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 * zlib_wrapper.c
 22 */
 23
 24
 25#include <linux/mutex.h>
 26#include <linux/buffer_head.h>
 27#include <linux/slab.h>
 28#include <linux/zlib.h>
 29#include <linux/vmalloc.h>
 30
 31#include "squashfs_fs.h"
 32#include "squashfs_fs_sb.h"
 33#include "squashfs.h"
 34#include "decompressor.h"
 35
 36static void *zlib_init(struct squashfs_sb_info *dummy, void *buff, int len)
 37{
 38	z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
 39	if (stream == NULL)
 40		goto failed;
 41	stream->workspace = vmalloc(zlib_inflate_workspacesize());
 42	if (stream->workspace == NULL)
 43		goto failed;
 44
 45	return stream;
 46
 47failed:
 48	ERROR("Failed to allocate zlib workspace\n");
 49	kfree(stream);
 50	return ERR_PTR(-ENOMEM);
 51}
 52
 53
 54static void zlib_free(void *strm)
 55{
 56	z_stream *stream = strm;
 57
 58	if (stream)
 59		vfree(stream->workspace);
 60	kfree(stream);
 61}
 62
 63
 64static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 65	struct buffer_head **bh, int b, int offset, int length, int srclength,
 66	int pages)
 67{
 68	int zlib_err, zlib_init = 0;
 69	int k = 0, page = 0;
 70	z_stream *stream = msblk->stream;
 71
 72	mutex_lock(&msblk->read_data_mutex);
 73
 74	stream->avail_out = 0;
 75	stream->avail_in = 0;
 76
 77	do {
 78		if (stream->avail_in == 0 && k < b) {
 79			int avail = min(length, msblk->devblksize - offset);
 80			length -= avail;
 81			wait_on_buffer(bh[k]);
 82			if (!buffer_uptodate(bh[k]))
 83				goto release_mutex;
 84
 85			stream->next_in = bh[k]->b_data + offset;
 86			stream->avail_in = avail;
 87			offset = 0;
 88		}
 89
 90		if (stream->avail_out == 0 && page < pages) {
 91			stream->next_out = buffer[page++];
 92			stream->avail_out = PAGE_CACHE_SIZE;
 93		}
 94
 95		if (!zlib_init) {
 96			zlib_err = zlib_inflateInit(stream);
 97			if (zlib_err != Z_OK) {
 98				ERROR("zlib_inflateInit returned unexpected "
 99					"result 0x%x, srclength %d\n",
100					zlib_err, srclength);
101				goto release_mutex;
102			}
103			zlib_init = 1;
104		}
105
106		zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
107
108		if (stream->avail_in == 0 && k < b)
109			put_bh(bh[k++]);
110	} while (zlib_err == Z_OK);
111
112	if (zlib_err != Z_STREAM_END) {
113		ERROR("zlib_inflate error, data probably corrupt\n");
114		goto release_mutex;
115	}
116
117	zlib_err = zlib_inflateEnd(stream);
118	if (zlib_err != Z_OK) {
119		ERROR("zlib_inflate error, data probably corrupt\n");
120		goto release_mutex;
121	}
122
123	if (k < b) {
124		ERROR("zlib_uncompress error, data remaining\n");
125		goto release_mutex;
126	}
127
128	length = stream->total_out;
129	mutex_unlock(&msblk->read_data_mutex);
130	return length;
131
132release_mutex:
133	mutex_unlock(&msblk->read_data_mutex);
134
135	for (; k < b; k++)
136		put_bh(bh[k]);
137
138	return -EIO;
139}
140
141const struct squashfs_decompressor squashfs_zlib_comp_ops = {
142	.init = zlib_init,
143	.free = zlib_free,
144	.decompress = zlib_uncompress,
145	.id = ZLIB_COMPRESSION,
146	.name = "zlib",
147	.supported = 1
148};
149