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1/*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
5 * Phillip Lougher <phillip@squashfs.org.uk>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2,
10 * or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 * dir.c
22 */
23
24/*
25 * This file implements code to read directories from disk.
26 *
27 * See namei.c for a description of directory organisation on disk.
28 */
29
30#include <linux/fs.h>
31#include <linux/vfs.h>
32#include <linux/slab.h>
33
34#include "squashfs_fs.h"
35#include "squashfs_fs_sb.h"
36#include "squashfs_fs_i.h"
37#include "squashfs.h"
38
39static const unsigned char squashfs_filetype_table[] = {
40 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
41};
42
43/*
44 * Lookup offset (f_pos) in the directory index, returning the
45 * metadata block containing it.
46 *
47 * If we get an error reading the index then return the part of the index
48 * (if any) we have managed to read - the index isn't essential, just
49 * quicker.
50 */
51static int get_dir_index_using_offset(struct super_block *sb,
52 u64 *next_block, int *next_offset, u64 index_start, int index_offset,
53 int i_count, u64 f_pos)
54{
55 struct squashfs_sb_info *msblk = sb->s_fs_info;
56 int err, i, index, length = 0;
57 struct squashfs_dir_index dir_index;
58
59 TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
60 i_count, f_pos);
61
62 /*
63 * Translate from external f_pos to the internal f_pos. This
64 * is offset by 3 because we invent "." and ".." entries which are
65 * not actually stored in the directory.
66 */
67 if (f_pos < 3)
68 return f_pos;
69 f_pos -= 3;
70
71 for (i = 0; i < i_count; i++) {
72 err = squashfs_read_metadata(sb, &dir_index, &index_start,
73 &index_offset, sizeof(dir_index));
74 if (err < 0)
75 break;
76
77 index = le32_to_cpu(dir_index.index);
78 if (index > f_pos)
79 /*
80 * Found the index we're looking for.
81 */
82 break;
83
84 err = squashfs_read_metadata(sb, NULL, &index_start,
85 &index_offset, le32_to_cpu(dir_index.size) + 1);
86 if (err < 0)
87 break;
88
89 length = index;
90 *next_block = le32_to_cpu(dir_index.start_block) +
91 msblk->directory_table;
92 }
93
94 *next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
95
96 /*
97 * Translate back from internal f_pos to external f_pos.
98 */
99 return length + 3;
100}
101
102
103static int squashfs_readdir(struct file *file, void *dirent, filldir_t filldir)
104{
105 struct inode *inode = file->f_dentry->d_inode;
106 struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
107 u64 block = squashfs_i(inode)->start + msblk->directory_table;
108 int offset = squashfs_i(inode)->offset, length = 0, dir_count, size,
109 type, err;
110 unsigned int inode_number;
111 struct squashfs_dir_header dirh;
112 struct squashfs_dir_entry *dire;
113
114 TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);
115
116 dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
117 if (dire == NULL) {
118 ERROR("Failed to allocate squashfs_dir_entry\n");
119 goto finish;
120 }
121
122 /*
123 * Return "." and ".." entries as the first two filenames in the
124 * directory. To maximise compression these two entries are not
125 * stored in the directory, and so we invent them here.
126 *
127 * It also means that the external f_pos is offset by 3 from the
128 * on-disk directory f_pos.
129 */
130 while (file->f_pos < 3) {
131 char *name;
132 int i_ino;
133
134 if (file->f_pos == 0) {
135 name = ".";
136 size = 1;
137 i_ino = inode->i_ino;
138 } else {
139 name = "..";
140 size = 2;
141 i_ino = squashfs_i(inode)->parent;
142 }
143
144 TRACE("Calling filldir(%p, %s, %d, %lld, %d, %d)\n",
145 dirent, name, size, file->f_pos, i_ino,
146 squashfs_filetype_table[1]);
147
148 if (filldir(dirent, name, size, file->f_pos, i_ino,
149 squashfs_filetype_table[1]) < 0) {
150 TRACE("Filldir returned less than 0\n");
151 goto finish;
152 }
153
154 file->f_pos += size;
155 }
156
157 length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
158 squashfs_i(inode)->dir_idx_start,
159 squashfs_i(inode)->dir_idx_offset,
160 squashfs_i(inode)->dir_idx_cnt,
161 file->f_pos);
162
163 while (length < i_size_read(inode)) {
164 /*
165 * Read directory header
166 */
167 err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
168 &offset, sizeof(dirh));
169 if (err < 0)
170 goto failed_read;
171
172 length += sizeof(dirh);
173
174 dir_count = le32_to_cpu(dirh.count) + 1;
175
176 /* dir_count should never be larger than 256 */
177 if (dir_count > 256)
178 goto failed_read;
179
180 while (dir_count--) {
181 /*
182 * Read directory entry.
183 */
184 err = squashfs_read_metadata(inode->i_sb, dire, &block,
185 &offset, sizeof(*dire));
186 if (err < 0)
187 goto failed_read;
188
189 size = le16_to_cpu(dire->size) + 1;
190
191 /* size should never be larger than SQUASHFS_NAME_LEN */
192 if (size > SQUASHFS_NAME_LEN)
193 goto failed_read;
194
195 err = squashfs_read_metadata(inode->i_sb, dire->name,
196 &block, &offset, size);
197 if (err < 0)
198 goto failed_read;
199
200 length += sizeof(*dire) + size;
201
202 if (file->f_pos >= length)
203 continue;
204
205 dire->name[size] = '\0';
206 inode_number = le32_to_cpu(dirh.inode_number) +
207 ((short) le16_to_cpu(dire->inode_number));
208 type = le16_to_cpu(dire->type);
209
210 TRACE("Calling filldir(%p, %s, %d, %lld, %x:%x, %d, %d)"
211 "\n", dirent, dire->name, size,
212 file->f_pos,
213 le32_to_cpu(dirh.start_block),
214 le16_to_cpu(dire->offset),
215 inode_number,
216 squashfs_filetype_table[type]);
217
218 if (filldir(dirent, dire->name, size, file->f_pos,
219 inode_number,
220 squashfs_filetype_table[type]) < 0) {
221 TRACE("Filldir returned less than 0\n");
222 goto finish;
223 }
224
225 file->f_pos = length;
226 }
227 }
228
229finish:
230 kfree(dire);
231 return 0;
232
233failed_read:
234 ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
235 kfree(dire);
236 return 0;
237}
238
239
240const struct file_operations squashfs_dir_ops = {
241 .read = generic_read_dir,
242 .readdir = squashfs_readdir,
243 .llseek = default_llseek,
244};
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Squashfs - a compressed read only filesystem for Linux
4 *
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6 * Phillip Lougher <phillip@squashfs.org.uk>
7 *
8 * dir.c
9 */
10
11/*
12 * This file implements code to read directories from disk.
13 *
14 * See namei.c for a description of directory organisation on disk.
15 */
16
17#include <linux/fs.h>
18#include <linux/vfs.h>
19#include <linux/slab.h>
20
21#include "squashfs_fs.h"
22#include "squashfs_fs_sb.h"
23#include "squashfs_fs_i.h"
24#include "squashfs.h"
25
26static const unsigned char squashfs_filetype_table[] = {
27 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
28};
29
30/*
31 * Lookup offset (f_pos) in the directory index, returning the
32 * metadata block containing it.
33 *
34 * If we get an error reading the index then return the part of the index
35 * (if any) we have managed to read - the index isn't essential, just
36 * quicker.
37 */
38static int get_dir_index_using_offset(struct super_block *sb,
39 u64 *next_block, int *next_offset, u64 index_start, int index_offset,
40 int i_count, u64 f_pos)
41{
42 struct squashfs_sb_info *msblk = sb->s_fs_info;
43 int err, i, index, length = 0;
44 unsigned int size;
45 struct squashfs_dir_index dir_index;
46
47 TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
48 i_count, f_pos);
49
50 /*
51 * Translate from external f_pos to the internal f_pos. This
52 * is offset by 3 because we invent "." and ".." entries which are
53 * not actually stored in the directory.
54 */
55 if (f_pos <= 3)
56 return f_pos;
57 f_pos -= 3;
58
59 for (i = 0; i < i_count; i++) {
60 err = squashfs_read_metadata(sb, &dir_index, &index_start,
61 &index_offset, sizeof(dir_index));
62 if (err < 0)
63 break;
64
65 index = le32_to_cpu(dir_index.index);
66 if (index > f_pos)
67 /*
68 * Found the index we're looking for.
69 */
70 break;
71
72 size = le32_to_cpu(dir_index.size) + 1;
73
74 /* size should never be larger than SQUASHFS_NAME_LEN */
75 if (size > SQUASHFS_NAME_LEN)
76 break;
77
78 err = squashfs_read_metadata(sb, NULL, &index_start,
79 &index_offset, size);
80 if (err < 0)
81 break;
82
83 length = index;
84 *next_block = le32_to_cpu(dir_index.start_block) +
85 msblk->directory_table;
86 }
87
88 *next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
89
90 /*
91 * Translate back from internal f_pos to external f_pos.
92 */
93 return length + 3;
94}
95
96
97static int squashfs_readdir(struct file *file, struct dir_context *ctx)
98{
99 struct inode *inode = file_inode(file);
100 struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
101 u64 block = squashfs_i(inode)->start + msblk->directory_table;
102 int offset = squashfs_i(inode)->offset, length, err;
103 unsigned int inode_number, dir_count, size, type;
104 struct squashfs_dir_header dirh;
105 struct squashfs_dir_entry *dire;
106
107 TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);
108
109 dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
110 if (dire == NULL) {
111 ERROR("Failed to allocate squashfs_dir_entry\n");
112 goto finish;
113 }
114
115 /*
116 * Return "." and ".." entries as the first two filenames in the
117 * directory. To maximise compression these two entries are not
118 * stored in the directory, and so we invent them here.
119 *
120 * It also means that the external f_pos is offset by 3 from the
121 * on-disk directory f_pos.
122 */
123 while (ctx->pos < 3) {
124 char *name;
125 int i_ino;
126
127 if (ctx->pos == 0) {
128 name = ".";
129 size = 1;
130 i_ino = inode->i_ino;
131 } else {
132 name = "..";
133 size = 2;
134 i_ino = squashfs_i(inode)->parent;
135 }
136
137 if (!dir_emit(ctx, name, size, i_ino,
138 squashfs_filetype_table[1]))
139 goto finish;
140
141 ctx->pos += size;
142 }
143
144 length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
145 squashfs_i(inode)->dir_idx_start,
146 squashfs_i(inode)->dir_idx_offset,
147 squashfs_i(inode)->dir_idx_cnt,
148 ctx->pos);
149
150 while (length < i_size_read(inode)) {
151 /*
152 * Read directory header
153 */
154 err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
155 &offset, sizeof(dirh));
156 if (err < 0)
157 goto failed_read;
158
159 length += sizeof(dirh);
160
161 dir_count = le32_to_cpu(dirh.count) + 1;
162
163 if (dir_count > SQUASHFS_DIR_COUNT)
164 goto failed_read;
165
166 while (dir_count--) {
167 /*
168 * Read directory entry.
169 */
170 err = squashfs_read_metadata(inode->i_sb, dire, &block,
171 &offset, sizeof(*dire));
172 if (err < 0)
173 goto failed_read;
174
175 size = le16_to_cpu(dire->size) + 1;
176
177 /* size should never be larger than SQUASHFS_NAME_LEN */
178 if (size > SQUASHFS_NAME_LEN)
179 goto failed_read;
180
181 err = squashfs_read_metadata(inode->i_sb, dire->name,
182 &block, &offset, size);
183 if (err < 0)
184 goto failed_read;
185
186 length += sizeof(*dire) + size;
187
188 if (ctx->pos >= length)
189 continue;
190
191 dire->name[size] = '\0';
192 inode_number = le32_to_cpu(dirh.inode_number) +
193 ((short) le16_to_cpu(dire->inode_number));
194 type = le16_to_cpu(dire->type);
195
196 if (type > SQUASHFS_MAX_DIR_TYPE)
197 goto failed_read;
198
199 if (!dir_emit(ctx, dire->name, size,
200 inode_number,
201 squashfs_filetype_table[type]))
202 goto finish;
203
204 ctx->pos = length;
205 }
206 }
207
208finish:
209 kfree(dire);
210 return 0;
211
212failed_read:
213 ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
214 kfree(dire);
215 return 0;
216}
217
218
219const struct file_operations squashfs_dir_ops = {
220 .read = generic_read_dir,
221 .iterate_shared = squashfs_readdir,
222 .llseek = generic_file_llseek,
223};