linux/fs/squashfs/xz_wrapper.c
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   1/*
   2 * Squashfs - a compressed read only filesystem for Linux
   3 *
   4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   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 * xz_wrapper.c
  22 */
  23
  24
  25#include <linux/mutex.h>
  26#include <linux/buffer_head.h>
  27#include <linux/slab.h>
  28#include <linux/xz.h>
  29#include <linux/bitops.h>
  30
  31#include "squashfs_fs.h"
  32#include "squashfs_fs_sb.h"
  33#include "squashfs.h"
  34#include "decompressor.h"
  35
  36struct squashfs_xz {
  37        struct xz_dec *state;
  38        struct xz_buf buf;
  39};
  40
  41struct comp_opts {
  42        __le32 dictionary_size;
  43        __le32 flags;
  44};
  45
  46static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
  47        int len)
  48{
  49        struct comp_opts *comp_opts = buff;
  50        struct squashfs_xz *stream;
  51        int dict_size = msblk->block_size;
  52        int err, n;
  53
  54        if (comp_opts) {
  55                /* check compressor options are the expected length */
  56                if (len < sizeof(*comp_opts)) {
  57                        err = -EIO;
  58                        goto failed;
  59                }
  60
  61                dict_size = le32_to_cpu(comp_opts->dictionary_size);
  62
  63                /* the dictionary size should be 2^n or 2^n+2^(n+1) */
  64                n = ffs(dict_size) - 1;
  65                if (dict_size != (1 << n) && dict_size != (1 << n) +
  66                                                (1 << (n + 1))) {
  67                        err = -EIO;
  68                        goto failed;
  69                }
  70        }
  71
  72        dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);
  73
  74        stream = kmalloc(sizeof(*stream), GFP_KERNEL);
  75        if (stream == NULL) {
  76                err = -ENOMEM;
  77                goto failed;
  78        }
  79
  80        stream->state = xz_dec_init(XZ_PREALLOC, dict_size);
  81        if (stream->state == NULL) {
  82                kfree(stream);
  83                err = -ENOMEM;
  84                goto failed;
  85        }
  86
  87        return stream;
  88
  89failed:
  90        ERROR("Failed to initialise xz decompressor\n");
  91        return ERR_PTR(err);
  92}
  93
  94
  95static void squashfs_xz_free(void *strm)
  96{
  97        struct squashfs_xz *stream = strm;
  98
  99        if (stream) {
 100                xz_dec_end(stream->state);
 101                kfree(stream);
 102        }
 103}
 104
 105
 106static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 107        struct buffer_head **bh, int b, int offset, int length, int srclength,
 108        int pages)
 109{
 110        enum xz_ret xz_err;
 111        int avail, total = 0, k = 0, page = 0;
 112        struct squashfs_xz *stream = msblk->stream;
 113
 114        mutex_lock(&msblk->read_data_mutex);
 115
 116        xz_dec_reset(stream->state);
 117        stream->buf.in_pos = 0;
 118        stream->buf.in_size = 0;
 119        stream->buf.out_pos = 0;
 120        stream->buf.out_size = PAGE_CACHE_SIZE;
 121        stream->buf.out = buffer[page++];
 122
 123        do {
 124                if (stream->buf.in_pos == stream->buf.in_size && k < b) {
 125                        avail = min(length, msblk->devblksize - offset);
 126                        length -= avail;
 127                        wait_on_buffer(bh[k]);
 128                        if (!buffer_uptodate(bh[k]))
 129                                goto release_mutex;
 130
 131                        stream->buf.in = bh[k]->b_data + offset;
 132                        stream->buf.in_size = avail;
 133                        stream->buf.in_pos = 0;
 134                        offset = 0;
 135                }
 136
 137                if (stream->buf.out_pos == stream->buf.out_size
 138                                                        && page < pages) {
 139                        stream->buf.out = buffer[page++];
 140                        stream->buf.out_pos = 0;
 141                        total += PAGE_CACHE_SIZE;
 142                }
 143
 144                xz_err = xz_dec_run(stream->state, &stream->buf);
 145
 146                if (stream->buf.in_pos == stream->buf.in_size && k < b)
 147                        put_bh(bh[k++]);
 148        } while (xz_err == XZ_OK);
 149
 150        if (xz_err != XZ_STREAM_END) {
 151                ERROR("xz_dec_run error, data probably corrupt\n");
 152                goto release_mutex;
 153        }
 154
 155        if (k < b) {
 156                ERROR("xz_uncompress error, input remaining\n");
 157                goto release_mutex;
 158        }
 159
 160        total += stream->buf.out_pos;
 161        mutex_unlock(&msblk->read_data_mutex);
 162        return total;
 163
 164release_mutex:
 165        mutex_unlock(&msblk->read_data_mutex);
 166
 167        for (; k < b; k++)
 168                put_bh(bh[k]);
 169
 170        return -EIO;
 171}
 172
 173const struct squashfs_decompressor squashfs_xz_comp_ops = {
 174        .init = squashfs_xz_init,
 175        .free = squashfs_xz_free,
 176        .decompress = squashfs_xz_uncompress,
 177        .id = XZ_COMPRESSION,
 178        .name = "xz",
 179        .supported = 1
 180};
 181
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