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/highmem.h>
28 #include <linux/fs.h>
29
30 #include "squashfs_fs.h"
31 #include "squashfs_fs_sb.h"
32 #include "decompressor.h"
33 #include "squashfs.h"
34 #include "page_actor.h"
35
36 /*
37 * This file (and decompressor.h) implements a decompressor framework for
38 * Squashfs, allowing multiple decompressors to be easily supported
39 */
40
41 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
42 NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
43 };
44
45 #ifndef CONFIG_SQUASHFS_LZ4
46 static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
47 NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
48 };
49 #endif
50
51 #ifndef CONFIG_SQUASHFS_LZO
52 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
53 NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
54 };
55 #endif
56
57 #ifndef CONFIG_SQUASHFS_XZ
58 static const struct squashfs_decompressor squashfs_xz_comp_ops = {
59 NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
60 };
61 #endif
62
63 #ifndef CONFIG_SQUASHFS_ZLIB
64 static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
65 NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
66 };
67 #endif
68
69 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
70 NULL, NULL, NULL, NULL, 0, "unknown", 0
71 };
72
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
80 };
81
82
squashfs_lookup_decompressor(int id)83 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
84 {
85 int i;
86
87 for (i = 0; decompressor[i]->id; i++)
88 if (id == decompressor[i]->id)
89 break;
90
91 return decompressor[i];
92 }
93
94
get_comp_opts(struct super_block * sb,unsigned short flags)95 static void *get_comp_opts(struct super_block *sb, unsigned short flags)
96 {
97 struct squashfs_sb_info *msblk = sb->s_fs_info;
98 void *comp_opts, *buffer = NULL;
99 struct page *page;
100 struct squashfs_page_actor *actor = NULL;
101 int length = 0;
102
103 if (!SQUASHFS_COMP_OPTS(flags))
104 return squashfs_comp_opts(msblk, buffer, length);
105
106 /*
107 * Read decompressor specific options from file system if present
108 */
109
110 page = alloc_page(GFP_KERNEL);
111 if (!page)
112 return ERR_PTR(-ENOMEM);
113
114 actor = squashfs_page_actor_init(&page, 1, 0, NULL);
115 if (actor == NULL) {
116 comp_opts = ERR_PTR(-ENOMEM);
117 goto actor_error;
118 }
119
120 length = squashfs_read_data(sb,
121 sizeof(struct squashfs_super_block), 0, NULL, actor);
122
123 if (length < 0) {
124 comp_opts = ERR_PTR(length);
125 goto read_error;
126 }
127
128 buffer = kmap_atomic(page);
129 comp_opts = squashfs_comp_opts(msblk, buffer, length);
130 kunmap_atomic(buffer);
131
132 read_error:
133 squashfs_page_actor_free(actor, 0);
134 actor_error:
135 __free_page(page);
136 return comp_opts;
137 }
138
139
squashfs_decompressor_setup(struct super_block * sb,unsigned short flags)140 void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
141 {
142 struct squashfs_sb_info *msblk = sb->s_fs_info;
143 void *stream, *comp_opts = get_comp_opts(sb, flags);
144
145 if (IS_ERR(comp_opts))
146 return comp_opts;
147
148 stream = squashfs_decompressor_create(msblk, comp_opts);
149 if (IS_ERR(stream))
150 kfree(comp_opts);
151
152 return stream;
153 }
154