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1 /* Copyright (C) 1991, 1992, 1996, 1998, 2004 Free Software Foundation, Inc.
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2 This file is derived from mkstemp.c from the GNU C Library.
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3
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4 The GNU C Library is free software; you can redistribute it and/or
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5 modify it under the terms of the GNU Library General Public License as
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6 published by the Free Software Foundation; either version 2 of the
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7 License, or (at your option) any later version.
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8
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9 The GNU C Library is distributed in the hope that it will be useful,
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10 but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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12 Library General Public License for more details.
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13
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14 You should have received a copy of the GNU Library General Public
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15 License along with the GNU C Library; see the file COPYING.LIB. If not,
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16 write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
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17 Boston, MA 02110-1301, USA. */
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18
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19 #ifdef HAVE_CONFIG_H
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20 #include "config.h"
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21 #endif
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22
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23 #include <sys/types.h>
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24 #ifdef HAVE_STDLIB_H
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25 #include <stdlib.h>
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26 #endif
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27 #ifdef HAVE_STRING_H
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28 #include <string.h>
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29 #endif
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30 #include <errno.h>
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31 #include <stdio.h>
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32 #include <fcntl.h>
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33 #ifdef HAVE_UNISTD_H
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34 #include <unistd.h>
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35 #endif
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36 #ifdef HAVE_SYS_TIME_H
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37 #include <sys/time.h>
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38 #endif
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39 #include "ansidecl.h"
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40
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41 /* We need to provide a type for gcc_uint64_t. */
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42 #ifdef __GNUC__
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43 __extension__ typedef unsigned long long gcc_uint64_t;
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44 #else
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45 typedef unsigned long gcc_uint64_t;
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46 #endif
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47
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48 #ifndef TMP_MAX
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49 #define TMP_MAX 16384
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50 #endif
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51
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52 #ifndef O_BINARY
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53 # define O_BINARY 0
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54 #endif
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55
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56 /*
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57
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58 @deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})
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59
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60 Generate a unique temporary file name from @var{pattern}.
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61 @var{pattern} has the form:
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62
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63 @example
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64 @var{path}/ccXXXXXX@var{suffix}
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65 @end example
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66
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67 @var{suffix_len} tells us how long @var{suffix} is (it can be zero
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68 length). The last six characters of @var{pattern} before @var{suffix}
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69 must be @samp{XXXXXX}; they are replaced with a string that makes the
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70 filename unique. Returns a file descriptor open on the file for
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71 reading and writing.
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72
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73 @end deftypefn
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74
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75 */
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76
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77 int
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78 mkstemps (char *pattern, int suffix_len)
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79 {
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80 static const char letters[]
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81 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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82 static gcc_uint64_t value;
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83 #ifdef HAVE_GETTIMEOFDAY
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84 struct timeval tv;
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85 #endif
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86 char *XXXXXX;
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87 size_t len;
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88 int count;
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89
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90 len = strlen (pattern);
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91
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92 if ((int) len < 6 + suffix_len
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93 || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))
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94 {
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95 return -1;
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96 }
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97
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98 XXXXXX = &pattern[len - 6 - suffix_len];
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99
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100 #ifdef HAVE_GETTIMEOFDAY
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101 /* Get some more or less random data. */
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102 gettimeofday (&tv, NULL);
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103 value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
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104 #else
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105 value += getpid ();
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106 #endif
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107
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108 for (count = 0; count < TMP_MAX; ++count)
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109 {
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110 gcc_uint64_t v = value;
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111 int fd;
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112
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113 /* Fill in the random bits. */
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114 XXXXXX[0] = letters[v % 62];
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115 v /= 62;
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116 XXXXXX[1] = letters[v % 62];
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117 v /= 62;
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118 XXXXXX[2] = letters[v % 62];
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119 v /= 62;
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120 XXXXXX[3] = letters[v % 62];
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121 v /= 62;
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122 XXXXXX[4] = letters[v % 62];
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123 v /= 62;
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124 XXXXXX[5] = letters[v % 62];
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125
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126 fd = open (pattern, O_BINARY|O_RDWR|O_CREAT|O_EXCL, 0600);
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127 if (fd >= 0)
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128 /* The file does not exist. */
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129 return fd;
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130 if (errno != EEXIST
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131 #ifdef EISDIR
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132 && errno != EISDIR
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133 #endif
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134 )
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135 /* Fatal error (EPERM, ENOSPC etc). Doesn't make sense to loop. */
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136 break;
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137
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138 /* This is a random value. It is only necessary that the next
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139 TMP_MAX values generated by adding 7777 to VALUE are different
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140 with (module 2^32). */
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141 value += 7777;
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142 }
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143
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144 /* We return the null string if we can't find a unique file name. */
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145 pattern[0] = '\0';
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146 return -1;
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147 }
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