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_fs_i.h"
  33 #include "squashfs.h"
  34 #include "decompressor.h"
  35
  36 static void *zlib_init(struct squashfs_sb_info *dummy)
  37 {
  38         z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
  39         if (stream == NULL)
  40                 goto failed;
  41         stream->workspace = kmalloc(zlib_inflate_workspacesize(),
  42                 GFP_KERNEL);
  43         if (stream->workspace == NULL)
  44                 goto failed;
  45
  46         return stream;
  47
  48 failed:
  49         ERROR("Failed to allocate zlib workspace\n");
  50         kfree(stream);
  51         return NULL;
  52 }
  53
  54
  55 static void zlib_free(void *strm)
  56 {
  57         z_stream *stream = strm;
  58
  59         if (stream)
  60                 kfree(stream->workspace);
  61         kfree(stream);
  62 }
  63
  64
  65 static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
  66         struct buffer_head **bh, int b, int offset, int length, int srclength,
  67         int pages)
  68 {
  69         int zlib_err = 0, zlib_init = 0;
  70         int avail, bytes, k = 0, page = 0;
  71         z_stream *stream = msblk->stream;
  72
  73         mutex_lock(&msblk->read_data_mutex);
  74
  75         stream->avail_out = 0;
  76         stream->avail_in = 0;
  77
  78         bytes = length;
  79         do {
  80                 if (stream->avail_in == 0 && k < b) {
  81                         avail = min(bytes, msblk->devblksize - offset);
  82                         bytes -= avail;
  83                         wait_on_buffer(bh[k]);
  84                         if (!buffer_uptodate(bh[k]))
  85                                 goto release_mutex;
  86
  87                         if (avail == 0) {
  88                                 offset = 0;
  89                                 put_bh(bh[k++]);
  90                                 continue;
  91                         }
  92
  93                         stream->next_in = bh[k]->b_data + offset;
  94                         stream->avail_in = avail;
  95                         offset = 0;
  96                 }
  97
  98                 if (stream->avail_out == 0 && page < pages) {
  99                         stream->next_out = buffer[page++];
 100                         stream->avail_out = PAGE_CACHE_SIZE;
 101                 }
 102
 103                 if (!zlib_init) {
 104                         zlib_err = zlib_inflateInit(stream);
 105                         if (zlib_err != Z_OK) {
 106                                 ERROR("zlib_inflateInit returned unexpected "
 107                                         "result 0x%x, srclength %d\n",
 108                                         zlib_err, srclength);
 109                                 goto release_mutex;
 110                         }
 111                         zlib_init = 1;
 112                 }
 113
 114                 zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
 115
 116                 if (stream->avail_in == 0 && k < b)
 117                         put_bh(bh[k++]);
 118         } while (zlib_err == Z_OK);
 119
 120         if (zlib_err != Z_STREAM_END) {
 121                 ERROR("zlib_inflate error, data probably corrupt\n");
 122                 goto release_mutex;
 123         }
 124
 125         zlib_err = zlib_inflateEnd(stream);
 126         if (zlib_err != Z_OK) {
 127                 ERROR("zlib_inflate error, data probably corrupt\n");
 128                 goto release_mutex;
 129         }
 130
 131         length = stream->total_out;
 132         mutex_unlock(&msblk->read_data_mutex);
 133         return length;
 134
 135 release_mutex:
 136         mutex_unlock(&msblk->read_data_mutex);
 137
 138         for (; k < b; k++)
 139                 put_bh(bh[k]);
 140
 141         return -EIO;
 142 }
 143
 144 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 145         .init = zlib_init,
 146         .free = zlib_free,
 147         .decompress = zlib_uncompress,
 148         .id = ZLIB_COMPRESSION,
 149         .name = "zlib",
 150         .supported = 1
 151 };
 152