fs/squashfs/xz_wrapper.c

   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 #include "page_actor.h"
  36
  37 struct squashfs_xz {
  38         struct xz_dec *state;
  39         struct xz_buf buf;
  40 };
  41
  42 struct disk_comp_opts {
  43         __le32 dictionary_size;
  44         __le32 flags;
  45 };
  46
  47 struct comp_opts {
  48         int dict_size;
  49 };
  50
  51 static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
  52         void *buff, int len)
  53 {
  54         struct disk_comp_opts *comp_opts = buff;
  55         struct comp_opts *opts;
  56         int err = 0, n;
  57
  58         opts = kmalloc(sizeof(*opts), GFP_KERNEL);
  59         if (opts == NULL) {
  60                 err = -ENOMEM;
  61                 goto out2;
  62         }
  63
  64         if (comp_opts) {
  65                 /* check compressor options are the expected length */
  66                 if (len < sizeof(*comp_opts)) {
  67                         err = -EIO;
  68                         goto out;
  69                 }
  70
  71                 opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
  72
  73                 /* the dictionary size should be 2^n or 2^n+2^(n+1) */
  74                 n = ffs(opts->dict_size) - 1;
  75                 if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
  76                                                 (1 << (n + 1))) {
  77                         err = -EIO;
  78                         goto out;
  79                 }
  80         } else
  81                 /* use defaults */
  82                 opts->dict_size = max_t(int, msblk->block_size,
  83                                                         SQUASHFS_METADATA_SIZE);
  84
  85         return opts;
  86
  87 out:
  88         kfree(opts);
  89 out2:
  90         return ERR_PTR(err);
  91 }
  92
  93
  94 static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff)
  95 {
  96         struct comp_opts *comp_opts = buff;
  97         struct squashfs_xz *stream;
  98         int err;
  99
 100         stream = kmalloc(sizeof(*stream), GFP_KERNEL);
 101         if (stream == NULL) {
 102                 err = -ENOMEM;
 103                 goto failed;
 104         }
 105
 106         stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size);
 107         if (stream->state == NULL) {
 108                 kfree(stream);
 109                 err = -ENOMEM;
 110                 goto failed;
 111         }
 112
 113         return stream;
 114
 115 failed:
 116         ERROR("Failed to initialise xz decompressor\n");
 117         return ERR_PTR(err);
 118 }
 119
 120
 121 static void squashfs_xz_free(void *strm)
 122 {
 123         struct squashfs_xz *stream = strm;
 124
 125         if (stream) {
 126                 xz_dec_end(stream->state);
 127                 kfree(stream);
 128         }
 129 }
 130
 131
 132 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
 133         struct buffer_head **bh, int b, int offset, int length,
 134         struct squashfs_page_actor *output)
 135 {
 136         enum xz_ret xz_err;
 137         int avail, total = 0, k = 0;
 138         struct squashfs_xz *stream = strm;
 139
 140         xz_dec_reset(stream->state);
 141         stream->buf.in_pos = 0;
 142         stream->buf.in_size = 0;
 143         stream->buf.out_pos = 0;
 144         stream->buf.out_size = PAGE_CACHE_SIZE;
 145         stream->buf.out = squashfs_first_page(output);
 146
 147         do {
 148                 if (stream->buf.in_pos == stream->buf.in_size && k < b) {
 149                         avail = min(length, msblk->devblksize - offset);
 150                         length -= avail;
 151                         stream->buf.in = bh[k]->b_data + offset;
 152                         stream->buf.in_size = avail;
 153                         stream->buf.in_pos = 0;
 154                         offset = 0;
 155                 }
 156
 157                 if (stream->buf.out_pos == stream->buf.out_size) {
 158                         stream->buf.out = squashfs_next_page(output);
 159                         if (stream->buf.out != NULL) {
 160                                 stream->buf.out_pos = 0;
 161                                 total += PAGE_CACHE_SIZE;
 162                         }
 163                 }
 164
 165                 xz_err = xz_dec_run(stream->state, &stream->buf);
 166
 167                 if (stream->buf.in_pos == stream->buf.in_size && k < b)
 168                         put_bh(bh[k++]);
 169         } while (xz_err == XZ_OK);
 170
 171         squashfs_finish_page(output);
 172
 173         if (xz_err != XZ_STREAM_END || k < b)
 174                 goto out;
 175
 176         return total + stream->buf.out_pos;
 177
 178 out:
 179         for (; k < b; k++)
 180                 put_bh(bh[k]);
 181
 182         return -EIO;
 183 }
 184
 185 const struct squashfs_decompressor squashfs_xz_comp_ops = {
 186         .init = squashfs_xz_init,
 187         .comp_opts = squashfs_xz_comp_opts,
 188         .free = squashfs_xz_free,
 189         .decompress = squashfs_xz_uncompress,
 190         .id = XZ_COMPRESSION,
 191         .name = "xz",
 192         .supported = 1
 193 };