160 lines
3.4 KiB
C
160 lines
3.4 KiB
C
|
/*++
|
||
|
|
/* NAME
|
||
|
|
/* dot_lockfile 3
|
||
|
|
/* SUMMARY
|
||
|
|
/* dotlock file management
|
||
|
|
/* SYNOPSIS
|
||
|
|
/* #include <dot_lockfile.h>
|
||
|
|
/*
|
||
|
|
/* int dot_lockfile(path, why)
|
||
|
|
/* const char *path;
|
||
|
|
/* VSTRING *why;
|
||
|
|
/*
|
||
|
|
/* void dot_unlockfile(path)
|
||
|
|
/* const char *path;
|
||
|
|
/* DESCRIPTION
|
||
|
|
/* dot_lockfile() constructs a lock file name by appending ".lock" to
|
||
|
|
/* \fIpath\fR and creates the named file exclusively. It tries several
|
||
|
|
/* times and attempts to break stale locks. A negative result value
|
||
|
|
/* means no lock file could be created.
|
||
|
|
/*
|
||
|
|
/* dot_unlockfile() attempts to remove the lock file created by
|
||
|
|
/* dot_lockfile().
|
||
|
|
/*
|
||
|
|
/* Arguments:
|
||
|
|
/* .IP path
|
||
|
|
/* Name of the file to be locked or unlocked.
|
||
|
|
/* .IP why
|
||
|
|
/* A null pointer, or storage for the reason why a lock file could
|
||
|
|
/* not be created.
|
||
|
|
/* CONFIGURATION PARAMETERS
|
||
|
|
/* deliver_lock_attempts, how many times to try to create a lock
|
||
|
|
/* deliver_lock_delay, how long to wait between attempts
|
||
|
|
/* stale_lock_time, when to break a stale lock
|
||
|
|
/* LICENSE
|
||
|
|
/* .ad
|
||
|
|
/* .fi
|
||
|
|
/* The Secure Mailer license must be distributed with this software.
|
||
|
|
/* AUTHOR(S)
|
||
|
|
/* Wietse Venema
|
||
|
|
/* IBM T.J. Watson Research
|
||
|
|
/* P.O. Box 704
|
||
|
|
/* Yorktown Heights, NY 10598, USA
|
||
|
|
/*--*/
|
||
|
|
|
||
|
|
/* System library. */
|
||
|
|
|
||
|
|
#include "sys_defs.h"
|
||
|
|
#include <sys/stat.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <errno.h>
|
||
|
|
#include <time.h>
|
||
|
|
|
||
|
|
/* Utility library. */
|
||
|
|
|
||
|
|
#include <vstring.h>
|
||
|
|
#include <stringops.h>
|
||
|
|
#include <mymalloc.h>
|
||
|
|
|
||
|
|
/* Global library. */
|
||
|
|
|
||
|
|
#include "mail_params.h"
|
||
|
|
#include "dot_lockfile.h"
|
||
|
|
|
||
|
|
/* dot_lockfile - create user.lock file */
|
||
|
|
|
||
|
|
int dot_lockfile(const char *path, VSTRING *why)
|
||
|
|
{
|
||
|
|
char *lock_file;
|
||
|
|
int count;
|
||
|
|
struct stat st;
|
||
|
|
int fd;
|
||
|
|
int status = -1;
|
||
|
|
|
||
|
|
lock_file = concatenate(path, ".lock", (char *) 0);
|
||
|
|
|
||
|
|
for (count = 0; /* void */ ; count++) {
|
||
|
|
if (count >= var_flock_tries)
|
||
|
|
break;
|
||
|
|
if (count > 0)
|
||
|
|
sleep(var_flock_delay);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Attempt to create the lock. This code relies on O_EXCL | O_CREAT
|
||
|
|
* to not follow symlinks.
|
||
|
|
*/
|
||
|
|
if ((fd = open(lock_file, O_WRONLY | O_EXCL | O_CREAT, 0)) >= 0) {
|
||
|
|
close(fd);
|
||
|
|
status = 0;
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* We can deal only with "file exists" errors. Any other error means
|
||
|
|
* we better give up trying.
|
||
|
|
*/
|
||
|
|
if (errno != EEXIST)
|
||
|
|
break;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Break the lock when it is too old. Give up when we are unable to
|
||
|
|
* remove a stale lock.
|
||
|
|
*/
|
||
|
|
if (stat(lock_file, &st) == 0)
|
||
|
|
if (time((time_t *) 0) > st.st_ctime + var_flock_stale)
|
||
|
|
if (unlink(lock_file) < 0)
|
||
|
|
if (errno != ENOENT)
|
||
|
|
break;
|
||
|
|
errno = EEXIST;
|
||
|
|
}
|
||
|
|
if (status && why)
|
||
|
|
vstring_sprintf(why, "unable to create lock file %s: %m", lock_file);
|
||
|
|
|
||
|
|
myfree(lock_file);
|
||
|
|
return (status);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* dot_unlockfile - remove .lock file */
|
||
|
|
|
||
|
|
void dot_unlockfile(const char *path)
|
||
|
|
{
|
||
|
|
char *lock_file;
|
||
|
|
|
||
|
|
lock_file = concatenate(path, ".lock", (char *) 0);
|
||
|
|
(void) unlink(lock_file);
|
||
|
|
myfree(lock_file);
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef TEST
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Test program for setting a .lock file.
|
||
|
|
*
|
||
|
|
* Usage: dot_lockfile filename
|
||
|
|
*
|
||
|
|
* Creates filename.lock and removes it.
|
||
|
|
*/
|
||
|
|
#include <msg.h>
|
||
|
|
#include <vstream.h>
|
||
|
|
#include <msg_vstream.h>
|
||
|
|
#include <mail_conf.h>
|
||
|
|
|
||
|
|
main(int argc, char **argv)
|
||
|
|
{
|
||
|
|
VSTRING *why = vstring_alloc(100);
|
||
|
|
|
||
|
|
msg_vstream_init(argv[0], VSTREAM_ERR);
|
||
|
|
if (argc != 2)
|
||
|
|
msg_fatal("usage: %s file-to-be-locked", argv[0]);
|
||
|
|
mail_conf_read();
|
||
|
|
if (dot_lockfile(argv[1], why) < 0)
|
||
|
|
msg_fatal("%s", vstring_str(why));
|
||
|
|
dot_unlockfile(argv[1]);
|
||
|
|
vstring_free(why);
|
||
|
|
return (0);
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|