1 /* Copyright (C) 1991-1999, 2000, 2001 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 The GNU C Library is free software; you can redistribute it and/or 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. 8 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 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, write to the Free 16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 17 02111-1307 USA. */ 18 19 #if HAVE_CONFIG_H 20 # include <config.h> 21 #endif 22 23 #include <sys/types.h> 24 #include <assert.h> 25 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 40 # define __GT_BIGFILE 1 41 # define __GT_DIR 2 42 # define __GT_NOCREATE 3 43 #endif 44 45 #if STDC_HEADERS || _LIBC 46 # include <stddef.h> 47 # include <stdlib.h> 48 # include <string.h> 49 #endif 50 51 #if HAVE_FCNTL_H || _LIBC 52 # include <fcntl.h> 53 #endif 54 55 #if HAVE_SYS_TIME_H || _LIBC 56 # include <sys/time.h> 57 #endif 58 59 #if HAVE_STDINT_H || _LIBC 60 # include <stdint.h> 61 #endif 62 63 #if HAVE_UNISTD_H || _LIBC 64 # include <unistd.h> 65 #endif 66 67 #include <sys/stat.h> 68 #if STAT_MACROS_BROKEN 69 # undef S_ISDIR 70 #endif 71 #if !defined S_ISDIR && defined S_IFDIR 72 # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR) 73 #endif 74 #if !S_IRUSR && S_IREAD 75 # define S_IRUSR S_IREAD 76 #endif 77 #if !S_IRUSR 78 # define S_IRUSR 00400 79 #endif 80 #if !S_IWUSR && S_IWRITE 81 # define S_IWUSR S_IWRITE 82 #endif 83 #if !S_IWUSR 84 # define S_IWUSR 00200 85 #endif 86 #if !S_IXUSR && S_IEXEC 87 # define S_IXUSR S_IEXEC 88 #endif 89 #if !S_IXUSR 90 # define S_IXUSR 00100 91 #endif 92 93 #if _LIBC 94 # define struct_stat64 struct stat64 95 #else 96 # define struct_stat64 struct stat 97 # define __getpid getpid 98 # define __gettimeofday gettimeofday 99 # define __mkdir mkdir 100 # define __open open 101 # define __open64 open 102 # define __lxstat64(version, path, buf) lstat (path, buf) 103 # define __xstat64(version, path, buf) stat (path, buf) 104 #endif 105 106 #define __secure_getenv getenv 107 108 #if 0 109 #ifdef _LIBC 110 # include <hp-timing.h> 111 # if HP_TIMING_AVAIL 112 # define RANDOM_BITS(Var) \ 113 if (__builtin_expect (value == UINT64_C (0), 0)) \ 114 { \ 115 /* If this is the first time this function is used initialize \ 116 the variable we accumulate the value in to some somewhat \ 117 random value. If we'd not do this programs at startup time \ 118 might have a reduced set of possible names, at least on slow \ 119 machines. */ \ 120 struct timeval tv; \ 121 __gettimeofday (&tv, NULL); \ 122 value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \ 123 } \ 124 HP_TIMING_NOW (Var) 125 # endif 126 #endif 127 #endif 128 129 /* Use the widest available unsigned type if uint64_t is not 130 available. The algorithm below extracts a number less than 62**6 131 (approximately 2**35.725) from uint64_t, so ancient hosts where 132 uintmax_t is only 32 bits lose about 3.725 bits of randomness, 133 which is better than not having mkstemp at all. */ 134 #if !defined UINT64_MAX && !defined uint64_t 135 # define uint64_t uintmax_t 136 #endif 137 138 int __path_search(char *tmpl, size_t tmpl_len, const char *dir, 139 const char *pfx, int try_tmpdir); 140 int __gen_tempname(char *tmpl, int kind); 141 142 /* Return nonzero if DIR is an existent directory. */ 143 static int 144 direxists(const char *dir) 145 { 146 struct stat st; 147 return stat(dir, &st) == 0 && S_ISDIR(st.st_mode); 148 } 149 150 151 /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is 152 non-null and exists, uses it; otherwise uses the first of $TMPDIR, 153 P_tmpdir, /tmp that exists. Copies into TMPL a template suitable 154 for use with mk[s]temp. Will fail (-1) if DIR is non-null and 155 doesn't exist, none of the searched dirs exists, or there's not 156 enough space in TMPL. */ 157 int 158 __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx, 159 int try_tmpdir) 160 { 161 const char *d; 162 size_t dlen, plen; 163 164 if (!pfx || !pfx[0]) 165 { 166 pfx = "file"; 167 plen = 4; 168 } 169 else 170 { 171 plen = strlen (pfx); 172 if (plen > 5) 173 plen = 5; 174 } 175 176 if (try_tmpdir) 177 { 178 d = __secure_getenv ("TMPDIR"); 179 if (d != NULL && direxists (d)) 180 dir = d; 181 else if (dir != NULL && direxists (dir)) 182 /* nothing */ ; 183 else 184 dir = NULL; 185 } 186 if (dir == NULL) 187 { 188 if (direxists (P_tmpdir)) 189 dir = P_tmpdir; 190 else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp")) 191 dir = "/tmp"; 192 else 193 { 194 __set_errno (ENOENT); 195 return -1; 196 } 197 } 198 199 dlen = strlen (dir); 200 while (dlen > 1 && dir[dlen - 1] == '/') 201 dlen--; /* remove trailing slashes */ 202 203 /* check we have room for "${dir}/${pfx}XXXXXX\0" */ 204 if (tmpl_len < dlen + 1 + plen + 6 + 1) 205 { 206 __set_errno (EINVAL); 207 return -1; 208 } 209 210 sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx); 211 return 0; 212 } 213 214 /* These are the characters used in temporary filenames. */ 215 static const char letters[] = 216 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 217 218 /* 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. 222 223 KIND may be one of: 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. 230 231 We use a clever algorithm to get hard-to-predict names. */ 232 int 233 __gen_tempname (char *tmpl, int kind) 234 { 235 int len; 236 char *XXXXXX; 237 static uint64_t value; 238 uint64_t random_time_bits; 239 unsigned int count; 240 int fd = -1; 241 int save_errno = errno; 242 struct stat st; 243 244 /* 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; 251 252 /* 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; 255 256 len = strlen (tmpl); 257 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX")) 258 { 259 __set_errno (EINVAL); 260 return -1; 261 } 262 263 /* This is where the Xs start. */ 264 XXXXXX = &tmpl[len - 6]; 265 266 /* Get some more or less random data. */ 267 #ifdef RANDOM_BITS 268 RANDOM_BITS (random_time_bits); 269 #else 270 # if HAVE_GETTIMEOFDAY || _LIBC 271 { 272 struct timeval tv; 273 gettimeofday(&tv, NULL); 274 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; 275 } 276 # else 277 random_time_bits = time (NULL); 278 # endif 279 #endif 280 value += random_time_bits ^ getpid(); 281 282 for (count = 0; count < attempts; value += 7777, ++count) 283 { 284 uint64_t v = value; 285 286 /* Fill in the random bits. */ 287 XXXXXX[0] = letters[v % 62]; 288 v /= 62; 289 XXXXXX[1] = letters[v % 62]; 290 v /= 62; 291 XXXXXX[2] = letters[v % 62]; 292 v /= 62; 293 XXXXXX[3] = letters[v % 62]; 294 v /= 62; 295 XXXXXX[4] = letters[v % 62]; 296 v /= 62; 297 XXXXXX[5] = letters[v % 62]; 298 299 switch (kind) 300 { 301 case __GT_FILE: 302 case __GT_BIGFILE: 303 fd = open(tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); 304 break; 305 306 case __GT_DIR: 307 fd = mkdir(tmpl, S_IRUSR | S_IWUSR | S_IXUSR); 308 break; 309 310 case __GT_NOCREATE: 311 /* This case is backward from the other three. __gen_tempname 312 succeeds if __xstat fails because the name does not exist. 313 Note the continue to bypass the common logic at the bottom 314 of the loop. */ 315 if (stat(tmpl, &st) < 0) 316 { 317 if (errno == ENOENT) 318 { 319 __set_errno (save_errno); 320 return 0; 321 } 322 else 323 /* Give up now. */ 324 return -1; 325 } 326 continue; 327 328 default: 329 assert (! "invalid KIND in __gen_tempname"); 330 } 331 332 if (fd >= 0) 333 { 334 __set_errno (save_errno); 335 return fd; 336 } 337 else if (errno != EEXIST) 338 return -1; 339 } 340 341 /* We got out of the loop because we ran out of combinations to try. */ 342 __set_errno (EEXIST); 343 return -1; 344 } 345