[net-next-2.6.git] / fs / squashfs / block.c

/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
 * Phillip Lougher <phillip@lougher.demon.co.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.
 *
 * block.c
 */

/*
 * This file implements the low-level routines to read and decompress
 * datablocks and metadata blocks.
 */

#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/zlib.h>

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

/*
 * Read the metadata block length, this is stored in the first two
 * bytes of the metadata block.
 */
static struct buffer_head *get_block_length(struct super_block *sb,
			u64 *cur_index, int *offset, int *length)
{
	struct squashfs_sb_info *msblk = sb->s_fs_info;
	struct buffer_head *bh;

	bh = sb_bread(sb, *cur_index);
	if (bh == NULL)
		return NULL;

	if (msblk->devblksize - *offset == 1) {
		*length = (unsigned char) bh->b_data[*offset];
		put_bh(bh);
		bh = sb_bread(sb, ++(*cur_index));
		if (bh == NULL)
			return NULL;
		*length |= (unsigned char) bh->b_data[0] << 8;
		*offset = 1;
	} else {
		*length = (unsigned char) bh->b_data[*offset] |
			(unsigned char) bh->b_data[*offset + 1] << 8;
		*offset += 2;
	}

	return bh;
}


/*
 * Read and decompress a metadata block or datablock.  Length is non-zero
 * if a datablock is being read (the size is stored elsewhere in the
 * filesystem), otherwise the length is obtained from the first two bytes of
 * the metadata block.  A bit in the length field indicates if the block
 * is stored uncompressed in the filesystem (usually because compression
 * generated a larger block - this does occasionally happen with zlib).
 */
int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
			int length, u64 *next_index, int srclength, int pages)
{
	struct squashfs_sb_info *msblk = sb->s_fs_info;
	struct buffer_head **bh;
	int offset = index & ((1 << msblk->devblksize_log2) - 1);
	u64 cur_index = index >> msblk->devblksize_log2;
	int bytes, compressed, b = 0, k = 0, page = 0, avail;


	bh = kcalloc((msblk->block_size >> msblk->devblksize_log2) + 1,
				sizeof(*bh), GFP_KERNEL);
	if (bh == NULL)
		return -ENOMEM;

	if (length) {
		/*
		 * Datablock.
		 */
		bytes = -offset;
		compressed = SQUASHFS_COMPRESSED_BLOCK(length);
		length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
		if (next_index)
			*next_index = index + length;

		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
			index, compressed ? "" : "un", length, srclength);

		if (length < 0 || length > srclength ||
				(index + length) > msblk->bytes_used)
			goto read_failure;

		for (b = 0; bytes < length; b++, cur_index++) {
			bh[b] = sb_getblk(sb, cur_index);
			if (bh[b] == NULL)
				goto block_release;
			bytes += msblk->devblksize;
		}
		ll_rw_block(READ, b, bh);
	} else {
		/*
		 * Metadata block.
		 */
		if ((index + 2) > msblk->bytes_used)
			goto read_failure;

		bh[0] = get_block_length(sb, &cur_index, &offset, &length);
		if (bh[0] == NULL)
			goto read_failure;
		b = 1;

		bytes = msblk->devblksize - offset;
		compressed = SQUASHFS_COMPRESSED(length);
		length = SQUASHFS_COMPRESSED_SIZE(length);
		if (next_index)
			*next_index = index + length + 2;

		TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
				compressed ? "" : "un", length);

		if (length < 0 || length > srclength ||
					(index + length) > msblk->bytes_used)
			goto block_release;

		for (; bytes < length; b++) {
			bh[b] = sb_getblk(sb, ++cur_index);
			if (bh[b] == NULL)
				goto block_release;
			bytes += msblk->devblksize;
		}
		ll_rw_block(READ, b - 1, bh + 1);
	}

	if (compressed) {
		int zlib_err = 0, zlib_init = 0;

		/*
		 * Uncompress block.
		 */

		mutex_lock(&msblk->read_data_mutex);

		msblk->stream.avail_out = 0;
		msblk->stream.avail_in = 0;

		bytes = length;
		do {
			if (msblk->stream.avail_in == 0 && k < b) {
				avail = min(bytes, msblk->devblksize - offset);
				bytes -= avail;
				wait_on_buffer(bh[k]);
				if (!buffer_uptodate(bh[k]))
					goto release_mutex;

				if (avail == 0) {
					offset = 0;
					put_bh(bh[k++]);
					continue;
				}

				msblk->stream.next_in = bh[k]->b_data + offset;
				msblk->stream.avail_in = avail;
				offset = 0;
			}

			if (msblk->stream.avail_out == 0 && page < pages) {
				msblk->stream.next_out = buffer[page++];
				msblk->stream.avail_out = PAGE_CACHE_SIZE;
			}

			if (!zlib_init) {
				zlib_err = zlib_inflateInit(&msblk->stream);
				if (zlib_err != Z_OK) {
					ERROR("zlib_inflateInit returned"
						" unexpected result 0x%x,"
						" srclength %d\n", zlib_err,
						srclength);
					goto release_mutex;
				}
				zlib_init = 1;
			}

			zlib_err = zlib_inflate(&msblk->stream, Z_SYNC_FLUSH);

			if (msblk->stream.avail_in == 0 && k < b)
				put_bh(bh[k++]);
		} while (zlib_err == Z_OK);

		if (zlib_err != Z_STREAM_END) {
			ERROR("zlib_inflate error, data probably corrupt\n");
			goto release_mutex;
		}

		zlib_err = zlib_inflateEnd(&msblk->stream);
		if (zlib_err != Z_OK) {
			ERROR("zlib_inflate error, data probably corrupt\n");
			goto release_mutex;
		}
		length = msblk->stream.total_out;
		mutex_unlock(&msblk->read_data_mutex);
	} else {
		/*
		 * Block is uncompressed.
		 */
		int i, in, pg_offset = 0;

		for (i = 0; i < b; i++) {
			wait_on_buffer(bh[i]);
			if (!buffer_uptodate(bh[i]))
				goto block_release;
		}

		for (bytes = length; k < b; k++) {
			in = min(bytes, msblk->devblksize - offset);
			bytes -= in;
			while (in) {
				if (pg_offset == PAGE_CACHE_SIZE) {
					page++;
					pg_offset = 0;
				}
				avail = min_t(int, in, PAGE_CACHE_SIZE -
						pg_offset);
				memcpy(buffer[page] + pg_offset,
						bh[k]->b_data + offset, avail);
				in -= avail;
				pg_offset += avail;
				offset += avail;
			}
			offset = 0;
			put_bh(bh[k]);
		}
	}

	kfree(bh);
	return length;

release_mutex:
	mutex_unlock(&msblk->read_data_mutex);

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

read_failure:
	ERROR("squashfs_read_data failed to read block 0x%llx\n",
					(unsigned long long) index);
	kfree(bh);
	return -EIO;
}
Commit	Line	Data
e2780ab1 PL	1	/*
	2	* Squashfs - a compressed read only filesystem for Linux
	3	*
	4	* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
	5	* Phillip Lougher <phillip@lougher.demon.co.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	* block.c
	22	*/
	23
	24	/*
	25	* This file implements the low-level routines to read and decompress
	26	* datablocks and metadata blocks.
	27	*/
	28
	29	#include <linux/fs.h>
	30	#include <linux/vfs.h>
	31	#include <linux/slab.h>
	32	#include <linux/mutex.h>
	33	#include <linux/string.h>
	34	#include <linux/buffer_head.h>
	35	#include <linux/zlib.h>
	36
	37	#include "squashfs_fs.h"
	38	#include "squashfs_fs_sb.h"
	39	#include "squashfs_fs_i.h"
	40	#include "squashfs.h"
	41
	42	/*
	43	* Read the metadata block length, this is stored in the first two
	44	* bytes of the metadata block.
	45	*/
	46	static struct buffer_head get_block_length(struct super_block sb,
	47	u64 cur_index, int offset, int *length)
	48	{
	49	struct squashfs_sb_info *msblk = sb->s_fs_info;
	50	struct buffer_head *bh;
	51
	52	bh = sb_bread(sb, *cur_index);
	53	if (bh == NULL)
	54	return NULL;
	55
	56	if (msblk->devblksize - *offset == 1) {
	57	length = (unsigned char) bh->b_data[offset];
	58	put_bh(bh);
	59	bh = sb_bread(sb, ++(*cur_index));
	60	if (bh == NULL)
	61	return NULL;
	62	*length \|= (unsigned char) bh->b_data[0] << 8;
	63	*offset = 1;
	64	} else {
65	length = (unsigned char) bh->b_data[offset] \|
66	(unsigned char) bh->b_data[*offset + 1] << 8;
67	*offset += 2;
68	}
69
70	return bh;
71	}
72
73
74	/*
75	* Read and decompress a metadata block or datablock. Length is non-zero
76	* if a datablock is being read (the size is stored elsewhere in the
77	* filesystem), otherwise the length is obtained from the first two bytes of
78	* the metadata block. A bit in the length field indicates if the block
79	* is stored uncompressed in the filesystem (usually because compression
80	* generated a larger block - this does occasionally happen with zlib).
81	*/
82	int squashfs_read_data(struct super_block sb, void *buffer, u64 index,
118e1ef6	83	int length, u64 *next_index, int srclength, int pages)
e2780ab1 PL	84	{
	85	struct squashfs_sb_info *msblk = sb->s_fs_info;
	86	struct buffer_head **bh;
	87	int offset = index & ((1 << msblk->devblksize_log2) - 1);
	88	u64 cur_index = index >> msblk->devblksize_log2;
	89	int bytes, compressed, b = 0, k = 0, page = 0, avail;
	90
	91
	92	bh = kcalloc((msblk->block_size >> msblk->devblksize_log2) + 1,
	93	sizeof(*bh), GFP_KERNEL);
	94	if (bh == NULL)
	95	return -ENOMEM;
	96
	97	if (length) {
	98	/*
	99	* Datablock.
	100	*/
	101	bytes = -offset;
	102	compressed = SQUASHFS_COMPRESSED_BLOCK(length);
	103	length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
	104	if (next_index)
	105	*next_index = index + length;
	106
	107	TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
	108	index, compressed ? "" : "un", length, srclength);
	109
	110	if (length < 0 \|\| length > srclength \|\|
	111	(index + length) > msblk->bytes_used)
	112	goto read_failure;
	113
	114	for (b = 0; bytes < length; b++, cur_index++) {
	115	bh[b] = sb_getblk(sb, cur_index);
	116	if (bh[b] == NULL)
	117	goto block_release;
	118	bytes += msblk->devblksize;
	119	}
	120	ll_rw_block(READ, b, bh);
	121	} else {
	122	/*
	123	* Metadata block.
	124	*/
	125	if ((index + 2) > msblk->bytes_used)
	126	goto read_failure;
	127
	128	bh[0] = get_block_length(sb, &cur_index, &offset, &length);
	129	if (bh[0] == NULL)
	130	goto read_failure;
	131	b = 1;
	132
	133	bytes = msblk->devblksize - offset;
	134	compressed = SQUASHFS_COMPRESSED(length);
	135	length = SQUASHFS_COMPRESSED_SIZE(length);
	136	if (next_index)
	137	*next_index = index + length + 2;
	138
	139	TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
	140	compressed ? "" : "un", length);
	141
	142	if (length < 0 \|\| length > srclength \|\|
	143	(index + length) > msblk->bytes_used)
	144	goto block_release;
	145
	146	for (; bytes < length; b++) {
	147	bh[b] = sb_getblk(sb, ++cur_index);
148	if (bh[b] == NULL)
149	goto block_release;
150	bytes += msblk->devblksize;
151	}
152	ll_rw_block(READ, b - 1, bh + 1);
153	}
154
155	if (compressed) {
156	int zlib_err = 0, zlib_init = 0;
157
158	/*
159	* Uncompress block.
160	*/
161
162	mutex_lock(&msblk->read_data_mutex);
163
164	msblk->stream.avail_out = 0;
165	msblk->stream.avail_in = 0;
166
167	bytes = length;
168	do {
169	if (msblk->stream.avail_in == 0 && k < b) {
170	avail = min(bytes, msblk->devblksize - offset);
171	bytes -= avail;
172	wait_on_buffer(bh[k]);
173	if (!buffer_uptodate(bh[k]))
174	goto release_mutex;
175
176	if (avail == 0) {
177	offset = 0;
178	put_bh(bh[k++]);
179	continue;
180	}
181
182	msblk->stream.next_in = bh[k]->b_data + offset;
183	msblk->stream.avail_in = avail;
184	offset = 0;
185	}
186
363911d0	187	if (msblk->stream.avail_out == 0 && page < pages) {
e2780ab1 PL	188	msblk->stream.next_out = buffer[page++];
	189	msblk->stream.avail_out = PAGE_CACHE_SIZE;
	190	}
	191
	192	if (!zlib_init) {
	193	zlib_err = zlib_inflateInit(&msblk->stream);
	194	if (zlib_err != Z_OK) {
	195	ERROR("zlib_inflateInit returned"
	196	" unexpected result 0x%x,"
	197	" srclength %d\n", zlib_err,
	198	srclength);
	199	goto release_mutex;
	200	}
	201	zlib_init = 1;
	202	}
	203
363911d0	204	zlib_err = zlib_inflate(&msblk->stream, Z_SYNC_FLUSH);
e2780ab1 PL	205
	206	if (msblk->stream.avail_in == 0 && k < b)
	207	put_bh(bh[k++]);
	208	} while (zlib_err == Z_OK);
	209
	210	if (zlib_err != Z_STREAM_END) {
363911d0	211	ERROR("zlib_inflate error, data probably corrupt\n");
e2780ab1 PL	212	goto release_mutex;
	213	}
	214
	215	zlib_err = zlib_inflateEnd(&msblk->stream);
	216	if (zlib_err != Z_OK) {
363911d0	217	ERROR("zlib_inflate error, data probably corrupt\n");
e2780ab1 PL	218	goto release_mutex;
	219	}
	220	length = msblk->stream.total_out;
	221	mutex_unlock(&msblk->read_data_mutex);
	222	} else {
	223	/*
	224	* Block is uncompressed.
	225	*/
	226	int i, in, pg_offset = 0;
	227
	228	for (i = 0; i < b; i++) {
	229	wait_on_buffer(bh[i]);
	230	if (!buffer_uptodate(bh[i]))
	231	goto block_release;
	232	}
	233
	234	for (bytes = length; k < b; k++) {
	235	in = min(bytes, msblk->devblksize - offset);
	236	bytes -= in;
	237	while (in) {
	238	if (pg_offset == PAGE_CACHE_SIZE) {
	239	page++;
	240	pg_offset = 0;
	241	}
	242	avail = min_t(int, in, PAGE_CACHE_SIZE -
	243	pg_offset);
	244	memcpy(buffer[page] + pg_offset,
	245	bh[k]->b_data + offset, avail);
	246	in -= avail;
	247	pg_offset += avail;
	248	offset += avail;
	249	}
	250	offset = 0;
	251	put_bh(bh[k]);
	252	}
	253	}
	254
	255	kfree(bh);
	256	return length;
	257
	258	release_mutex:
	259	mutex_unlock(&msblk->read_data_mutex);
	260
	261	block_release:
	262	for (; k < b; k++)
	263	put_bh(bh[k]);
	264
	265	read_failure:
118e1ef6 PL	266	ERROR("squashfs_read_data failed to read block 0x%llx\n",
118e1ef6 PL	267	(unsigned long long) index);
e2780ab1 PL	268	kfree(bh);
	269	return -EIO;
	270	}