
|
}
|
|
pNew->isDelete = isDelete;
|
|
#endif
|
|
if( rc!=SQLITE_OK ){
|
|
if( dirfd>=0 ) robust_close(pNew, dirfd, __LINE__);
|
|
if( h>=0 ) robust_close(pNew, h, __LINE__);
|
|
}else{
|
|
pNew->pMethod = pLockingStyle;
|
|
OpenCounter(+1);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Open a file descriptor to the directory containing file zFilename.
|
|
** If successful, *pFd is set to the opened file descriptor and
|
|
** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM
|
|
** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined
|
|
** value.
|
|
**
|
|
** If SQLITE_OK is returned, the caller is responsible for closing
|
|
** the file descriptor *pFd using close().
|
|
*/
|
|
static int openDirectory(const char *zFilename, int *pFd){
|
|
int ii;
|
|
int fd = -1;
|
|
char zDirname[MAX_PATHNAME+1];
|
|
|
|
sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
|
|
for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
|
|
if( ii>0 ){
|
|
zDirname[ii] = '\0';
|
|
fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
|
|
if( fd>=0 ){
|
|
#ifdef FD_CLOEXEC
|
|
osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
|
|
#endif
|
|
OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
|
|
}
|
|
}
|
|
*pFd = fd;
|
|
return (fd>=0?SQLITE_OK:unixLogError(SQLITE_CANTOPEN_BKPT, "open", zDirname));
|
|
}
|
|
|
|
/*
|
|
** Return the name of a directory in which to put temporary files.
|
|
** If no suitable temporary file directory can be found, return NULL.
|
|
*/
|
|
static const char *unixTempFileDir(void){
|
|
static const char *azDirs[] = {
|
|
0,
|
|
0,
|
|
"/var/tmp",
|
|
"/usr/tmp",
|
|
"/tmp",
|
|
0 /* List terminator */
|
|
};
|
|
unsigned int i;
|
|
struct stat buf;
|
|
const char *zDir = 0;
|
|
|
|
azDirs[0] = sqlite3_temp_directory;
|
|
if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
|
|
for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); zDir=azDirs[i++]){
|
|
if( zDir==0 ) continue;
|
|
if( osStat(zDir, &buf) ) continue;
|
|
if( !S_ISDIR(buf.st_mode) ) continue;
|
|
if( osAccess(zDir, 07) ) continue;
|
|
break;
|
|
}
|
|
return zDir;
|
|
}
|
|
|
|
/*
|
|
** Create a temporary file name in zBuf. zBuf must be allocated
|
|
** by the calling process and must be big enough to hold at least
|
|
** pVfs->mxPathname bytes.
|
|
*/
|
|
static int unixGetTempname(int nBuf, char *zBuf){
|
|
static const unsigned char zChars[] =
|
|
"abcdefghijklmnopqrstuvwxyz"
|
|
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
|
|
"0123456789";
|
|
unsigned int i, j;
|
|
const char *zDir;
|
|
|
|
/* It's odd to simulate an io-error here, but really this is just
|
|
** using the io-error infrastructure to test that SQLite handles this
|
|
** function failing.
|
|
*/
|
|
SimulateIOError( return SQLITE_IOERR );
|
|
|
|
zDir = unixTempFileDir();
|
|
if( zDir==0 ) zDir = ".";
|
|
|
|
/* Check that the output buffer is large enough for the temporary file
|
|
** name. If it is not, return SQLITE_ERROR.
|
|
*/
|
|
if( (strlen(zDir) + strlen(SQLITE_TEMP_FILE_PREFIX) + 17) >= (size_t)nBuf ){
|
|
return SQLITE_ERROR;
|
|
}
|
|
|
|
do{
|
|
sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir);
|
|
j = (int)strlen(zBuf);
|
|
sqlite3_randomness(15, &zBuf[j]);
|
|
for(i=0; i<15; i++, j++){
|
|
zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
|
|
}
|
|
zBuf[j] = 0;
|
|
}while( osAccess(zBuf,0)==0 );
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
|
|
/*
|
|
** Routine to transform a unixFile into a proxy-locking unixFile.
|
|
** Implementation in the proxy-lock division, but used by unixOpen()
|
|
** if SQLITE_PREFER_PROXY_LOCKING is defined.
|
|
*/
|
|
static int proxyTransformUnixFile(unixFile*, const char*);
|
|
#endif
|
|
|
|
/*
|
|
** Search for an unused file descriptor that was opened on the database
|
|
** file (not a journal or master-journal file) identified by pathname
|
|
** zPath with SQLITE_OPEN_XXX flags matching those passed as the second
|
|
** argument to this function.
|
|
**
|
|
** Such a file descriptor may exist if a database connection was closed
|
|
** but the associated file descriptor could not be closed because some
|
|
** other file descriptor open on the same file is holding a file-lock.
|
|
** Refer to comments in the unixClose() function and the lengthy comment
|
|
** describing "Posix Advisory Locking" at the start of this file for
|
|
** further details. Also, ticket #4018.
|
|
**
|
|
** If a suitable file descriptor is found, then it is returned. If no
|
|
** such file descriptor is located, -1 is returned.
|
|
*/
|
|
static UnixUnusedFd *findReusableFd(const char *zPath, int flags){
|
|
UnixUnusedFd *pUnused = 0;
|
|
|
|
/* Do not search for an unused file descriptor on vxworks. Not because
|
|
** vxworks would not benefit from the change (it might, we're not sure),
|
|
** but because no way to test it is currently available. It is better
|
|
** not to risk breaking vxworks support for the sake of such an obscure
|
|
** feature. */
|
|
#if !OS_VXWORKS
|
|
struct stat sStat; /* Results of stat() call */
|
|
|
|
/* A stat() call may fail for various reasons. If this happens, it is
|
|
** almost certain that an open() call on the same path will also fail.
|
|
** For this reason, if an error occurs in the stat() call here, it is
|
|
** ignored and -1 is returned. The caller will try to open a new file
|
|
** descriptor on the same path, fail, and return an error to SQLite.
|
|
**
|
|
** Even if a subsequent open() call does succeed, the consequences of
|
|
** not searching for a resusable file descriptor are not dire. */
|
|
if( 0==stat(zPath, &sStat) ){
|
|
unixInodeInfo *pInode;
|
|
|
|
unixEnterMutex();
|
|
pInode = inodeList;
|
|
while( pInode && (pInode->fileId.dev!=sStat.st_dev
|
|
|| pInode->fileId.ino!=sStat.st_ino) ){
|
|
pInode = pInode->pNext;
|
|
}
|
|
if( pInode ){
|
|
UnixUnusedFd **pp;
|
|
for(pp=&pInode->pUnused; *pp && (*pp)->flags!=flags; pp=&((*pp)->pNext));
|
|
pUnused = *pp;
|
|
if( pUnused ){
|
|
*pp = pUnused->pNext;
|
|
}
|
|
}
|
|
unixLeaveMutex();
|
|
}
|
|
#endif /* if !OS_VXWORKS */
|
|
return pUnused;
|
|
}
|
|
|
|
/*
|
|
** This function is called by unixOpen() to determine the unix permissions
|
|
** to create new files with. If no error occurs, then SQLITE_OK is returned
|
|
** and a value suitable for passing as the third argument to open(2) is
|
|
** written to *pMode. If an IO error occurs, an SQLite error code is
|
|
** returned and the value of *pMode is not modified.
|
|
**
|
|
** If the file being opened is a temporary file, it is always created with
|
|
** the octal permissions 0600 (read/writable by owner only). If the file
|
|
** is a database or master journal file, it is created with the permissions
|
|
** mask SQLITE_DEFAULT_FILE_PERMISSIONS.
|
|
**
|
|
** Finally, if the file being opened is a WAL or regular journal file, then
|
|
** this function queries the file-system for the permissions on the
|
|
** corresponding database file and sets *pMode to this value. Whenever
|
|
** possible, WAL and journal files are created using the same permissions
|
|
** as the associated database file.
|
|
*/
|
|
static int findCreateFileMode(
|
|
const char *zPath, /* Path of file (possibly) being created */
|
|
int flags, /* Flags passed as 4th argument to xOpen() */
|
|
mode_t *pMode /* OUT: Permissions to open file with */
|
|
){
|
|
int rc = SQLITE_OK; /* Return Code */
|
|
if( flags & (SQLITE_OPEN_WAL|SQLITE_OPEN_MAIN_JOURNAL) ){
|
|
char zDb[MAX_PATHNAME+1]; /* Database file path */
|
|
int nDb; /* Number of valid bytes in zDb */
|
|
struct stat sStat; /* Output of stat() on database file */
|
|
|
|
/* zPath is a path to a WAL or journal file. The following block derives
|
|
** the path to the associated database file from zPath. This block handles
|
|
** the following naming conventions:
|
|
**
|
|
** "<path to db>-journal"
|
|
** "<path to db>-wal"
|
|
** "<path to db>-journal-NNNN"
|
|
** "<path to db>-wal-NNNN"
|
|
**
|
|
** where NNNN is a 4 digit decimal number. The NNNN naming schemes are
|
|
** used by the test_multiplex.c module.
|
|
*/
|
|
nDb = sqlite3Strlen30(zPath) - 1;
|
|
while( nDb>0 && zPath[nDb]!='l' ) nDb--;
|
|
nDb -= ((flags & SQLITE_OPEN_WAL) ? 3 : 7);
|
|
memcpy(zDb, zPath, nDb);
|
|
zDb[nDb] = '\0';
|
|
|
|
if( 0==stat(zDb, &sStat) ){
|
|
*pMode = sStat.st_mode & 0777;
|
|
}else{
|
|
rc = SQLITE_IOERR_FSTAT;
|
|
}
|
|
}else if( flags & SQLITE_OPEN_DELETEONCLOSE ){
|
|
*pMode = 0600;
|
|
}else{
|
|
*pMode = SQLITE_DEFAULT_FILE_PERMISSIONS;
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Open the file zPath.
|
|
**
|
|
** Previously, the SQLite OS layer used three functions in place of this
|
|
** one:
|
|
**
|
|
** sqlite3OsOpenReadWrite();
|
|
** sqlite3OsOpenReadOnly();
|
|
** sqlite3OsOpenExclusive();
|
|
**
|
|
** These calls correspond to the following combinations of flags:
|
|
**
|
|
** ReadWrite() -> (READWRITE | CREATE)
|
|
** ReadOnly() -> (READONLY)
|
|
** OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE)
|
|
**
|
|
** The old OpenExclusive() accepted a boolean argument - "delFlag". If
|
|
** true, the file was configured to be automatically deleted when the
|
|
** file handle closed. To achieve the same effect using this new
|
|
** interface, add the DELETEONCLOSE flag to those specified above for
|
|
** OpenExclusive().
|
|
*/
|
|
static int unixOpen(
|
|
sqlite3_vfs *pVfs, /* The VFS for which this is the xOpen method */
|
|
const char *zPath, /* Pathname of file to be opened */
|
|
sqlite3_file *pFile, /* The file descriptor to be filled in */
|
|
int flags, /* Input flags to control the opening */
|
|
int *pOutFlags /* Output flags returned to SQLite core */
|
|
){
|
|
unixFile *p = (unixFile *)pFile;
|
|
int fd = -1; /* File descriptor returned by open() */
|
|
int dirfd = -1; /* Directory file descriptor */
|
|
int openFlags = 0; /* Flags to pass to open() */
|
|
int eType = flags&0xFFFFFF00; /* Type of file to open */
|
|
int noLock; /* True to omit locking primitives */
|
|
int rc = SQLITE_OK; /* Function Return Code */
|
|
|
|
int isExclusive = (flags & SQLITE_OPEN_EXCLUSIVE);
|
|
int isDelete = (flags & SQLITE_OPEN_DELETEONCLOSE);
|
|
int isCreate = (flags & SQLITE_OPEN_CREATE);
|
|
int isReadonly = (flags & SQLITE_OPEN_READONLY);
|
|
int isReadWrite = (flags & SQLITE_OPEN_READWRITE);
|
|
#if SQLITE_ENABLE_LOCKING_STYLE
|
|
int isAutoProxy = (flags & SQLITE_OPEN_AUTOPROXY);
|
|
#endif
|
|
|
|
/* If creating a master or main-file journal, this function will open
|
|
** a file-descriptor on the directory too. The first time unixSync()
|
|
** is called the directory file descriptor will be fsync()ed and close()d.
|
|
*/
|
|
int isOpenDirectory = (isCreate && (
|
|
eType==SQLITE_OPEN_MASTER_JOURNAL
|
|
|| eType==SQLITE_OPEN_MAIN_JOURNAL
|
|
|| eType==SQLITE_OPEN_WAL
|
|
));
|
|
|
|
/* If argument zPath is a NULL pointer, this function is required to open
|
|
** a temporary file. Use this buffer to store the file name in.
|
|
*/
|
|
char zTmpname[MAX_PATHNAME+1];
|
|
const char *zName = zPath;
|
|
|
|
/* Check the following statements are true:
|
|
**
|
|
** (a) Exactly one of the READWRITE and READONLY flags must be set, and
|
|
** (b) if CREATE is set, then READWRITE must also be set, and
|
|
** (c) if EXCLUSIVE is set, then CREATE must also be set.
|
|
** (d) if DELETEONCLOSE is set, then CREATE must also be set.
|
|
*/
|
|
assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
|
|
assert(isCreate==0 || isReadWrite);
|
|
assert(isExclusive==0 || isCreate);
|
|
assert(isDelete==0 || isCreate);
|
|
|
|
/* The main DB, main journal, WAL file and master journal are never
|
|
** automatically deleted. Nor are they ever temporary files. */
|
|
assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
|
|
assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
|
|
assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
|
|
assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );
|
|
|
|
/* Assert that the upper layer has set one of the "file-type" flags. */
|
|
assert( eType==SQLITE_OPEN_MAIN_DB || eType==SQLITE_OPEN_TEMP_DB
|
|
|| eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL
|
|
|| eType==SQLITE_OPEN_SUBJOURNAL || eType==SQLITE_OPEN_MASTER_JOURNAL
|
|
|| eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
|
|
);
|
|
|
|
memset(p, 0, sizeof(unixFile));
|
|
|
|
if( eType==SQLITE_OPEN_MAIN_DB ){
|
|
UnixUnusedFd *pUnused;
|
|
pUnused = findReusableFd(zName, flags);
|
|
if( pUnused ){
|
|
fd = pUnused->fd;
|
|
}else{
|
|
pUnused = sqlite3_malloc(sizeof(*pUnused));
|
|
if( !pUnused ){
|
|
return SQLITE_NOMEM;
|
|
}
|
|
}
|
|
p->pUnused = pUnused;
|
|
}else if( !zName ){
|
|
/* If zName is NULL, the upper layer is requesting a temp file. */
|
|
assert(isDelete && !isOpenDirectory);
|
|
rc = unixGetTempname(MAX_PATHNAME+1, zTmpname);
|
|
if( rc!=SQLITE_OK ){
|
|
return rc;
|
|
}
|
|
zName = zTmpname;
|
|
}
|
|
|
|
/* Determine the value of the flags parameter passed to POSIX function
|
|
** open(). These must be calculated even if open() is not called, as
|
|
** they may be stored as part of the file handle and used by the
|
|
** 'conch file' locking functions later on. */
|
|
if( isReadonly ) openFlags |= O_RDONLY;
|
|
if( isReadWrite ) openFlags |= O_RDWR;
|
|
if( isCreate ) openFlags |= O_CREAT;
|
|
if( isExclusive ) openFlags |= (O_EXCL|O_NOFOLLOW);
|
|
openFlags |= (O_LARGEFILE|O_BINARY);
|
|
|
|
if( fd<0 ){
|
|
mode_t openMode; /* Permissions to create file with */
|
|
rc = findCreateFileMode(zName, flags, &openMode);
|
|
if( rc!=SQLITE_OK ){
|
|
assert( !p->pUnused );
|
|
assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL );
|
|
return rc;
|
|
}
|
|
fd = robust_open(zName, openFlags, openMode);
|
|
OSTRACE(("OPENX %-3d %s 0%o\n", fd, zName, openFlags));
|
|
if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){
|
|
/* Failed to open the file for read/write access. Try read-only. */
|
|
flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
|
|
openFlags &= ~(O_RDWR|O_CREAT);
|
|
flags |= SQLITE_OPEN_READONLY;
|
|
openFlags |= O_RDONLY;
|
|
isReadonly = 1;
|
|
fd = robust_open(zName, openFlags, openMode);
|
|
}
|
|
if( fd<0 ){
|
|
rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zName);
|
|
goto open_finished;
|
|
}
|
|
}
|
|
assert( fd>=0 );
|
|
if( pOutFlags ){
|
|
*pOutFlags = flags;
|
|
}
|
|
|
|
if( p->pUnused ){
|
|
p->pUnused->fd = fd;
|
|
p->pUnused->flags = flags;
|
|
}
|
|
|
|
if( isDelete ){
|
|
#if OS_VXWORKS
|
|
zPath = zName;
|
|
#else
|
|
unlink(zName);
|
|
#endif
|
|
}
|
|
#if SQLITE_ENABLE_LOCKING_STYLE
|
|
else{
|
|
p->openFlags = openFlags;
|
|
}
|
|
#endif
|
|
|
|
if( isOpenDirectory ){
|
|
rc = openDirectory(zPath, &dirfd);
|
|
if( rc!=SQLITE_OK ){
|
|
/* It is safe to close fd at this point, because it is guaranteed not
|
|
** to be open on a database file. If it were open on a database file,
|
|
** it would not be safe to close as this would release any locks held
|
|
** on the file by this process. */
|
|
assert( eType!=SQLITE_OPEN_MAIN_DB );
|
|
robust_close(p, fd, __LINE__);
|
|
goto open_finished;
|
|
}
|
|
}
|
|
|
|
#ifdef FD_CLOEXEC
|
|
osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
|
|
#endif
|
|
|
|
noLock = eType!=SQLITE_OPEN_MAIN_DB;
|
|
|
|
|
|
#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
|
|
struct statfs fsInfo;
|
|
if( fstatfs(fd, &fsInfo) == -1 ){
|
|
((unixFile*)pFile)->lastErrno = errno;
|
|
if( dirfd>=0 ) robust_close(p, dirfd, __LINE__);
|
|
robust_close(p, fd, __LINE__);
|
|
return SQLITE_IOERR_ACCESS;
|
|
}
|
|
if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
|
|
((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
|
|
}
|
|
#endif
|
|
|
|
#if SQLITE_ENABLE_LOCKING_STYLE
|
|
#if SQLITE_PREFER_PROXY_LOCKING
|
|
isAutoProxy = 1;
|
|
#endif
|
|
if( isAutoProxy && (zPath!=NULL) && (!noLock) && pVfs->xOpen ){
|
|
char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING");
|
|
int useProxy = 0;
|
|
|
|
/* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 0 means
|
|
** never use proxy, NULL means use proxy for non-local files only. */
|
|
if( envforce!=NULL ){
|
|
useProxy = atoi(envforce)>0;
|
|
}else{
|
|
struct statfs fsInfo;
|
|
if( statfs(zPath, &fsInfo) == -1 ){
|
|
/* In theory, the close(fd) call is sub-optimal. If the file opened
|
|
** with fd is a database file, and there are other connections open
|
|
** on that file that are currently holding advisory locks on it,
|
|
** then the call to close() will cancel those locks. In practice,
|
|
** we're assuming that statfs() doesn't fail very often. At least
|
|
** not while other file descriptors opened by the same process on
|
|
** the same file are working. */
|
|
p->lastErrno = errno;
|
|
if( dirfd>=0 ){
|
|
robust_close(p, dirfd, __LINE__);
|
|
}
|
|
robust_close(p, fd, __LINE__);
|
|
rc = SQLITE_IOERR_ACCESS;
|
|
goto open_finished;
|
|
}
|
|
useProxy = !(fsInfo.f_flags&MNT_LOCAL);
|
|
}
|
|
if( useProxy ){
|
|
rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
|
|
isDelete, isReadonly);
|
|
if( rc==SQLITE_OK ){
|
|
rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
|
|
if( rc!=SQLITE_OK ){
|
|
/* Use unixClose to clean up the resources added in fillInUnixFile
|
|
** and clear all the structure's references. Specifically,
|
|
** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op
|
|
*/
|
|
unixClose(pFile);
|
|
return rc;
|
|
}
|
|
}
|
|
goto open_finished;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
|
|
isDelete, isReadonly);
|
|
open_finished:
|
|
if( rc!=SQLITE_OK ){
|
|
sqlite3_free(p->pUnused);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
|
|
/*
|
|
** Delete the file at zPath. If the dirSync argument is true, fsync()
|
|
** the directory after deleting the file.
|
|
*/
|
|
static int unixDelete(
|
|
sqlite3_vfs *NotUsed, /* VFS containing this as the xDelete method */
|
|
const char *zPath, /* Name of file to be deleted */
|
|
int dirSync /* If true, fsync() directory after deleting file */
|
|
){
|
|
int rc = SQLITE_OK;
|
|
UNUSED_PARAMETER(NotUsed);
|
|
SimulateIOError(return SQLITE_IOERR_DELETE);
|
|
if( unlink(zPath)==(-1) && errno!=ENOENT ){
|
|
return unixLogError(SQLITE_IOERR_DELETE, "unlink", zPath);
|
|
}
|
|
#ifndef SQLITE_DISABLE_DIRSYNC
|
|
if( dirSync ){
|
|
int fd;
|
|
rc = openDirectory(zPath, &fd);
|
|
if( rc==SQLITE_OK ){
|
|
#if OS_VXWORKS
|
|
if( fsync(fd)==-1 )
|
|
#else
|
|
if( fsync(fd) )
|
|
#endif
|
|
{
|
|
rc = unixLogError(SQLITE_IOERR_DIR_FSYNC, "fsync", zPath);
|
|
}
|
|
robust_close(0, fd, __LINE__);
|
|
}
|
|
}
|
|
#endif
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Test the existance of or access permissions of file zPath. The
|
|
** test performed depends on the value of flags:
|
|
**
|
|
** SQLITE_ACCESS_EXISTS: Return 1 if the file exists
|
|
** SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
|
|
** SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
|
|
**
|
|
** Otherwise return 0.
|
|
*/
|
|
static int unixAccess(
|
|
sqlite3_vfs *NotUsed, /* The VFS containing this xAccess method */
|
|
const char *zPath, /* Path of the file to examine */
|
|
int flags, /* What do we want to learn about the zPath file? */
|
|
int *pResOut /* Write result boolean here */
|
|
){
|
|
int amode = 0;
|
|
UNUSED_PARAMETER(NotUsed);
|
|
SimulateIOError( return SQLITE_IOERR_ACCESS; );
|
|
switch( flags ){
|
|
case SQLITE_ACCESS_EXISTS:
|
|
amode = F_OK;
|
|
break;
|
|
case SQLITE_ACCESS_READWRITE:
|
|
amode = W_OK|R_OK;
|
|
break;
|
|
case SQLITE_ACCESS_READ:
|
|
amode = R_OK;
|
|
break;
|
|
|
|
default:
|
|
assert(!"Invalid flags argument");
|
|
}
|
|
*pResOut = (osAccess(zPath, amode)==0);
|
|
if( flags==SQLITE_ACCESS_EXISTS && *pResOut ){
|
|
struct stat buf;
|
|
if( 0==stat(zPath, &buf) && buf.st_size==0 ){
|
|
*pResOut = 0;
|
|
}
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
/*
|
|
** Turn a relative pathname into a full pathname. The relative path
|
|
** is stored as a nul-terminated string in the buffer pointed to by
|
|
** zPath.
|
|
**
|
|
** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes
|
|
** (in this case, MAX_PATHNAME bytes). The full-path is written to
|
|
** this buffer before returning.
|
|
*/
|
|
static int unixFullPathname(
|
|
sqlite3_vfs *pVfs, /* Pointer to vfs object */
|
|
const char *zPath, /* Possibly relative input path */
|
|
int nOut, /* Size of output buffer in bytes */
|
|
char *zOut /* Output buffer */
|
|
){
|
|
|
|
/* It's odd to simulate an io-error here, but really this is just
|
|
** using the io-error infrastructure to test that SQLite handles this
|
|
** function failing. This function could fail if, for example, the
|
|
** current working directory has been unlinked.
|
|
*/
|
|
SimulateIOError( return SQLITE_ERROR );
|
|
|
|
assert( pVfs->mxPathname==MAX_PATHNAME );
|
|
UNUSED_PARAMETER(pVfs);
|
|
|
|
zOut[nOut-1] = '\0';
|
|
if( zPath[0]=='/' ){
|
|
sqlite3_snprintf(nOut, zOut, "%s", zPath);
|
|
}else{
|
|
int nCwd;
|
|
if( osGetcwd(zOut, nOut-1)==0 ){
|
|
return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath);
|
|
}
|
|
nCwd = (int)strlen(zOut);
|
|
sqlite3_snprintf(nOut-nCwd, &zOut[nCwd], "/%s", zPath);
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
#ifndef SQLITE_OMIT_LOAD_EXTENSION
|
|
/*
|
|
** Interfaces for opening a shared library, finding entry points
|
|
** within the shared library, and closing the shared library.
|
|
*/
|
|
#include <dlfcn.h>
|
|
static void *unixDlOpen(sqlite3_vfs *NotUsed, const char *zFilename){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
|
|
}
|
|
|
|
/*
|
|
** SQLite calls this function immediately after a call to unixDlSym() or
|
|
** unixDlOpen() fails (returns a null pointer). If a more detailed error
|
|
** message is available, it is written to zBufOut. If no error message
|
|
** is available, zBufOut is left unmodified and SQLite uses a default
|
|
** error message.
|
|
*/
|
|
static void unixDlError(sqlite3_vfs *NotUsed, int nBuf, char *zBufOut){
|
|
const char *zErr;
|
|
UNUSED_PARAMETER(NotUsed);
|
|
unixEnterMutex();
|
|
zErr = dlerror();
|
|
if( zErr ){
|
|
sqlite3_snprintf(nBuf, zBufOut, "%s", zErr);
|
|
}
|
|
unixLeaveMutex();
|
|
}
|
|
static void (*unixDlSym(sqlite3_vfs *NotUsed, void *p, const char*zSym))(void){
|
|
/*
|
|
** GCC with -pedantic-errors says that C90 does not allow a void* to be
|
|
** cast into a pointer to a function. And yet the library dlsym() routine
|
|
** returns a void* which is really a pointer to a function. So how do we
|
|
** use dlsym() with -pedantic-errors?
|
|
**
|
|
** Variable x below is defined to be a pointer to a function taking
|
|
** parameters void* and const char* and returning a pointer to a function.
|
|
** We initialize x by assigning it a pointer to the dlsym() function.
|
|
** (That assignment requires a cast.) Then we call the function that
|
|
** x points to.
|
|
**
|
|
** This work-around is unlikely to work correctly on any system where
|
|
** you really cannot cast a function pointer into void*. But then, on the
|
|
** other hand, dlsym() will not work on such a system either, so we have
|
|
** not really lost anything.
|
|
*/
|
|
void (*(*x)(void*,const char*))(void);
|
|
UNUSED_PARAMETER(NotUsed);
|
|
x = (void(*(*)(void*,const char*))(void))dlsym;
|
|
return (*x)(p, zSym);
|
|
}
|
|
static void unixDlClose(sqlite3_vfs *NotUsed, void *pHandle){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
dlclose(pHandle);
|
|
}
|
|
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
|
|
#define unixDlOpen 0
|
|
#define unixDlError 0
|
|
#define unixDlSym 0
|
|
#define unixDlClose 0
|
|
#endif
|
|
|
|
/*
|
|
** Write nBuf bytes of random data to the supplied buffer zBuf.
|
|
*/
|
|
static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
assert((size_t)nBuf>=(sizeof(time_t)+sizeof(int)));
|
|
|
|
/* We have to initialize zBuf to prevent valgrind from reporting
|
|
** errors. The reports issued by valgrind are incorrect - we would
|
|
** prefer that the randomness be increased by making use of the
|
|
** uninitialized space in zBuf - but valgrind errors tend to worry
|
|
** some users. Rather than argue, it seems easier just to initialize
|
|
** the whole array and silence valgrind, even if that means less randomness
|
|
** in the random seed.
|
|
**
|
|
** When testing, initializing zBuf[] to zero is all we do. That means
|
|
** that we always use the same random number sequence. This makes the
|
|
** tests repeatable.
|
|
*/
|
|
memset(zBuf, 0, nBuf);
|
|
#if !defined(SQLITE_TEST)
|
|
{
|
|
int pid, fd;
|
|
fd = robust_open("/dev/urandom", O_RDONLY, 0);
|
|
if( fd<0 ){
|
|
time_t t;
|
|
time(&t);
|
|
memcpy(zBuf, &t, sizeof(t));
|
|
pid = getpid();
|
|
memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
|
|
assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
|
|
nBuf = sizeof(t) + sizeof(pid);
|
|
}else{
|
|
do{ nBuf = osRead(fd, zBuf, nBuf); }while( nBuf<0 && errno==EINTR );
|
|
robust_close(0, fd, __LINE__);
|
|
}
|
|
}
|
|
#endif
|
|
return nBuf;
|
|
}
|
|
|
|
|
|
/*
|
|
** Sleep for a little while. Return the amount of time slept.
|
|
** The argument is the number of microseconds we want to sleep.
|
|
** The return value is the number of microseconds of sleep actually
|
|
** requested from the underlying operating system, a number which
|
|
** might be greater than or equal to the argument, but not less
|
|
** than the argument.
|
|
*/
|
|
static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
|
|
#if OS_VXWORKS
|
|
struct timespec sp;
|
|
|
|
sp.tv_sec = microseconds / 1000000;
|
|
sp.tv_nsec = (microseconds % 1000000) * 1000;
|
|
nanosleep(&sp, NULL);
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return microseconds;
|
|
#elif defined(HAVE_USLEEP) && HAVE_USLEEP
|
|
usleep(microseconds);
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return microseconds;
|
|
#else
|
|
int seconds = (microseconds+999999)/1000000;
|
|
sleep(seconds);
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return seconds*1000000;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
** The following variable, if set to a non-zero value, is interpreted as
|
|
** the number of seconds since 1970 and is used to set the result of
|
|
** sqlite3OsCurrentTime() during testing.
|
|
*/
|
|
#ifdef SQLITE_TEST
|
|
int sqlite3_current_time = 0; /* Fake system time in seconds since 1970. */
|
|
#endif
|
|
|
|
/*
|
|
** Find the current time (in Universal Coordinated Time). Write into *piNow
|
|
** the current time and date as a Julian Day number times 86_400_000. In
|
|
** other words, write into *piNow the number of milliseconds since the Julian
|
|
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
|
|
** proleptic Gregorian calendar.
|
|
**
|
|
** On success, return 0. Return 1 if the time and date cannot be found.
|
|
*/
|
|
static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){
|
|
static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
|
|
#if defined(NO_GETTOD)
|
|
time_t t;
|
|
time(&t);
|
|
*piNow = ((sqlite3_int64)t)*1000 + unixEpoch;
|
|
#elif OS_VXWORKS
|
|
struct timespec sNow;
|
|
clock_gettime(CLOCK_REALTIME, &sNow);
|
|
*piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_nsec/1000000;
|
|
#else
|
|
struct timeval sNow;
|
|
gettimeofday(&sNow, 0);
|
|
*piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_usec/1000;
|
|
#endif
|
|
|
|
#ifdef SQLITE_TEST
|
|
if( sqlite3_current_time ){
|
|
*piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
|
|
}
|
|
#endif
|
|
UNUSED_PARAMETER(NotUsed);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** Find the current time (in Universal Coordinated Time). Write the
|
|
** current time and date as a Julian Day number into *prNow and
|
|
** return 0. Return 1 if the time and date cannot be found.
|
|
*/
|
|
static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
|
|
sqlite3_int64 i;
|
|
UNUSED_PARAMETER(NotUsed);
|
|
unixCurrentTimeInt64(0, &i);
|
|
*prNow = i/86400000.0;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** We added the xGetLastError() method with the intention of providing
|
|
** better low-level error messages when operating-system problems come up
|
|
** during SQLite operation. But so far, none of that has been implemented
|
|
** in the core. So this routine is never called. For now, it is merely
|
|
** a place-holder.
|
|
*/
|
|
static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){
|
|
UNUSED_PARAMETER(NotUsed);
|
|
UNUSED_PARAMETER(NotUsed2);
|
|
UNUSED_PARAMETER(NotUsed3);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
************************ End of sqlite3_vfs methods ***************************
|
|
******************************************************************************/
|
|
|
|
/******************************************************************************
|
|
************************** Begin Proxy Locking ********************************
|
|
**
|
|
** Proxy locking is a "uber-locking-method" in this sense: It uses the
|
|
** other locking methods on secondary lock files. Proxy locking is a
|
|
** meta-layer over top of the primitive locking implemented above. For
|
|
** this reason, the division that implements of proxy locking is deferred
|
|
** until late in the file (here) after all of the other I/O methods have
|
|
** been defined - so that the primitive locking methods are available
|
|
** as services to help with the implementation of proxy locking.
|
|
**
|
|
****
|
|
**
|
|
** The default locking schemes in SQLite use byte-range locks on the
|
|
** database file to coordinate safe, concurrent access by multiple readers
|
|
** and writers [http://sqlite.org/lockingv3.html]. The five file locking
|
|
** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented
|
|
** as POSIX read & write locks over fixed set of locations (via fsctl),
|
|
** on AFP and SMB only exclusive byte-range locks are available via fsctl
|
|
** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states.
|
|
** To simulate a F_RDLCK on the shared range, on AFP a randomly selected
|
|
** address in the shared range is taken for a SHARED lock, the entire
|
|
** shared range is taken for an EXCLUSIVE lock):
|
|
**
|
|
** PENDING_BYTE 0x40000000
|
|
** RESERVED_BYTE 0x40000001
|
|
** SHARED_RANGE 0x40000002 -> 0x40000200
|
|
**
|
|
** This works well on the local file system, but shows a nearly 100x
|
|
** slowdown in read performance on AFP because the AFP client disables
|
|
** the read cache when byte-range locks are present. Enabling the read
|
|
** cache exposes a cache coherency problem that is present on all OS X
|
|
** supported network file systems. NFS and AFP both observe the
|
|
** close-to-open semantics for ensuring cache coherency
|
|
** [http://nfs.sourceforge.net/#faq_a8], which does not effectively
|
|
** address the requirements for concurrent database access by multiple
|
|
** readers and writers
|
|
** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html].
|
|
**
|
|
** To address the performance and cache coherency issues, proxy file locking
|
|
** changes the way database access is controlled by limiting access to a
|
|
** single host at a time and moving file locks off of the database file
|
|
** and onto a proxy file on the local file system.
|
|
**
|
|
**
|
|
** Using proxy locks
|
|
** -----------------
|
|
**
|
|
** C APIs
|
|
**
|
|
** sqlite3_file_control(db, dbname, SQLITE_SET_LOCKPROXYFILE,
|
|
** <proxy_path> | ":auto:");
|
|
** sqlite3_file_control(db, dbname, SQLITE_GET_LOCKPROXYFILE, &<proxy_path>);
|
|
**
|
|
**
|
|
** SQL pragmas
|
|
**
|
|
** PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto:
|
|
** PRAGMA [database.]lock_proxy_file
|
|
**
|
|
** Specifying ":auto:" means that if there is a conch file with a matching
|
|
** host ID in it, the proxy path in the conch file will be used, otherwise
|
|
** a proxy path based on the user's temp dir
|
|
** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the
|
|
** actual proxy file name is generated from the name and path of the
|
|
** database file. For example:
|
|
**
|
|
** For database path "/Users/me/foo.db"
|
|
** The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:")
|
|
**
|
|
** Once a lock proxy is configured for a database connection, it can not
|
|
** be removed, however it may be switched to a different proxy path via
|
|
** the above APIs (assuming the conch file is not being held by another
|
|
** connection or process).
|
|
**
|
|
**
|
|
** How proxy locking works
|
|
** -----------------------
|
|
**
|
|
** Proxy file locking relies primarily on two new supporting files:
|
|
**
|
|
** * conch file to limit access to the database file to a single host
|
|
** at a time
|
|
**
|
|
** * proxy file to act as a proxy for the advisory locks normally
|
|
** taken on the database
|
|
**
|
|
** The conch file - to use a proxy file, sqlite must first "hold the conch"
|
|
** by taking an sqlite-style shared lock on the conch file, reading the
|
|
** contents and comparing the host's unique host ID (see below) and lock
|
|
** proxy path against the values stored in the conch. The conch file is
|
|
** stored in the same directory as the database file and the file name
|
|
** is patterned after the database file name as ".<databasename>-conch".
|
|
** If the conch file does not exist, or it's contents do not match the
|
|
** host ID and/or proxy path, then the lock is escalated to an exclusive
|
|
** lock and the conch file contents is updated with the host ID and proxy
|
|
** path and the lock is downgraded to a shared lock again. If the conch
|
|
** is held by another process (with a shared lock), the exclusive lock
|
|
** will fail and SQLITE_BUSY is returned.
|
|
**
|
|
** The proxy file - a single-byte file used for all advisory file locks
|
|
** normally taken on the database file. This allows for safe sharing
|
|
** of the database file for multiple readers and writers on the same
|
|
** host (the conch ensures that they all use the same local lock file).
|
|
**
|
|
** Requesting the lock proxy does not immediately take the conch, it is
|
|
** only taken when the first request to lock database file is made.
|
|
** This matches the semantics of the traditional locking behavior, where
|
|
** opening a connection to a database file does not take a lock on it.
|
|
** The shared lock and an open file descriptor are maintained until
|
|
** the connection to the database is closed.
|
|
**
|
|
** The proxy file and the lock file are never deleted so they only need
|
|
** to be created the first time they are used.
|
|
**
|
|
** Configuration options
|
|
** ---------------------
|
|
**
|
|
** SQLITE_PREFER_PROXY_LOCKING
|
|
**
|
|
** Database files accessed on non-local file systems are
|
|
** automatically configured for proxy locking, lock files are
|
|
** named automatically using the same logic as
|
|
** PRAGMA lock_proxy_file=":auto:"
|
|
**
|
|
** SQLITE_PROXY_DEBUG
|
|
**
|
|
** Enables the logging of error messages during host id file
|
|
** retrieval and creation
|
|
**
|
|
** LOCKPROXYDIR
|
|
**
|
|
** Overrides the default directory used for lock proxy files that
|
|
** are named automatically via the ":auto:" setting
|
|
**
|
|
** SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
|
|
**
|
|
** Permissions to use when creating a directory for storing the
|
|
** lock proxy files, only used when LOCKPROXYDIR is not set.
|
|
**
|
|
**
|
|
** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING,
|
|
** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will
|
|
** force proxy locking to be used for every database file opened, and 0
|
|
** will force automatic proxy locking to be disabled for all database
|
|
** files (explicity calling the SQLITE_SET_LOCKPROXYFILE pragma or
|
|
** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING).
|
|
*/
|
|
|
|
/*
|
|
** Proxy locking is only available on MacOSX
|
|
*/
|
|
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
|
|
|
|
/*
|
|
** The proxyLockingContext has the path and file structures for the remote
|
|
** and local proxy files in it
|
|
*/
|
|
typedef struct proxyLockingContext proxyLockingContext;
|
|
struct proxyLockingContext {
|
|
unixFile *conchFile; /* Open conch file */
|
|
char *conchFilePath; /* Name of the conch file */
|
|
unixFile *lockProxy; /* Open proxy lock file */
|
|
char *lockProxyPath; /* Name of the proxy lock file */
|
|
char *dbPath; /* Name of the open file */
|
|
int conchHeld; /* 1 if the conch is held, -1 if lockless */
|
|
void *oldLockingContext; /* Original lockingcontext to restore on close */
|
|
sqlite3_io_methods const *pOldMethod; /* Original I/O methods for close */
|
|
};
|
|
|
|
/*
|
|
** The proxy lock file path for the database at dbPath is written into lPath,
|
|
** which must point to valid, writable memory large enough for a maxLen length
|
|
** file path.
|
|
*/
|
|
static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){
|
|
int len;
|
|
int dbLen;
|
|
int i;
|
|
|
|
#ifdef LOCKPROXYDIR
|
|
len = strlcpy(lPath, LOCKPROXYDIR, maxLen);
|
|
#else
|
|
# ifdef _CS_DARWIN_USER_TEMP_DIR
|
|
{
|
|
if( !confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen) ){
|
|
OSTRACE(("GETLOCKPATH failed %s errno=%d pid=%d\n",
|
|
lPath, errno, getpid()));
|
|
return SQLITE_IOERR_LOCK;
|
|
}
|
|
len = strlcat(lPath, "sqliteplocks", maxLen);
|
|
}
|
|
# else
|
|
len = strlcpy(lPath, "/tmp/", maxLen);
|
|
# endif
|
|
#endif
|
|
|
|
if( lPath[len-1]!='/' ){
|
|
len = strlcat(lPath, "/", maxLen);
|
|
}
|
|
|
|
/* transform the db path to a unique cache name */
|
|
dbLen = (int)strlen(dbPath);
|
|
for( i=0; i<dbLen && (i+len+7)<(int)maxLen; i++){
|
|
char c = dbPath[i];
|
|
lPath[i+len] = (c=='/')?'_':c;
|
|
}
|
|
lPath[i+len]='\0';
|
|
strlcat(lPath, ":auto:", maxLen);
|
|
OSTRACE(("GETLOCKPATH proxy lock path=%s pid=%d\n", lPath, getpid()));
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Creates the lock file and any missing directories in lockPath
|
|
*/
|
|
static int proxyCreateLockPath(const char *lockPath){
|
|
int i, len;
|
|
char buf[MAXPATHLEN];
|
|
int start = 0;
|
|
|
|
assert(lockPath!=NULL);
|
|
/* try to create all the intermediate directories */
|
|
len = (int)strlen(lockPath);
|
|
buf[0] = lockPath[0];
|
|
for( i=1; i<len; i++ ){
|
|
if( lockPath[i] == '/' && (i - start > 0) ){
|
|
/* only mkdir if leaf dir != "." or "/" or ".." */
|
|
if( i-start>2 || (i-start==1 && buf[start] != '.' && buf[start] != '/')
|
|
|| (i-start==2 && buf[start] != '.' && buf[start+1] != '.') ){
|
|
buf[i]='\0';
|
|
if( mkdir(buf, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){
|
|
int err=errno;
|
|
if( err!=EEXIST ) {
|
|
OSTRACE(("CREATELOCKPATH FAILED creating %s, "
|
|
"'%s' proxy lock path=%s pid=%d\n",
|
|
buf, strerror(err), lockPath, getpid()));
|
|
return err;
|
|
}
|
|
}
|
|
}
|
|
start=i+1;
|
|
}
|
|
buf[i] = lockPath[i];
|
|
}
|
|
OSTRACE(("CREATELOCKPATH proxy lock path=%s pid=%d\n", lockPath, getpid()));
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** Create a new VFS file descriptor (stored in memory obtained from
|
|
** sqlite3_malloc) and open the file named "path" in the file descriptor.
|
|
**
|
|
** The caller is responsible not only for closing the file descriptor
|
|
** but also for freeing the memory associated with the file descriptor.
|
|
*/
|
|
static int proxyCreateUnixFile(
|
|
const char *path, /* path for the new unixFile */
|
|
unixFile **ppFile, /* unixFile created and returned by ref */
|
|
int islockfile /* if non zero missing dirs will be created */
|
|
) {
|
|
int fd = -1;
|
|
int dirfd = -1;
|
|
unixFile *pNew;
|
|
int rc = SQLITE_OK;
|
|
int openFlags = O_RDWR | O_CREAT;
|
|
sqlite3_vfs dummyVfs;
|
|
int terrno = 0;
|
|
UnixUnusedFd *pUnused = NULL;
|
|
|
|
/* 1. first try to open/create the file
|
|
** 2. if that fails, and this is a lock file (not-conch), try creating
|
|
** the parent directories and then try again.
|
|
** 3. if that fails, try to open the file read-only
|
|
** otherwise return BUSY (if lock file) or CANTOPEN for the conch file
|
|
*/
|
|
pUnused = findReusableFd(path, openFlags);
|
|
if( pUnused ){
|
|
fd = pUnused->fd;
|
|
}else{
|
|
pUnused = sqlite3_malloc(sizeof(*pUnused));
|
|
if( !pUnused ){
|
|
return SQLITE_NOMEM;
|
|
}
|
|
}
|
|
if( fd<0 ){
|
|
fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
|
|
terrno = errno;
|
|
if( fd<0 && errno==ENOENT && islockfile ){
|
|
if( proxyCreateLockPath(path) == SQLITE_OK ){
|
|
fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
|
|
}
|
|
}
|
|
}
|
|
if( fd<0 ){
|
|
openFlags = O_RDONLY;
|
|
fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
|
|
terrno = errno;
|
|
}
|
|
if( fd<0 ){
|
|
if( islockfile ){
|
|
return SQLITE_BUSY;
|
|
}
|
|
switch (terrno) {
|
|
case EACCES:
|
|
return SQLITE_PERM;
|
|
case EIO:
|
|
return SQLITE_IOERR_LOCK; /* even though it is the conch */
|
|
default:
|
|
return SQLITE_CANTOPEN_BKPT;
|
|
}
|
|
}
|
|
|
|
pNew = (unixFile *)sqlite3_malloc(sizeof(*pNew));
|
|
if( pNew==NULL ){
|
|
rc = SQLITE_NOMEM;
|
|
goto end_create_proxy;
|
|
}
|
|
memset(pNew, 0, sizeof(unixFile));
|
|
pNew->openFlags = openFlags;
|
|
dummyVfs.pAppData = (void*)&autolockIoFinder;
|
|
pUnused->fd = fd;
|
|
pUnused->flags = openFlags;
|
|
pNew->pUnused = pUnused;
|
|
|
|
rc = fillInUnixFile(&dummyVfs, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0, 0);
|
|
if( rc==SQLITE_OK ){
|
|
*ppFile = pNew;
|
|
return SQLITE_OK;
|
|
}
|
|
end_create_proxy:
|
|
robust_close(pNew, fd, __LINE__);
|
|
sqlite3_free(pNew);
|
|
sqlite3_free(pUnused);
|
|
return rc;
|
|
}
|
|
|
|
#ifdef SQLITE_TEST
|
|
/* simulate multiple hosts by creating unique hostid file paths */
|
|
int sqlite3_hostid_num = 0;
|
|
#endif
|
|
|
|
#define PROXY_HOSTIDLEN 16 /* conch file host id length */
|
|
|
|
/* Not always defined in the headers as it ought to be */
|
|
extern int gethostuuid(uuid_t id, const struct timespec *wait);
|
|
|
|
/* get the host ID via gethostuuid(), pHostID must point to PROXY_HOSTIDLEN
|
|
** bytes of writable memory.
|
|
*/
|
|
static int proxyGetHostID(unsigned char *pHostID, int *pError){
|
|
assert(PROXY_HOSTIDLEN == sizeof(uuid_t));
|
|
memset(pHostID, 0, PROXY_HOSTIDLEN);
|
|
#if defined(__MAX_OS_X_VERSION_MIN_REQUIRED)\
|
|
&& __MAC_OS_X_VERSION_MIN_REQUIRED<1050
|
|
{
|
|
static const struct timespec timeout = {1, 0}; /* 1 sec timeout */
|
|
if( gethostuuid(pHostID, &timeout) ){
|
|
int err = errno;
|
|
if( pError ){
|
|
*pError = err;
|
|
}
|
|
return SQLITE_IOERR;
|
|
}
|
|
}
|
|
#endif
|
|
#ifdef SQLITE_TEST
|
|
/* simulate multiple hosts by creating unique hostid file paths */
|
|
if( sqlite3_hostid_num != 0){
|
|
pHostID[0] = (char)(pHostID[0] + (char)(sqlite3_hostid_num & 0xFF));
|
|
}
|
|
#endif
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* The conch file contains the header, host id and lock file path
|
|
*/
|
|
#define PROXY_CONCHVERSION 2 /* 1-byte header, 16-byte host id, path */
|
|
#define PROXY_HEADERLEN 1 /* conch file header length */
|
|
#define PROXY_PATHINDEX (PROXY_HEADERLEN+PROXY_HOSTIDLEN)
|
|
#define PROXY_MAXCONCHLEN (PROXY_HEADERLEN+PROXY_HOSTIDLEN+MAXPATHLEN)
|
|
|
|
/*
|
|
** Takes an open conch file, copies the contents to a new path and then moves
|
|
** it back. The newly created file's file descriptor is assigned to the
|
|
** conch file structure and finally the original conch file descriptor is
|
|
** closed. Returns zero if successful.
|
|
*/
|
|
static int proxyBreakConchLock(unixFile *pFile, uuid_t myHostID){
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
unixFile *conchFile = pCtx->conchFile;
|
|
char tPath[MAXPATHLEN];
|
|
char buf[PROXY_MAXCONCHLEN];
|
|
char *cPath = pCtx->conchFilePath;
|
|
size_t readLen = 0;
|
|
size_t pathLen = 0;
|
|
char errmsg[64] = "";
|
|
int fd = -1;
|
|
int rc = -1;
|
|
UNUSED_PARAMETER(myHostID);
|
|
|
|
/* create a new path by replace the trailing '-conch' with '-break' */
|
|
pathLen = strlcpy(tPath, cPath, MAXPATHLEN);
|
|
if( pathLen>MAXPATHLEN || pathLen<6 ||
|
|
(strlcpy(&tPath[pathLen-5], "break", 6) != 5) ){
|
|
sqlite3_snprintf(sizeof(errmsg),errmsg,"path error (len %d)",(int)pathLen);
|
|
goto end_breaklock;
|
|
}
|
|
/* read the conch content */
|
|
readLen = osPread(conchFile->h, buf, PROXY_MAXCONCHLEN, 0);
|
|
if( readLen<PROXY_PATHINDEX ){
|
|
sqlite3_snprintf(sizeof(errmsg),errmsg,"read error (len %d)",(int)readLen);
|
|
goto end_breaklock;
|
|
}
|
|
/* write it out to the temporary break file */
|
|
fd = robust_open(tPath, (O_RDWR|O_CREAT|O_EXCL),
|
|
SQLITE_DEFAULT_FILE_PERMISSIONS);
|
|
if( fd<0 ){
|
|
sqlite3_snprintf(sizeof(errmsg), errmsg, "create failed (%d)", errno);
|
|
goto end_breaklock;
|
|
}
|
|
if( osPwrite(fd, buf, readLen, 0) != (ssize_t)readLen ){
|
|
sqlite3_snprintf(sizeof(errmsg), errmsg, "write failed (%d)", errno);
|
|
goto end_breaklock;
|
|
}
|
|
if( rename(tPath, cPath) ){
|
|
sqlite3_snprintf(sizeof(errmsg), errmsg, "rename failed (%d)", errno);
|
|
goto end_breaklock;
|
|
}
|
|
rc = 0;
|
|
fprintf(stderr, "broke stale lock on %s\n", cPath);
|
|
robust_close(pFile, conchFile->h, __LINE__);
|
|
conchFile->h = fd;
|
|
conchFile->openFlags = O_RDWR | O_CREAT;
|
|
|
|
end_breaklock:
|
|
if( rc ){
|
|
if( fd>=0 ){
|
|
unlink(tPath);
|
|
robust_close(pFile, fd, __LINE__);
|
|
}
|
|
fprintf(stderr, "failed to break stale lock on %s, %s\n", cPath, errmsg);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/* Take the requested lock on the conch file and break a stale lock if the
|
|
** host id matches.
|
|
*/
|
|
static int proxyConchLock(unixFile *pFile, uuid_t myHostID, int lockType){
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
unixFile *conchFile = pCtx->conchFile;
|
|
int rc = SQLITE_OK;
|
|
int nTries = 0;
|
|
struct timespec conchModTime;
|
|
|
|
do {
|
|
rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType);
|
|
nTries ++;
|
|
if( rc==SQLITE_BUSY ){
|
|
/* If the lock failed (busy):
|
|
* 1st try: get the mod time of the conch, wait 0.5s and try again.
|
|
* 2nd try: fail if the mod time changed or host id is different, wait
|
|
* 10 sec and try again
|
|
* 3rd try: break the lock unless the mod time has changed.
|
|
*/
|
|
struct stat buf;
|
|
if( osFstat(conchFile->h, &buf) ){
|
|
pFile->lastErrno = errno;
|
|
return SQLITE_IOERR_LOCK;
|
|
}
|
|
|
|
if( nTries==1 ){
|
|
conchModTime = buf.st_mtimespec;
|
|
usleep(500000); /* wait 0.5 sec and try the lock again*/
|
|
continue;
|
|
}
|
|
|
|
assert( nTries>1 );
|
|
if( conchModTime.tv_sec != buf.st_mtimespec.tv_sec ||
|
|
conchModTime.tv_nsec != buf.st_mtimespec.tv_nsec ){
|
|
return SQLITE_BUSY;
|
|
}
|
|
|
|
if( nTries==2 ){
|
|
char tBuf[PROXY_MAXCONCHLEN];
|
|
int len = osPread(conchFile->h, tBuf, PROXY_MAXCONCHLEN, 0);
|
|
if( len<0 ){
|
|
pFile->lastErrno = errno;
|
|
return SQLITE_IOERR_LOCK;
|
|
}
|
|
if( len>PROXY_PATHINDEX && tBuf[0]==(char)PROXY_CONCHVERSION){
|
|
/* don't break the lock if the host id doesn't match */
|
|
if( 0!=memcmp(&tBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN) ){
|
|
return SQLITE_BUSY;
|
|
}
|
|
}else{
|
|
/* don't break the lock on short read or a version mismatch */
|
|
return SQLITE_BUSY;
|
|
}
|
|
usleep(10000000); /* wait 10 sec and try the lock again */
|
|
continue;
|
|
}
|
|
|
|
assert( nTries==3 );
|
|
if( 0==proxyBreakConchLock(pFile, myHostID) ){
|
|
rc = SQLITE_OK;
|
|
if( lockType==EXCLUSIVE_LOCK ){
|
|
rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK);
|
|
}
|
|
if( !rc ){
|
|
rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType);
|
|
}
|
|
}
|
|
}
|
|
} while( rc==SQLITE_BUSY && nTries<3 );
|
|
|
|
return rc;
|
|
}
|
|
|
|
/* Takes the conch by taking a shared lock and read the contents conch, if
|
|
** lockPath is non-NULL, the host ID and lock file path must match. A NULL
|
|
** lockPath means that the lockPath in the conch file will be used if the
|
|
** host IDs match, or a new lock path will be generated automatically
|
|
** and written to the conch file.
|
|
*/
|
|
static int proxyTakeConch(unixFile *pFile){
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
|
|
if( pCtx->conchHeld!=0 ){
|
|
return SQLITE_OK;
|
|
}else{
|
|
unixFile *conchFile = pCtx->conchFile;
|
|
uuid_t myHostID;
|
|
int pError = 0;
|
|
char readBuf[PROXY_MAXCONCHLEN];
|
|
char lockPath[MAXPATHLEN];
|
|
char *tempLockPath = NULL;
|
|
int rc = SQLITE_OK;
|
|
int createConch = 0;
|
|
int hostIdMatch = 0;
|
|
int readLen = 0;
|
|
int tryOldLockPath = 0;
|
|
int forceNewLockPath = 0;
|
|
|
|
OSTRACE(("TAKECONCH %d for %s pid=%d\n", conchFile->h,
|
|
(pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), getpid()));
|
|
|
|
rc = proxyGetHostID(myHostID, &pError);
|
|
if( (rc&0xff)==SQLITE_IOERR ){
|
|
pFile->lastErrno = pError;
|
|
goto end_takeconch;
|
|
}
|
|
rc = proxyConchLock(pFile, myHostID, SHARED_LOCK);
|
|
if( rc!=SQLITE_OK ){
|
|
goto end_takeconch;
|
|
}
|
|
/* read the existing conch file */
|
|
readLen = seekAndRead((unixFile*)conchFile, 0, readBuf, PROXY_MAXCONCHLEN);
|
|
if( readLen<0 ){
|
|
/* I/O error: lastErrno set by seekAndRead */
|
|
pFile->lastErrno = conchFile->lastErrno;
|
|
rc = SQLITE_IOERR_READ;
|
|
goto end_takeconch;
|
|
}else if( readLen<=(PROXY_HEADERLEN+PROXY_HOSTIDLEN) ||
|
|
readBuf[0]!=(char)PROXY_CONCHVERSION ){
|
|
/* a short read or version format mismatch means we need to create a new
|
|
** conch file.
|
|
*/
|
|
createConch = 1;
|
|
}
|
|
/* if the host id matches and the lock path already exists in the conch
|
|
** we'll try to use the path there, if we can't open that path, we'll
|
|
** retry with a new auto-generated path
|
|
*/
|
|
do { /* in case we need to try again for an :auto: named lock file */
|
|
|
|
if( !createConch && !forceNewLockPath ){
|
|
hostIdMatch = !memcmp(&readBuf[PROXY_HEADERLEN], myHostID,
|
|
PROXY_HOSTIDLEN);
|
|
/* if the conch has data compare the contents */
|
|
if( !pCtx->lockProxyPath ){
|
|
/* for auto-named local lock file, just check the host ID and we'll
|
|
** use the local lock file path that's already in there
|
|
*/
|
|
if( hostIdMatch ){
|
|
size_t pathLen = (readLen - PROXY_PATHINDEX);
|
|
|
|
if( pathLen>=MAXPATHLEN ){
|
|
pathLen=MAXPATHLEN-1;
|
|
}
|
|
memcpy(lockPath, &readBuf[PROXY_PATHINDEX], pathLen);
|
|
lockPath[pathLen] = 0;
|
|
tempLockPath = lockPath;
|
|
tryOldLockPath = 1;
|
|
/* create a copy of the lock path if the conch is taken */
|
|
goto end_takeconch;
|
|
}
|
|
}else if( hostIdMatch
|
|
&& !strncmp(pCtx->lockProxyPath, &readBuf[PROXY_PATHINDEX],
|
|
readLen-PROXY_PATHINDEX)
|
|
){
|
|
/* conch host and lock path match */
|
|
goto end_takeconch;
|
|
}
|
|
}
|
|
|
|
/* if the conch isn't writable and doesn't match, we can't take it */
|
|
if( (conchFile->openFlags&O_RDWR) == 0 ){
|
|
rc = SQLITE_BUSY;
|
|
goto end_takeconch;
|
|
}
|
|
|
|
/* either the conch didn't match or we need to create a new one */
|
|
if( !pCtx->lockProxyPath ){
|
|
proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN);
|
|
tempLockPath = lockPath;
|
|
/* create a copy of the lock path _only_ if the conch is taken */
|
|
}
|
|
|
|
/* update conch with host and path (this will fail if other process
|
|
** has a shared lock already), if the host id matches, use the big
|
|
** stick.
|
|
*/
|
|
futimes(conchFile->h, NULL);
|
|
if( hostIdMatch && !createConch ){
|
|
if( conchFile->pInode && conchFile->pInode->nShared>1 ){
|
|
/* We are trying for an exclusive lock but another thread in this
|
|
** same process is still holding a shared lock. */
|
|
rc = SQLITE_BUSY;
|
|
} else {
|
|
rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK);
|
|
}
|
|
}else{
|
|
rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, EXCLUSIVE_LOCK);
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
char writeBuffer[PROXY_MAXCONCHLEN];
|
|
int writeSize = 0;
|
|
|
|
writeBuffer[0] = (char)PROXY_CONCHVERSION;
|
|
memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN);
|
|
if( pCtx->lockProxyPath!=NULL ){
|
|
strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath, MAXPATHLEN);
|
|
}else{
|
|
strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN);
|
|
}
|
|
writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]);
|
|
robust_ftruncate(conchFile->h, writeSize);
|
|
rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0);
|
|
fsync(conchFile->h);
|
|
/* If we created a new conch file (not just updated the contents of a
|
|
** valid conch file), try to match the permissions of the database
|
|
*/
|
|
if( rc==SQLITE_OK && createConch ){
|
|
struct stat buf;
|
|
int err = osFstat(pFile->h, &buf);
|
|
if( err==0 ){
|
|
mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP |
|
|
S_IROTH|S_IWOTH);
|
|
/* try to match the database file R/W permissions, ignore failure */
|
|
#ifndef SQLITE_PROXY_DEBUG
|
|
osFchmod(conchFile->h, cmode);
|
|
#else
|
|
do{
|
|
rc = osFchmod(conchFile->h, cmode);
|
|
}while( rc==(-1) && errno==EINTR );
|
|
if( rc!=0 ){
|
|
int code = errno;
|
|
fprintf(stderr, "fchmod %o FAILED with %d %s\n",
|
|
cmode, code, strerror(code));
|
|
} else {
|
|
fprintf(stderr, "fchmod %o SUCCEDED\n",cmode);
|
|
}
|
|
}else{
|
|
int code = errno;
|
|
fprintf(stderr, "STAT FAILED[%d] with %d %s\n",
|
|
err, code, strerror(code));
|
|
#endif
|
|
}
|
|
}
|
|
}
|
|
conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);
|
|
|
|
end_takeconch:
|
|
OSTRACE(("TRANSPROXY: CLOSE %d\n", pFile->h));
|
|
if( rc==SQLITE_OK && pFile->openFlags ){
|
|
if( pFile->h>=0 ){
|
|
robust_close(pFile, pFile->h, __LINE__);
|
|
}
|
|
pFile->h = -1;
|
|
int fd = robust_open(pCtx->dbPath, pFile->openFlags,
|
|
SQLITE_DEFAULT_FILE_PERMISSIONS);
|
|
OSTRACE(("TRANSPROXY: OPEN %d\n", fd));
|
|
if( fd>=0 ){
|
|
pFile->h = fd;
|
|
}else{
|
|
rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called
|
|
during locking */
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK && !pCtx->lockProxy ){
|
|
char *path = tempLockPath ? tempLockPath : pCtx->lockProxyPath;
|
|
rc = proxyCreateUnixFile(path, &pCtx->lockProxy, 1);
|
|
if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && tryOldLockPath ){
|
|
/* we couldn't create the proxy lock file with the old lock file path
|
|
** so try again via auto-naming
|
|
*/
|
|
forceNewLockPath = 1;
|
|
tryOldLockPath = 0;
|
|
continue; /* go back to the do {} while start point, try again */
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
/* Need to make a copy of path if we extracted the value
|
|
** from the conch file or the path was allocated on the stack
|
|
*/
|
|
if( tempLockPath ){
|
|
pCtx->lockProxyPath = sqlite3DbStrDup(0, tempLockPath);
|
|
if( !pCtx->lockProxyPath ){
|
|
rc = SQLITE_NOMEM;
|
|
}
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
pCtx->conchHeld = 1;
|
|
|
|
if( pCtx->lockProxy->pMethod == &afpIoMethods ){
|
|
afpLockingContext *afpCtx;
|
|
afpCtx = (afpLockingContext *)pCtx->lockProxy->lockingContext;
|
|
afpCtx->dbPath = pCtx->lockProxyPath;
|
|
}
|
|
} else {
|
|
conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
|
|
}
|
|
OSTRACE(("TAKECONCH %d %s\n", conchFile->h,
|
|
rc==SQLITE_OK?"ok":"failed"));
|
|
return rc;
|
|
} while (1); /* in case we need to retry the :auto: lock file -
|
|
** we should never get here except via the 'continue' call. */
|
|
}
|
|
}
|
|
|
|
/*
|
|
** If pFile holds a lock on a conch file, then release that lock.
|
|
*/
|
|
static int proxyReleaseConch(unixFile *pFile){
|
|
int rc = SQLITE_OK; /* Subroutine return code */
|
|
proxyLockingContext *pCtx; /* The locking context for the proxy lock */
|
|
unixFile *conchFile; /* Name of the conch file */
|
|
|
|
pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
conchFile = pCtx->conchFile;
|
|
OSTRACE(("RELEASECONCH %d for %s pid=%d\n", conchFile->h,
|
|
(pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"),
|
|
getpid()));
|
|
if( pCtx->conchHeld>0 ){
|
|
rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
|
|
}
|
|
pCtx->conchHeld = 0;
|
|
OSTRACE(("RELEASECONCH %d %s\n", conchFile->h,
|
|
(rc==SQLITE_OK ? "ok" : "failed")));
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Given the name of a database file, compute the name of its conch file.
|
|
** Store the conch filename in memory obtained from sqlite3_malloc().
|
|
** Make *pConchPath point to the new name. Return SQLITE_OK on success
|
|
** or SQLITE_NOMEM if unable to obtain memory.
|
|
**
|
|
** The caller is responsible for ensuring that the allocated memory
|
|
** space is eventually freed.
|
|
**
|
|
** *pConchPath is set to NULL if a memory allocation error occurs.
|
|
*/
|
|
static int proxyCreateConchPathname(char *dbPath, char **pConchPath){
|
|
int i; /* Loop counter */
|
|
int len = (int)strlen(dbPath); /* Length of database filename - dbPath */
|
|
char *conchPath; /* buffer in which to construct conch name */
|
|
|
|
/* Allocate space for the conch filename and initialize the name to
|
|
** the name of the original database file. */
|
|
*pConchPath = conchPath = (char *)sqlite3_malloc(len + 8);
|
|
if( conchPath==0 ){
|
|
return SQLITE_NOMEM;
|
|
}
|
|
memcpy(conchPath, dbPath, len+1);
|
|
|
|
/* now insert a "." before the last / character */
|
|
for( i=(len-1); i>=0; i-- ){
|
|
if( conchPath[i]=='/' ){
|
|
i++;
|
|
break;
|
|
}
|
|
}
|
|
conchPath[i]='.';
|
|
while ( i<len ){
|
|
conchPath[i+1]=dbPath[i];
|
|
i++;
|
|
}
|
|
|
|
/* append the "-conch" suffix to the file */
|
|
memcpy(&conchPath[i+1], "-conch", 7);
|
|
assert( (int)strlen(conchPath) == len+7 );
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
/* Takes a fully configured proxy locking-style unix file and switches
|
|
** the local lock file path
|
|
*/
|
|
static int switchLockProxyPath(unixFile *pFile, const char *path) {
|
|
proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
|
|
char *oldPath = pCtx->lockProxyPath;
|
|
int rc = SQLITE_OK;
|
|
|
|
if( pFile->eFileLock!=NO_LOCK ){
|
|
return SQLITE_BUSY;
|
|
}
|
|
|
|
/* nothing to do if the path is NULL, :auto: or matches the existing path */
|
|
if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ||
|
|
(oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){
|
|
return SQLITE_OK;
|
|
}else{
|
|
unixFile *lockProxy = pCtx->lockProxy;
|
|
pCtx->lockProxy=NULL;
|
|
pCtx->conchHeld = 0;
|
|
if( lockProxy!=NULL ){
|
|
rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy);
|
|
if( rc ) return rc;
|
|
sqlite3_free(lockProxy);
|
|
}
|
|
sqlite3_free(oldPath);
|
|
pCtx->lockProxyPath = sqlite3DbStrDup(0, path);
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** pFile is a file that has been opened by a prior xOpen call. dbPath
|
|
** is a string buffer at least MAXPATHLEN+1 characters in size.
|
|
**
|
|
** This routine find the filename associated with pFile and writes it
|
|
** int dbPath.
|
|
*/
|
|
static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){
|
|
#if defined(__APPLE__)
|
|
if( pFile->pMethod == &afpIoMethods ){
|
|
/* afp style keeps a reference to the db path in the filePath field
|
|
** of the struct */
|
|
assert( (int)strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
|
|
strlcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath, MAXPATHLEN);
|
|
} else
|
|
#endif
|
|
if( pFile->pMethod == &dotlockIoMethods ){
|
|
/* dot lock style uses the locking context to store the dot lock
|
|
** file path */
|
|
int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX);
|
|
memcpy(dbPath, (char *)pFile->lockingContext, len + 1);
|
|
}else{
|
|
/* all other styles use the locking context to store the db file path */
|
|
assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
|
|
strlcpy(dbPath, (char *)pFile->lockingContext, MAXPATHLEN);
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Takes an already filled in unix file and alters it so all file locking
|
|
** will be performed on the local proxy lock file. The following fields
|
|
** are preserved in the locking context so that they can be restored and
|
|
** the unix structure properly cleaned up at close time:
|
|
** ->lockingContext
|
|
** ->pMethod
|
|
*/
|
|
static int proxyTransformUnixFile(unixFile *pFile, const char *path) {
|
|
proxyLockingContext *pCtx;
|
|
char dbPath[MAXPATHLEN+1]; /* Name of the database file */
|
|
char *lockPath=NULL;
|
|
int rc = SQLITE_OK;
|
|
|
|
if( pFile->eFileLock!=NO_LOCK ){
|
|
return SQLITE_BUSY;
|
|
}
|
|
proxyGetDbPathForUnixFile(pFile, dbPath);
|
|
if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){
|
|
lockPath=NULL;
|
|
}else{
|
|
lockPath=(char *)path;
|
|
}
|
|
|
|
OSTRACE(("TRANSPROXY %d for %s pid=%d\n", pFile->h,
|
|
(lockPath ? lockPath : ":auto:"), getpid()));
|
|
|
|
pCtx = sqlite3_malloc( sizeof(*pCtx) );
|
|
if( pCtx==0 ){
|
|
return SQLITE_NOMEM;
|
|
}
|
|
memset(pCtx, 0, sizeof(*pCtx));
|
|
|
|
rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath);
|
|
if( rc==SQLITE_OK ){
|
|
rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile, 0);
|
|
if( rc==SQLITE_CANTOPEN && ((pFile->openFlags&O_RDWR) == 0) ){
|
|
/* if (a) the open flags are not O_RDWR, (b) the conch isn't there, and
|
|
** (c) the file system is read-only, then enable no-locking access.
|
|
** Ugh, since O_RDONLY==0x0000 we test for !O_RDWR since unixOpen asserts
|
|
** that openFlags will have only one of O_RDONLY or O_RDWR.
|
|
*/
|
|
struct statfs fsInfo;
|
|
struct stat conchInfo;
|
|
int goLockless = 0;
|
|
|
|
if( osStat(pCtx->conchFilePath, &conchInfo) == -1 ) {
|
|
int err = errno;
|
|
if( (err==ENOENT) && (statfs(dbPath, &fsInfo) != -1) ){
|
|
goLockless = (fsInfo.f_flags&MNT_RDONLY) == MNT_RDONLY;
|
|
}
|
|
}
|
|
if( goLockless ){
|
|
pCtx->conchHeld = -1; /* read only FS/ lockless */
|
|
rc = SQLITE_OK;
|
|
}
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK && lockPath ){
|
|
pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath);
|
|
}
|
|
|
|
if( rc==SQLITE_OK ){
|
|
pCtx->dbPath = sqlite3DbStrDup(0, dbPath);
|
|
if( pCtx->dbPath==NULL ){
|
|
rc = SQLITE_NOMEM;
|
|
}
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
/* all memory is allocated, proxys are created and assigned,
|
|
** switch the locking context and pMethod then return.
|
|
*/
|
|
pCtx->oldLockingContext = pFile->lockingContext;
|
|
pFile->lockingContext = pCtx;
|
|
pCtx->pOldMethod = pFile->pMethod;
|
|
pFile->pMethod = &proxyIoMethods;
|
|
}else{
|
|
if( pCtx->conchFile ){
|
|
pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile);
|
|
sqlite3_free(pCtx->conchFile);
|
|
}
|
|
sqlite3DbFree(0, pCtx->lockProxyPath);
|
|
sqlite3_free(pCtx->conchFilePath);
|
|
sqlite3_free(pCtx);
|
|
}
|
|
OSTRACE(("TRANSPROXY %d %s\n", pFile->h,
|
|
(rc==SQLITE_OK ? "ok" : "failed")));
|
|
return rc;
|
|
}
|
|
|
|
|
|
/*
|
|
** This routine handles sqlite3_file_control() calls that are specific
|
|
** to proxy locking.
|
|
*/
|
|
static int proxyFileControl(sqlite3_file *id, int op, void *pArg){
|
|
switch( op ){
|
|
case SQLITE_GET_LOCKPROXYFILE: {
|
|
unixFile *pFile = (unixFile*)id;
|
|
if( pFile->pMethod == &proxyIoMethods ){
|
|
proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
|
|
proxyTakeConch(pFile);
|
|
if( pCtx->lockProxyPath ){
|
|
*(const char **)pArg = pCtx->lockProxyPath;
|
|
}else{
|
|
*(const char **)pArg = ":auto: (not held)";
|
|
}
|
|
} else {
|
|
*(const char **)pArg = NULL;
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
case SQLITE_SET_LOCKPROXYFILE: {
|
|
unixFile *pFile = (unixFile*)id;
|
|
int rc = SQLITE_OK;
|
|
int isProxyStyle = (pFile->pMethod == &proxyIoMethods);
|
|
if( pArg==NULL || (const char *)pArg==0 ){
|
|
if( isProxyStyle ){
|
|
/* turn off proxy locking - not supported */
|
|
rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
|
|
}else{
|
|
/* turn off proxy locking - already off - NOOP */
|
|
rc = SQLITE_OK;
|
|
}
|
|
}else{
|
|
const char *proxyPath = (const char *)pArg;
|
|
if( isProxyStyle ){
|
|
proxyLockingContext *pCtx =
|
|
(proxyLockingContext*)pFile->lockingContext;
|
|
if( !strcmp(pArg, ":auto:")
|
|
|| (pCtx->lockProxyPath &&
|
|
!strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN))
|
|
){
|
|
rc = SQLITE_OK;
|
|
}else{
|
|
rc = switchLockProxyPath(pFile, proxyPath);
|
|
}
|
|
}else{
|
|
/* turn on proxy file locking */
|
|
rc = proxyTransformUnixFile(pFile, proxyPath);
|
|
}
|
|
}
|
|
return rc;
|
|
}
|
|
default: {
|
|
assert( 0 ); /* The call assures that only valid opcodes are sent */
|
|
}
|
|
}
|
|
/*NOTREACHED*/
|
|
return SQLITE_ERROR;
|
|
}
|
|
|
|
/*
|
|
** Within this division (the proxying locking implementation) the procedures
|
|
** above this point are all utilities. The lock-related methods of the
|
|
** proxy-locking sqlite3_io_method object follow.
|
|
*/
|
|
|
|
|
|
/*
|
|
** This routine checks if there is a RESERVED lock held on the specified
|
|
** file by this or any other process. If such a lock is held, set *pResOut
|
|
** to a non-zero value otherwise *pResOut is set to zero. The return value
|
|
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
|
|
*/
|
|
static int proxyCheckReservedLock(sqlite3_file *id, int *pResOut) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
int rc = proxyTakeConch(pFile);
|
|
if( rc==SQLITE_OK ){
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
if( pCtx->conchHeld>0 ){
|
|
unixFile *proxy = pCtx->lockProxy;
|
|
return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut);
|
|
}else{ /* conchHeld < 0 is lockless */
|
|
pResOut=0;
|
|
}
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Lock the file with the lock specified by parameter eFileLock - one
|
|
** of the following:
|
|
**
|
|
** (1) SHARED_LOCK
|
|
** (2) RESERVED_LOCK
|
|
** (3) PENDING_LOCK
|
|
** (4) EXCLUSIVE_LOCK
|
|
**
|
|
** Sometimes when requesting one lock state, additional lock states
|
|
** are inserted in between. The locking might fail on one of the later
|
|
** transitions leaving the lock state different from what it started but
|
|
** still short of its goal. The following chart shows the allowed
|
|
** transitions and the inserted intermediate states:
|
|
**
|
|
** UNLOCKED -> SHARED
|
|
** SHARED -> RESERVED
|
|
** SHARED -> (PENDING) -> EXCLUSIVE
|
|
** RESERVED -> (PENDING) -> EXCLUSIVE
|
|
** PENDING -> EXCLUSIVE
|
|
**
|
|
** This routine will only increase a lock. Use the sqlite3OsUnlock()
|
|
** routine to lower a locking level.
|
|
*/
|
|
static int proxyLock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
int rc = proxyTakeConch(pFile);
|
|
if( rc==SQLITE_OK ){
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
if( pCtx->conchHeld>0 ){
|
|
unixFile *proxy = pCtx->lockProxy;
|
|
rc = proxy->pMethod->xLock((sqlite3_file*)proxy, eFileLock);
|
|
pFile->eFileLock = proxy->eFileLock;
|
|
}else{
|
|
/* conchHeld < 0 is lockless */
|
|
}
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
|
|
/*
|
|
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
|
|
** must be either NO_LOCK or SHARED_LOCK.
|
|
**
|
|
** If the locking level of the file descriptor is already at or below
|
|
** the requested locking level, this routine is a no-op.
|
|
*/
|
|
static int proxyUnlock(sqlite3_file *id, int eFileLock) {
|
|
unixFile *pFile = (unixFile*)id;
|
|
int rc = proxyTakeConch(pFile);
|
|
if( rc==SQLITE_OK ){
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
if( pCtx->conchHeld>0 ){
|
|
unixFile *proxy = pCtx->lockProxy;
|
|
rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, eFileLock);
|
|
pFile->eFileLock = proxy->eFileLock;
|
|
}else{
|
|
/* conchHeld < 0 is lockless */
|
|
}
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Close a file that uses proxy locks.
|
|
*/
|
|
static int proxyClose(sqlite3_file *id) {
|
|
if( id ){
|
|
unixFile *pFile = (unixFile*)id;
|
|
proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
|
|
unixFile *lockProxy = pCtx->lockProxy;
|
|
unixFile *conchFile = pCtx->conchFile;
|
|
int rc = SQLITE_OK;
|
|
|
|
if( lockProxy ){
|
|
rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK);
|
|
if( rc ) return rc;
|
|
rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy);
|
|
if( rc ) return rc;
|
|
sqlite3_free(lockProxy);
|
|
pCtx->lockProxy = 0;
|
|
}
|
|
if( conchFile ){
|
|
if( pCtx->conchHeld ){
|
|
rc = proxyReleaseConch(pFile);
|
|
if( rc ) return rc;
|
|
}
|
|
rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile);
|
|
if( rc ) return rc;
|
|
sqlite3_free(conchFile);
|
|
}
|
|
sqlite3DbFree(0, pCtx->lockProxyPath);
|
|
sqlite3_free(pCtx->conchFilePath);
|
|
sqlite3DbFree(0, pCtx->dbPath);
|
|
/* restore the original locking context and pMethod then close it */
|
|
pFile->lockingContext = pCtx->oldLockingContext;
|
|
pFile->pMethod = pCtx->pOldMethod;
|
|
sqlite3_free(pCtx);
|
|
return pFile->pMethod->xClose(id);
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
|
|
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
|
|
/*
|
|
** The proxy locking style is intended for use with AFP filesystems.
|
|
** And since AFP is only supported on MacOSX, the proxy locking is also
|
|
** restricted to MacOSX.
|
|
**
|
|
**
|
|
******************* End of the proxy lock implementation **********************
|
|
******************************************************************************/
|
|
|
|
/*
|
|
** Initialize the operating system interface.
|
|
**
|
|
** This routine registers all VFS implementations for unix-like operating
|
|
** systems. This routine, and the sqlite3_os_end() routine that follows,
|
|
** should be the only routines in this file that are visible from other
|
|
** files.
|
|
**
|
|
** This routine is called once during SQLite initialization and by a
|
|
** single thread. The memory allocation and mutex subsystems have not
|
|
** necessarily been initialized when this routine is called, and so they
|
|
** should not be used.
|
|
*/
|
|
int sqlite3_os_init(void){
|
|
/*
|
|
** The following macro defines an initializer for an sqlite3_vfs object.
|
|
** The name of the VFS is NAME. The pAppData is a pointer to a pointer
|
|
** to the "finder" function. (pAppData is a pointer to a pointer because
|
|
** silly C90 rules prohibit a void* from being cast to a function pointer
|
|
** and so we have to go through the intermediate pointer to avoid problems
|
|
** when compiling with -pedantic-errors on GCC.)
|
|
**
|
|
** The FINDER parameter to this macro is the name of the pointer to the
|
|
** finder-function. The finder-function returns a pointer to the
|
|
** sqlite_io_methods object that implements the desired locking
|
|
** behaviors. See the division above that contains the IOMETHODS
|
|
** macro for addition information on finder-functions.
|
|
**
|
|
** Most finders simply return a pointer to a fixed sqlite3_io_methods
|
|
** object. But the "autolockIoFinder" available on MacOSX does a little
|
|
** more than that; it looks at the filesystem type that hosts the
|
|
** database file and tries to choose an locking method appropriate for
|
|
** that filesystem time.
|
|
*/
|
|
#define UNIXVFS(VFSNAME, FINDER) { \
|
|
3, /* iVersion */ \
|
|
sizeof(unixFile), /* szOsFile */ \
|
|
MAX_PATHNAME, /* mxPathname */ \
|
|
0, /* pNext */ \
|
|
VFSNAME, /* zName */ \
|
|
(void*)&FINDER, /* pAppData */ \
|
|
unixOpen, /* xOpen */ \
|
|
unixDelete, /* xDelete */ \
|
|
unixAccess, /* xAccess */ \
|
|
unixFullPathname, /* xFullPathname */ \
|
|
unixDlOpen, /* xDlOpen */ \
|
|
unixDlError, /* xDlError */ \
|
|
unixDlSym, /* xDlSym */ \
|
|
unixDlClose, /* xDlClose */ \
|
|
unixRandomness, /* xRandomness */ \
|
|
unixSleep, /* xSleep */ \
|
|
unixCurrentTime, /* xCurrentTime */ \
|
|
unixGetLastError, /* xGetLastError */ \
|
|
unixCurrentTimeInt64, /* xCurrentTimeInt64 */ \
|
|
unixSetSystemCall, /* xSetSystemCall */ \
|
|
unixGetSystemCall, /* xGetSystemCall */ \
|
|
unixNextSystemCall, /* xNextSystemCall */ \
|
|
}
|
|
|
|
/*
|
|
** All default VFSes for unix are contained in the following array.
|
|
**
|
|
** Note that the sqlite3_vfs.pNext field of the VFS object is modified
|
|
** by the SQLite core when the VFS is registered. So the following
|
|
** array cannot be const.
|
|
*/
|
|
static sqlite3_vfs aVfs[] = {
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
|
|
UNIXVFS("unix", autolockIoFinder ),
|
|
#else
|
|
UNIXVFS("unix", posixIoFinder ),
|
|
#endif
|
|
UNIXVFS("unix-none", nolockIoFinder ),
|
|
UNIXVFS("unix-dotfile", dotlockIoFinder ),
|
|
UNIXVFS("unix-excl", posixIoFinder ),
|
|
#if OS_VXWORKS
|
|
UNIXVFS("unix-namedsem", semIoFinder ),
|
|
#endif
|
|
#if SQLITE_ENABLE_LOCKING_STYLE
|
|
UNIXVFS("unix-posix", posixIoFinder ),
|
|
#if !OS_VXWORKS
|
|
UNIXVFS("unix-flock", flockIoFinder ),
|
|
#endif
|
|
#endif
|
|
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
|
|
UNIXVFS("unix-afp", afpIoFinder ),
|
|
UNIXVFS("unix-nfs", nfsIoFinder ),
|
|
UNIXVFS("unix-proxy", proxyIoFinder ),
|
|
#endif
|
|
};
|
|
unsigned int i; /* Loop counter */
|
|
|
|
/* Register all VFSes defined in the aVfs[] array */
|
|
for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
|
|
sqlite3_vfs_register(&aVfs[i], i==0);
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Shutdown the operating system interface.
|
|
**
|
|
** Some operating systems might need to do some cleanup in this routine,
|
|
** to release dynamically allocated objects. But not on unix.
|
|
** This routine is a no-op for unix.
|
|
*/
|
|
int sqlite3_os_end(void){
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
#endif /* SQLITE_OS_UNIX */
|