/*

 * Squashfs - a compressed read only filesystem for Linux

 *

 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008

 * Phillip Lougher <phillip@squashfs.org.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.

 *

 * 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/barebox-wrapper.h>

#include <linux/fs.h>

#include <malloc.h>

#include "squashfs_fs.h"

#include "squashfs_fs_sb.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, u64 next_table, unsigned short no_ids)

{

  unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);

  __le64 *table;

  TRACE("In read_id_index_table, length %d\n", length);

  /* Sanity check values */

  /* there should always be at least one id */

  if (no_ids == 0)

    return ERR_PTR(-EINVAL);

  /*

   * length bytes should not extend into the next table - this check

   * also traps instances where id_table_start is incorrectly larger

   * than the next table start

   */

  if (id_table_start + length > next_table)

    return ERR_PTR(-EINVAL);

  table = squashfs_read_table(sb, id_table_start, length);

  /*

   * table[0] points to the first id lookup table metadata block, this

   * should be less than id_table_start

   */

  if (!IS_ERR(table) && le64_to_cpu(table[0]) >= id_table_start) {

    kfree(table);

    return ERR_PTR(-EINVAL);

  }

  return table;

}