fs/squashfs/zlib_wrapper.c

   1 /*
   2  * Squashfs - a compressed read only filesystem for Linux
   3  *
   4  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   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  * zlib_wrapper.c
  22  */
  23
  24
  25 #include <linux/mutex.h>
  26 #include <linux/buffer_head.h>
  27 #include <linux/slab.h>
  28 #include <linux/zlib.h>
  29
  30 #include "squashfs_fs.h"
  31 #include "squashfs_fs_sb.h"
  32 #include "squashfs.h"
  33 #include "decompressor.h"
  34
  35 static void *zlib_init(struct squashfs_sb_info *dummy)
  36 {
  37         z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
  38         if (stream == NULL)
  39                 goto failed;
  40         stream->workspace = kmalloc(zlib_inflate_workspacesize(),
  41                 GFP_KERNEL);
  42         if (stream->workspace == NULL)
  43                 goto failed;
  44
  45         return stream;
  46
  47 failed:
  48         ERROR("Failed to allocate zlib workspace\n");
  49         kfree(stream);
  50         return NULL;
  51 }
  52
  53
  54 static void zlib_free(void *strm)
  55 {
  56         z_stream *stream = strm;
  57
  58         if (stream)
  59                 kfree(stream->workspace);
  60         kfree(stream);
  61 }
  62
  63
  64 static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
  65         struct buffer_head **bh, int b, int offset, int length, int srclength,
  66         int pages)
  67 {
  68         int zlib_err, zlib_init = 0;
  69         int k = 0, page = 0;
  70         z_stream *stream = msblk->stream;
  71
  72         mutex_lock(&msblk->read_data_mutex);
  73
  74         stream->avail_out = 0;
  75         stream->avail_in = 0;
  76
  77         do {
  78                 if (stream->avail_in == 0 && k < b) {
  79                         int avail = min(length, msblk->devblksize - offset);
  80                         length -= avail;
  81                         wait_on_buffer(bh[k]);
  82                         if (!buffer_uptodate(bh[k]))
  83                                 goto release_mutex;
  84
  85                         stream->next_in = bh[k]->b_data + offset;
  86                         stream->avail_in = avail;
  87                         offset = 0;
  88                 }
  89
  90                 if (stream->avail_out == 0 && page < pages) {
  91                         stream->next_out = buffer[page++];
  92                         stream->avail_out = PAGE_CACHE_SIZE;
  93                 }
  94
  95                 if (!zlib_init) {
  96                         zlib_err = zlib_inflateInit(stream);
  97                         if (zlib_err != Z_OK) {
  98                                 ERROR("zlib_inflateInit returned unexpected "
  99                                         "result 0x%x, srclength %d\n",
 100                                         zlib_err, srclength);
 101                                 goto release_mutex;
 102                         }
 103                         zlib_init = 1;
 104                 }
 105
 106                 zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
 107
 108                 if (stream->avail_in == 0 && k < b)
 109                         put_bh(bh[k++]);
 110         } while (zlib_err == Z_OK);
 111
 112         if (zlib_err != Z_STREAM_END) {
 113                 ERROR("zlib_inflate error, data probably corrupt\n");
 114                 goto release_mutex;
 115         }
 116
 117         zlib_err = zlib_inflateEnd(stream);
 118         if (zlib_err != Z_OK) {
 119                 ERROR("zlib_inflate error, data probably corrupt\n");
 120                 goto release_mutex;
 121         }
 122
 123         if (k < b) {
 124                 ERROR("zlib_uncompress error, data remaining\n");
 125                 goto release_mutex;
 126         }
 127
 128         length = stream->total_out;
 129         mutex_unlock(&msblk->read_data_mutex);
 130         return length;
 131
 132 release_mutex:
 133         mutex_unlock(&msblk->read_data_mutex);
 134
 135         for (; k < b; k++)
 136                 put_bh(bh[k]);
 137
 138         return -EIO;
 139 }
 140
 141 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 142         .init = zlib_init,
 143         .free = zlib_free,
 144         .decompress = zlib_uncompress,
 145         .id = ZLIB_COMPRESSION,
 146         .name = "zlib",
 147         .supported = 1
 148 };
 149