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 
40 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
41 	NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
42 };
43 
44 #ifndef CONFIG_SQUASHFS_LZ4
45 static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
46 	NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
47 };
48 #endif
49 
50 #ifndef CONFIG_SQUASHFS_LZO
51 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
52 	NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
53 };
54 #endif
55 
56 #ifndef CONFIG_SQUASHFS_XZ
57 static const struct squashfs_decompressor squashfs_xz_comp_ops = {
58 	NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
59 };
60 #endif
61 
62 #ifndef CONFIG_SQUASHFS_ZLIB
63 static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
64 	NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
65 };
66 #endif
67 
68 #ifndef CONFIG_SQUASHFS_ZSTD
69 static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
70 	NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
71 };
72 #endif
73 
74 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
75 	NULL, NULL, NULL, NULL, 0, "unknown", 0
76 };
77 
78 static const struct squashfs_decompressor *decompressor[] = {
79 	&squashfs_zlib_comp_ops,
80 	&squashfs_lz4_comp_ops,
81 	&squashfs_lzo_comp_ops,
82 	&squashfs_xz_comp_ops,
83 	&squashfs_lzma_unsupported_comp_ops,
84 	&squashfs_zstd_comp_ops,
85 	&squashfs_unknown_comp_ops
86 };
87 
88 
squashfs_lookup_decompressor(int id)89 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
90 {
91 	int i;
92 
93 	for (i = 0; decompressor[i]->id; i++)
94 		if (id == decompressor[i]->id)
95 			break;
96 
97 	return decompressor[i];
98 }
99 
100 
get_comp_opts(struct super_block * sb,unsigned short flags)101 static void *get_comp_opts(struct super_block *sb, unsigned short flags)
102 {
103 	struct squashfs_sb_info *msblk = sb->s_fs_info;
104 	void *buffer = NULL, *comp_opts;
105 	struct squashfs_page_actor *actor = NULL;
106 	int length = 0;
107 
108 	/*
109 	 * Read decompressor specific options from file system if present
110 	 */
111 	if (SQUASHFS_COMP_OPTS(flags)) {
112 		buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
113 		if (buffer == NULL) {
114 			comp_opts = ERR_PTR(-ENOMEM);
115 			goto out;
116 		}
117 
118 		actor = squashfs_page_actor_init(&buffer, 1, 0);
119 		if (actor == NULL) {
120 			comp_opts = ERR_PTR(-ENOMEM);
121 			goto out;
122 		}
123 
124 		length = squashfs_read_data(sb,
125 			sizeof(struct squashfs_super_block), 0, NULL, actor);
126 
127 		if (length < 0) {
128 			comp_opts = ERR_PTR(length);
129 			goto out;
130 		}
131 	}
132 
133 	comp_opts = squashfs_comp_opts(msblk, buffer, length);
134 
135 out:
136 	kfree(actor);
137 	kfree(buffer);
138 	return comp_opts;
139 }
140 
141 
squashfs_decompressor_setup(struct super_block * sb,unsigned short flags)142 void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
143 {
144 	struct squashfs_sb_info *msblk = sb->s_fs_info;
145 	void *stream, *comp_opts = get_comp_opts(sb, flags);
146 
147 	if (IS_ERR(comp_opts))
148 		return comp_opts;
149 
150 	stream = squashfs_decompressor_create(msblk, comp_opts);
151 	if (IS_ERR(stream))
152 		kfree(comp_opts);
153 
154 	return stream;
155 }
156