[821] | 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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