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
 36struct squashfs_xz {
 37	struct xz_dec *state;
 38	struct xz_buf buf;
 39};
 40
 41struct comp_opts {
 42	__le32 dictionary_size;
 43	__le32 flags;
 44};
 45
 46static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
 47	int len)
 48{
 49	struct comp_opts *comp_opts = buff;
 50	struct squashfs_xz *stream;
 51	int dict_size = msblk->block_size;
 52	int err, n;
 53
 54	if (comp_opts) {
 55		/* check compressor options are the expected length */
 56		if (len < sizeof(*comp_opts)) {
 57			err = -EIO;
 58			goto failed;
 59		}
 60
 61		dict_size = le32_to_cpu(comp_opts->dictionary_size);
 62
 63		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
 64		n = ffs(dict_size) - 1;
 65		if (dict_size != (1 << n) && dict_size != (1 << n) +
 66						(1 << (n + 1))) {
 67			err = -EIO;
 68			goto failed;
 69		}
 70	}
 71
 72	dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);
 73
 74	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
 75	if (stream == NULL) {
 76		err = -ENOMEM;
 77		goto failed;
 78	}
 79
 80	stream->state = xz_dec_init(XZ_PREALLOC, dict_size);
 81	if (stream->state == NULL) {
 82		kfree(stream);
 83		err = -ENOMEM;
 84		goto failed;
 85	}
 86
 87	return stream;
 88
 89failed:
 90	ERROR("Failed to initialise xz decompressor\n");
 91	return ERR_PTR(err);
 92}
 93
 94
 95static void squashfs_xz_free(void *strm)
 96{
 97	struct squashfs_xz *stream = strm;
 98
 99	if (stream) {
100		xz_dec_end(stream->state);
101		kfree(stream);
102	}
103}
104
105
106static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
107	struct buffer_head **bh, int b, int offset, int length, int srclength,
108	int pages)
109{
110	enum xz_ret xz_err;
111	int avail, total = 0, k = 0, page = 0;
112	struct squashfs_xz *stream = msblk->stream;
113
114	mutex_lock(&msblk->read_data_mutex);
115
116	xz_dec_reset(stream->state);
117	stream->buf.in_pos = 0;
118	stream->buf.in_size = 0;
119	stream->buf.out_pos = 0;
120	stream->buf.out_size = PAGE_CACHE_SIZE;
121	stream->buf.out = buffer[page++];
122
123	do {
124		if (stream->buf.in_pos == stream->buf.in_size && k < b) {
125			avail = min(length, msblk->devblksize - offset);
126			length -= avail;
127			wait_on_buffer(bh[k]);
128			if (!buffer_uptodate(bh[k]))
129				goto release_mutex;
130
131			stream->buf.in = bh[k]->b_data + offset;
132			stream->buf.in_size = avail;
133			stream->buf.in_pos = 0;
134			offset = 0;
135		}
136
137		if (stream->buf.out_pos == stream->buf.out_size
138							&& page < pages) {
139			stream->buf.out = buffer[page++];
140			stream->buf.out_pos = 0;
141			total += PAGE_CACHE_SIZE;
142		}
143
144		xz_err = xz_dec_run(stream->state, &stream->buf);
145
146		if (stream->buf.in_pos == stream->buf.in_size && k < b)
147			put_bh(bh[k++]);
148	} while (xz_err == XZ_OK);
149
150	if (xz_err != XZ_STREAM_END) {
151		ERROR("xz_dec_run error, data probably corrupt\n");
152		goto release_mutex;
153	}
154
155	if (k < b) {
156		ERROR("xz_uncompress error, input remaining\n");
157		goto release_mutex;
158	}
159
160	total += stream->buf.out_pos;
161	mutex_unlock(&msblk->read_data_mutex);
162	return total;
163
164release_mutex:
165	mutex_unlock(&msblk->read_data_mutex);
166
167	for (; k < b; k++)
168		put_bh(bh[k]);
169
170	return -EIO;
171}
172
173const struct squashfs_decompressor squashfs_xz_comp_ops = {
174	.init = squashfs_xz_init,
175	.free = squashfs_xz_free,
176	.decompress = squashfs_xz_uncompress,
177	.id = XZ_COMPRESSION,
178	.name = "xz",
179	.supported = 1
180};