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 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 2, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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
46 #if STDC_HEADERS || _LIBC
53 #if HAVE_FCNTL_H || _LIBC
57 #if HAVE_SYS_TIME_H || _LIBC
58 # include <sys/time.h>
61 #if HAVE_STDINT_H || _LIBC
65 # include <inttypes.h>
68 #if HAVE_UNISTD_H || _LIBC
73 #if STAT_MACROS_BROKEN
76 #if !defined S_ISDIR && defined S_IFDIR
77 # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
79 #if !S_IRUSR && S_IREAD
80 # define S_IRUSR S_IREAD
83 # define S_IRUSR 00400
85 #if !S_IWUSR && S_IWRITE
86 # define S_IWUSR S_IWRITE
89 # define S_IWUSR 00200
91 #if !S_IXUSR && S_IEXEC
92 # define S_IXUSR S_IEXEC
95 # define S_IXUSR 00100
99 # define struct_stat64 struct stat64
101 # define struct_stat64 struct stat
102 # define __getpid getpid
103 # define __gettimeofday gettimeofday
104 # define __mkdir mkdir
106 # define __open64 open
107 # define __lxstat64(version, path, buf) lstat (path, buf)
108 # define __xstat64(version, path, buf) stat (path, buf)
111 #if ! (HAVE___SECURE_GETENV || _LIBC)
112 # define __secure_getenv getenv
116 # include <hp-timing.h>
118 # define RANDOM_BITS(Var) \
119 if (__builtin_expect (value == UINT64_C (0), 0)) \
121 /* If this is the first time this function is used initialize \
122 the variable we accumulate the value in to some somewhat \
123 random value. If we'd not do this programs at startup time \
124 might have a reduced set of possible names, at least on slow \
127 __gettimeofday (&tv, NULL); \
128 value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \
134 /* Use the widest available unsigned type if uint64_t is not
135 available. The algorithm below extracts a number less than 62**6
136 (approximately 2**35.725) from uint64_t, so ancient hosts where
137 uintmax_t is only 32 bits lose about 3.725 bits of randomness,
138 which is better than not having mkstemp at all. */
139 #if !defined UINT64_MAX && !defined uint64_t
140 # define uint64_t uintmax_t
143 /* Return nonzero if DIR is an existent directory. */
145 direxists (const char *dir)
148 return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
151 /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is
152 non-null and exists, uses it; otherwise uses the first of $TMPDIR,
153 P_tmpdir, /tmp that exists. Copies into TMPL a template suitable
154 for use with mk[s]temp. Will fail (-1) if DIR is non-null and
155 doesn't exist, none of the searched dirs exists, or there's not
156 enough space in TMPL. */
158 __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
178 d = __secure_getenv ("TMPDIR");
179 if (d != NULL && direxists (d))
181 else if (dir != NULL && direxists (dir))
188 if (direxists (P_tmpdir))
190 else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
194 __set_errno (ENOENT);
200 while (dlen > 1 && dir[dlen - 1] == '/')
201 dlen--; /* remove trailing slashes */
203 /* check we have room for "${dir}/${pfx}XXXXXX\0" */
204 if (tmpl_len < dlen + 1 + plen + 6 + 1)
206 __set_errno (EINVAL);
210 sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
214 /* These are the characters used in temporary filenames. */
215 static const char letters[] =
216 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
218 /* Generate a temporary file name based on TMPL. TMPL must match the
219 rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
220 does not exist at the time of the call to __gen_tempname. TMPL is
221 overwritten with the result.
224 __GT_NOCREATE: simply verify that the name does not exist
225 at the time of the call.
226 __GT_FILE: create the file using open(O_CREAT|O_EXCL)
227 and return a read-write fd. The file is mode 0600.
228 __GT_BIGFILE: same as __GT_FILE but use open64().
229 __GT_DIR: create a directory, which will be mode 0700.
231 We use a clever algorithm to get hard-to-predict names. */
233 __gen_tempname (char *tmpl, int kind)
237 static uint64_t value;
238 uint64_t random_time_bits;
241 int save_errno = errno;
244 /* A lower bound on the number of temporary files to attempt to
245 generate. The maximum total number of temporary file names that
246 can exist for a given template is 62**6. It should never be
247 necessary to try all these combinations. Instead if a reasonable
248 number of names is tried (we define reasonable as 62**3) fail to
249 give the system administrator the chance to remove the problems. */
250 unsigned int attempts_min = 62 * 62 * 62;
252 /* The number of times to attempt to generate a temporary file. To
253 conform to POSIX, this must be no smaller than TMP_MAX. */
254 unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
257 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
259 __set_errno (EINVAL);
263 /* This is where the Xs start. */
264 XXXXXX = &tmpl[len - 6];
266 /* Get some more or less random data. */
268 RANDOM_BITS (random_time_bits);
270 # if HAVE_GETTIMEOFDAY || _LIBC
273 __gettimeofday (&tv, NULL);
274 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
277 random_time_bits = time (NULL);
280 value += random_time_bits ^ __getpid ();
282 for (count = 0; count < attempts; value += 7777, ++count)
286 /* Fill in the random bits. */
287 XXXXXX[0] = letters[v % 62];
289 XXXXXX[1] = letters[v % 62];
291 XXXXXX[2] = letters[v % 62];
293 XXXXXX[3] = letters[v % 62];
295 XXXXXX[4] = letters[v % 62];
297 XXXXXX[5] = letters[v % 62];
302 fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
306 fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
310 fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
314 /* This case is backward from the other three. __gen_tempname
315 succeeds if __xstat fails because the name does not exist.
316 Note the continue to bypass the common logic at the bottom
318 if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
322 __set_errno (save_errno);
332 assert (! "invalid KIND in __gen_tempname");
337 __set_errno (save_errno);
340 else if (errno != EEXIST)
344 /* We got out of the loop because we ran out of combinations to try. */
345 __set_errno (EEXIST);