1/* $NetBSD: tempname.c,v 1.1.1.1 2016/01/14 00:11:29 christos Exp $ */ 2 3/* tempname.c - generate the name of a temporary file. 4 5 Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 6 2000, 2001, 2002, 2003 Free Software Foundation, Inc. 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 2, or (at your option) 11 any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License along 19 with this program; if not, write to the Free Software Foundation, 20 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 21 22#if HAVE_CONFIG_H 23# include <config.h> 24#endif 25 26#include <sys/types.h> 27#include <assert.h> 28 29#include <errno.h> 30#ifndef __set_errno 31# define __set_errno(Val) errno = (Val) 32#endif 33 34#include <stdio.h> 35#ifndef P_tmpdir 36# define P_tmpdir "/tmp" 37#endif 38#ifndef TMP_MAX 39# define TMP_MAX 238328 40#endif 41#ifndef __GT_FILE 42# define __GT_FILE 0 43# define __GT_BIGFILE 1 44# define __GT_DIR 2 45# define __GT_NOCREATE 3 46#endif 47 48#include <stddef.h> 49#include <stdlib.h> 50#include <string.h> 51 52#if HAVE_FCNTL_H || _LIBC 53# include <fcntl.h> 54#endif 55 56#if HAVE_SYS_TIME_H || _LIBC 57# include <sys/time.h> 58#endif 59 60#if HAVE_STDINT_H || _LIBC 61# include <stdint.h> 62#endif 63#if HAVE_INTTYPES_H 64# include <inttypes.h> 65#endif 66 67#if HAVE_UNISTD_H || _LIBC 68# include <unistd.h> 69#endif 70 71#include <sys/stat.h> 72#if STAT_MACROS_BROKEN 73# undef S_ISDIR 74#endif 75#if !defined S_ISDIR && defined S_IFDIR 76# define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR) 77#endif 78#if !S_IRUSR && S_IREAD 79# define S_IRUSR S_IREAD 80#endif 81#if !S_IRUSR 82# define S_IRUSR 00400 83#endif 84#if !S_IWUSR && S_IWRITE 85# define S_IWUSR S_IWRITE 86#endif 87#if !S_IWUSR 88# define S_IWUSR 00200 89#endif 90#if !S_IXUSR && S_IEXEC 91# define S_IXUSR S_IEXEC 92#endif 93#if !S_IXUSR 94# define S_IXUSR 00100 95#endif 96 97#if _LIBC 98# define struct_stat64 struct stat64 99#else 100# define struct_stat64 struct stat 101# define __getpid getpid 102# define __gettimeofday gettimeofday 103# define __mkdir mkdir 104# define __open open 105# define __open64 open 106# define __lxstat64(version, path, buf) lstat (path, buf) 107# define __xstat64(version, path, buf) stat (path, buf) 108#endif 109 110#if ! (HAVE___SECURE_GETENV || _LIBC) 111# define __secure_getenv getenv 112#endif 113 114#ifdef _LIBC 115# include <hp-timing.h> 116# if HP_TIMING_AVAIL 117# define RANDOM_BITS(Var) \ 118 if (__builtin_expect (value == UINT64_C (0), 0)) \ 119 { \ 120 /* If this is the first time this function is used initialize \ 121 the variable we accumulate the value in to some somewhat \ 122 random value. If we'd not do this programs at startup time \ 123 might have a reduced set of possible names, at least on slow \ 124 machines. */ \ 125 struct timeval tv; \ 126 __gettimeofday (&tv, NULL); \ 127 value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \ 128 } \ 129 HP_TIMING_NOW (Var) 130# endif 131#endif 132 133/* Use the widest available unsigned type if uint64_t is not 134 available. The algorithm below extracts a number less than 62**6 135 (approximately 2**35.725) from uint64_t, so ancient hosts where 136 uintmax_t is only 32 bits lose about 3.725 bits of randomness, 137 which is better than not having mkstemp at all. */ 138#if !defined UINT64_MAX && !defined uint64_t 139# define uint64_t uintmax_t 140#endif 141 142/* Return nonzero if DIR is an existent directory. */ 143static int 144direxists (const char *dir) 145{ 146 struct_stat64 buf; 147 return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode); 148} 149 150/* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is 151 non-null and exists, uses it; otherwise uses the first of $TMPDIR, 152 P_tmpdir, /tmp that exists. Copies into TMPL a template suitable 153 for use with mk[s]temp. Will fail (-1) if DIR is non-null and 154 doesn't exist, none of the searched dirs exists, or there's not 155 enough space in TMPL. */ 156int 157__path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx, 158 int try_tmpdir) 159{ 160 const char *d; 161 size_t dlen, plen; 162 163 if (!pfx || !pfx[0]) 164 { 165 pfx = "file"; 166 plen = 4; 167 } 168 else 169 { 170 plen = strlen (pfx); 171 if (plen > 5) 172 plen = 5; 173 } 174 175 if (try_tmpdir) 176 { 177 d = __secure_getenv ("TMPDIR"); 178 if (d != NULL && direxists (d)) 179 dir = d; 180 else if (dir != NULL && direxists (dir)) 181 /* nothing */ ; 182 else 183 dir = NULL; 184 } 185 if (dir == NULL) 186 { 187 if (direxists (P_tmpdir)) 188 dir = P_tmpdir; 189 else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp")) 190 dir = "/tmp"; 191 else 192 { 193 __set_errno (ENOENT); 194 return -1; 195 } 196 } 197 198 dlen = strlen (dir); 199 while (dlen > 1 && dir[dlen - 1] == '/') 200 dlen--; /* remove trailing slashes */ 201 202 /* check we have room for "${dir}/${pfx}XXXXXX\0" */ 203 if (tmpl_len < dlen + 1 + plen + 6 + 1) 204 { 205 __set_errno (EINVAL); 206 return -1; 207 } 208 209 sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx); 210 return 0; 211} 212 213/* These are the characters used in temporary filenames. */ 214static const char letters[] = 215"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 216 217/* Generate a temporary file name based on TMPL. TMPL must match the 218 rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed 219 does not exist at the time of the call to __gen_tempname. TMPL is 220 overwritten with the result. 221 222 KIND may be one of: 223 __GT_NOCREATE: simply verify that the name does not exist 224 at the time of the call. 225 __GT_FILE: create the file using open(O_CREAT|O_EXCL) 226 and return a read-write fd. The file is mode 0600. 227 __GT_BIGFILE: same as __GT_FILE but use open64(). 228 __GT_DIR: create a directory, which will be mode 0700. 229 230 We use a clever algorithm to get hard-to-predict names. */ 231int 232__gen_tempname (char *tmpl, int kind) 233{ 234 int len; 235 char *XXXXXX; 236 static uint64_t value; 237 uint64_t random_time_bits; 238 unsigned int count; 239 int fd = -1; 240 int save_errno = errno; 241 struct_stat64 st; 242 243 /* A lower bound on the number of temporary files to attempt to 244 generate. The maximum total number of temporary file names that 245 can exist for a given template is 62**6. It should never be 246 necessary to try all these combinations. Instead if a reasonable 247 number of names is tried (we define reasonable as 62**3) fail to 248 give the system administrator the chance to remove the problems. */ 249 unsigned int attempts_min = 62 * 62 * 62; 250 251 /* The number of times to attempt to generate a temporary file. To 252 conform to POSIX, this must be no smaller than TMP_MAX. */ 253 unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min; 254 255 len = strlen (tmpl); 256 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX")) 257 { 258 __set_errno (EINVAL); 259 return -1; 260 } 261 262 /* This is where the Xs start. */ 263 XXXXXX = &tmpl[len - 6]; 264 265 /* Get some more or less random data. */ 266#ifdef RANDOM_BITS 267 RANDOM_BITS (random_time_bits); 268#else 269# if HAVE_GETTIMEOFDAY || _LIBC 270 { 271 struct timeval tv; 272 __gettimeofday (&tv, NULL); 273 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; 274 } 275# else 276 random_time_bits = time (NULL); 277# endif 278#endif 279 value += random_time_bits ^ __getpid (); 280 281 for (count = 0; count < attempts; value += 7777, ++count) 282 { 283 uint64_t v = value; 284 285 /* Fill in the random bits. */ 286 XXXXXX[0] = letters[v % 62]; 287 v /= 62; 288 XXXXXX[1] = letters[v % 62]; 289 v /= 62; 290 XXXXXX[2] = letters[v % 62]; 291 v /= 62; 292 XXXXXX[3] = letters[v % 62]; 293 v /= 62; 294 XXXXXX[4] = letters[v % 62]; 295 v /= 62; 296 XXXXXX[5] = letters[v % 62]; 297 298 switch (kind) 299 { 300 case __GT_FILE: 301 fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); 302 break; 303 304 case __GT_BIGFILE: 305 fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); 306 break; 307 308 case __GT_DIR: 309 fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR); 310 break; 311 312 case __GT_NOCREATE: 313 /* This case is backward from the other three. __gen_tempname 314 succeeds if __xstat fails because the name does not exist. 315 Note the continue to bypass the common logic at the bottom 316 of the loop. */ 317 if (__lxstat64 (_STAT_VER, tmpl, &st) < 0) 318 { 319 if (errno == ENOENT) 320 { 321 __set_errno (save_errno); 322 return 0; 323 } 324 else 325 /* Give up now. */ 326 return -1; 327 } 328 continue; 329 330 default: 331 assert (! "invalid KIND in __gen_tempname"); 332 } 333 334 if (fd >= 0) 335 { 336 __set_errno (save_errno); 337 return fd; 338 } 339 else if (errno != EEXIST) 340 return -1; 341 } 342 343 /* We got out of the loop because we ran out of combinations to try. */ 344 __set_errno (EEXIST); 345 return -1; 346} 347