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. */ 98static 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. */ 110static int 111gen_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.) */ 201char * 202mkdtemp (char *template) 203{ 204 if (gen_tempname (template)) 205 return NULL; 206 else 207 return template; 208} 209