text: /*
   * 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.
   *
   * 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 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_fs_i.h"
  #include "squashfs.h"
  
  /*
   * Map uid/gid index into real 32-bit uid/gid using the id look up table
   */
  int squashfs_get_id(struct super_block *sb, unsigned int index,
  					unsigned int *id)
  {
  	struct squashfs_sb_info *msblk = sb->s_fs_info;
  	int block = SQUASHFS_ID_BLOCK(index);
  	int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
  	u64 start_block = le64_to_cpu(msblk->id_table[block]);
  	__le32 disk_id;
  	int err;
  
  	err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset,
  							sizeof(disk_id));
  	if (err < 0)
  		return err;
  
  	*id = le32_to_cpu(disk_id);
  	return 0;
  }
  
  
  /*
   * Read uncompressed id lookup table indexes from disk into memory
   */
  __le64 *squashfs_read_id_index_table(struct super_block *sb,
  			u64 id_table_start, unsigned short no_ids)
  {
  	unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
  	__le64 *id_table;
  	int err;
  
  	TRACE("In read_id_index_table, length %d\n", length);
  
  	/* Allocate id lookup table indexes */
  	id_table = kmalloc(length, GFP_KERNEL);
  	if (id_table == NULL) {
  		ERROR("Failed to allocate id index table\n");
  		return ERR_PTR(-ENOMEM);
  	}
  
  	err = squashfs_read_table(sb, id_table, id_table_start, length);
  	if (err < 0) {
  		ERROR("unable to read id index table\n");
  		kfree(id_table);
  		return ERR_PTR(err);
  	}
  
  	return id_table;
  }
  