1/* Copyright (C) 1991-1999, 2000, 2001 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2, or (at your option) 7 any later version. 8 9 This program 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 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software Foundation, 16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 17 18#if HAVE_CONFIG_H 19# include <config.h> 20#endif 21 22#include <sys/types.h> 23#include <assert.h> 24 25#include <errno.h> 26#ifndef __set_errno 27# define __set_errno(Val) errno = (Val) 28#endif 29 30#include <stdio.h> 31#ifndef P_tmpdir 32# define P_tmpdir "/tmp" 33#endif 34#ifndef TMP_MAX 35# define TMP_MAX 238328 36#endif 37#ifndef __GT_FILE 38# define __GT_FILE 0 39# define __GT_BIGFILE 1 40# define __GT_DIR 2 41# define __GT_NOCREATE 3 42#endif 43 44#if STDC_HEADERS || _LIBC 45# include <stddef.h> 46# include <string.h> 47#endif 48 49#include <stdlib.h> 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#if ! (HAVE___SECURE_GETENV || _LIBC) 107# define __secure_getenv getenv 108#endif 109 110#ifdef _LIBC 111# include <hp-timing.h> 112# if HP_TIMING_AVAIL 113# define RANDOM_BITS(Var) \ 114 if (__builtin_expect (value == UINT64_C (0), 0)) \ 115 { \ 116 /* If this is the first time this function is used initialize \ 117 the variable we accumulate the value in to some somewhat \ 118 random value. If we'd not do this programs at startup time \ 119 might have a reduced set of possible names, at least on slow \ 120 machines. */ \ 121 struct timeval tv; \ 122 __gettimeofday (&tv, NULL); \ 123 value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \ 124 } \ 125 HP_TIMING_NOW (Var) 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/* Return nonzero if DIR is an existent directory. */ 139static int 140direxists (const char *dir) 141{ 142 struct_stat64 buf; 143 return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode); 144} 145 146/* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is 147 non-null and exists, uses it; otherwise uses the first of $TMPDIR, 148 P_tmpdir, /tmp that exists. Copies into TMPL a template suitable 149 for use with mk[s]temp. Will fail (-1) if DIR is non-null and 150 doesn't exist, none of the searched dirs exists, or there's not 151 enough space in TMPL. */ 152int 153__path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx, 154 int try_tmpdir) 155{ 156 const char *d; 157 size_t dlen, plen; 158 159 if (!pfx || !pfx[0]) 160 { 161 pfx = "file"; 162 plen = 4; 163 } 164 else 165 { 166 plen = strlen (pfx); 167 if (plen > 5) 168 plen = 5; 169 } 170 171 if (try_tmpdir) 172 { 173 d = __secure_getenv ("TMPDIR"); 174 if (d != NULL && direxists (d)) 175 dir = d; 176 else if (dir != NULL && direxists (dir)) 177 /* nothing */ ; 178 else 179 dir = NULL; 180 } 181 if (dir == NULL) 182 { 183 if (direxists (P_tmpdir)) 184 dir = P_tmpdir; 185 else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp")) 186 dir = "/tmp"; 187 else 188 { 189 __set_errno (ENOENT); 190 return -1; 191 } 192 } 193 194 dlen = strlen (dir); 195 while (dlen > 1 && dir[dlen - 1] == '/') 196 dlen--; /* remove trailing slashes */ 197 198 /* check we have room for "${dir}/${pfx}XXXXXX\0" */ 199 if (tmpl_len < dlen + 1 + plen + 6 + 1) 200 { 201 __set_errno (EINVAL); 202 return -1; 203 } 204 205 sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx); 206 return 0; 207} 208 209/* These are the characters used in temporary filenames. */ 210static const char letters[] = 211"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 212 213/* Generate a temporary file name based on TMPL. TMPL must match the 214 rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed 215 does not exist at the time of the call to __gen_tempname. TMPL is 216 overwritten with the result. 217 218 KIND may be one of: 219 __GT_NOCREATE: simply verify that the name does not exist 220 at the time of the call. 221 __GT_FILE: create the file using open(O_CREAT|O_EXCL) 222 and return a read-write fd. The file is mode 0600. 223 __GT_BIGFILE: same as __GT_FILE but use open64(). 224 __GT_DIR: create a directory, which will be mode 0700. 225 226 We use a clever algorithm to get hard-to-predict names. */ 227int 228__gen_tempname (char *tmpl, int kind) 229{ 230 int len; 231 char *XXXXXX; 232 static uint64_t value; 233 uint64_t random_time_bits; 234 unsigned int count; 235 int fd = -1; 236 int save_errno = errno; 237 struct_stat64 st; 238 239 /* A lower bound on the number of temporary files to attempt to 240 generate. The maximum total number of temporary file names that 241 can exist for a given template is 62**6. It should never be 242 necessary to try all these combinations. Instead if a reasonable 243 number of names is tried (we define reasonable as 62**3) fail to 244 give the system administrator the chance to remove the problems. */ 245 unsigned int attempts_min = 62 * 62 * 62; 246 247 /* The number of times to attempt to generate a temporary file. To 248 conform to POSIX, this must be no smaller than TMP_MAX. */ 249 unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min; 250 251 len = strlen (tmpl); 252 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX")) 253 { 254 __set_errno (EINVAL); 255 return -1; 256 } 257 258 /* This is where the Xs start. */ 259 XXXXXX = &tmpl[len - 6]; 260 261 /* Get some more or less random data. */ 262#ifdef RANDOM_BITS 263 RANDOM_BITS (random_time_bits); 264#else 265# if HAVE_GETTIMEOFDAY || _LIBC 266 { 267 struct timeval tv; 268 __gettimeofday (&tv, NULL); 269 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; 270 } 271# else 272 random_time_bits = time (NULL); 273# endif 274#endif 275 value += random_time_bits ^ __getpid (); 276 277 for (count = 0; count < attempts; value += 7777, ++count) 278 { 279 uint64_t v = value; 280 281 /* Fill in the random bits. */ 282 XXXXXX[0] = letters[v % 62]; 283 v /= 62; 284 XXXXXX[1] = letters[v % 62]; 285 v /= 62; 286 XXXXXX[2] = letters[v % 62]; 287 v /= 62; 288 XXXXXX[3] = letters[v % 62]; 289 v /= 62; 290 XXXXXX[4] = letters[v % 62]; 291 v /= 62; 292 XXXXXX[5] = letters[v % 62]; 293 294 switch (kind) 295 { 296 case __GT_FILE: 297 fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); 298 break; 299 300 case __GT_BIGFILE: 301 fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); 302 break; 303 304 case __GT_DIR: 305 fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR); 306 break; 307 308 case __GT_NOCREATE: 309 /* This case is backward from the other three. __gen_tempname 310 succeeds if __xstat fails because the name does not exist. 311 Note the continue to bypass the common logic at the bottom 312 of the loop. */ 313 if (__lxstat64 (_STAT_VER, tmpl, &st) < 0) 314 { 315 if (errno == ENOENT) 316 { 317 __set_errno (save_errno); 318 return 0; 319 } 320 else 321 /* Give up now. */ 322 return -1; 323 } 324 continue; 325 326 default: 327 assert (! "invalid KIND in __gen_tempname"); 328 } 329 330 if (fd >= 0) 331 { 332 __set_errno (save_errno); 333 return fd; 334 } 335 else if (errno != EEXIST) 336 return -1; 337 } 338 339 /* We got out of the loop because we ran out of combinations to try. */ 340 __set_errno (EEXIST); 341 return -1; 342} 343