1 | /*
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2 | * namei.c --- ext2fs directory lookup operations
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3 | *
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4 | * Copyright (C) 1993, 1994, 1994, 1995 Theodore Ts'o.
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5 | *
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6 | * %Begin-Header%
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7 | * This file may be redistributed under the terms of the GNU Public
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8 | * License.
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9 | * %End-Header%
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10 | */
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11 |
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12 | #include <stdio.h>
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13 | #include <string.h>
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14 | #if HAVE_UNISTD_H
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15 | #include <unistd.h>
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16 | #endif
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17 |
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18 | /* #define NAMEI_DEBUG */
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19 |
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20 | #include "ext2_fs.h"
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21 | #include "ext2fs.h"
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22 |
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23 | static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
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24 | const char *pathname, size_t pathlen, int follow,
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25 | int link_count, char *buf, ext2_ino_t *res_inode);
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26 |
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27 | static errcode_t follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
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28 | ext2_ino_t inode, int link_count,
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29 | char *buf, ext2_ino_t *res_inode)
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30 | {
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31 | char *pathname;
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32 | char *buffer = 0;
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33 | errcode_t retval;
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34 | struct ext2_inode ei;
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35 |
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36 | #ifdef NAMEI_DEBUG
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37 | printf("follow_link: root=%lu, dir=%lu, inode=%lu, lc=%d\n",
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38 | root, dir, inode, link_count);
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39 |
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40 | #endif
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41 | retval = ext2fs_read_inode (fs, inode, &ei);
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42 | if (retval) return retval;
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43 | if (!LINUX_S_ISLNK (ei.i_mode)) {
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44 | *res_inode = inode;
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45 | return 0;
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46 | }
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47 | if (link_count++ > 5) {
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48 | return EXT2_ET_SYMLINK_LOOP;
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49 | }
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50 | if (ext2fs_inode_data_blocks(fs,&ei)) {
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51 | retval = ext2fs_get_mem(fs->blocksize, &buffer);
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52 | if (retval)
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53 | return retval;
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54 | retval = io_channel_read_blk(fs->io, ei.i_block[0], 1, buffer);
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55 | if (retval) {
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56 | ext2fs_free_mem(&buffer);
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57 | return retval;
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58 | }
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59 | pathname = buffer;
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60 | } else
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61 | pathname = (char *)&(ei.i_block[0]);
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62 | retval = open_namei(fs, root, dir, pathname, ei.i_size, 1,
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63 | link_count, buf, res_inode);
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64 | ext2fs_free_mem(&buffer);
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65 | return retval;
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66 | }
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67 |
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68 | /*
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69 | * This routine interprets a pathname in the context of the current
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70 | * directory and the root directory, and returns the inode of the
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71 | * containing directory, and a pointer to the filename of the file
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72 | * (pointing into the pathname) and the length of the filename.
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73 | */
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74 | static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
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75 | const char *pathname, int pathlen,
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76 | int link_count, char *buf,
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77 | const char **name, int *namelen,
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78 | ext2_ino_t *res_inode)
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79 | {
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80 | char c;
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81 | const char *thisname;
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82 | int len;
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83 | ext2_ino_t inode;
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84 | errcode_t retval;
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85 |
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86 | if ((c = *pathname) == '/') {
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87 | dir = root;
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88 | pathname++;
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89 | pathlen--;
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90 | }
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91 | while (1) {
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92 | thisname = pathname;
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93 | for (len=0; --pathlen >= 0;len++) {
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94 | c = *(pathname++);
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95 | if (c == '/')
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96 | break;
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97 | }
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98 | if (pathlen < 0)
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99 | break;
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100 | retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode);
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101 | if (retval) return retval;
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102 | retval = follow_link (fs, root, dir, inode,
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103 | link_count, buf, &dir);
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104 | if (retval) return retval;
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105 | }
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106 | *name = thisname;
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107 | *namelen = len;
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108 | *res_inode = dir;
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109 | return 0;
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110 | }
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111 |
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112 | static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
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113 | const char *pathname, size_t pathlen, int follow,
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114 | int link_count, char *buf, ext2_ino_t *res_inode)
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115 | {
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116 | const char *basename;
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117 | int namelen;
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118 | ext2_ino_t dir, inode;
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119 | errcode_t retval;
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120 |
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121 | #ifdef NAMEI_DEBUG
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122 | printf("open_namei: root=%lu, dir=%lu, path=%*s, lc=%d\n",
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123 | root, base, pathlen, pathname, link_count);
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124 | #endif
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125 | retval = dir_namei(fs, root, base, pathname, pathlen,
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126 | link_count, buf, &basename, &namelen, &dir);
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127 | if (retval) return retval;
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128 | if (!namelen) { /* special case: '/usr/' etc */
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129 | *res_inode=dir;
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130 | return 0;
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131 | }
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132 | retval = ext2fs_lookup (fs, dir, basename, namelen, buf, &inode);
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133 | if (retval)
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134 | return retval;
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135 | if (follow) {
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136 | retval = follow_link(fs, root, dir, inode, link_count,
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137 | buf, &inode);
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138 | if (retval)
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139 | return retval;
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140 | }
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141 | #ifdef NAMEI_DEBUG
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142 | printf("open_namei: (link_count=%d) returns %lu\n",
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143 | link_count, inode);
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144 | #endif
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145 | *res_inode = inode;
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146 | return 0;
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147 | }
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148 |
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149 | errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
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150 | const char *name, ext2_ino_t *inode)
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151 | {
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152 | char *buf;
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153 | errcode_t retval;
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154 |
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155 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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156 |
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157 | retval = ext2fs_get_mem(fs->blocksize, &buf);
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158 | if (retval)
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159 | return retval;
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160 |
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161 | retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0,
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162 | buf, inode);
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163 |
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164 | ext2fs_free_mem(&buf);
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165 | return retval;
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166 | }
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167 |
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168 | errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
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169 | const char *name, ext2_ino_t *inode)
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170 | {
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171 | char *buf;
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172 | errcode_t retval;
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173 |
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174 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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175 |
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176 | retval = ext2fs_get_mem(fs->blocksize, &buf);
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177 | if (retval)
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178 | return retval;
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179 |
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180 | retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0,
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181 | buf, inode);
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182 |
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183 | ext2fs_free_mem(&buf);
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184 | return retval;
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185 | }
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186 |
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187 | errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
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188 | ext2_ino_t inode, ext2_ino_t *res_inode)
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189 | {
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190 | char *buf;
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191 | errcode_t retval;
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192 |
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193 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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194 |
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195 | retval = ext2fs_get_mem(fs->blocksize, &buf);
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196 | if (retval)
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197 | return retval;
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198 |
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199 | retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode);
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200 |
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201 | ext2fs_free_mem(&buf);
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202 | return retval;
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203 | }
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204 |
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