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_CACHE_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_CACHE_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};
194