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428
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1 /*
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2 * realpath.c -- canonicalize pathname by removing symlinks
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3 * Copyright (C) 1993 Rick Sladkey <jrs@world.std.com>
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4 *
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5
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6 This file is part of XEmacs.
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7
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8 XEmacs is free software; you can redistribute it and/or modify it
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9 under the terms of the GNU General Public License as published by the
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10 Free Software Foundation; either version 2, or (at your option) any
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11 later version.
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12
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13 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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16 for more details.
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17
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18 You should have received a copy of the GNU General Public License
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19 along with XEmacs; see the file COPYING. If not, write to
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20 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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21 Boston, MA 02111-1307, USA. */
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22
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23 /* Synched up with: Not in FSF. */
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24
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25 #include <config.h>
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446
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26 #include "lisp.h"
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442
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27
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558
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28 #include "sysfile.h"
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428
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29
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446
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30 /* First char after start of absolute filename. */
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31 #define ABS_START(name) (name + ABS_LENGTH (name))
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32
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33 #if defined (WIN32_NATIVE)
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34 /* Length of start of absolute filename. */
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35 # define ABS_LENGTH(name) (win32_abs_start (name))
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36 static int win32_abs_start (const char * name);
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37 /* System dependent version of readlink. */
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38 # define system_readlink win32_readlink
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39 #else
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40 # ifdef CYGWIN
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41 # define ABS_LENGTH(name) (IS_DIRECTORY_SEP (*name) ? \
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42 (IS_DIRECTORY_SEP (name[1]) ? 2 : 1) : 0)
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43 # define system_readlink cygwin_readlink
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44 # else
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45 # define ABS_LENGTH(name) (IS_DIRECTORY_SEP (*name) ? 1 : 0)
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46 # define system_readlink readlink
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47 # endif /* CYGWIN */
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48 #endif /* WIN32_NATIVE */
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49
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50 #if defined (WIN32_NATIVE) || defined (CYGWIN)
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51 #include "syswindows.h"
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52 /* Emulate readlink on win32 - finds real name (i.e. correct case) of
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53 a file. UNC servers and shares are lower-cased. Directories must be
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54 given without trailing '/'. One day, this could read Win2K's
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55 reparse points. */
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56 static int
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57 win32_readlink (const char * name, char * buf, int size)
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58 {
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59 WIN32_FIND_DATA find_data;
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60 HANDLE dir_handle = NULL;
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61 int len = 0;
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62 int err = 0;
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63 const char* lastname;
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64 int count = 0;
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65 const char* tmp;
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66 char* res = NULL;
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67
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68 assert (*name);
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69
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70 /* Sort of check we have a valid filename. */
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558
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71 if (strpbrk (name, "*?|<>\"") || strlen (name) >= PATH_MAX)
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446
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72 {
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73 errno = EIO;
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74 return -1;
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75 }
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76
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77 /* Find start of filename */
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78 lastname = name + strlen (name);
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79 while (lastname > name && !IS_DIRECTORY_SEP (lastname[-1]))
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80 --lastname;
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81
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82 /* Count slashes in unc path */
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83 if (ABS_LENGTH (name) == 2)
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84 for (tmp = name; *tmp; tmp++)
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85 if (IS_DIRECTORY_SEP (*tmp))
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86 count++;
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87
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88 if (count >= 2 && count < 4)
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89 {
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90 /* UNC server or share name: just copy lowercased name. */
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91 res = find_data.cFileName;
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92 for (tmp = lastname; *tmp; tmp++)
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93 *res++ = tolower (*tmp);
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94 *res = '\0';
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95 }
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96 else
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97 dir_handle = FindFirstFile (name, &find_data);
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98
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99 if (res || dir_handle != INVALID_HANDLE_VALUE)
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100 {
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101 if ((len = strlen (find_data.cFileName)) < size)
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102 {
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103 if (strcmp (lastname, find_data.cFileName) == 0)
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104 /* Signal that the name is already OK. */
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105 err = EINVAL;
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106 else
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107 memcpy (buf, find_data.cFileName, len + 1);
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108 }
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109 else
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110 err = ENAMETOOLONG;
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111 if (!res) FindClose (dir_handle);
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112 }
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113 else
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114 err = ENOENT;
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115
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116 errno = err;
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117 return err ? -1 : len;
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118 }
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119 #endif /* WIN32_NATIVE || CYGWIN */
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120
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121 #ifdef CYGWIN
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122 /* Call readlink and try to find out the correct case for the file. */
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123 static int
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124 cygwin_readlink (const char * name, char * buf, int size)
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125 {
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126 int n = readlink (name, buf, size);
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462
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127 if (n < 0 && errno == EINVAL)
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446
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128 {
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129 /* The file may exist, but isn't a symlink. Try to find the
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130 right name. */
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131 char* tmp = alloca (cygwin_posix_to_win32_path_list_buf_size (name));
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132 cygwin_posix_to_win32_path_list (name, tmp);
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133 n = win32_readlink (tmp, buf, size);
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134 }
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135 return n;
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136 }
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137 #endif /* CYGWIN */
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138
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139 #ifdef WIN32_NATIVE
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140 #ifndef ELOOP
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141 #define ELOOP 10062 /* = WSAELOOP in winsock.h */
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142 #endif
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143 /* Length of start of absolute filename. */
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144 static int
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145 win32_abs_start (const char * name)
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146 {
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147 if (isalpha (*name) && IS_DEVICE_SEP (name[1])
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148 && IS_DIRECTORY_SEP (name[2]))
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149 return 3;
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150 else if (IS_DIRECTORY_SEP (*name))
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151 return IS_DIRECTORY_SEP (name[1]) ? 2 : 1;
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152 else
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153 return 0;
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154 }
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155 #endif /* WIN32_NATIVE */
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156
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440
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157 #if !defined (HAVE_GETCWD) && defined (HAVE_GETWD)
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158 #undef getcwd
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159 #define getcwd(buffer, len) getwd (buffer)
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160 #endif
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161
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428
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162 #ifndef PATH_MAX
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440
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163 # if defined (_POSIX_PATH_MAX)
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164 # define PATH_MAX _POSIX_PATH_MAX
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165 # elif defined (MAXPATHLEN)
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166 # define PATH_MAX MAXPATHLEN
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167 # else
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168 # define PATH_MAX 1024
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169 # endif
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428
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170 #endif
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171
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172 #define MAX_READLINKS 32
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173
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440
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174 char * xrealpath (const char *path, char resolved_path []);
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428
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175 char *
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176 xrealpath (const char *path, char resolved_path [])
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177 {
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178 char copy_path[PATH_MAX];
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179 char *new_path = resolved_path;
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180 char *max_path;
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446
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181 #if defined (S_IFLNK) || defined (WIN32_NATIVE)
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428
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182 int readlinks = 0;
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183 char link_path[PATH_MAX];
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184 int n;
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446
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185 int abslen = ABS_LENGTH (path);
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428
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186 #endif
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187
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188 /* Make a copy of the source path since we may need to modify it. */
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442
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189 strcpy (copy_path, path);
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428
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190 path = copy_path;
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191 max_path = copy_path + PATH_MAX - 2;
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446
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192
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442
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193 #ifdef WIN32_NATIVE
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446
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194 /* Check for c:/... or //server/... */
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195 if (abslen == 2 || abslen == 3)
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428
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196 {
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446
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197 strncpy (new_path, path, abslen);
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462
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198 /* Make sure drive letter is lowercased. */
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199 if (abslen == 3)
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200 *new_path = tolower (*new_path);
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446
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201 new_path += abslen;
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202 path += abslen;
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428
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203 }
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446
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204 /* No drive letter, but a beginning slash? Prepend drive letter. */
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205 else if (abslen == 1)
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428
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206 {
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440
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207 getcwd (new_path, PATH_MAX - 1);
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428
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208 new_path += 3;
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209 path++;
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210 }
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446
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211 /* Just a path name, prepend the current directory */
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428
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212 else
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213 {
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440
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214 getcwd (new_path, PATH_MAX - 1);
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446
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215 new_path += strlen (new_path);
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216 if (!IS_DIRECTORY_SEP (new_path[-1]))
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217 *new_path++ = DIRECTORY_SEP;
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428
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218 }
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219 #else
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440
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220 /* If it's a relative pathname use getcwd for starters. */
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446
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221 if (abslen == 0)
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428
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222 {
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440
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223 getcwd (new_path, PATH_MAX - 1);
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446
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224 new_path += strlen (new_path);
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225 if (!IS_DIRECTORY_SEP (new_path[-1]))
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226 *new_path++ = DIRECTORY_SEP;
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428
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227 }
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228 else
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229 {
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446
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230 /* Copy first directory sep. May have two on cygwin. */
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231 strncpy (new_path, path, abslen);
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232 new_path += abslen;
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233 path += abslen;
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428
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234 }
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235 #endif
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236 /* Expand each slash-separated pathname component. */
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237 while (*path != '\0')
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238 {
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239 /* Ignore stray "/". */
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446
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240 if (IS_DIRECTORY_SEP (*path))
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428
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241 {
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242 path++;
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243 continue;
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244 }
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245
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246 if (*path == '.')
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247 {
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248 /* Ignore ".". */
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446
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249 if (path[1] == '\0' || IS_DIRECTORY_SEP (path[1]))
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428
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250 {
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251 path++;
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252 continue;
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253 }
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254
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442
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255 /* Handle ".." */
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256 if (path[1] == '.' &&
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446
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257 (path[2] == '\0' || IS_DIRECTORY_SEP (path[2])))
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428
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258 {
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442
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259 path += 2;
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428
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260
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442
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261 /* Ignore ".." at root. */
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446
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262 if (new_path == ABS_START (resolved_path))
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442
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263 continue;
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428
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264
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442
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265 /* Handle ".." by backing up. */
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446
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266 --new_path;
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267 while (!IS_DIRECTORY_SEP (new_path[-1]))
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268 --new_path;
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442
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269 continue;
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428
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270 }
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271 }
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272
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273 /* Safely copy the next pathname component. */
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446
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274 while (*path != '\0' && !IS_DIRECTORY_SEP (*path))
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428
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275 {
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276 if (path > max_path)
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277 {
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278 errno = ENAMETOOLONG;
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279 return NULL;
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280 }
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281 *new_path++ = *path++;
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282 }
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283
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446
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284 #if defined (S_IFLNK) || defined (WIN32_NATIVE)
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428
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285 /* See if latest pathname component is a symlink. */
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286 *new_path = '\0';
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446
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287 n = system_readlink (resolved_path, link_path, PATH_MAX - 1);
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428
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288
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289 if (n < 0)
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290 {
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291 /* EINVAL means the file exists but isn't a symlink. */
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462
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292 #ifdef CYGWIN
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293 if (errno != EINVAL && errno != ENOENT)
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294 #else
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295 if (errno != EINVAL)
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296 #endif
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428
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297 return NULL;
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298 }
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299 else
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300 {
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301 /* Protect against infinite loops. */
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302 if (readlinks++ > MAX_READLINKS)
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303 {
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304 errno = ELOOP;
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305 return NULL;
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306 }
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307
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308 /* Note: readlink doesn't add the null byte. */
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309 link_path[n] = '\0';
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446
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310
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311 if (ABS_LENGTH (link_path) > 0)
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428
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312 /* Start over for an absolute symlink. */
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446
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313 new_path = resolved_path + ABS_LENGTH (link_path) - 1;
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428
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314 else
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315 /* Otherwise back up over this component. */
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446
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316 for (--new_path; !IS_DIRECTORY_SEP (*new_path); --new_path)
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317 assert (new_path > resolved_path);
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428
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318
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319 /* Safe sex check. */
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320 if (strlen(path) + n >= PATH_MAX)
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321 {
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322 errno = ENAMETOOLONG;
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323 return NULL;
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324 }
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325
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326 /* Insert symlink contents into path. */
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327 strcat(link_path, path);
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328 strcpy(copy_path, link_path);
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329 path = copy_path;
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330 }
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446
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331 #endif /* S_IFLNK || WIN32_NATIVE */
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332 *new_path++ = DIRECTORY_SEP;
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428
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333 }
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334
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335 /* Delete trailing slash but don't whomp a lone slash. */
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446
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336 if (new_path != ABS_START (resolved_path) && IS_DIRECTORY_SEP (new_path[-1]))
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428
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337 new_path--;
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338
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339 /* Make sure it's null terminated. */
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340 *new_path = '\0';
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446
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341
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428
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342 return resolved_path;
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343 }
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