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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