LXR linux/fs/squashfs/zlib

   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
  37static 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
  48failed:
  49        ERROR("Failed to allocate zlib workspace\n");
  50        kfree(stream);
  51        return ERR_PTR(-ENOMEM);
  52}
  53
  54
  55static 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
  65static 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
 120out:
 121        for (; k < b; k++)
 122                put_bh(bh[k]);
 123
 124        return -EIO;
 125}
 126
 127const 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
 136