1 /* Copyright (C) 1999, 2001-2003, 2006 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 along 15 with this program; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 17 18 /* Extracted from misc/mkdtemp.c and sysdeps/posix/tempname.c. */ 19 20 #include <config.h> 21 22 /* Specification. */ 23 #include "mkdtemp.h" 24 25 #include <errno.h> 26 #ifndef __set_errno 27 # define __set_errno(Val) errno = (Val) 28 #endif 29 30 #include <stddef.h> 31 #include <stdint.h> 32 #include <stdlib.h> 33 #include <string.h> 34 35 #include <stdio.h> 36 #ifndef TMP_MAX 37 # define TMP_MAX 238328 38 #endif 39 40 #include <unistd.h> 41 42 #if HAVE_GETTIMEOFDAY || _LIBC 43 # if HAVE_SYS_TIME_H || _LIBC 44 # include <sys/time.h> 45 # endif 46 #else 47 # if HAVE_TIME_H || _LIBC 48 # include <time.h> 49 # endif 50 #endif 51 52 #include <sys/stat.h> 53 #if !defined S_ISDIR && defined S_IFDIR 54 # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR) 55 #endif 56 #if !S_IRUSR && S_IREAD 57 # define S_IRUSR S_IREAD 58 #endif 59 #if !S_IRUSR 60 # define S_IRUSR 00400 61 #endif 62 #if !S_IWUSR && S_IWRITE 63 # define S_IWUSR S_IWRITE 64 #endif 65 #if !S_IWUSR 66 # define S_IWUSR 00200 67 #endif 68 #if !S_IXUSR && S_IEXEC 69 # define S_IXUSR S_IEXEC 70 #endif 71 #if !S_IXUSR 72 # define S_IXUSR 00100 73 #endif 74 75 #ifdef __MINGW32__ 76 # include <io.h> 77 /* mingw's _mkdir() function has 1 argument, but we pass 2 arguments. 78 Therefore we have to disable the argument count checking. */ 79 # define mkdir ((int (*)()) _mkdir) 80 #endif 81 82 #if !_LIBC 83 # define __getpid getpid 84 # define __gettimeofday gettimeofday 85 # define __mkdir mkdir 86 #endif 87 88 /* Use the widest available unsigned type if uint64_t is not 89 available. The algorithm below extracts a number less than 62**6 90 (approximately 2**35.725) from uint64_t, so ancient hosts where 91 uintmax_t is only 32 bits lose about 3.725 bits of randomness, 92 which is better than not having mkstemp at all. */ 93 #if !defined UINT64_MAX && !defined uint64_t 94 # define uint64_t uintmax_t 95 #endif 96 97 /* These are the characters used in temporary filenames. */ 98 static const char letters[] = 99 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 100 101 /* Generate a temporary file name based on TMPL. TMPL must match the 102 rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed 103 does not exist at the time of the call to __gen_tempname. TMPL is 104 overwritten with the result. 105 106 KIND is: 107 __GT_DIR: create a directory, which will be mode 0700. 108 109 We use a clever algorithm to get hard-to-predict names. */ 110 static int 111 gen_tempname (char *tmpl) 112 { 113 int len; 114 char *XXXXXX; 115 static uint64_t value; 116 uint64_t random_time_bits; 117 unsigned int count; 118 int fd = -1; 119 int save_errno = errno; 120 121 /* A lower bound on the number of temporary files to attempt to 122 generate. The maximum total number of temporary file names that 123 can exist for a given template is 62**6. It should never be 124 necessary to try all these combinations. Instead if a reasonable 125 number of names is tried (we define reasonable as 62**3) fail to 126 give the system administrator the chance to remove the problems. */ 127 #define ATTEMPTS_MIN (62 * 62 * 62) 128 129 /* The number of times to attempt to generate a temporary file. To 130 conform to POSIX, this must be no smaller than TMP_MAX. */ 131 #if ATTEMPTS_MIN < TMP_MAX 132 unsigned int attempts = TMP_MAX; 133 #else 134 unsigned int attempts = ATTEMPTS_MIN; 135 #endif 136 137 len = strlen (tmpl); 138 if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX")) 139 { 140 __set_errno (EINVAL); 141 return -1; 142 } 143 144 /* This is where the Xs start. */ 145 XXXXXX = &tmpl[len - 6]; 146 147 /* Get some more or less random data. */ 148 #ifdef RANDOM_BITS 149 RANDOM_BITS (random_time_bits); 150 #else 151 # if HAVE_GETTIMEOFDAY || _LIBC 152 { 153 struct timeval tv; 154 __gettimeofday (&tv, NULL); 155 random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; 156 } 157 # else 158 random_time_bits = time (NULL); 159 # endif 160 #endif 161 value += random_time_bits ^ __getpid (); 162 163 for (count = 0; count < attempts; value += 7777, ++count) 164 { 165 uint64_t v = value; 166 167 /* Fill in the random bits. */ 168 XXXXXX[0] = letters[v % 62]; 169 v /= 62; 170 XXXXXX[1] = letters[v % 62]; 171 v /= 62; 172 XXXXXX[2] = letters[v % 62]; 173 v /= 62; 174 XXXXXX[3] = letters[v % 62]; 175 v /= 62; 176 XXXXXX[4] = letters[v % 62]; 177 v /= 62; 178 XXXXXX[5] = letters[v % 62]; 179 180 fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR); 181 182 if (fd >= 0) 183 { 184 __set_errno (save_errno); 185 return fd; 186 } 187 else if (errno != EEXIST) 188 return -1; 189 } 190 191 /* We got out of the loop because we ran out of combinations to try. */ 192 __set_errno (EEXIST); 193 return -1; 194 } 195 196 /* Generate a unique temporary directory from TEMPLATE. 197 The last six characters of TEMPLATE must be "XXXXXX"; 198 they are replaced with a string that makes the filename unique. 199 The directory is created, mode 700, and its name is returned. 200 (This function comes from OpenBSD.) */ 201 char * 202 mkdtemp (char *template) 203 { 204 if (gen_tempname (template)) 205 return NULL; 206 else 207 return template; 208 } 209