fs/squashfs/xattr_id.c

   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  */
  41 int 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 }