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 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
48 #if STDC_HEADERS || _LIBC
54 #if HAVE_FCNTL_H || _LIBC
58 #if HAVE_SYS_TIME_H || _LIBC
59 # include <sys/time.h>
62 #if HAVE_STDINT_H || _LIBC
66 # include <inttypes.h>
69 #if HAVE_UNISTD_H || _LIBC
74 #if STAT_MACROS_BROKEN
77 #if !defined S_ISDIR && defined S_IFDIR
78 # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
80 #if !S_IRUSR && S_IREAD
81 # define S_IRUSR S_IREAD
84 # define S_IRUSR 00400
86 #if !S_IWUSR && S_IWRITE
87 # define S_IWUSR S_IWRITE
90 # define S_IWUSR 00200
92 #if !S_IXUSR && S_IEXEC
93 # define S_IXUSR S_IEXEC
96 # define S_IXUSR 00100
100 # define struct_stat64 struct stat64
102 # define struct_stat64 struct stat
103 # define __getpid getpid
104 # define __gettimeofday gettimeofday
105 # define __mkdir mkdir
107 # define __open64 open
108 # define __lxstat64(version, path, buf) lstat (path, buf)
109 # define __xstat64(version, path, buf) stat (path, buf)
112 #if ! (HAVE___SECURE_GETENV || _LIBC)
113 # define __secure_getenv getenv
117 # include <hp-timing.h>
119 # define RANDOM_BITS(Var) \
120 if (__builtin_expect (value == UINT64_C (0), 0)) \
122 /* If this is the first time this function is used initialize \
123 the variable we accumulate the value in to some somewhat \
124 random value. If we'd not do this programs at startup time \
125 might have a reduced set of possible names, at least on slow \
128 __gettimeofday (&tv, NULL); \
129 value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \
135 /* Use the widest available unsigned type if uint64_t is not
136 available. The algorithm below extracts a number less than 62**6
137 (approximately 2**35.725) from uint64_t, so ancient hosts where
138 uintmax_t is only 32 bits lose about 3.725 bits of randomness,
139 which is better than not having mkstemp at all. */
140 #if !defined UINT64_MAX && !defined uint64_t
141 # define uint64_t uintmax_t
144 /* Return nonzero if DIR is an existent directory. */
146 direxists (const char *dir)
149 return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
152 /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is
153 non-null and exists, uses it; otherwise uses the first of $TMPDIR,
154 P_tmpdir, /tmp that exists. Copies into TMPL a template suitable
155 for use with mk[s]temp. Will fail (-1) if DIR is non-null and
156 doesn't exist, none of the searched dirs exists, or there's not
157 enough space in TMPL. */
159 __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
179 d = __secure_getenv ("TMPDIR");
180 if (d != NULL && direxists (d))
182 else if (dir != NULL && direxists (dir))
189 if (direxists (P_tmpdir))
191 else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
195 __set_errno (ENOENT);
201 while (dlen > 1 && dir[dlen - 1] == '/')
202 dlen--; /* remove trailing slashes */
204 /* check we have room for "${dir}/${pfx}XXXXXX\0" */
205 if (tmpl_len < dlen + 1 + plen + 6 + 1)
207 __set_errno (EINVAL);
211 sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
215 /* These are the characters used in temporary filenames. */
216 static const char letters[] =
217 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
219 /* Generate a temporary file name based on TMPL. TMPL must match the
220 rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
221 does not exist at the time of the call to __gen_tempname. TMPL is
222 overwritten with the result.
225 __GT_NOCREATE: simply verify that the name does not exist
226 at the time of the call.
227 __GT_FILE: create the file using open(O_CREAT|O_EXCL)
228 and return a read-write fd. The file is mode 0600.
229 __GT_BIGFILE: same as __GT_FILE but use open64().
230 __GT_DIR: create a directory, which will be mode 0700.
232 We use a clever algorithm to get hard-to-predict names. */
234 __gen_tempname (char *tmpl, int kind)
238 static uint64_t value;
239 uint64_t random_time_bits;
242 int save_errno = errno;
245 /* A lower bound on the number of temporary files to attempt to
246 generate. The maximum total number of temporary file names that
247 can exist for a given template is 62**6. It should never be
248 necessary to try all these combinations. Instead if a reasonable
249 number of names is tried (we define reasonable as 62**3) fail to
250 give the system administrator the chance to remove the problems. */
251 unsigned int attempts_min = 62 * 62 * 62;
253 /* The number of times to attempt to generate a temporary file. To
254 conform to POSIX, this must be no smaller than TMP_MAX. */
255 unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
258 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
260 __set_errno (EINVAL);
264 /* This is where the Xs start. */
265 XXXXXX = &tmpl[len - 6];
267 /* Get some more or less random data. */
269 RANDOM_BITS (random_time_bits);
271 # if HAVE_GETTIMEOFDAY || _LIBC
274 __gettimeofday (&tv, NULL);
275 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
278 random_time_bits = time (NULL);
281 value += random_time_bits ^ __getpid ();
283 for (count = 0; count < attempts; value += 7777, ++count)
287 /* Fill in the random bits. */
288 XXXXXX[0] = letters[v % 62];
290 XXXXXX[1] = letters[v % 62];
292 XXXXXX[2] = letters[v % 62];
294 XXXXXX[3] = letters[v % 62];
296 XXXXXX[4] = letters[v % 62];
298 XXXXXX[5] = letters[v % 62];
303 fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
307 fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
311 fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
315 /* This case is backward from the other three. __gen_tempname
316 succeeds if __xstat fails because the name does not exist.
317 Note the continue to bypass the common logic at the bottom
319 if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
323 __set_errno (save_errno);
333 assert (! "invalid KIND in __gen_tempname");
338 __set_errno (save_errno);
341 else if (errno != EEXIST)
345 /* We got out of the loop because we ran out of combinations to try. */
346 __set_errno (EEXIST);