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@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  * 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 #include <linux/vmalloc.h>
  30
  31 #include "squashfs_fs.h"
  32 #include "squashfs_fs_sb.h"
  33 #include "squashfs.h"
  34 #include "decompressor.h"
  35 #include "page_actor.h"
  36
  37 static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
  38 {
  39         z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
  40         if (stream == NULL)
  41                 goto failed;
  42         stream->workspace = vmalloc(zlib_inflate_workspacesize());
  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 ERR_PTR(-ENOMEM);
  52 }
  53
  54
  55 static void zlib_free(void *strm)
  56 {
  57         z_stream *stream = strm;
  58
  59         if (stream)
  60                 vfree(stream->workspace);
  61         kfree(stream);
  62 }
  63
  64
  65 static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
  66         struct buffer_head **bh, int b, int offset, int length,
  67         struct squashfs_page_actor *output)
  68 {
  69         int zlib_err, zlib_init = 0, k = 0;
  70         z_stream *stream = strm;
  71
  72         stream->avail_out = PAGE_CACHE_SIZE;
  73         stream->next_out = squashfs_first_page(output);
  74         stream->avail_in = 0;
  75
  76         do {
  77                 if (stream->avail_in == 0 && k < b) {
  78                         int avail = min(length, msblk->devblksize - offset);
  79                         length -= avail;
  80                         stream->next_in = bh[k]->b_data + offset;
  81                         stream->avail_in = avail;
  82                         offset = 0;
  83                 }
  84
  85                 if (stream->avail_out == 0) {
  86                         stream->next_out = squashfs_next_page(output);
  87                         if (stream->next_out != NULL)
  88                                 stream->avail_out = PAGE_CACHE_SIZE;
  89                 }
  90
  91                 if (!zlib_init) {
  92                         zlib_err = zlib_inflateInit(stream);
  93                         if (zlib_err != Z_OK) {
  94                                 squashfs_finish_page(output);
  95                                 goto out;
  96                         }
  97                         zlib_init = 1;
  98                 }
  99
 100                 zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
 101
 102                 if (stream->avail_in == 0 && k < b)
 103                         put_bh(bh[k++]);
 104         } while (zlib_err == Z_OK);
 105
 106         squashfs_finish_page(output);
 107
 108         if (zlib_err != Z_STREAM_END)
 109                 goto out;
 110
 111         zlib_err = zlib_inflateEnd(stream);
 112         if (zlib_err != Z_OK)
 113                 goto out;
 114
 115         if (k < b)
 116                 goto out;
 117
 118         return stream->total_out;
 119
 120 out:
 121         for (; k < b; k++)
 122                 put_bh(bh[k]);
 123
 124         return -EIO;
 125 }
 126
 127 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 128         .init = zlib_init,
 129         .free = zlib_free,
 130         .decompress = zlib_uncompress,
 131         .id = ZLIB_COMPRESSION,
 132         .name = "zlib",
 133         .supported = 1
 134 };
 135