aboutsummaryrefslogtreecommitdiffstats
path: root/fs/squashfs/xz_wrapper.c
blob: 1760b7d108f66a55614102c43713ef315592374e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
 * Phillip Lougher <phillip@squashfs.org.uk>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * xz_wrapper.c
 */


#include <linux/mutex.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/xz.h>
#include <linux/bitops.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "decompressor.h"

struct squashfs_xz {
	struct xz_dec *state;
	struct xz_buf buf;
};

struct comp_opts {
	__le32 dictionary_size;
	__le32 flags;
};

static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
	int len)
{
	struct comp_opts *comp_opts = buff;
	struct squashfs_xz *stream;
	int dict_size = msblk->block_size;
	int err, n;

	if (comp_opts) {
		/* check compressor options are the expected length */
		if (len < sizeof(*comp_opts)) {
			err = -EIO;
			goto failed;
		}

		dict_size = le32_to_cpu(comp_opts->dictionary_size);

		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
		n = ffs(dict_size) - 1;
		if (dict_size != (1 << n) && dict_size != (1 << n) +
						(1 << (n + 1))) {
			err = -EIO;
			goto failed;
		}
	}

	dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);

	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
	if (stream == NULL) {
		err = -ENOMEM;
		goto failed;
	}

	stream->state = xz_dec_init(XZ_PREALLOC, dict_size);
	if (stream->state == NULL) {
		kfree(stream);
		err = -ENOMEM;
		goto failed;
	}

	return stream;

failed:
	ERROR("Failed to initialise xz decompressor\n");
	return ERR_PTR(err);
}


static void squashfs_xz_free(void *strm)
{
	struct squashfs_xz *stream = strm;

	if (stream) {
		xz_dec_end(stream->state);
		kfree(stream);
	}
}


static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
	struct buffer_head **bh, int b, int offset, int length, int srclength,
	int pages)
{
	enum xz_ret xz_err;
	int avail, total = 0, k = 0, page = 0;
	struct squashfs_xz *stream = msblk->stream;

	mutex_lock(&msblk->read_data_mutex);

	xz_dec_reset(stream->state);
	stream->buf.in_pos = 0;
	stream->buf.in_size = 0;
	stream->buf.out_pos = 0;
	stream->buf.out_size = PAGE_CACHE_SIZE;
	stream->buf.out = buffer[page++];

	do {
		if (stream->buf.in_pos == stream->buf.in_size && k < b) {
			avail = min(length, msblk->devblksize - offset);
			length -= avail;
			wait_on_buffer(bh[k]);
			if (!buffer_uptodate(bh[k]))
				goto release_mutex;

			stream->buf.in = bh[k]->b_data + offset;
			stream->buf.in_size = avail;
			stream->buf.in_pos = 0;
			offset = 0;
		}

		if (stream->buf.out_pos == stream->buf.out_size
							&& page < pages) {
			stream->buf.out = buffer[page++];
			stream->buf.out_pos = 0;
			total += PAGE_CACHE_SIZE;
		}

		xz_err = xz_dec_run(stream->state, &stream->buf);

		if (stream->buf.in_pos == stream->buf.in_size && k < b)
			put_bh(bh[k++]);
	} while (xz_err == XZ_OK);

	if (xz_err != XZ_STREAM_END) {
		ERROR("xz_dec_run error, data probably corrupt\n");
		goto release_mutex;
	}

	if (k < b) {
		ERROR("xz_uncompress error, input remaining\n");
		goto release_mutex;
	}

	total += stream->buf.out_pos;
	mutex_unlock(&msblk->read_data_mutex);
	return total;

release_mutex:
	mutex_unlock(&msblk->read_data_mutex);

	for (; k < b; k++)
		put_bh(bh[k]);

	return -EIO;
}

const struct squashfs_decompressor squashfs_xz_comp_ops = {
	.init = squashfs_xz_init,
	.free = squashfs_xz_free,
	.decompress = squashfs_xz_uncompress,
	.id = XZ_COMPRESSION,
	.name = "xz",
	.supported = 1
};