block/cloop.c

   1 /*
   2  * QEMU Block driver for CLOOP images
   3  *
   4  * Copyright (c) 2004 Johannes E. Schindelin
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #include "qemu-common.h"
  25 #include "block_int.h"
  26 #include "module.h"
  27 #include <zlib.h>
  28
  29 typedef struct BDRVCloopState {
  30     uint32_t block_size;
  31     uint32_t n_blocks;
  32     uint64_t* offsets;
  33     uint32_t sectors_per_block;
  34     uint32_t current_block;
  35     uint8_t *compressed_block;
  36     uint8_t *uncompressed_block;
  37     z_stream zstream;
  38 } BDRVCloopState;
  39
  40 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
  41 {
  42     const char* magic_version_2_0="#!/bin/sh\n"
  43         "#V2.0 Format\n"
  44         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
  45     int length=strlen(magic_version_2_0);
  46     if(length>buf_size)
  47         length=buf_size;
  48     if(!memcmp(magic_version_2_0,buf,length))
  49         return 2;
  50     return 0;
  51 }
  52
  53 static int cloop_open(BlockDriverState *bs, int flags)
  54 {
  55     BDRVCloopState *s = bs->opaque;
  56     uint32_t offsets_size,max_compressed_block_size=1,i;
  57
  58     bs->read_only = 1;
  59
  60     /* read header */
  61     if (bdrv_pread(bs->file, 128, &s->block_size, 4) < 4) {
  62         goto cloop_close;
  63     }
  64     s->block_size = be32_to_cpu(s->block_size);
  65
  66     if (bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4) < 4) {
  67         goto cloop_close;
  68     }
  69     s->n_blocks = be32_to_cpu(s->n_blocks);
  70
  71     /* read offsets */
  72     offsets_size = s->n_blocks * sizeof(uint64_t);
  73     s->offsets = g_malloc(offsets_size);
  74     if (bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size) <
  75             offsets_size) {
  76         goto cloop_close;
  77     }
  78     for(i=0;i<s->n_blocks;i++) {
  79         s->offsets[i]=be64_to_cpu(s->offsets[i]);
  80         if(i>0) {
  81             uint32_t size=s->offsets[i]-s->offsets[i-1];
  82             if(size>max_compressed_block_size)
  83                 max_compressed_block_size=size;
  84         }
  85     }
  86
  87     /* initialize zlib engine */
  88     s->compressed_block = g_malloc(max_compressed_block_size+1);
  89     s->uncompressed_block = g_malloc(s->block_size);
  90     if(inflateInit(&s->zstream) != Z_OK)
  91         goto cloop_close;
  92     s->current_block=s->n_blocks;
  93
  94     s->sectors_per_block = s->block_size/512;
  95     bs->total_sectors = s->n_blocks*s->sectors_per_block;
  96     return 0;
  97
  98 cloop_close:
  99     return -1;
 100 }
 101
 102 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 103 {
 104     BDRVCloopState *s = bs->opaque;
 105
 106     if(s->current_block != block_num) {
 107         int ret;
 108         uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
 109
 110         ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
 111                          bytes);
 112         if (ret != bytes)
 113             return -1;
 114
 115         s->zstream.next_in = s->compressed_block;
 116         s->zstream.avail_in = bytes;
 117         s->zstream.next_out = s->uncompressed_block;
 118         s->zstream.avail_out = s->block_size;
 119         ret = inflateReset(&s->zstream);
 120         if(ret != Z_OK)
 121             return -1;
 122         ret = inflate(&s->zstream, Z_FINISH);
 123         if(ret != Z_STREAM_END || s->zstream.total_out != s->block_size)
 124             return -1;
 125
 126         s->current_block = block_num;
 127     }
 128     return 0;
 129 }
 130
 131 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 132                     uint8_t *buf, int nb_sectors)
 133 {
 134     BDRVCloopState *s = bs->opaque;
 135     int i;
 136
 137     for(i=0;i<nb_sectors;i++) {
 138         uint32_t sector_offset_in_block=((sector_num+i)%s->sectors_per_block),
 139             block_num=(sector_num+i)/s->sectors_per_block;
 140         if(cloop_read_block(bs, block_num) != 0)
 141             return -1;
 142         memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);
 143     }
 144     return 0;
 145 }
 146
 147 static void cloop_close(BlockDriverState *bs)
 148 {
 149     BDRVCloopState *s = bs->opaque;
 150     if(s->n_blocks>0)
 151         free(s->offsets);
 152     free(s->compressed_block);
 153     free(s->uncompressed_block);
 154     inflateEnd(&s->zstream);
 155 }
 156
 157 static BlockDriver bdrv_cloop = {
 158     .format_name        = "cloop",
 159     .instance_size      = sizeof(BDRVCloopState),
 160     .bdrv_probe         = cloop_probe,
 161     .bdrv_open          = cloop_open,
 162     .bdrv_read          = cloop_read,
 163     .bdrv_close         = cloop_close,
 164 };
 165
 166 static void bdrv_cloop_init(void)
 167 {
 168     bdrv_register(&bdrv_cloop);
 169 }
 170
 171 block_init(bdrv_cloop_init);