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04277e02 | 1 | /* Copyright (C) 1991-2019 Free Software Foundation, Inc. |
478b92f0 | 2 | This file is part of the GNU C Library. |
28f540f4 | 3 | |
478b92f0 | 4 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
28f540f4 | 8 | |
478b92f0 UD |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
28f540f4 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
28f540f4 | 17 | |
c7aec4be | 18 | #if !_LIBC |
46c3f8cd | 19 | # include <config.h> |
c7aec4be | 20 | # include "tempname.h" |
46c3f8cd UD |
21 | #endif |
22 | ||
28f540f4 | 23 | #include <sys/types.h> |
2e65ca2b | 24 | #include <assert.h> |
28f540f4 | 25 | |
46c3f8cd UD |
26 | #include <errno.h> |
27 | #ifndef __set_errno | |
28 | # define __set_errno(Val) errno = (Val) | |
29 | #endif | |
30 | ||
31 | #include <stdio.h> | |
32 | #ifndef P_tmpdir | |
33 | # define P_tmpdir "/tmp" | |
34 | #endif | |
35 | #ifndef TMP_MAX | |
36 | # define TMP_MAX 238328 | |
37 | #endif | |
38 | #ifndef __GT_FILE | |
39 | # define __GT_FILE 0 | |
d7e23b02 UD |
40 | # define __GT_DIR 1 |
41 | # define __GT_NOCREATE 2 | |
46c3f8cd | 42 | #endif |
c7aec4be WN |
43 | #if !_LIBC && (GT_FILE != __GT_FILE || GT_DIR != __GT_DIR \ |
44 | || GT_NOCREATE != __GT_NOCREATE) | |
45 | # error report this to bug-gnulib@gnu.org | |
46c3f8cd UD |
46 | #endif |
47 | ||
c7aec4be WN |
48 | #include <stddef.h> |
49 | #include <stdlib.h> | |
50 | #include <string.h> | |
46c3f8cd | 51 | |
c7aec4be WN |
52 | #include <fcntl.h> |
53 | #include <sys/time.h> | |
54 | #include <stdint.h> | |
55 | #include <unistd.h> | |
46c3f8cd UD |
56 | |
57 | #include <sys/stat.h> | |
46c3f8cd UD |
58 | |
59 | #if _LIBC | |
60 | # define struct_stat64 struct stat64 | |
c7aec4be | 61 | # define __secure_getenv __libc_secure_getenv |
46c3f8cd UD |
62 | #else |
63 | # define struct_stat64 struct stat | |
c7aec4be | 64 | # define __gen_tempname gen_tempname |
46c3f8cd UD |
65 | # define __getpid getpid |
66 | # define __gettimeofday gettimeofday | |
67 | # define __mkdir mkdir | |
68 | # define __open open | |
c7aec4be WN |
69 | # define __lxstat64(version, file, buf) lstat (file, buf) |
70 | # define __secure_getenv secure_getenv | |
46c3f8cd UD |
71 | #endif |
72 | ||
3b5c1b57 UD |
73 | #ifdef _LIBC |
74 | # include <hp-timing.h> | |
75 | # if HP_TIMING_AVAIL | |
76 | # define RANDOM_BITS(Var) \ | |
a1ffb40e | 77 | if (__glibc_unlikely (value == UINT64_C (0))) \ |
3b5c1b57 UD |
78 | { \ |
79 | /* If this is the first time this function is used initialize \ | |
80 | the variable we accumulate the value in to some somewhat \ | |
81 | random value. If we'd not do this programs at startup time \ | |
82 | might have a reduced set of possible names, at least on slow \ | |
83 | machines. */ \ | |
84 | struct timeval tv; \ | |
85 | __gettimeofday (&tv, NULL); \ | |
86 | value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \ | |
87 | } \ | |
88 | HP_TIMING_NOW (Var) | |
89 | # endif | |
90 | #endif | |
91 | ||
f2615995 UD |
92 | /* Use the widest available unsigned type if uint64_t is not |
93 | available. The algorithm below extracts a number less than 62**6 | |
94 | (approximately 2**35.725) from uint64_t, so ancient hosts where | |
95 | uintmax_t is only 32 bits lose about 3.725 bits of randomness, | |
96 | which is better than not having mkstemp at all. */ | |
97 | #if !defined UINT64_MAX && !defined uint64_t | |
98 | # define uint64_t uintmax_t | |
99 | #endif | |
100 | ||
c7aec4be | 101 | #if _LIBC |
28f540f4 RM |
102 | /* Return nonzero if DIR is an existent directory. */ |
103 | static int | |
7cabd57c | 104 | direxists (const char *dir) |
28f540f4 | 105 | { |
46c3f8cd | 106 | struct_stat64 buf; |
8edf6e0d | 107 | return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode); |
28f540f4 RM |
108 | } |
109 | ||
7cabd57c UD |
110 | /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is |
111 | non-null and exists, uses it; otherwise uses the first of $TMPDIR, | |
112 | P_tmpdir, /tmp that exists. Copies into TMPL a template suitable | |
113 | for use with mk[s]temp. Will fail (-1) if DIR is non-null and | |
114 | doesn't exist, none of the searched dirs exists, or there's not | |
115 | enough space in TMPL. */ | |
116 | int | |
60876a75 UD |
117 | __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx, |
118 | int try_tmpdir) | |
28f540f4 | 119 | { |
7cabd57c UD |
120 | const char *d; |
121 | size_t dlen, plen; | |
122 | ||
123 | if (!pfx || !pfx[0]) | |
124 | { | |
125 | pfx = "file"; | |
126 | plen = 4; | |
127 | } | |
28f540f4 RM |
128 | else |
129 | { | |
7cabd57c UD |
130 | plen = strlen (pfx); |
131 | if (plen > 5) | |
132 | plen = 5; | |
28f540f4 | 133 | } |
28f540f4 | 134 | |
60876a75 UD |
135 | if (try_tmpdir) |
136 | { | |
c7aec4be | 137 | d = __secure_getenv ("TMPDIR"); |
60876a75 UD |
138 | if (d != NULL && direxists (d)) |
139 | dir = d; | |
140 | else if (dir != NULL && direxists (dir)) | |
141 | /* nothing */ ; | |
5a7cb1a2 UD |
142 | else |
143 | dir = NULL; | |
60876a75 | 144 | } |
e9dcb080 | 145 | if (dir == NULL) |
28f540f4 | 146 | { |
b61af6fc UD |
147 | if (direxists (P_tmpdir)) |
148 | dir = P_tmpdir; | |
149 | else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp")) | |
150 | dir = "/tmp"; | |
151 | else | |
152 | { | |
153 | __set_errno (ENOENT); | |
154 | return -1; | |
155 | } | |
28f540f4 | 156 | } |
28f540f4 RM |
157 | |
158 | dlen = strlen (dir); | |
28f540f4 | 159 | while (dlen > 1 && dir[dlen - 1] == '/') |
7cabd57c | 160 | dlen--; /* remove trailing slashes */ |
28f540f4 | 161 | |
7cabd57c UD |
162 | /* check we have room for "${dir}/${pfx}XXXXXX\0" */ |
163 | if (tmpl_len < dlen + 1 + plen + 6 + 1) | |
28f540f4 | 164 | { |
7cabd57c UD |
165 | __set_errno (EINVAL); |
166 | return -1; | |
28f540f4 | 167 | } |
28f540f4 | 168 | |
04166d6e | 169 | sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx); |
7cabd57c UD |
170 | return 0; |
171 | } | |
c7aec4be | 172 | #endif /* _LIBC */ |
7cabd57c | 173 | |
c7aec4be | 174 | /* These are the characters used in temporary file names. */ |
7cabd57c UD |
175 | static const char letters[] = |
176 | "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; | |
177 | ||
178 | /* Generate a temporary file name based on TMPL. TMPL must match the | |
7f3146e7 UD |
179 | rules for mk[s]temp (i.e. end in "XXXXXX", possibly with a suffix). |
180 | The name constructed does not exist at the time of the call to | |
181 | __gen_tempname. TMPL is overwritten with the result. | |
2e65ca2b UD |
182 | |
183 | KIND may be one of: | |
184 | __GT_NOCREATE: simply verify that the name does not exist | |
185 | at the time of the call. | |
186 | __GT_FILE: create the file using open(O_CREAT|O_EXCL) | |
187 | and return a read-write fd. The file is mode 0600. | |
2e65ca2b | 188 | __GT_DIR: create a directory, which will be mode 0700. |
7cabd57c UD |
189 | |
190 | We use a clever algorithm to get hard-to-predict names. */ | |
191 | int | |
7f3146e7 | 192 | __gen_tempname (char *tmpl, int suffixlen, int flags, int kind) |
7cabd57c UD |
193 | { |
194 | int len; | |
195 | char *XXXXXX; | |
196 | static uint64_t value; | |
46c3f8cd | 197 | uint64_t random_time_bits; |
8e9b2075 UD |
198 | unsigned int count; |
199 | int fd = -1; | |
7cabd57c | 200 | int save_errno = errno; |
46c3f8cd | 201 | struct_stat64 st; |
28f540f4 | 202 | |
8e9b2075 UD |
203 | /* A lower bound on the number of temporary files to attempt to |
204 | generate. The maximum total number of temporary file names that | |
205 | can exist for a given template is 62**6. It should never be | |
c7aec4be | 206 | necessary to try all of these combinations. Instead if a reasonable |
8e9b2075 UD |
207 | number of names is tried (we define reasonable as 62**3) fail to |
208 | give the system administrator the chance to remove the problems. */ | |
cec40916 | 209 | #define ATTEMPTS_MIN (62 * 62 * 62) |
8e9b2075 UD |
210 | |
211 | /* The number of times to attempt to generate a temporary file. To | |
212 | conform to POSIX, this must be no smaller than TMP_MAX. */ | |
cec40916 UD |
213 | #if ATTEMPTS_MIN < TMP_MAX |
214 | unsigned int attempts = TMP_MAX; | |
215 | #else | |
216 | unsigned int attempts = ATTEMPTS_MIN; | |
217 | #endif | |
8e9b2075 | 218 | |
7cabd57c | 219 | len = strlen (tmpl); |
7f3146e7 | 220 | if (len < 6 + suffixlen || memcmp (&tmpl[len - 6 - suffixlen], "XXXXXX", 6)) |
7cabd57c | 221 | { |
a7ab2023 | 222 | __set_errno (EINVAL); |
7cabd57c UD |
223 | return -1; |
224 | } | |
28f540f4 | 225 | |
7cabd57c | 226 | /* This is where the Xs start. */ |
7f3146e7 | 227 | XXXXXX = &tmpl[len - 6 - suffixlen]; |
d68171ed | 228 | |
a7ab2023 | 229 | /* Get some more or less random data. */ |
f2615995 UD |
230 | #ifdef RANDOM_BITS |
231 | RANDOM_BITS (random_time_bits); | |
232 | #else | |
46c3f8cd UD |
233 | { |
234 | struct timeval tv; | |
235 | __gettimeofday (&tv, NULL); | |
236 | random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; | |
237 | } | |
46c3f8cd UD |
238 | #endif |
239 | value += random_time_bits ^ __getpid (); | |
28f540f4 | 240 | |
8e9b2075 | 241 | for (count = 0; count < attempts; value += 7777, ++count) |
a7ab2023 UD |
242 | { |
243 | uint64_t v = value; | |
244 | ||
245 | /* Fill in the random bits. */ | |
246 | XXXXXX[0] = letters[v % 62]; | |
247 | v /= 62; | |
248 | XXXXXX[1] = letters[v % 62]; | |
249 | v /= 62; | |
250 | XXXXXX[2] = letters[v % 62]; | |
251 | v /= 62; | |
252 | XXXXXX[3] = letters[v % 62]; | |
253 | v /= 62; | |
254 | XXXXXX[4] = letters[v % 62]; | |
255 | v /= 62; | |
256 | XXXXXX[5] = letters[v % 62]; | |
28f540f4 | 257 | |
2e65ca2b | 258 | switch (kind) |
7cabd57c | 259 | { |
2e65ca2b | 260 | case __GT_FILE: |
d7e23b02 | 261 | fd = __open (tmpl, |
e8a32126 | 262 | (flags & ~O_ACCMODE) |
d7e23b02 | 263 | | O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); |
2e65ca2b UD |
264 | break; |
265 | ||
266 | case __GT_DIR: | |
46c3f8cd | 267 | fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR); |
2e65ca2b UD |
268 | break; |
269 | ||
270 | case __GT_NOCREATE: | |
271 | /* This case is backward from the other three. __gen_tempname | |
272 | succeeds if __xstat fails because the name does not exist. | |
273 | Note the continue to bypass the common logic at the bottom | |
274 | of the loop. */ | |
72c65ff4 | 275 | if (__lxstat64 (_STAT_VER, tmpl, &st) < 0) |
7cabd57c UD |
276 | { |
277 | if (errno == ENOENT) | |
28f540f4 | 278 | { |
7cabd57c UD |
279 | __set_errno (save_errno); |
280 | return 0; | |
28f540f4 | 281 | } |
7cabd57c UD |
282 | else |
283 | /* Give up now. */ | |
284 | return -1; | |
28f540f4 | 285 | } |
2e65ca2b UD |
286 | continue; |
287 | ||
288 | default: | |
289 | assert (! "invalid KIND in __gen_tempname"); | |
c7aec4be | 290 | abort (); |
2e65ca2b UD |
291 | } |
292 | ||
293 | if (fd >= 0) | |
294 | { | |
295 | __set_errno (save_errno); | |
296 | return fd; | |
28f540f4 | 297 | } |
2e65ca2b UD |
298 | else if (errno != EEXIST) |
299 | return -1; | |
28f540f4 RM |
300 | } |
301 | ||
302 | /* We got out of the loop because we ran out of combinations to try. */ | |
7cabd57c UD |
303 | __set_errno (EEXIST); |
304 | return -1; | |
28f540f4 | 305 | } |