345 lines
8.7 KiB
C
345 lines
8.7 KiB
C
/* $NetBSD: tempname.c,v 1.1.1.1 2003/01/26 00:43:15 wiz Exp $ */
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/* Copyright (C) 1991-1999, 2000, 2001 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <sys/types.h>
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#include <assert.h>
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#include <errno.h>
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#ifndef __set_errno
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# define __set_errno(Val) errno = (Val)
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#endif
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#include <stdio.h>
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#ifndef P_tmpdir
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# define P_tmpdir "/tmp"
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#endif
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#ifndef TMP_MAX
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# define TMP_MAX 238328
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#endif
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#ifndef __GT_FILE
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# define __GT_FILE 0
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# define __GT_BIGFILE 1
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# define __GT_DIR 2
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# define __GT_NOCREATE 3
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#endif
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#if STDC_HEADERS || _LIBC
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# include <stddef.h>
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# include <string.h>
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#endif
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#include <stdlib.h>
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#if HAVE_FCNTL_H || _LIBC
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# include <fcntl.h>
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#endif
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#if HAVE_SYS_TIME_H || _LIBC
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# include <sys/time.h>
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#endif
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#if HAVE_STDINT_H || _LIBC
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# include <stdint.h>
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#endif
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#if HAVE_UNISTD_H || _LIBC
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# include <unistd.h>
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#endif
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#include <sys/stat.h>
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#if STAT_MACROS_BROKEN
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# undef S_ISDIR
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#endif
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#if !defined S_ISDIR && defined S_IFDIR
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# define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
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#endif
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#if !S_IRUSR && S_IREAD
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# define S_IRUSR S_IREAD
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#endif
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#if !S_IRUSR
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# define S_IRUSR 00400
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#endif
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#if !S_IWUSR && S_IWRITE
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# define S_IWUSR S_IWRITE
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#endif
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#if !S_IWUSR
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# define S_IWUSR 00200
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#endif
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#if !S_IXUSR && S_IEXEC
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# define S_IXUSR S_IEXEC
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#endif
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#if !S_IXUSR
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# define S_IXUSR 00100
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#endif
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#if _LIBC
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# define struct_stat64 struct stat64
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#else
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# define struct_stat64 struct stat
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# define __getpid getpid
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# define __gettimeofday gettimeofday
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# define __mkdir mkdir
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# define __open open
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# define __open64 open
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# define __lxstat64(version, path, buf) lstat (path, buf)
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# define __xstat64(version, path, buf) stat (path, buf)
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#endif
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#if ! (HAVE___SECURE_GETENV || _LIBC)
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# define __secure_getenv getenv
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#endif
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#ifdef _LIBC
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# include <hp-timing.h>
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# if HP_TIMING_AVAIL
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# define RANDOM_BITS(Var) \
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if (__builtin_expect (value == UINT64_C (0), 0)) \
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{ \
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/* If this is the first time this function is used initialize \
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the variable we accumulate the value in to some somewhat \
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random value. If we'd not do this programs at startup time \
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might have a reduced set of possible names, at least on slow \
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machines. */ \
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struct timeval tv; \
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__gettimeofday (&tv, NULL); \
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value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \
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} \
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HP_TIMING_NOW (Var)
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# endif
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#endif
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/* Use the widest available unsigned type if uint64_t is not
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available. The algorithm below extracts a number less than 62**6
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(approximately 2**35.725) from uint64_t, so ancient hosts where
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uintmax_t is only 32 bits lose about 3.725 bits of randomness,
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which is better than not having mkstemp at all. */
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#if !defined UINT64_MAX && !defined uint64_t
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# define uint64_t uintmax_t
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#endif
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/* Return nonzero if DIR is an existent directory. */
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static int
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direxists (const char *dir)
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{
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struct_stat64 buf;
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return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
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}
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/* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is
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non-null and exists, uses it; otherwise uses the first of $TMPDIR,
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P_tmpdir, /tmp that exists. Copies into TMPL a template suitable
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for use with mk[s]temp. Will fail (-1) if DIR is non-null and
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doesn't exist, none of the searched dirs exists, or there's not
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enough space in TMPL. */
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int
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__path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
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int try_tmpdir)
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{
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const char *d;
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size_t dlen, plen;
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if (!pfx || !pfx[0])
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{
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pfx = "file";
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plen = 4;
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}
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else
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{
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plen = strlen (pfx);
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if (plen > 5)
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plen = 5;
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}
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if (try_tmpdir)
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{
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d = __secure_getenv ("TMPDIR");
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if (d != NULL && direxists (d))
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dir = d;
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else if (dir != NULL && direxists (dir))
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/* nothing */ ;
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else
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dir = NULL;
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}
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if (dir == NULL)
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{
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if (direxists (P_tmpdir))
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dir = P_tmpdir;
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else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
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dir = "/tmp";
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else
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{
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__set_errno (ENOENT);
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return -1;
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}
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}
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dlen = strlen (dir);
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while (dlen > 1 && dir[dlen - 1] == '/')
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dlen--; /* remove trailing slashes */
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/* check we have room for "${dir}/${pfx}XXXXXX\0" */
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if (tmpl_len < dlen + 1 + plen + 6 + 1)
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{
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__set_errno (EINVAL);
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return -1;
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}
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sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
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return 0;
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}
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/* These are the characters used in temporary filenames. */
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static const char letters[] =
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"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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/* Generate a temporary file name based on TMPL. TMPL must match the
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rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
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does not exist at the time of the call to __gen_tempname. TMPL is
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overwritten with the result.
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KIND may be one of:
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__GT_NOCREATE: simply verify that the name does not exist
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at the time of the call.
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__GT_FILE: create the file using open(O_CREAT|O_EXCL)
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and return a read-write fd. The file is mode 0600.
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__GT_BIGFILE: same as __GT_FILE but use open64().
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__GT_DIR: create a directory, which will be mode 0700.
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We use a clever algorithm to get hard-to-predict names. */
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int
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__gen_tempname (char *tmpl, int kind)
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{
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int len;
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char *XXXXXX;
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static uint64_t value;
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uint64_t random_time_bits;
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unsigned int count;
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int fd = -1;
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int save_errno = errno;
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struct_stat64 st;
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/* A lower bound on the number of temporary files to attempt to
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generate. The maximum total number of temporary file names that
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can exist for a given template is 62**6. It should never be
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necessary to try all these combinations. Instead if a reasonable
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number of names is tried (we define reasonable as 62**3) fail to
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give the system administrator the chance to remove the problems. */
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unsigned int attempts_min = 62 * 62 * 62;
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/* The number of times to attempt to generate a temporary file. To
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conform to POSIX, this must be no smaller than TMP_MAX. */
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unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
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len = strlen (tmpl);
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if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
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{
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__set_errno (EINVAL);
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return -1;
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}
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/* This is where the Xs start. */
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XXXXXX = &tmpl[len - 6];
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/* Get some more or less random data. */
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#ifdef RANDOM_BITS
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RANDOM_BITS (random_time_bits);
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#else
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# if HAVE_GETTIMEOFDAY || _LIBC
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{
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struct timeval tv;
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__gettimeofday (&tv, NULL);
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random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
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}
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# else
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random_time_bits = time (NULL);
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# endif
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#endif
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value += random_time_bits ^ __getpid ();
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for (count = 0; count < attempts; value += 7777, ++count)
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{
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uint64_t v = value;
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/* Fill in the random bits. */
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XXXXXX[0] = letters[v % 62];
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v /= 62;
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XXXXXX[1] = letters[v % 62];
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v /= 62;
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XXXXXX[2] = letters[v % 62];
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v /= 62;
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XXXXXX[3] = letters[v % 62];
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v /= 62;
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XXXXXX[4] = letters[v % 62];
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v /= 62;
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XXXXXX[5] = letters[v % 62];
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switch (kind)
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{
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case __GT_FILE:
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fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
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break;
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case __GT_BIGFILE:
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fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
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break;
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case __GT_DIR:
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fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
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break;
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case __GT_NOCREATE:
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/* This case is backward from the other three. __gen_tempname
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succeeds if __xstat fails because the name does not exist.
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Note the continue to bypass the common logic at the bottom
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of the loop. */
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if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
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{
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if (errno == ENOENT)
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{
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__set_errno (save_errno);
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return 0;
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}
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else
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/* Give up now. */
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return -1;
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}
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continue;
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default:
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assert (! "invalid KIND in __gen_tempname");
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}
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if (fd >= 0)
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{
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__set_errno (save_errno);
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return fd;
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}
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else if (errno != EEXIST)
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return -1;
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}
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/* We got out of the loop because we ran out of combinations to try. */
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__set_errno (EEXIST);
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return -1;
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}
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