1 /* tempname.c - generate the name of a temporary file.
3 Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
4 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation,
18 Inc., 51 Franklin Street, Boston, MA 02110-1301, USA. */
24 #include <sys/types.h>
29 # define __set_errno(Val) errno = (Val)
34 # define P_tmpdir "/tmp"
37 # define TMP_MAX 238328
41 # define __GT_BIGFILE 1
43 # define __GT_NOCREATE 3
50 #if HAVE_FCNTL_H || _LIBC
54 #if HAVE_SYS_TIME_H || _LIBC
55 # include <sys/time.h>
58 #if HAVE_STDINT_H || _LIBC
62 # include <inttypes.h>
65 #if HAVE_UNISTD_H || _LIBC
70 #if STAT_MACROS_BROKEN
73 #if !defined S_ISDIR && defined S_IFDIR
74 # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
76 #if !S_IRUSR && S_IREAD
77 # define S_IRUSR S_IREAD
80 # define S_IRUSR 00400
82 #if !S_IWUSR && S_IWRITE
83 # define S_IWUSR S_IWRITE
86 # define S_IWUSR 00200
88 #if !S_IXUSR && S_IEXEC
89 # define S_IXUSR S_IEXEC
92 # define S_IXUSR 00100
96 # define struct_stat64 struct stat64
98 # define struct_stat64 struct stat
99 # define __getpid getpid
100 # define __gettimeofday gettimeofday
101 #ifdef MKDIR_TAKES_ONE_ARG
102 # define __mkdir(pathname,mode) mkdir((pathname))
104 # define __mkdir mkdir
107 # define __open64 open
109 # define __lxstat64(version, path, buf) lstat (path, buf)
111 # define __lxstat64(version, path, buf) stat (path, buf)
113 # define __xstat64(version, path, buf) stat (path, buf)
116 #if ! (HAVE___SECURE_GETENV || _LIBC)
117 # define __secure_getenv getenv
121 # include <hp-timing.h>
123 # define RANDOM_BITS(Var) \
124 if (__builtin_expect (value == UINT64_C (0), 0)) \
126 /* If this is the first time this function is used initialize \
127 the variable we accumulate the value in to some somewhat \
128 random value. If we'd not do this programs at startup time \
129 might have a reduced set of possible names, at least on slow \
132 __gettimeofday (&tv, NULL); \
133 value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \
139 /* Use the widest available unsigned type if uint64_t is not
140 available. The algorithm below extracts a number less than 62**6
141 (approximately 2**35.725) from uint64_t, so ancient hosts where
142 uintmax_t is only 32 bits lose about 3.725 bits of randomness,
143 which is better than not having mkstemp at all. */
144 #if !defined UINT64_MAX && !defined uint64_t
145 # define uint64_t uintmax_t
148 /* Return nonzero if DIR is an existent directory. */
150 direxists (const char *dir)
153 return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
156 /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is
157 non-null and exists, uses it; otherwise uses the first of $TMPDIR,
158 P_tmpdir, /tmp that exists. Copies into TMPL a template suitable
159 for use with mk[s]temp. Will fail (-1) if DIR is non-null and
160 doesn't exist, none of the searched dirs exists, or there's not
161 enough space in TMPL. */
163 __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
183 d = __secure_getenv ("TMPDIR");
184 if (d != NULL && direxists (d))
186 else if (dir != NULL && direxists (dir))
193 if (direxists (P_tmpdir))
195 else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
199 __set_errno (ENOENT);
205 while (dlen > 1 && dir[dlen - 1] == '/')
206 dlen--; /* remove trailing slashes */
208 /* check we have room for "${dir}/${pfx}XXXXXX\0" */
209 if (tmpl_len < dlen + 1 + plen + 6 + 1)
211 __set_errno (EINVAL);
215 sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
219 /* These are the characters used in temporary filenames. */
220 static const char letters[] =
221 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
223 /* Generate a temporary file name based on TMPL. TMPL must match the
224 rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
225 does not exist at the time of the call to __gen_tempname. TMPL is
226 overwritten with the result.
229 __GT_NOCREATE: simply verify that the name does not exist
230 at the time of the call.
231 __GT_FILE: create the file using open(O_CREAT|O_EXCL)
232 and return a read-write fd. The file is mode 0600.
233 __GT_BIGFILE: same as __GT_FILE but use open64().
234 __GT_DIR: create a directory, which will be mode 0700.
236 We use a clever algorithm to get hard-to-predict names. */
238 __gen_tempname (char *tmpl, int kind)
242 static uint64_t value;
243 uint64_t random_time_bits;
246 int save_errno = errno;
249 /* A lower bound on the number of temporary files to attempt to
250 generate. The maximum total number of temporary file names that
251 can exist for a given template is 62**6. It should never be
252 necessary to try all these combinations. Instead if a reasonable
253 number of names is tried (we define reasonable as 62**3) fail to
254 give the system administrator the chance to remove the problems. */
255 unsigned int attempts_min = 62 * 62 * 62;
257 /* The number of times to attempt to generate a temporary file. To
258 conform to POSIX, this must be no smaller than TMP_MAX. */
259 unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
262 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
264 __set_errno (EINVAL);
268 /* This is where the Xs start. */
269 XXXXXX = &tmpl[len - 6];
271 /* Get some more or less random data. */
273 RANDOM_BITS (random_time_bits);
275 # if HAVE_GETTIMEOFDAY || _LIBC
278 __gettimeofday (&tv, NULL);
279 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
282 random_time_bits = time (NULL);
285 value += random_time_bits ^ __getpid ();
287 for (count = 0; count < attempts; value += 7777, ++count)
291 /* Fill in the random bits. */
292 XXXXXX[0] = letters[v % 62];
294 XXXXXX[1] = letters[v % 62];
296 XXXXXX[2] = letters[v % 62];
298 XXXXXX[3] = letters[v % 62];
300 XXXXXX[4] = letters[v % 62];
302 XXXXXX[5] = letters[v % 62];
307 fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
311 fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
315 fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
319 /* This case is backward from the other three. __gen_tempname
320 succeeds if __xstat fails because the name does not exist.
321 Note the continue to bypass the common logic at the bottom
323 if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
327 __set_errno (save_errno);
337 assert (! "invalid KIND in __gen_tempname");
342 __set_errno (save_errno);
345 else if (errno != EEXIST)
349 /* We got out of the loop because we ran out of combinations to try. */
350 __set_errno (EEXIST);