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@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  * 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 #include <linux/bitops.h>
  30
  31 #include "squashfs_fs.h"
  32 #include "squashfs_fs_sb.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 struct comp_opts {
  42         __le32 dictionary_size;
  43         __le32 flags;
  44 };
  45
  46 static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
  47         int len)
  48 {
  49         struct comp_opts *comp_opts = buff;
  50         struct squashfs_xz *stream;
  51         int dict_size = msblk->block_size;
  52         int err, n;
  53
  54         if (comp_opts) {
  55                 /* check compressor options are the expected length */
  56                 if (len < sizeof(*comp_opts)) {
  57                         err = -EIO;
  58                         goto failed;
  59                 }
  60
  61                 dict_size = le32_to_cpu(comp_opts->dictionary_size);
  62
  63                 /* the dictionary size should be 2^n or 2^n+2^(n+1) */
  64                 n = ffs(dict_size) - 1;
  65                 if (dict_size != (1 << n) && dict_size != (1 << n) +
  66                                                 (1 << (n + 1))) {
  67                         err = -EIO;
  68                         goto failed;
  69                 }
  70         }
  71
  72         dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);
  73
  74         stream = kmalloc(sizeof(*stream), GFP_KERNEL);
  75         if (stream == NULL) {
  76                 err = -ENOMEM;
  77                 goto failed;
  78         }
  79
  80         stream->state = xz_dec_init(XZ_PREALLOC, dict_size);
  81         if (stream->state == NULL) {
  82                 kfree(stream);
  83                 err = -ENOMEM;
  84                 goto failed;
  85         }
  86
  87         return stream;
  88
  89 failed:
  90         ERROR("Failed to initialise xz decompressor\n");
  91         return ERR_PTR(err);
  92 }
  93
  94
  95 static void squashfs_xz_free(void *strm)
  96 {
  97         struct squashfs_xz *stream = strm;
  98
  99         if (stream) {
 100                 xz_dec_end(stream->state);
 101                 kfree(stream);
 102         }
 103 }
 104
 105
 106 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 107         struct buffer_head **bh, int b, int offset, int length, int srclength,
 108         int pages)
 109 {
 110         enum xz_ret xz_err;
 111         int avail, total = 0, k = 0, page = 0;
 112         struct squashfs_xz *stream = msblk->stream;
 113
 114         mutex_lock(&msblk->read_data_mutex);
 115
 116         xz_dec_reset(stream->state);
 117         stream->buf.in_pos = 0;
 118         stream->buf.in_size = 0;
 119         stream->buf.out_pos = 0;
 120         stream->buf.out_size = PAGE_CACHE_SIZE;
 121         stream->buf.out = buffer[page++];
 122
 123         do {
 124                 if (stream->buf.in_pos == stream->buf.in_size && k < b) {
 125                         avail = min(length, msblk->devblksize - offset);
 126                         length -= avail;
 127                         wait_on_buffer(bh[k]);
 128                         if (!buffer_uptodate(bh[k]))
 129                                 goto release_mutex;
 130
 131                         stream->buf.in = bh[k]->b_data + offset;
 132                         stream->buf.in_size = avail;
 133                         stream->buf.in_pos = 0;
 134                         offset = 0;
 135                 }
 136
 137                 if (stream->buf.out_pos == stream->buf.out_size
 138                                                         && page < pages) {
 139                         stream->buf.out = buffer[page++];
 140                         stream->buf.out_pos = 0;
 141                         total += PAGE_CACHE_SIZE;
 142                 }
 143
 144                 xz_err = xz_dec_run(stream->state, &stream->buf);
 145
 146                 if (stream->buf.in_pos == stream->buf.in_size && k < b)
 147                         put_bh(bh[k++]);
 148         } while (xz_err == XZ_OK);
 149
 150         if (xz_err != XZ_STREAM_END) {
 151                 ERROR("xz_dec_run error, data probably corrupt\n");
 152                 goto release_mutex;
 153         }
 154
 155         if (k < b) {
 156                 ERROR("xz_uncompress error, input remaining\n");
 157                 goto release_mutex;
 158         }
 159
 160         total += stream->buf.out_pos;
 161         mutex_unlock(&msblk->read_data_mutex);
 162         return total;
 163
 164 release_mutex:
 165         mutex_unlock(&msblk->read_data_mutex);
 166
 167         for (; k < b; k++)
 168                 put_bh(bh[k]);
 169
 170         return -EIO;
 171 }
 172
 173 const struct squashfs_decompressor squashfs_xz_comp_ops = {
 174         .init = squashfs_xz_init,
 175         .free = squashfs_xz_free,
 176         .decompress = squashfs_xz_uncompress,
 177         .id = XZ_COMPRESSION,
 178         .name = "xz",
 179         .supported = 1
 180 };