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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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428
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27 #include <errno.h>
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442
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28
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428
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29 #ifdef HAVE_UNISTD_H
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30 #include <unistd.h>
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31 #endif
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442
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32
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446
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33 #if defined (HAVE_SYS_PARAM_H) && !defined (WIN32_NATIVE)
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442
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34 #include <sys/param.h>
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428
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35 #endif
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36
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442
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37 #ifdef WIN32_NATIVE
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428
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38 #include <direct.h>
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39 #endif
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40
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41 #include <sys/stat.h> /* for S_IFLNK */
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42
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446
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43 /* First char after start of absolute filename. */
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44 #define ABS_START(name) (name + ABS_LENGTH (name))
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45
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46 #if defined (WIN32_NATIVE)
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47 /* Length of start of absolute filename. */
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48 # define ABS_LENGTH(name) (win32_abs_start (name))
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49 static int win32_abs_start (const char * name);
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50 /* System dependent version of readlink. */
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51 # define system_readlink win32_readlink
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52 #else
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53 # ifdef CYGWIN
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54 # define ABS_LENGTH(name) (IS_DIRECTORY_SEP (*name) ? \
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55 (IS_DIRECTORY_SEP (name[1]) ? 2 : 1) : 0)
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56 # define system_readlink cygwin_readlink
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57 # else
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58 # define ABS_LENGTH(name) (IS_DIRECTORY_SEP (*name) ? 1 : 0)
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59 # define system_readlink readlink
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60 # endif /* CYGWIN */
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61 #endif /* WIN32_NATIVE */
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62
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63 #if defined (WIN32_NATIVE) || defined (CYGWIN)
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64 #include "syswindows.h"
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65 /* Emulate readlink on win32 - finds real name (i.e. correct case) of
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66 a file. UNC servers and shares are lower-cased. Directories must be
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67 given without trailing '/'. One day, this could read Win2K's
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68 reparse points. */
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69 static int
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70 win32_readlink (const char * name, char * buf, int size)
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71 {
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72 WIN32_FIND_DATA find_data;
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73 HANDLE dir_handle = NULL;
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74 int len = 0;
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75 int err = 0;
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76 const char* lastname;
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77 int count = 0;
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78 const char* tmp;
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79 char* res = NULL;
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80
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81 assert (*name);
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82
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83 /* Sort of check we have a valid filename. */
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84 if (strpbrk (name, "*?|<>\"") || strlen (name) >= MAX_PATH)
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85 {
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86 errno = EIO;
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87 return -1;
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88 }
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89
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90 /* Find start of filename */
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91 lastname = name + strlen (name);
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92 while (lastname > name && !IS_DIRECTORY_SEP (lastname[-1]))
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93 --lastname;
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94
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95 /* Count slashes in unc path */
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96 if (ABS_LENGTH (name) == 2)
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97 for (tmp = name; *tmp; tmp++)
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98 if (IS_DIRECTORY_SEP (*tmp))
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99 count++;
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100
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101 if (count >= 2 && count < 4)
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102 {
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103 /* UNC server or share name: just copy lowercased name. */
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104 res = find_data.cFileName;
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105 for (tmp = lastname; *tmp; tmp++)
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106 *res++ = tolower (*tmp);
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107 *res = '\0';
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108 }
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109 else
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110 dir_handle = FindFirstFile (name, &find_data);
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111
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112 if (res || dir_handle != INVALID_HANDLE_VALUE)
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113 {
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114 if ((len = strlen (find_data.cFileName)) < size)
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115 {
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116 if (strcmp (lastname, find_data.cFileName) == 0)
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117 /* Signal that the name is already OK. */
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118 err = EINVAL;
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119 else
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120 memcpy (buf, find_data.cFileName, len + 1);
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121 }
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122 else
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123 err = ENAMETOOLONG;
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124 if (!res) FindClose (dir_handle);
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125 }
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126 else
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127 err = ENOENT;
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128
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129 errno = err;
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130 return err ? -1 : len;
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131 }
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132 #endif /* WIN32_NATIVE || CYGWIN */
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133
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134 #ifdef CYGWIN
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135 /* Call readlink and try to find out the correct case for the file. */
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136 static int
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137 cygwin_readlink (const char * name, char * buf, int size)
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138 {
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139 int n = readlink (name, buf, size);
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140 if (n < 0)
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141 {
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142 /* The file may exist, but isn't a symlink. Try to find the
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143 right name. */
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144 char* tmp = alloca (cygwin_posix_to_win32_path_list_buf_size (name));
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145 cygwin_posix_to_win32_path_list (name, tmp);
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146 n = win32_readlink (tmp, buf, size);
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147 }
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148 return n;
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149 }
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150 #endif /* CYGWIN */
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151
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152 #ifdef WIN32_NATIVE
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153 #ifndef ELOOP
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154 #define ELOOP 10062 /* = WSAELOOP in winsock.h */
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155 #endif
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156 /* Length of start of absolute filename. */
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157 static int
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158 win32_abs_start (const char * name)
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159 {
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160 if (isalpha (*name) && IS_DEVICE_SEP (name[1])
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161 && IS_DIRECTORY_SEP (name[2]))
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162 return 3;
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163 else if (IS_DIRECTORY_SEP (*name))
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164 return IS_DIRECTORY_SEP (name[1]) ? 2 : 1;
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165 else
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166 return 0;
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167 }
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168 #endif /* WIN32_NATIVE */
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169
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440
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170 #if !defined (HAVE_GETCWD) && defined (HAVE_GETWD)
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171 #undef getcwd
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172 #define getcwd(buffer, len) getwd (buffer)
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173 #endif
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174
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428
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175 #ifndef PATH_MAX
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440
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176 # if defined (_POSIX_PATH_MAX)
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177 # define PATH_MAX _POSIX_PATH_MAX
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178 # elif defined (MAXPATHLEN)
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179 # define PATH_MAX MAXPATHLEN
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180 # else
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181 # define PATH_MAX 1024
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182 # endif
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428
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183 #endif
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184
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185 #define MAX_READLINKS 32
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186
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440
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187 char * xrealpath (const char *path, char resolved_path []);
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428
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188 char *
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189 xrealpath (const char *path, char resolved_path [])
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190 {
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191 char copy_path[PATH_MAX];
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192 char *new_path = resolved_path;
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193 char *max_path;
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446
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194 #if defined (S_IFLNK) || defined (WIN32_NATIVE)
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428
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195 int readlinks = 0;
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196 char link_path[PATH_MAX];
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197 int n;
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446
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198 int abslen = ABS_LENGTH (path);
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428
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199 #endif
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200
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201 /* Make a copy of the source path since we may need to modify it. */
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442
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202 strcpy (copy_path, path);
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428
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203 path = copy_path;
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204 max_path = copy_path + PATH_MAX - 2;
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446
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205
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442
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206 #ifdef WIN32_NATIVE
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446
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207 /* Check for c:/... or //server/... */
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208 if (abslen == 2 || abslen == 3)
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428
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209 {
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446
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210 strncpy (new_path, path, abslen);
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211 new_path += abslen;
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212 path += abslen;
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428
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213 }
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446
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214 /* No drive letter, but a beginning slash? Prepend drive letter. */
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215 else if (abslen == 1)
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428
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216 {
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440
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217 getcwd (new_path, PATH_MAX - 1);
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428
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218 new_path += 3;
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219 path++;
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220 }
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446
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221 /* Just a path name, prepend the current directory */
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428
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222 else
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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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440
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230 /* If it's a relative pathname use getcwd for starters. */
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446
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231 if (abslen == 0)
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428
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232 {
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440
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233 getcwd (new_path, PATH_MAX - 1);
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446
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234 new_path += strlen (new_path);
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235 if (!IS_DIRECTORY_SEP (new_path[-1]))
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236 *new_path++ = DIRECTORY_SEP;
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428
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237 }
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238 else
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239 {
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446
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240 /* Copy first directory sep. May have two on cygwin. */
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241 strncpy (new_path, path, abslen);
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242 new_path += abslen;
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243 path += abslen;
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428
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244 }
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245 #endif
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246 /* Expand each slash-separated pathname component. */
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247 while (*path != '\0')
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248 {
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249 /* Ignore stray "/". */
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446
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250 if (IS_DIRECTORY_SEP (*path))
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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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256 if (*path == '.')
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257 {
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258 /* Ignore ".". */
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446
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259 if (path[1] == '\0' || IS_DIRECTORY_SEP (path[1]))
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428
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260 {
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261 path++;
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262 continue;
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263 }
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264
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442
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265 /* Handle ".." */
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266 if (path[1] == '.' &&
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446
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267 (path[2] == '\0' || IS_DIRECTORY_SEP (path[2])))
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428
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268 {
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442
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269 path += 2;
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428
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270
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442
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271 /* Ignore ".." at root. */
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446
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272 if (new_path == ABS_START (resolved_path))
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442
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273 continue;
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428
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274
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442
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275 /* Handle ".." by backing up. */
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446
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276 --new_path;
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277 while (!IS_DIRECTORY_SEP (new_path[-1]))
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278 --new_path;
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442
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279 continue;
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428
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280 }
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281 }
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282
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283 /* Safely copy the next pathname component. */
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446
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284 while (*path != '\0' && !IS_DIRECTORY_SEP (*path))
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428
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285 {
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286 if (path > max_path)
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287 {
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288 errno = ENAMETOOLONG;
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289 return NULL;
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290 }
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291 *new_path++ = *path++;
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292 }
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293
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446
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294 #if defined (S_IFLNK) || defined (WIN32_NATIVE)
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428
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295 /* See if latest pathname component is a symlink. */
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296 *new_path = '\0';
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446
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297 n = system_readlink (resolved_path, link_path, PATH_MAX - 1);
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428
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298
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299 if (n < 0)
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300 {
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301 /* EINVAL means the file exists but isn't a symlink. */
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302 if (errno != EINVAL)
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303 return NULL;
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304 }
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305 else
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306 {
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307 /* Protect against infinite loops. */
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308 if (readlinks++ > MAX_READLINKS)
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309 {
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310 errno = ELOOP;
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311 return NULL;
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312 }
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313
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314 /* Note: readlink doesn't add the null byte. */
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315 link_path[n] = '\0';
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446
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316
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317 if (ABS_LENGTH (link_path) > 0)
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428
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318 /* Start over for an absolute symlink. */
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446
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319 new_path = resolved_path + ABS_LENGTH (link_path) - 1;
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428
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320 else
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321 /* Otherwise back up over this component. */
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446
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322 for (--new_path; !IS_DIRECTORY_SEP (*new_path); --new_path)
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323 assert (new_path > resolved_path);
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428
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324
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325 /* Safe sex check. */
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326 if (strlen(path) + n >= PATH_MAX)
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327 {
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328 errno = ENAMETOOLONG;
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329 return NULL;
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330 }
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331
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332 /* Insert symlink contents into path. */
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333 strcat(link_path, path);
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334 strcpy(copy_path, link_path);
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335 path = copy_path;
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336 }
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446
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337 #endif /* S_IFLNK || WIN32_NATIVE */
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338 *new_path++ = DIRECTORY_SEP;
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428
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339 }
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340
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341 /* Delete trailing slash but don't whomp a lone slash. */
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446
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342 if (new_path != ABS_START (resolved_path) && IS_DIRECTORY_SEP (new_path[-1]))
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428
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343 new_path--;
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344
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345 /* Make sure it's null terminated. */
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346 *new_path = '\0';
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446
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347
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348 #ifdef WIN32_NATIVE
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349 if (ABS_LENGTH (resolved_path) == 3)
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350 /* Lowercase drive letter. */
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351 *resolved_path = tolower (*resolved_path);
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352 #endif
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428
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353 return resolved_path;
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354 }
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