2 * Squashfs - a compressed read only filesystem for Linux
4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
5 * Phillip Lougher <phillip@squashfs.org.uk>
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.
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.
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.
24 #include <linux/types.h>
25 #include <linux/mutex.h>
26 #include <linux/slab.h>
27 #include <linux/highmem.h>
30 #include "squashfs_fs.h"
31 #include "squashfs_fs_sb.h"
32 #include "decompressor.h"
34 #include "page_actor.h"
37 * This file (and decompressor.h) implements a decompressor framework for
38 * Squashfs, allowing multiple decompressors to be easily supported
41 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
42 NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
45 #ifndef CONFIG_SQUASHFS_LZ4
46 static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
47 NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
51 #ifndef CONFIG_SQUASHFS_LZO
52 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
53 NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
57 #ifndef CONFIG_SQUASHFS_XZ
58 static const struct squashfs_decompressor squashfs_xz_comp_ops = {
59 NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
63 #ifndef CONFIG_SQUASHFS_ZLIB
64 static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
65 NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
69 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
70 NULL, NULL, NULL, NULL, 0, "unknown", 0
73 static const struct squashfs_decompressor *decompressor[] = {
74 &squashfs_zlib_comp_ops,
75 &squashfs_lz4_comp_ops,
76 &squashfs_lzo_comp_ops,
77 &squashfs_xz_comp_ops,
78 &squashfs_lzma_unsupported_comp_ops,
79 &squashfs_unknown_comp_ops
83 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
87 for (i = 0; decompressor[i]->id; i++)
88 if (id == decompressor[i]->id)
91 return decompressor[i];
95 static void *get_comp_opts(struct super_block *sb, unsigned short flags)
97 struct squashfs_sb_info *msblk = sb->s_fs_info;
98 void *comp_opts, *buffer = NULL;
100 struct squashfs_page_actor *actor = NULL;
103 if (!SQUASHFS_COMP_OPTS(flags))
104 return squashfs_comp_opts(msblk, buffer, length);
107 * Read decompressor specific options from file system if present
110 page = alloc_page(GFP_KERNEL);
112 return ERR_PTR(-ENOMEM);
114 actor = squashfs_page_actor_init(&page, 1, 0, NULL);
116 comp_opts = ERR_PTR(-ENOMEM);
120 length = squashfs_read_data(sb,
121 sizeof(struct squashfs_super_block), 0, NULL, actor);
124 comp_opts = ERR_PTR(length);
128 buffer = kmap_atomic(page);
129 comp_opts = squashfs_comp_opts(msblk, buffer, length);
130 kunmap_atomic(buffer);
133 squashfs_page_actor_free(actor, 0);
140 void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
142 struct squashfs_sb_info *msblk = sb->s_fs_info;
143 void *stream, *comp_opts = get_comp_opts(sb, flags);
145 if (IS_ERR(comp_opts))
148 stream = squashfs_decompressor_create(msblk, comp_opts);