// 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 <phillip@squashfs.org.uk>

   *

   * 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.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
  ", 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;

  }