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/*
* 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* fragment.c
*/
/*
* This file implements code to handle compressed fragments (tail-end packed
* datablocks).
*
* Regular files contain a fragment index which is mapped to a fragment
* location on disk and compressed size using a fragment lookup table.
* Like everything in Squashfs this fragment lookup table is itself stored
* compressed into metadata blocks. A second index table is used to locate
* these compressed metadata blocks. This index table for speed of access
* (and because it is small) is read at mount time and cached in memory.
*/
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/zlib.h>
#include <linux/squashfs_fs.h>
#include <linux/squashfs_fs_sb.h>
#include <linux/squashfs_fs_i.h>
#include "squashfs.h"
int get_fragment_location(struct super_block *s, unsigned int fragment,
long long *fragment__block)
{
struct squashfs_sb_info *msblk = s->s_fs_info;
int block = SQUASHFS_FRAGMENT_INDEX(fragment);
int offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment);
long long start_block = le64_to_cpu(msblk->fragment_index[block]);
struct squashfs_fragment_entry fragment_entry;
int size = 0;
if (!squashfs_read_metadata(s, &fragment_entry, start_block, offset,
sizeof(fragment_entry), &start_block, &offset))
goto out;
*fragment__block = le64_to_cpu(fragment_entry.start_block);
size = le32_to_cpu(fragment_entry.size);
out:
return size;
}
__le64 *read_fragment_index_table(struct super_block *s,
long long fragment_table_start, unsigned int fragments)
{
unsigned int length = SQUASHFS_FRAGMENT_INDEX_BYTES(fragments);
__le64 *fragment_index;
/* Allocate fragment index table */
fragment_index = kmalloc(length, GFP_KERNEL);
if (fragment_index == NULL) {
ERROR("Failed to allocate fragment index table\n");
return NULL;
}
if (!squashfs_read_data(s, fragment_index, fragment_table_start,
length | SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length)) {
ERROR("unable to read fragment index table\n");
kfree(fragment_index);
return NULL;
}
return fragment_index;
}
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