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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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572
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25 #define DONT_ENCAPSULATE
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428
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26 #include <config.h>
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446
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27 #include "lisp.h"
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442
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28
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558
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29 #include "sysfile.h"
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428
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30
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446
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31 /* First char after start of absolute filename. */
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32 #define ABS_START(name) (name + ABS_LENGTH (name))
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33
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34 #if defined (WIN32_NATIVE)
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35 /* Length of start of absolute filename. */
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36 # define ABS_LENGTH(name) (win32_abs_start (name))
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37 static int win32_abs_start (const char * name);
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38 /* System dependent version of readlink. */
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39 # define system_readlink win32_readlink
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40 #else
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41 # ifdef CYGWIN
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42 # define ABS_LENGTH(name) (IS_DIRECTORY_SEP (*name) ? \
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43 (IS_DIRECTORY_SEP (name[1]) ? 2 : 1) : 0)
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44 # define system_readlink cygwin_readlink
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45 # else
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46 # define ABS_LENGTH(name) (IS_DIRECTORY_SEP (*name) ? 1 : 0)
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47 # define system_readlink readlink
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48 # endif /* CYGWIN */
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49 #endif /* WIN32_NATIVE */
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50
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51 #if defined (WIN32_NATIVE) || defined (CYGWIN)
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52 #include "syswindows.h"
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53 /* Emulate readlink on win32 - finds real name (i.e. correct case) of
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54 a file. UNC servers and shares are lower-cased. Directories must be
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55 given without trailing '/'. One day, this could read Win2K's
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56 reparse points. */
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57 static int
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58 win32_readlink (const char * name, char * buf, int size)
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59 {
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60 WIN32_FIND_DATA find_data;
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61 HANDLE dir_handle = NULL;
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62 int len = 0;
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63 int err = 0;
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64 const char* lastname;
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65 int count = 0;
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66 const char* tmp;
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67 char* res = NULL;
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68
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69 assert (*name);
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70
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71 /* Sort of check we have a valid filename. */
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558
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72 if (strpbrk (name, "*?|<>\"") || strlen (name) >= PATH_MAX)
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446
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73 {
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74 errno = EIO;
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75 return -1;
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76 }
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77
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78 /* Find start of filename */
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79 lastname = name + strlen (name);
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80 while (lastname > name && !IS_DIRECTORY_SEP (lastname[-1]))
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81 --lastname;
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82
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83 /* Count slashes in unc path */
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84 if (ABS_LENGTH (name) == 2)
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85 for (tmp = name; *tmp; tmp++)
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86 if (IS_DIRECTORY_SEP (*tmp))
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87 count++;
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88
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89 if (count >= 2 && count < 4)
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90 {
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91 /* UNC server or share name: just copy lowercased name. */
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92 res = find_data.cFileName;
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93 for (tmp = lastname; *tmp; tmp++)
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94 *res++ = tolower (*tmp);
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95 *res = '\0';
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96 }
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97 else
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98 dir_handle = FindFirstFile (name, &find_data);
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99
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100 if (res || dir_handle != INVALID_HANDLE_VALUE)
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101 {
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102 if ((len = strlen (find_data.cFileName)) < size)
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103 {
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104 if (strcmp (lastname, find_data.cFileName) == 0)
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105 /* Signal that the name is already OK. */
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106 err = EINVAL;
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107 else
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108 memcpy (buf, find_data.cFileName, len + 1);
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109 }
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110 else
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111 err = ENAMETOOLONG;
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112 if (!res) FindClose (dir_handle);
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113 }
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114 else
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115 err = ENOENT;
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116
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117 errno = err;
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118 return err ? -1 : len;
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119 }
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120 #endif /* WIN32_NATIVE || CYGWIN */
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121
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122 #ifdef CYGWIN
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123 /* Call readlink and try to find out the correct case for the file. */
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124 static int
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125 cygwin_readlink (const char * name, char * buf, int size)
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126 {
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127 int n = readlink (name, buf, size);
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462
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128 if (n < 0 && errno == EINVAL)
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446
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129 {
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130 /* The file may exist, but isn't a symlink. Try to find the
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131 right name. */
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132 char* tmp = alloca (cygwin_posix_to_win32_path_list_buf_size (name));
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133 cygwin_posix_to_win32_path_list (name, tmp);
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134 n = win32_readlink (tmp, buf, size);
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135 }
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136 return n;
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137 }
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138 #endif /* CYGWIN */
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139
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140 #ifdef WIN32_NATIVE
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141 #ifndef ELOOP
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142 #define ELOOP 10062 /* = WSAELOOP in winsock.h */
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143 #endif
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144 /* Length of start of absolute filename. */
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145 static int
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146 win32_abs_start (const char * name)
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147 {
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148 if (isalpha (*name) && IS_DEVICE_SEP (name[1])
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149 && IS_DIRECTORY_SEP (name[2]))
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150 return 3;
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151 else if (IS_DIRECTORY_SEP (*name))
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152 return IS_DIRECTORY_SEP (name[1]) ? 2 : 1;
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153 else
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154 return 0;
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155 }
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156 #endif /* WIN32_NATIVE */
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157
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440
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158 #if !defined (HAVE_GETCWD) && defined (HAVE_GETWD)
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159 #undef getcwd
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160 #define getcwd(buffer, len) getwd (buffer)
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161 #endif
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162
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428
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163 #ifndef PATH_MAX
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440
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164 # if defined (_POSIX_PATH_MAX)
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165 # define PATH_MAX _POSIX_PATH_MAX
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166 # elif defined (MAXPATHLEN)
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167 # define PATH_MAX MAXPATHLEN
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168 # else
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169 # define PATH_MAX 1024
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170 # endif
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428
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171 #endif
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172
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173 #define MAX_READLINKS 32
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174
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440
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175 char * xrealpath (const char *path, char resolved_path []);
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428
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176 char *
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177 xrealpath (const char *path, char resolved_path [])
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178 {
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179 char copy_path[PATH_MAX];
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180 char *new_path = resolved_path;
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181 char *max_path;
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446
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182 #if defined (S_IFLNK) || defined (WIN32_NATIVE)
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428
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183 int readlinks = 0;
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184 char link_path[PATH_MAX];
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185 int n;
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446
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186 int abslen = ABS_LENGTH (path);
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428
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187 #endif
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188
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189 /* Make a copy of the source path since we may need to modify it. */
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442
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190 strcpy (copy_path, path);
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428
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191 path = copy_path;
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192 max_path = copy_path + PATH_MAX - 2;
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446
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193
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442
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194 #ifdef WIN32_NATIVE
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446
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195 /* Check for c:/... or //server/... */
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196 if (abslen == 2 || abslen == 3)
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428
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197 {
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446
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198 strncpy (new_path, path, abslen);
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462
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199 /* Make sure drive letter is lowercased. */
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200 if (abslen == 3)
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201 *new_path = tolower (*new_path);
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446
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202 new_path += abslen;
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203 path += abslen;
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428
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204 }
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446
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205 /* No drive letter, but a beginning slash? Prepend drive letter. */
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206 else if (abslen == 1)
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428
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207 {
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440
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208 getcwd (new_path, PATH_MAX - 1);
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428
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209 new_path += 3;
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210 path++;
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211 }
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446
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212 /* Just a path name, prepend the current directory */
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428
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213 else
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214 {
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440
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215 getcwd (new_path, PATH_MAX - 1);
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446
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216 new_path += strlen (new_path);
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217 if (!IS_DIRECTORY_SEP (new_path[-1]))
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218 *new_path++ = DIRECTORY_SEP;
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428
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219 }
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220 #else
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440
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221 /* If it's a relative pathname use getcwd for starters. */
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446
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222 if (abslen == 0)
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428
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223 {
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440
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224 getcwd (new_path, PATH_MAX - 1);
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446
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225 new_path += strlen (new_path);
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226 if (!IS_DIRECTORY_SEP (new_path[-1]))
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227 *new_path++ = DIRECTORY_SEP;
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428
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228 }
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229 else
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230 {
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446
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231 /* Copy first directory sep. May have two on cygwin. */
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232 strncpy (new_path, path, abslen);
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233 new_path += abslen;
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234 path += abslen;
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428
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235 }
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236 #endif
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237 /* Expand each slash-separated pathname component. */
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238 while (*path != '\0')
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239 {
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240 /* Ignore stray "/". */
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446
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241 if (IS_DIRECTORY_SEP (*path))
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428
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242 {
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243 path++;
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244 continue;
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245 }
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246
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247 if (*path == '.')
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248 {
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249 /* Ignore ".". */
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446
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250 if (path[1] == '\0' || IS_DIRECTORY_SEP (path[1]))
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428
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251 {
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252 path++;
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253 continue;
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254 }
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255
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442
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256 /* Handle ".." */
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257 if (path[1] == '.' &&
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446
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258 (path[2] == '\0' || IS_DIRECTORY_SEP (path[2])))
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428
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259 {
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442
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260 path += 2;
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428
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261
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442
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262 /* Ignore ".." at root. */
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446
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263 if (new_path == ABS_START (resolved_path))
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442
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264 continue;
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428
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265
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442
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266 /* Handle ".." by backing up. */
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446
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267 --new_path;
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268 while (!IS_DIRECTORY_SEP (new_path[-1]))
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269 --new_path;
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442
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270 continue;
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428
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271 }
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272 }
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273
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274 /* Safely copy the next pathname component. */
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446
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275 while (*path != '\0' && !IS_DIRECTORY_SEP (*path))
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428
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276 {
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277 if (path > max_path)
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278 {
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279 errno = ENAMETOOLONG;
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280 return NULL;
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281 }
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282 *new_path++ = *path++;
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283 }
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284
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446
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285 #if defined (S_IFLNK) || defined (WIN32_NATIVE)
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428
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286 /* See if latest pathname component is a symlink. */
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287 *new_path = '\0';
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446
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288 n = system_readlink (resolved_path, link_path, PATH_MAX - 1);
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428
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289
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290 if (n < 0)
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291 {
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292 /* EINVAL means the file exists but isn't a symlink. */
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462
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293 #ifdef CYGWIN
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294 if (errno != EINVAL && errno != ENOENT)
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295 #else
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296 if (errno != EINVAL)
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297 #endif
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428
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298 return NULL;
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299 }
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300 else
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301 {
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302 /* Protect against infinite loops. */
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303 if (readlinks++ > MAX_READLINKS)
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304 {
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305 errno = ELOOP;
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306 return NULL;
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307 }
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308
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309 /* Note: readlink doesn't add the null byte. */
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310 link_path[n] = '\0';
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446
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311
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312 if (ABS_LENGTH (link_path) > 0)
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428
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313 /* Start over for an absolute symlink. */
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446
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314 new_path = resolved_path + ABS_LENGTH (link_path) - 1;
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428
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315 else
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316 /* Otherwise back up over this component. */
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446
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317 for (--new_path; !IS_DIRECTORY_SEP (*new_path); --new_path)
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318 assert (new_path > resolved_path);
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428
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319
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320 /* Safe sex check. */
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321 if (strlen(path) + n >= PATH_MAX)
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322 {
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323 errno = ENAMETOOLONG;
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324 return NULL;
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325 }
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326
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327 /* Insert symlink contents into path. */
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328 strcat(link_path, path);
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329 strcpy(copy_path, link_path);
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330 path = copy_path;
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331 }
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446
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332 #endif /* S_IFLNK || WIN32_NATIVE */
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333 *new_path++ = DIRECTORY_SEP;
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428
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334 }
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335
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336 /* Delete trailing slash but don't whomp a lone slash. */
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446
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337 if (new_path != ABS_START (resolved_path) && IS_DIRECTORY_SEP (new_path[-1]))
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428
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338 new_path--;
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339
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340 /* Make sure it's null terminated. */
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341 *new_path = '\0';
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446
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342
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428
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343 return resolved_path;
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344 }
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