Merge tag 'for-linus-merge-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git...
[platform/adaptation/renesas_rcar/renesas_kernel.git] / fs / squashfs / dir.c
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
39 static 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  */
51 static 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
103 static 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, 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                 if (dir_count > SQUASHFS_DIR_COUNT)
177                         goto failed_read;
178
179                 while (dir_count--) {
180                         /*
181                          * Read directory entry.
182                          */
183                         err = squashfs_read_metadata(inode->i_sb, dire, &block,
184                                         &offset, sizeof(*dire));
185                         if (err < 0)
186                                 goto failed_read;
187
188                         size = le16_to_cpu(dire->size) + 1;
189
190                         /* size should never be larger than SQUASHFS_NAME_LEN */
191                         if (size > SQUASHFS_NAME_LEN)
192                                 goto failed_read;
193
194                         err = squashfs_read_metadata(inode->i_sb, dire->name,
195                                         &block, &offset, size);
196                         if (err < 0)
197                                 goto failed_read;
198
199                         length += sizeof(*dire) + size;
200
201                         if (file->f_pos >= length)
202                                 continue;
203
204                         dire->name[size] = '\0';
205                         inode_number = le32_to_cpu(dirh.inode_number) +
206                                 ((short) le16_to_cpu(dire->inode_number));
207                         type = le16_to_cpu(dire->type);
208
209                         TRACE("Calling filldir(%p, %s, %d, %lld, %x:%x, %d, %d)"
210                                         "\n", dirent, dire->name, size,
211                                         file->f_pos,
212                                         le32_to_cpu(dirh.start_block),
213                                         le16_to_cpu(dire->offset),
214                                         inode_number,
215                                         squashfs_filetype_table[type]);
216
217                         if (filldir(dirent, dire->name, size, file->f_pos,
218                                         inode_number,
219                                         squashfs_filetype_table[type]) < 0) {
220                                 TRACE("Filldir returned less than 0\n");
221                                 goto finish;
222                         }
223
224                         file->f_pos = length;
225                 }
226         }
227
228 finish:
229         kfree(dire);
230         return 0;
231
232 failed_read:
233         ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
234         kfree(dire);
235         return 0;
236 }
237
238
239 const struct file_operations squashfs_dir_ops = {
240         .read = generic_read_dir,
241         .readdir = squashfs_readdir,
242         .llseek = default_llseek,
243 };