fs/squashfs/lzma_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  * lzma_wrapper.c
  22  */
  23
  24 #include <asm/unaligned.h>
  25 #include <linux/buffer_head.h>
  26 #include <linux/mutex.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/decompress/unlzma.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 struct squashfs_lzma {
  37         void    *input;
  38         void    *output;
  39 };
  40
  41 /* decompress_unlzma.c is currently non re-entrant... */
  42 DEFINE_MUTEX(lzma_mutex);
  43
  44 /* decompress_unlzma.c doesn't provide any context in its callbacks... */
  45 static int lzma_error;
  46
  47 static void error(char *m)
  48 {
  49         ERROR("unlzma error: %s\n", m);
  50         lzma_error = 1;
  51 }
  52
  53
  54 static void *lzma_init(struct squashfs_sb_info *msblk)
  55 {
  56         struct squashfs_lzma *stream = kzalloc(sizeof(*stream), GFP_KERNEL);
  57         if (stream == NULL)
  58                 goto failed;
  59         stream->input = vmalloc(msblk->block_size);
  60         if (stream->input == NULL)
  61                 goto failed;
  62         stream->output = vmalloc(msblk->block_size);
  63         if (stream->output == NULL)
  64                 goto failed2;
  65
  66         return stream;
  67
  68 failed2:
  69         vfree(stream->input);
  70 failed:
  71         ERROR("failed to allocate lzma workspace\n");
  72         kfree(stream);
  73         return NULL;
  74 }
  75
  76
  77 static void lzma_free(void *strm)
  78 {
  79         struct squashfs_lzma *stream = strm;
  80
  81         if (stream) {
  82                 vfree(stream->input);
  83                 vfree(stream->output);
  84         }
  85         kfree(stream);
  86 }
  87
  88
  89 static int lzma_uncompress(struct squashfs_sb_info *msblk, void **buffer,
  90         struct buffer_head **bh, int b, int offset, int length, int srclength,
  91         int pages)
  92 {
  93         struct squashfs_lzma *stream = msblk->stream;
  94         void *buff = stream->input;
  95         int avail, i, bytes = length, res;
  96
  97         mutex_lock(&lzma_mutex);
  98
  99         for (i = 0; i < b; i++) {
 100                 wait_on_buffer(bh[i]);
 101                 if (!buffer_uptodate(bh[i]))
 102                         goto block_release;
 103
 104                 avail = min(bytes, msblk->devblksize - offset);
 105                 memcpy(buff, bh[i]->b_data + offset, avail);
 106                 buff += avail;
 107                 bytes -= avail;
 108                 offset = 0;
 109                 put_bh(bh[i]);
 110         }
 111
 112         lzma_error = 0;
 113         res = unlzma(stream->input, length, NULL, NULL, stream->output, NULL,
 114                                                         error);
 115         if (res || lzma_error)
 116                 goto failed;
 117
 118         /* uncompressed size is stored in the LZMA header (5 byte offset) */
 119         res = bytes = get_unaligned_le32(stream->input + 5);
 120         for (i = 0, buff = stream->output; bytes && i < pages; i++) {
 121                 avail = min_t(int, bytes, PAGE_CACHE_SIZE);
 122                 memcpy(buffer[i], buff, avail);
 123                 buff += avail;
 124                 bytes -= avail;
 125         }
 126         if (bytes)
 127                 goto failed;
 128
 129         mutex_unlock(&lzma_mutex);
 130         return res;
 131
 132 block_release:
 133         for (; i < b; i++)
 134                 put_bh(bh[i]);
 135
 136 failed:
 137         mutex_unlock(&lzma_mutex);
 138
 139         ERROR("lzma decompression failed, data probably corrupt\n");
 140         return -EIO;
 141 }
 142
 143 const struct squashfs_decompressor squashfs_lzma_comp_ops = {
 144         .init = lzma_init,
 145         .free = lzma_free,
 146         .decompress = lzma_uncompress,
 147         .id = LZMA_COMPRESSION,
 148         .name = "lzma",
 149         .supported = 1
 150 };
 151