source: src/linux/universal/linux-4.9/fs/squashfs/decompressor.c @ 31630

Last change on this file since 31630 was 31630, checked in by brainslayer, 2 weeks ago

new fs is compatible with standard squashfs, just smaller

File size: 3.7 KB
Line 
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_LZ4
45static 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
51static 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
57static 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
63static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
64        NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
65};
66#endif
67
68static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
69        NULL, NULL, NULL, NULL, 0, "unknown", 0
70};
71
72static const struct squashfs_decompressor *decompressor[] = {
73        &squashfs_zlib_comp_ops,
74        &squashfs_lz4_comp_ops,
75        &squashfs_lzo_comp_ops,
76        &squashfs_xz_comp_ops,
77        &squashfs_lzma_unsupported_comp_ops,
78        &squashfs_unknown_comp_ops
79};
80
81
82const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
83{
84        int i;
85
86        for (i = 0; decompressor[i]->id; i++)
87                if (id == decompressor[i]->id)
88                        break;
89
90        return decompressor[i];
91}
92
93
94static void *get_comp_opts(struct super_block *sb, unsigned short flags)
95{
96        struct squashfs_sb_info *msblk = sb->s_fs_info;
97        void *buffer = NULL, *comp_opts;
98        struct squashfs_page_actor *actor = NULL;
99        int length = 0;
100
101        /*
102         * Read decompressor specific options from file system if present
103         */
104        if (SQUASHFS_COMP_OPTS(flags)) {
105                buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
106                if (buffer == NULL) {
107                        comp_opts = ERR_PTR(-ENOMEM);
108                        goto out;
109                }
110
111                actor = squashfs_page_actor_init(&buffer, 1, 0);
112                if (actor == NULL) {
113                        comp_opts = ERR_PTR(-ENOMEM);
114                        goto out;
115                }
116
117                length = squashfs_read_data(sb,
118                        sizeof(struct squashfs_super_block), 0, NULL, actor);
119
120                if (length < 0) {
121                        comp_opts = ERR_PTR(length);
122                        goto out;
123                }
124        }
125
126        comp_opts = squashfs_comp_opts(msblk, buffer, length);
127
128out:
129        kfree(actor);
130        kfree(buffer);
131        return comp_opts;
132}
133
134
135void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
136{
137        struct squashfs_sb_info *msblk = sb->s_fs_info;
138        void *stream, *comp_opts = get_comp_opts(sb, flags);
139
140        if (IS_ERR(comp_opts))
141                return comp_opts;
142
143        stream = squashfs_decompressor_create(msblk, comp_opts);
144        if (IS_ERR(stream))
145                kfree(comp_opts);
146
147        return stream;
148}
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