fs/squashfs/xz_wrapper.c

   1 /*
   2  * Squashfs - a compressed read only filesystem for Linux
   3  *
   4  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 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  * xz_wrapper.c
  22  */
  23
  24
  25 #include <linux/mutex.h>
  26 #include <linux/buffer_head.h>
  27 #include <linux/slab.h>
  28 #include <linux/xz.h>
  29
  30 #include "squashfs_fs.h"
  31 #include "squashfs_fs_sb.h"
  32 #include "squashfs_fs_i.h"
  33 #include "squashfs.h"
  34 #include "decompressor.h"
  35
  36 struct squashfs_xz {
  37         struct xz_dec *state;
  38         struct xz_buf buf;
  39 };
  40
  41 static void *squashfs_xz_init(struct squashfs_sb_info *msblk)
  42 {
  43         int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
  44
  45         struct squashfs_xz *stream = kmalloc(sizeof(*stream), GFP_KERNEL);
  46         if (stream == NULL)
  47                 goto failed;
  48
  49         stream->state = xz_dec_init(XZ_PREALLOC, block_size);
  50         if (stream->state == NULL)
  51                 goto failed;
  52
  53         return stream;
  54
  55 failed:
  56         ERROR("Failed to allocate xz workspace\n");
  57         kfree(stream);
  58         return NULL;
  59 }
  60
  61
  62 static void squashfs_xz_free(void *strm)
  63 {
  64         struct squashfs_xz *stream = strm;
  65
  66         if (stream) {
  67                 xz_dec_end(stream->state);
  68                 kfree(stream);
  69         }
  70 }
  71
  72
  73 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
  74         struct buffer_head **bh, int b, int offset, int length, int srclength,
  75         int pages)
  76 {
  77         enum xz_ret xz_err;
  78         int avail, total = 0, k = 0, page = 0;
  79         struct squashfs_xz *stream = msblk->stream;
  80
  81         mutex_lock(&msblk->read_data_mutex);
  82
  83         xz_dec_reset(stream->state);
  84         stream->buf.in_pos = 0;
  85         stream->buf.in_size = 0;
  86         stream->buf.out_pos = 0;
  87         stream->buf.out_size = PAGE_CACHE_SIZE;
  88         stream->buf.out = buffer[page++];
  89
  90         do {
  91                 if (stream->buf.in_pos == stream->buf.in_size && k < b) {
  92                         avail = min(length, msblk->devblksize - offset);
  93                         length -= avail;
  94                         wait_on_buffer(bh[k]);
  95                         if (!buffer_uptodate(bh[k]))
  96                                 goto release_mutex;
  97
  98                         stream->buf.in = bh[k]->b_data + offset;
  99                         stream->buf.in_size = avail;
 100                         stream->buf.in_pos = 0;
 101                         offset = 0;
 102                 }
 103
 104                 if (stream->buf.out_pos == stream->buf.out_size
 105                                                         && page < pages) {
 106                         stream->buf.out = buffer[page++];
 107                         stream->buf.out_pos = 0;
 108                         total += PAGE_CACHE_SIZE;
 109                 }
 110
 111                 xz_err = xz_dec_run(stream->state, &stream->buf);
 112
 113                 if (stream->buf.in_pos == stream->buf.in_size && k < b)
 114                         put_bh(bh[k++]);
 115         } while (xz_err == XZ_OK);
 116
 117         if (xz_err != XZ_STREAM_END) {
 118                 ERROR("xz_dec_run error, data probably corrupt\n");
 119                 goto release_mutex;
 120         }
 121
 122         if (k < b) {
 123                 ERROR("xz_uncompress error, input remaining\n");
 124                 goto release_mutex;
 125         }
 126
 127         total += stream->buf.out_pos;
 128         mutex_unlock(&msblk->read_data_mutex);
 129         return total;
 130
 131 release_mutex:
 132         mutex_unlock(&msblk->read_data_mutex);
 133
 134         for (; k < b; k++)
 135                 put_bh(bh[k]);
 136
 137         return -EIO;
 138 }
 139
 140 const struct squashfs_decompressor squashfs_xz_comp_ops = {
 141         .init = squashfs_xz_init,
 142         .free = squashfs_xz_free,
 143         .decompress = squashfs_xz_uncompress,
 144         .id = XZ_COMPRESSION,
 145         .name = "xz",
 146         .supported = 1
 147 };