Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
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@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 * 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#include "page_actor.h"
34
35/*
36 * This file (and decompressor.h) implements a decompressor framework for
37 * Squashfs, allowing multiple decompressors to be easily supported
38 */
39
40static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
41 NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
42};
43
44#ifndef CONFIG_SQUASHFS_LZO
45static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
46 NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
47};
48#endif
49
50#ifndef CONFIG_SQUASHFS_XZ
51static const struct squashfs_decompressor squashfs_xz_comp_ops = {
52 NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
53};
54#endif
55
56#ifndef CONFIG_SQUASHFS_ZLIB
57static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
58 NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
59};
60#endif
61
62static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
63 NULL, NULL, NULL, NULL, 0, "unknown", 0
64};
65
66static const struct squashfs_decompressor *decompressor[] = {
67 &squashfs_zlib_comp_ops,
68 &squashfs_lzo_comp_ops,
69 &squashfs_xz_comp_ops,
70 &squashfs_lzma_unsupported_comp_ops,
71 &squashfs_unknown_comp_ops
72};
73
74
75const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
76{
77 int i;
78
79 for (i = 0; decompressor[i]->id; i++)
80 if (id == decompressor[i]->id)
81 break;
82
83 return decompressor[i];
84}
85
86
87static void *get_comp_opts(struct super_block *sb, unsigned short flags)
88{
89 struct squashfs_sb_info *msblk = sb->s_fs_info;
90 void *buffer = NULL, *comp_opts;
91 struct squashfs_page_actor *actor = NULL;
92 int length = 0;
93
94 /*
95 * Read decompressor specific options from file system if present
96 */
97 if (SQUASHFS_COMP_OPTS(flags)) {
98 buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
99 if (buffer == NULL) {
100 comp_opts = ERR_PTR(-ENOMEM);
101 goto out;
102 }
103
104 actor = squashfs_page_actor_init(&buffer, 1, 0);
105 if (actor == NULL) {
106 comp_opts = ERR_PTR(-ENOMEM);
107 goto out;
108 }
109
110 length = squashfs_read_data(sb,
111 sizeof(struct squashfs_super_block), 0, NULL, actor);
112
113 if (length < 0) {
114 comp_opts = ERR_PTR(length);
115 goto out;
116 }
117 }
118
119 comp_opts = squashfs_comp_opts(msblk, buffer, length);
120
121out:
122 kfree(actor);
123 kfree(buffer);
124 return comp_opts;
125}
126
127
128void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
129{
130 struct squashfs_sb_info *msblk = sb->s_fs_info;
131 void *stream, *comp_opts = get_comp_opts(sb, flags);
132
133 if (IS_ERR(comp_opts))
134 return comp_opts;
135
136 stream = squashfs_decompressor_create(msblk, comp_opts);
137 if (IS_ERR(stream))
138 kfree(comp_opts);
139
140 return stream;
141}