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

Last change on this file since 31630 was 31630, checked in by brainslayer, 4 months ago

new fs is compatible with standard squashfs, just smaller

File size: 4.3 KB
Line 
1/*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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 * xz_wrapper.c
22 */
23
24
25#include <linux/mutex.h>
26#include <linux/buffer_head.h>
27#include <linux/slab.h>
28#include <linux/xz.h>
29#include <linux/bitops.h>
30
31#include "squashfs_fs.h"
32#include "squashfs_fs_sb.h"
33#include "squashfs.h"
34#include "decompressor.h"
35#include "page_actor.h"
36
37struct squashfs_xz {
38        struct xz_dec *state;
39        struct xz_buf buf;
40};
41
42struct disk_comp_opts {
43        __le32 dictionary_size;
44        __le32 flags;
45};
46
47struct comp_opts {
48        int dict_size;
49};
50
51static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
52        void *buff, int len)
53{
54        struct disk_comp_opts *comp_opts = buff;
55        struct comp_opts *opts;
56        int err = 0, n;
57
58        opts = kmalloc(sizeof(*opts), GFP_KERNEL);
59        if (opts == NULL) {
60                err = -ENOMEM;
61                goto out2;
62        }
63
64        if (comp_opts) {
65                /* check compressor options are the expected length */
66                if (len < sizeof(*comp_opts)) {
67                        err = -EIO;
68                        goto out;
69                }
70
71                opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
72
73                /* the dictionary size should be 2^n or 2^n+2^(n+1) */
74                n = ffs(opts->dict_size) - 1;
75                if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
76                                                (1 << (n + 1))) {
77                        err = -EIO;
78                        goto out;
79                }
80        } else
81                /* use defaults */
82                opts->dict_size = max_t(int, msblk->block_size,
83                                                        SQUASHFS_METADATA_SIZE);
84
85        return opts;
86
87out:
88        kfree(opts);
89out2:
90        return ERR_PTR(err);
91}
92
93
94static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff)
95{
96        struct comp_opts *comp_opts = buff;
97        struct squashfs_xz *stream;
98        int err;
99
100        stream = kmalloc(sizeof(*stream), GFP_KERNEL);
101        if (stream == NULL) {
102                err = -ENOMEM;
103                goto failed;
104        }
105
106        stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size);
107        if (stream->state == NULL) {
108                kfree(stream);
109                err = -ENOMEM;
110                goto failed;
111        }
112
113        return stream;
114
115failed:
116        ERROR("Failed to initialise xz decompressor\n");
117        return ERR_PTR(err);
118}
119
120
121static void squashfs_xz_free(void *strm)
122{
123        struct squashfs_xz *stream = strm;
124
125        if (stream) {
126                xz_dec_end(stream->state);
127                kfree(stream);
128        }
129}
130
131
132static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
133        struct buffer_head **bh, int b, int offset, int length,
134        struct squashfs_page_actor *output)
135{
136        enum xz_ret xz_err;
137        int avail, total = 0, k = 0;
138        struct squashfs_xz *stream = strm;
139
140        xz_dec_reset(stream->state);
141        stream->buf.in_pos = 0;
142        stream->buf.in_size = 0;
143        stream->buf.out_pos = 0;
144        stream->buf.out_size = PAGE_SIZE;
145        stream->buf.out = squashfs_first_page(output);
146
147        do {
148                if (stream->buf.in_pos == stream->buf.in_size && k < b) {
149                        avail = min(length, msblk->devblksize - offset);
150                        length -= avail;
151                        stream->buf.in = bh[k]->b_data + offset;
152                        stream->buf.in_size = avail;
153                        stream->buf.in_pos = 0;
154                        offset = 0;
155                }
156
157                if (stream->buf.out_pos == stream->buf.out_size) {
158                        stream->buf.out = squashfs_next_page(output);
159                        if (stream->buf.out != NULL) {
160                                stream->buf.out_pos = 0;
161                                total += PAGE_SIZE;
162                        }
163                }
164
165                xz_err = xz_dec_run(stream->state, &stream->buf);
166
167                if (stream->buf.in_pos == stream->buf.in_size && k < b)
168                        put_bh(bh[k++]);
169        } while (xz_err == XZ_OK);
170
171        squashfs_finish_page(output);
172
173        if (xz_err != XZ_STREAM_END || k < b)
174                goto out;
175
176        return total + stream->buf.out_pos;
177
178out:
179        for (; k < b; k++)
180                put_bh(bh[k]);
181
182        return -EIO;
183}
184
185const struct squashfs_decompressor squashfs_xz_comp_ops = {
186        .init = squashfs_xz_init,
187        .comp_opts = squashfs_xz_comp_opts,
188        .free = squashfs_xz_free,
189        .decompress = squashfs_xz_uncompress,
190        .id = XZ_COMPRESSION,
191        .name = "xz",
192        .supported = 1
193};
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