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1 /* Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc. |
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2 This file is part of 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 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 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 General Public |
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15 License along with the GNU C Library; see the file COPYING. If |
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16 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
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17 Boston, MA 02111-1307, 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 #ifndef HAVE_TEMPNAM |
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24 |
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25 #include <errno.h> |
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26 #include <stddef.h> |
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27 #include <stdio.h> |
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28 #include <stdlib.h> |
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29 #include <string.h> |
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30 |
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31 #ifdef HAVE_UNISTD_H |
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32 #include <sys/types.h> |
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33 #include <unistd.h> |
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34 #endif |
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35 |
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36 #include <fcntl.h> |
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37 |
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38 #include "statdefs.h" |
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39 |
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40 #ifndef FILENAME_MAX |
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41 #ifdef MAXPATHLEN |
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42 #define FILENAME_MAX MAXPATHLEN |
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43 #else |
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44 #define FILENAME_MAX 1024 |
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45 #endif |
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46 #endif |
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47 |
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48 #ifndef P_tmpdir |
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49 #define P_tmpdir "/usr/tmp/" |
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50 #endif |
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51 |
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52 /* Return nonzero if DIR is an existent directory. */ |
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53 static int |
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54 diraccess (const char *dir) |
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55 { |
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56 struct stat buf; |
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57 return stat (dir, &buf) == 0 && S_ISDIR (buf.st_mode); |
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58 } |
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59 |
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60 /* Return nonzero if FILE exists. */ |
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61 static int |
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62 exists (const char *file) |
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63 { |
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64 /* We can stat the file even if we can't read its data. */ |
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65 struct stat st; |
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66 int save = errno; |
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67 if (stat (file, &st) == 0) |
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68 return 1; |
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69 else |
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70 { |
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71 /* We report that the file exists if stat failed for a reason other |
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72 than nonexistence. In this case, it may or may not exist, and we |
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73 don't know; but reporting that it does exist will never cause any |
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74 trouble, while reporting that it doesn't exist when it does would |
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75 violate the interface of __stdio_gen_tempname. */ |
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76 int exists = errno != ENOENT; |
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77 errno = save; |
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78 return exists; |
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79 } |
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80 } |
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81 |
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82 |
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83 /* These are the characters used in temporary filenames. */ |
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84 static const char letters[] = |
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85 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; |
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86 |
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87 /* Generate a temporary filename and return it (in a static buffer). If |
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88 STREAMPTR is not NULL, open a stream "w+b" on the file and set |
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89 *STREAMPTR to it. If DIR_SEARCH is nonzero, DIR and PFX are used as |
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90 described for tempnam. If not, a temporary filename in P_tmpdir with no |
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91 special prefix is generated. If LENPTR is not NULL, *LENPTR is set the |
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92 to length (including the terminating '\0') of the resultant filename, |
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93 which is returned. This goes through a cyclic pattern of all possible |
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94 filenames consisting of five decimal digits of the current pid and three |
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95 of the characters in `letters'. Data for tempnam and tmpnam is kept |
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96 separate, but when tempnam is using P_tmpdir and no prefix (i.e, it is |
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97 identical to tmpnam), the same data is used. Each potential filename is |
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98 tested for an already-existing file of the same name, and no name of an |
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99 existing file will be returned. When the cycle reaches its end |
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100 (12345ZZZ), NULL is returned. */ |
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101 char * |
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102 __stdio_gen_tempname (const char *dir, const char *pfx, |
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103 int dir_search, size_t *lenptr, |
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104 FILE **streamptr) |
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105 { |
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106 int saverrno = errno; |
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107 static const char tmpdir[] = P_tmpdir; |
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108 static size_t indices[2]; |
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109 size_t *idx; |
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110 static char buf[FILENAME_MAX]; |
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111 static pid_t oldpid = (pid_t) 0; |
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112 pid_t pid = getpid(); |
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113 register size_t len, plen, dlen; |
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114 |
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115 if (dir_search) |
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116 { |
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117 register const char *d = getenv("TMPDIR"); |
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118 if (d != NULL && !diraccess(d)) |
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119 d = NULL; |
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120 if (d == NULL && dir != NULL && diraccess(dir)) |
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121 d = dir; |
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122 if (d == NULL && diraccess(tmpdir)) |
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123 d = tmpdir; |
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124 if (d == NULL && diraccess("/tmp")) |
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125 d = "/tmp"; |
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126 if (d == NULL) |
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127 { |
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128 errno = ENOENT; |
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129 return NULL; |
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130 } |
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131 dir = d; |
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132 } |
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133 else |
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134 dir = tmpdir; |
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135 |
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136 dlen = strlen (dir); |
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137 |
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138 /* Remove trailing slashes from the directory name. */ |
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139 while (dlen > 1 && dir[dlen - 1] == '/') |
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140 --dlen; |
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141 |
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142 if (pfx != NULL && *pfx != '\0') |
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143 { |
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144 plen = strlen(pfx); |
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145 if (plen > 5) |
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146 plen = 5; |
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147 } |
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148 else |
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149 plen = 0; |
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150 |
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151 if (dir != tmpdir && !strcmp(dir, tmpdir)) |
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152 dir = tmpdir; |
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153 idx = &indices[(plen == 0 && dir == tmpdir) ? 1 : 0]; |
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154 |
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155 if (pid != oldpid) |
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156 { |
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157 oldpid = pid; |
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158 indices[0] = indices[1] = 0; |
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159 } |
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160 |
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161 len = dlen + 1 + plen + 5 + 3; |
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162 for (; *idx < ((sizeof (letters) - 1) * (sizeof (letters) - 1) * |
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163 (sizeof (letters) - 1)); |
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164 ++*idx) |
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165 { |
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166 /* Construct a file name and see if it already exists. |
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167 |
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168 We use a single counter in *IDX to cycle each of three |
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169 character positions through each of 62 possible letters. */ |
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170 |
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171 if (sizeof (buf) < len) |
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172 return NULL; |
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173 |
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174 sprintf (buf, "%.*s/%.*s%.5d%c%c%c", |
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175 (int) dlen, dir, (int) plen, |
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176 pfx, pid % 100000, |
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177 letters[*idx |
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178 % (sizeof (letters) - 1)], |
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179 letters[(*idx / (sizeof (letters) - 1)) |
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180 % (sizeof (letters) - 1)], |
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181 letters[(*idx / ((sizeof (letters) - 1) * |
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182 (sizeof (letters) - 1))) |
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183 % (sizeof (letters) - 1)] |
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184 ); |
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185 |
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186 if (! buf || strlen (buf) != (int) len) |
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187 return NULL; |
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188 |
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189 if (streamptr != NULL) |
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190 abort (); |
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191 else if (exists (buf)) |
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192 continue; |
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193 |
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194 /* If the file already existed we have continued the loop above, |
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195 so we only get here when we have a winning name to return. */ |
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196 |
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197 errno = saverrno; |
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198 |
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199 if (lenptr != NULL) |
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200 *lenptr = len + 1; |
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201 return buf; |
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202 } |
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203 |
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204 /* We got out of the loop because we ran out of combinations to try. */ |
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205 errno = EEXIST; /* ? */ |
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206 return NULL; |
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207 } |
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208 |
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209 #endif |
