1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * namei.c --- ext2fs directory lookup operations
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4 | *
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5 | * Copyright (C) 1993, 1994, 1994, 1995 Theodore Ts'o.
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6 | *
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7 | * %Begin-Header%
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8 | * This file may be redistributed under the terms of the GNU Public
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9 | * License.
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10 | * %End-Header%
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11 | */
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12 |
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13 | #include <stdio.h>
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14 | #include <string.h>
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15 | #if HAVE_UNISTD_H
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16 | #include <unistd.h>
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17 | #endif
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18 |
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19 | /* #define NAMEI_DEBUG */
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20 |
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21 | #include "ext2_fs.h"
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22 | #include "ext2fs.h"
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23 |
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24 | static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
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25 | const char *pathname, size_t pathlen, int follow,
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26 | int link_count, char *buf, ext2_ino_t *res_inode);
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27 |
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28 | static errcode_t follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
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29 | ext2_ino_t inode, int link_count,
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30 | char *buf, ext2_ino_t *res_inode)
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31 | {
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32 | char *pathname;
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33 | char *buffer = 0;
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34 | errcode_t retval;
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35 | struct ext2_inode ei;
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36 |
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37 | #ifdef NAMEI_DEBUG
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38 | printf("follow_link: root=%lu, dir=%lu, inode=%lu, lc=%d\n",
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39 | root, dir, inode, link_count);
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40 |
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41 | #endif
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42 | retval = ext2fs_read_inode (fs, inode, &ei);
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43 | if (retval) return retval;
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44 | if (!LINUX_S_ISLNK (ei.i_mode)) {
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45 | *res_inode = inode;
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46 | return 0;
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47 | }
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48 | if (link_count++ > 5) {
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49 | return EXT2_ET_SYMLINK_LOOP;
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50 | }
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51 | if (ext2fs_inode_data_blocks(fs,&ei)) {
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52 | retval = ext2fs_get_mem(fs->blocksize, &buffer);
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53 | if (retval)
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54 | return retval;
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55 | retval = io_channel_read_blk(fs->io, ei.i_block[0], 1, buffer);
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56 | if (retval) {
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57 | ext2fs_free_mem(&buffer);
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58 | return retval;
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59 | }
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60 | pathname = buffer;
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61 | } else
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62 | pathname = (char *)&(ei.i_block[0]);
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63 | retval = open_namei(fs, root, dir, pathname, ei.i_size, 1,
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64 | link_count, buf, res_inode);
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65 | ext2fs_free_mem(&buffer);
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66 | return retval;
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67 | }
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68 |
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69 | /*
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70 | * This routine interprets a pathname in the context of the current
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71 | * directory and the root directory, and returns the inode of the
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72 | * containing directory, and a pointer to the filename of the file
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73 | * (pointing into the pathname) and the length of the filename.
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74 | */
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75 | static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
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76 | const char *pathname, int pathlen,
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77 | int link_count, char *buf,
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78 | const char **name, int *namelen,
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79 | ext2_ino_t *res_inode)
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80 | {
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81 | char c;
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82 | const char *thisname;
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83 | int len;
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84 | ext2_ino_t inode;
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85 | errcode_t retval;
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86 |
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87 | if ((c = *pathname) == '/') {
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88 | dir = root;
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89 | pathname++;
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90 | pathlen--;
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91 | }
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92 | while (1) {
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93 | thisname = pathname;
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94 | for (len=0; --pathlen >= 0;len++) {
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95 | c = *(pathname++);
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96 | if (c == '/')
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97 | break;
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98 | }
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99 | if (pathlen < 0)
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100 | break;
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101 | retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode);
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102 | if (retval) return retval;
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103 | retval = follow_link (fs, root, dir, inode,
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104 | link_count, buf, &dir);
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105 | if (retval) return retval;
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106 | }
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107 | *name = thisname;
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108 | *namelen = len;
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109 | *res_inode = dir;
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110 | return 0;
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111 | }
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112 |
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113 | static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
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114 | const char *pathname, size_t pathlen, int follow,
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115 | int link_count, char *buf, ext2_ino_t *res_inode)
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116 | {
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117 | const char *basename;
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118 | int namelen;
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119 | ext2_ino_t dir, inode;
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120 | errcode_t retval;
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121 |
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122 | #ifdef NAMEI_DEBUG
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123 | printf("open_namei: root=%lu, dir=%lu, path=%*s, lc=%d\n",
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124 | root, base, pathlen, pathname, link_count);
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125 | #endif
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126 | retval = dir_namei(fs, root, base, pathname, pathlen,
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127 | link_count, buf, &basename, &namelen, &dir);
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128 | if (retval) return retval;
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129 | if (!namelen) { /* special case: '/usr/' etc */
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130 | *res_inode=dir;
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131 | return 0;
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132 | }
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133 | retval = ext2fs_lookup (fs, dir, basename, namelen, buf, &inode);
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134 | if (retval)
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135 | return retval;
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136 | if (follow) {
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137 | retval = follow_link(fs, root, dir, inode, link_count,
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138 | buf, &inode);
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139 | if (retval)
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140 | return retval;
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141 | }
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142 | #ifdef NAMEI_DEBUG
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143 | printf("open_namei: (link_count=%d) returns %lu\n",
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144 | link_count, inode);
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145 | #endif
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146 | *res_inode = inode;
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147 | return 0;
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148 | }
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149 |
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150 | errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
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151 | const char *name, ext2_ino_t *inode)
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152 | {
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153 | char *buf;
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154 | errcode_t retval;
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155 |
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156 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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157 |
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158 | retval = ext2fs_get_mem(fs->blocksize, &buf);
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159 | if (retval)
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160 | return retval;
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161 |
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162 | retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0,
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163 | buf, inode);
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164 |
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165 | ext2fs_free_mem(&buf);
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166 | return retval;
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167 | }
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168 |
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169 | errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
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170 | const char *name, ext2_ino_t *inode)
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171 | {
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172 | char *buf;
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173 | errcode_t retval;
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174 |
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175 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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176 |
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177 | retval = ext2fs_get_mem(fs->blocksize, &buf);
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178 | if (retval)
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179 | return retval;
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180 |
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181 | retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0,
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182 | buf, inode);
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183 |
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184 | ext2fs_free_mem(&buf);
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185 | return retval;
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186 | }
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187 |
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188 | errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
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189 | ext2_ino_t inode, ext2_ino_t *res_inode)
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190 | {
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191 | char *buf;
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192 | errcode_t retval;
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193 |
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194 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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195 |
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196 | retval = ext2fs_get_mem(fs->blocksize, &buf);
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197 | if (retval)
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198 | return retval;
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199 |
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200 | retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode);
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201 |
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202 | ext2fs_free_mem(&buf);
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203 | return retval;
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204 | }
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205 |
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