mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
89 lines
2.6 KiB
89 lines
2.6 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
/* |
|
* Squashfs - a compressed read only filesystem for Linux |
|
* |
|
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 |
|
* Phillip Lougher <[email protected]> |
|
* |
|
* 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. This second 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 "squashfs_fs.h" |
|
#include "squashfs_fs_sb.h" |
|
#include "squashfs.h" |
|
|
|
/* |
|
* Look-up fragment using the fragment index table. Return the on disk |
|
* location of the fragment and its compressed size |
|
*/ |
|
int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment, |
|
u64 *fragment_block) |
|
{ |
|
struct squashfs_sb_info *msblk = sb->s_fs_info; |
|
int block, offset, size; |
|
struct squashfs_fragment_entry fragment_entry; |
|
u64 start_block; |
|
|
|
if (fragment >= msblk->fragments) |
|
return -EIO; |
|
block = SQUASHFS_FRAGMENT_INDEX(fragment); |
|
offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment); |
|
|
|
start_block = le64_to_cpu(msblk->fragment_index[block]); |
|
|
|
size = squashfs_read_metadata(sb, &fragment_entry, &start_block, |
|
&offset, sizeof(fragment_entry)); |
|
if (size < 0) |
|
return size; |
|
|
|
*fragment_block = le64_to_cpu(fragment_entry.start_block); |
|
return squashfs_block_size(fragment_entry.size); |
|
} |
|
|
|
|
|
/* |
|
* Read the uncompressed fragment lookup table indexes off disk into memory |
|
*/ |
|
__le64 *squashfs_read_fragment_index_table(struct super_block *sb, |
|
u64 fragment_table_start, u64 next_table, unsigned int fragments) |
|
{ |
|
unsigned int length = SQUASHFS_FRAGMENT_INDEX_BYTES(fragments); |
|
__le64 *table; |
|
|
|
/* |
|
* Sanity check, length bytes should not extend into the next table - |
|
* this check also traps instances where fragment_table_start is |
|
* incorrectly larger than the next table start |
|
*/ |
|
if (fragment_table_start + length > next_table) |
|
return ERR_PTR(-EINVAL); |
|
|
|
table = squashfs_read_table(sb, fragment_table_start, length); |
|
|
|
/* |
|
* table[0] points to the first fragment table metadata block, this |
|
* should be less than fragment_table_start |
|
*/ |
|
if (!IS_ERR(table) && le64_to_cpu(table[0]) >= fragment_table_start) { |
|
kfree(table); |
|
return ERR_PTR(-EINVAL); |
|
} |
|
|
|
return table; |
|
}
|
|
|