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1 /* Copyright (C) 1991-2017 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 #elif HAVE_TIME_H
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39 #include <time.h>
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40 #endif
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41 #include "ansidecl.h"
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42
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43 /* We need to provide a type for gcc_uint64_t. */
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44 #ifdef __GNUC__
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45 __extension__ typedef unsigned long long gcc_uint64_t;
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46 #else
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47 typedef unsigned long gcc_uint64_t;
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48 #endif
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49
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50 #ifndef TMP_MAX
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51 #define TMP_MAX 16384
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52 #endif
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53
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54 #ifndef O_BINARY
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55 # define O_BINARY 0
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56 #endif
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57
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58 /*
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59
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60 @deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})
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61
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62 Generate a unique temporary file name from @var{pattern}.
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63 @var{pattern} has the form:
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64
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65 @example
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66 @var{path}/ccXXXXXX@var{suffix}
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67 @end example
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68
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69 @var{suffix_len} tells us how long @var{suffix} is (it can be zero
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70 length). The last six characters of @var{pattern} before @var{suffix}
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71 must be @samp{XXXXXX}; they are replaced with a string that makes the
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72 filename unique. Returns a file descriptor open on the file for
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73 reading and writing.
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74
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75 @end deftypefn
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76
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77 */
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78
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79 int
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80 mkstemps (char *pattern, int suffix_len)
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81 {
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82 static const char letters[]
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83 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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84 static gcc_uint64_t value;
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85 #ifdef HAVE_GETTIMEOFDAY
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86 struct timeval tv;
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87 #endif
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88 char *XXXXXX;
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89 size_t len;
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90 int count;
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91
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92 len = strlen (pattern);
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93
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94 if ((int) len < 6 + suffix_len
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95 || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))
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96 {
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97 return -1;
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98 }
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99
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100 XXXXXX = &pattern[len - 6 - suffix_len];
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101
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102 #ifdef HAVE_GETTIMEOFDAY
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103 /* Get some more or less random data. */
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104 gettimeofday (&tv, NULL);
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105 value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
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106 #else
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107 value += getpid ();
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108 #endif
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109
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110 for (count = 0; count < TMP_MAX; ++count)
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111 {
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112 gcc_uint64_t v = value;
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113 int fd;
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114
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115 /* Fill in the random bits. */
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116 XXXXXX[0] = letters[v % 62];
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117 v /= 62;
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118 XXXXXX[1] = letters[v % 62];
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119 v /= 62;
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120 XXXXXX[2] = letters[v % 62];
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121 v /= 62;
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122 XXXXXX[3] = letters[v % 62];
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123 v /= 62;
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124 XXXXXX[4] = letters[v % 62];
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125 v /= 62;
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126 XXXXXX[5] = letters[v % 62];
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127
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128 fd = open (pattern, O_BINARY|O_RDWR|O_CREAT|O_EXCL, 0600);
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129 if (fd >= 0)
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130 /* The file does not exist. */
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131 return fd;
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132 if (errno != EEXIST
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133 #ifdef EISDIR
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134 && errno != EISDIR
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135 #endif
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136 )
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137 /* Fatal error (EPERM, ENOSPC etc). Doesn't make sense to loop. */
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138 break;
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139
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140 /* This is a random value. It is only necessary that the next
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141 TMP_MAX values generated by adding 7777 to VALUE are different
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142 with (module 2^32). */
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143 value += 7777;
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144 }
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145
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146 /* We return the null string if we can't find a unique file name. */
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147 pattern[0] = '\0';
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148 return -1;
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149 }
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