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/zlib.h>
  28
  29 #include "squashfs_fs.h"
  30 #include "squashfs_fs_sb.h"
  31 #include "squashfs_fs_i.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 = 0, zlib_init = 0;
  69         int avail, bytes, 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         bytes = length;
  78         do {
  79                 if (stream->avail_in == 0 && k < b) {
  80                         avail = min(bytes, msblk->devblksize - offset);
  81                         bytes -= avail;
  82                         wait_on_buffer(bh[k]);
  83                         if (!buffer_uptodate(bh[k]))
  84                                 goto release_mutex;
  85
  86                         if (avail == 0) {
  87                                 offset = 0;
  88                                 put_bh(bh[k++]);
  89                                 continue;
  90                         }
  91
  92                         stream->next_in = bh[k]->b_data + offset;
  93                         stream->avail_in = avail;
  94                         offset = 0;
  95                 }
  96
  97                 if (stream->avail_out == 0 && page < pages) {
  98                         stream->next_out = buffer[page++];
  99                         stream->avail_out = PAGE_CACHE_SIZE;
 100                 }
 101
 102                 if (!zlib_init) {
 103                         zlib_err = zlib_inflateInit(stream);
 104                         if (zlib_err != Z_OK) {
 105                                 ERROR("zlib_inflateInit returned unexpected "
 106                                         "result 0x%x, srclength %d\n",
 107                                         zlib_err, srclength);
 108                                 goto release_mutex;
 109                         }
 110                         zlib_init = 1;
 111                 }
 112
 113                 zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
 114
 115                 if (stream->avail_in == 0 && k < b)
 116                         put_bh(bh[k++]);
 117         } while (zlib_err == Z_OK);
 118
 119         if (zlib_err != Z_STREAM_END) {
 120                 ERROR("zlib_inflate error, data probably corrupt\n");
 121                 goto release_mutex;
 122         }
 123
 124         zlib_err = zlib_inflateEnd(stream);
 125         if (zlib_err != Z_OK) {
 126                 ERROR("zlib_inflate error, data probably corrupt\n");
 127                 goto release_mutex;
 128         }
 129
 130         mutex_unlock(&msblk->read_data_mutex);
 131         return stream->total_out;
 132
 133 release_mutex:
 134         mutex_unlock(&msblk->read_data_mutex);
 135
 136         for (; k < b; k++)
 137                 put_bh(bh[k]);
 138
 139         return -EIO;
 140 }
 141
 142 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 143         .init = zlib_init,
 144         .free = zlib_free,
 145         .decompress = zlib_uncompress,
 146         .id = ZLIB_COMPRESSION,
 147         .name = "zlib",
 148         .supported = 1
 149 };
 150