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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.
*
* id.c
*/
/*
* This file implements code to handle uids and gids.
*
* For space efficiency regular files store uid and gid indexes, which are
* converted to 32-bit uids/gids using an id look up table. This table is
* stored compressed into metadata blocks. A second index table is used to
* locate these. 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_id(struct super_block *s, unsigned int index, unsigned int *id)
{
struct squashfs_sb_info *msblk = s->s_fs_info;
int block = SQUASHFS_ID_BLOCK(index);
int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
long long start_block = le64_to_cpu(msblk->id_table[block]);
__le32 disk_id;
if (!squashfs_read_metadata(s, &disk_id, start_block, offset,
sizeof(__le32), &start_block, &offset))
return 0;
*id = le32_to_cpu(disk_id);
return 1;
}
__le64 *read_id_index_table(struct super_block *s, long long id_table_start,
unsigned short no_ids)
{
unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
__le64 *id_table;
TRACE("In read_id_index_table, length %d\n", length);
/* Allocate id index table */
id_table = kmalloc(length, GFP_KERNEL);
if (id_table == NULL) {
ERROR("Failed to allocate id index table\n");
return NULL;
}
if (!squashfs_read_data(s, id_table, id_table_start, length |
SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length)) {
ERROR("unable to read id index table\n");
kfree(id_table);
return NULL;
}
return id_table;
}
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