fs/squashfs/xattr_id.c

   1 /*
   2  * Squashfs - a compressed read only filesystem for Linux
   3  *
   4  * Copyright (c) 2010
   5  * Phillip Lougher <phillip@lougher.demon.co.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_fs_i.h"
  36 #include "squashfs.h"
  37 #include "xattr.h"
  38
  39 /*
  40  * Map xattr id using the xattr id look up table
  41  */
  42 int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
  43                 int *count, unsigned int *size, unsigned long long *xattr)
  44 {
  45         struct squashfs_sb_info *msblk = sb->s_fs_info;
  46         int block = SQUASHFS_XATTR_BLOCK(index);
  47         int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
  48         u64 start_block = le64_to_cpu(msblk->xattr_id_table[block]);
  49         struct squashfs_xattr_id id;
  50         int err;
  51
  52         err = squashfs_read_metadata(sb, &id, &start_block, &offset,
  53                                                         sizeof(id));
  54         if (err < 0)
  55                 return err;
  56
  57         *xattr = le64_to_cpu(id.xattr);
  58         *size = le32_to_cpu(id.size);
  59         *count = le32_to_cpu(id.count);
  60         return 0;
  61 }
  62
  63
  64 /*
  65  * Read uncompressed xattr id lookup table indexes from disk into memory
  66  */
  67 __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
  68                 u64 *xattr_table_start, int *xattr_ids)
  69 {
  70         unsigned int len;
  71         __le64 *xid_table;
  72         struct squashfs_xattr_id_table id_table;
  73         int err;
  74
  75         err = squashfs_read_table(sb, &id_table, start, sizeof(id_table));
  76         if (err < 0) {
  77                 ERROR("unable to read xattr id table\n");
  78                 return ERR_PTR(err);
  79         }
  80         *xattr_table_start = le64_to_cpu(id_table.xattr_table_start);
  81         *xattr_ids = le32_to_cpu(id_table.xattr_ids);
  82         len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
  83
  84         TRACE("In read_xattr_index_table, length %d\n", len);
  85
  86         /* Allocate xattr id lookup table indexes */
  87         xid_table = kmalloc(len, GFP_KERNEL);
  88         if (xid_table == NULL) {
  89                 ERROR("Failed to allocate xattr id index table\n");
  90                 return ERR_PTR(-ENOMEM);
  91         }
  92
  93         err = squashfs_read_table(sb, xid_table, start + sizeof(id_table), len);
  94         if (err < 0) {
  95                 ERROR("unable to read xattr id index table\n");
  96                 kfree(xid_table);
  97                 return ERR_PTR(err);
  98         }
  99
 100         return xid_table;
 101 }