linux/fs/squashfs/xattr_id.c
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   1/*
   2 * Squashfs - a compressed read only filesystem for Linux
   3 *
   4 * Copyright (c) 2010
   5 * Phillip Lougher <phillip@squashfs.org.uk>
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; either version 2,
  10 * or (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20 *
  21 * xattr_id.c
  22 */
  23
  24/*
  25 * This file implements code to map the 32-bit xattr id stored in the inode
  26 * into the on disk location of the xattr data.
  27 */
  28
  29#include <linux/fs.h>
  30#include <linux/vfs.h>
  31#include <linux/slab.h>
  32
  33#include "squashfs_fs.h"
  34#include "squashfs_fs_sb.h"
  35#include "squashfs.h"
  36#include "xattr.h"
  37
  38/*
  39 * Map xattr id using the xattr id look up table
  40 */
  41int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
  42                int *count, unsigned int *size, unsigned long long *xattr)
  43{
  44        struct squashfs_sb_info *msblk = sb->s_fs_info;
  45        int block = SQUASHFS_XATTR_BLOCK(index);
  46        int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
  47        u64 start_block = le64_to_cpu(msblk->xattr_id_table[block]);
  48        struct squashfs_xattr_id id;
  49        int err;
  50
  51        err = squashfs_read_metadata(sb, &id, &start_block, &offset,
  52                                                        sizeof(id));
  53        if (err < 0)
  54                return err;
  55
  56        *xattr = le64_to_cpu(id.xattr);
  57        *size = le32_to_cpu(id.size);
  58        *count = le32_to_cpu(id.count);
  59        return 0;
  60}
  61
  62
  63/*
  64 * Read uncompressed xattr id lookup table indexes from disk into memory
  65 */
  66__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
  67                u64 *xattr_table_start, int *xattr_ids)
  68{
  69        unsigned int len;
  70        struct squashfs_xattr_id_table *id_table;
  71
  72        id_table = squashfs_read_table(sb, start, sizeof(*id_table));
  73        if (IS_ERR(id_table))
  74                return (__le64 *) id_table;
  75
  76        *xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
  77        *xattr_ids = le32_to_cpu(id_table->xattr_ids);
  78        kfree(id_table);
  79
  80        /* Sanity check values */
  81
  82        /* there is always at least one xattr id */
  83        if (*xattr_ids == 0)
  84                return ERR_PTR(-EINVAL);
  85
  86        /* xattr_table should be less than start */
  87        if (*xattr_table_start >= start)
  88                return ERR_PTR(-EINVAL);
  89
  90        len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
  91
  92        TRACE("In read_xattr_index_table, length %d\n", len);
  93
  94        return squashfs_read_table(sb, start + sizeof(*id_table), len);
  95}
  96
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