1 /*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
5 * Phillip Lougher <phillip@lougher.demon.co.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 * decompressor.c
22 */
23
24 #include <linux/types.h>
25 #include <linux/mutex.h>
26 #include <linux/slab.h>
27 #include <linux/buffer_head.h>
28
29 #include "squashfs_fs.h"
30 #include "squashfs_fs_sb.h"
31 #include "decompressor.h"
32 #include "squashfs.h"
33
34 /*
35 * This file (and decompressor.h) implements a decompressor framework for
36 * Squashfs, allowing multiple decompressors to be easily supported
37 */
38
39 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
40 NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
41 };
42
43 #ifndef CONFIG_SQUASHFS_LZO
44 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
45 NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
46 };
47 #endif
48
49 #ifndef CONFIG_SQUASHFS_XZ
50 static const struct squashfs_decompressor squashfs_xz_comp_ops = {
51 NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
52 };
53 #endif
54
55 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
56 NULL, NULL, NULL, 0, "unknown", 0
57 };
58
59 static const struct squashfs_decompressor *decompressor[] = {
60 &squashfs_zlib_comp_ops,
61 &squashfs_lzo_comp_ops,
62 &squashfs_xz_comp_ops,
63 &squashfs_lzma_unsupported_comp_ops,
64 &squashfs_unknown_comp_ops
65 };
66
67
squashfs_lookup_decompressor(int id)68 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
69 {
70 int i;
71
72 for (i = 0; decompressor[i]->id; i++)
73 if (id == decompressor[i]->id)
74 break;
75
76 return decompressor[i];
77 }
78
79
squashfs_decompressor_init(struct super_block * sb,unsigned short flags)80 void *squashfs_decompressor_init(struct super_block *sb, unsigned short flags)
81 {
82 struct squashfs_sb_info *msblk = sb->s_fs_info;
83 void *strm, *buffer = NULL;
84 int length = 0;
85
86 /*
87 * Read decompressor specific options from file system if present
88 */
89 if (SQUASHFS_COMP_OPTS(flags)) {
90 buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
91 if (buffer == NULL)
92 return ERR_PTR(-ENOMEM);
93
94 length = squashfs_read_data(sb, &buffer,
95 sizeof(struct squashfs_super_block), 0, NULL,
96 PAGE_CACHE_SIZE, 1);
97
98 if (length < 0) {
99 strm = ERR_PTR(length);
100 goto finished;
101 }
102 }
103
104 strm = msblk->decompressor->init(msblk, buffer, length);
105
106 finished:
107 kfree(buffer);
108
109 return strm;
110 }
111