1 /* Copyright (C) 1991, 1992, 1996, 1998, 2004 Free Software Foundation, Inc. 2 This file is derived from mkstemp.c from 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 Library General Public License as 6 published by the Free Software Foundation; either version 2 of the 7 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 Library General Public License for more details. 13 14 You should have received a copy of the GNU Library General Public 15 License along with the GNU C Library; see the file COPYING.LIB. If not, 16 write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor, 17 Boston, MA 02110-1301, USA. */ 18 19 #ifdef HAVE_CONFIG_H 20 #include "config.h" 21 #endif 22 23 #include <sys/types.h> 24 #ifdef HAVE_STDLIB_H 25 #include <stdlib.h> 26 #endif 27 #ifdef HAVE_STRING_H 28 #include <string.h> 29 #endif 30 #include <errno.h> 31 #include <stdio.h> 32 #include <fcntl.h> 33 #ifdef HAVE_UNISTD_H 34 #include <unistd.h> 35 #endif 36 #ifdef HAVE_SYS_TIME_H 37 #include <sys/time.h> 38 #endif 39 #include "ansidecl.h" 40 41 /* We need to provide a type for gcc_uint64_t. */ 42 #ifdef __GNUC__ 43 __extension__ typedef unsigned long long gcc_uint64_t; 44 #else 45 typedef unsigned long gcc_uint64_t; 46 #endif 47 48 #ifndef TMP_MAX 49 #define TMP_MAX 16384 50 #endif 51 52 /* 53 54 @deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len}) 55 56 Generate a unique temporary file name from @var{pattern}. 57 @var{pattern} has the form: 58 59 @example 60 @var{path}/ccXXXXXX@var{suffix} 61 @end example 62 63 @var{suffix_len} tells us how long @var{suffix} is (it can be zero 64 length). The last six characters of @var{pattern} before @var{suffix} 65 must be @samp{XXXXXX}; they are replaced with a string that makes the 66 filename unique. Returns a file descriptor open on the file for 67 reading and writing. 68 69 @end deftypefn 70 71 */ 72 73 int 74 mkstemps (char *pattern, int suffix_len) 75 { 76 static const char letters[] 77 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 78 static gcc_uint64_t value; 79 #ifdef HAVE_GETTIMEOFDAY 80 struct timeval tv; 81 #endif 82 char *XXXXXX; 83 size_t len; 84 int count; 85 86 len = strlen (pattern); 87 88 if ((int) len < 6 + suffix_len 89 || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6)) 90 { 91 return -1; 92 } 93 94 XXXXXX = &pattern[len - 6 - suffix_len]; 95 96 #ifdef HAVE_GETTIMEOFDAY 97 /* Get some more or less random data. */ 98 gettimeofday (&tv, NULL); 99 value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid (); 100 #else 101 value += getpid (); 102 #endif 103 104 for (count = 0; count < TMP_MAX; ++count) 105 { 106 gcc_uint64_t v = value; 107 int fd; 108 109 /* Fill in the random bits. */ 110 XXXXXX[0] = letters[v % 62]; 111 v /= 62; 112 XXXXXX[1] = letters[v % 62]; 113 v /= 62; 114 XXXXXX[2] = letters[v % 62]; 115 v /= 62; 116 XXXXXX[3] = letters[v % 62]; 117 v /= 62; 118 XXXXXX[4] = letters[v % 62]; 119 v /= 62; 120 XXXXXX[5] = letters[v % 62]; 121 122 fd = open (pattern, O_RDWR|O_CREAT|O_EXCL, 0600); 123 if (fd >= 0) 124 /* The file does not exist. */ 125 return fd; 126 127 /* This is a random value. It is only necessary that the next 128 TMP_MAX values generated by adding 7777 to VALUE are different 129 with (module 2^32). */ 130 value += 7777; 131 } 132 133 /* We return the null string if we can't find a unique file name. */ 134 pattern[0] = '\0'; 135 return -1; 136 } 137