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     int fd;
  31     uint32_t block_size;
  32     uint32_t n_blocks;
  33     uint64_t* offsets;
  34     uint32_t sectors_per_block;
  35     uint32_t current_block;
  36     uint8_t *compressed_block;
  37     uint8_t *uncompressed_block;
  38     z_stream zstream;
  39 } BDRVCloopState;
  40
  41 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
  42 {
  43     const char* magic_version_2_0="#!/bin/sh\n"
  44         "#V2.0 Format\n"
  45         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
  46     int length=strlen(magic_version_2_0);
  47     if(length>buf_size)
  48         length=buf_size;
  49     if(!memcmp(magic_version_2_0,buf,length))
  50         return 2;
  51     return 0;
  52 }
  53
  54 static int cloop_open(BlockDriverState *bs, const char *filename, int flags)
  55 {
  56     BDRVCloopState *s = bs->opaque;
  57     uint32_t offsets_size,max_compressed_block_size=1,i;
  58
  59     s->fd = open(filename, O_RDONLY | O_BINARY);
  60     if (s->fd < 0)
  61         return -errno;
  62     bs->read_only = 1;
  63
  64     /* read header */
  65     if (pread(s->fd, &s->block_size, 4, 128) < 4) {
  66         goto cloop_close;
  67     }
  68     s->block_size = be32_to_cpu(s->block_size);
  69
  70     if (pread(s->fd, &s->n_blocks, 4, 128 + 4) < 4) {
  71         goto cloop_close;
  72     }
  73     s->n_blocks = be32_to_cpu(s->n_blocks);
  74
  75     /* read offsets */
  76     offsets_size = s->n_blocks * sizeof(uint64_t);
  77     s->offsets = qemu_malloc(offsets_size);
  78     if (pread(s->fd, s->offsets, offsets_size, 128 + 4 + 4) < offsets_size) {
  79         goto cloop_close;
  80     }
  81     for(i=0;i<s->n_blocks;i++) {
  82         s->offsets[i]=be64_to_cpu(s->offsets[i]);
  83         if(i>0) {
  84             uint32_t size=s->offsets[i]-s->offsets[i-1];
  85             if(size>max_compressed_block_size)
  86                 max_compressed_block_size=size;
  87         }
  88     }
  89
  90     /* initialize zlib engine */
  91     s->compressed_block = qemu_malloc(max_compressed_block_size+1);
  92     s->uncompressed_block = qemu_malloc(s->block_size);
  93     if(inflateInit(&s->zstream) != Z_OK)
  94         goto cloop_close;
  95     s->current_block=s->n_blocks;
  96
  97     s->sectors_per_block = s->block_size/512;
  98     bs->total_sectors = s->n_blocks*s->sectors_per_block;
  99     return 0;
 100
 101 cloop_close:
 102     close(s->fd);
 103     return -1;
 104 }
 105
 106 static inline int cloop_read_block(BDRVCloopState *s,int block_num)
 107 {
 108     if(s->current_block != block_num) {
 109         int ret;
 110         uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
 111
 112         ret = pread(s->fd, s->compressed_block, bytes, s->offsets[block_num]);
 113         if (ret != bytes)
 114             return -1;
 115
 116         s->zstream.next_in = s->compressed_block;
 117         s->zstream.avail_in = bytes;
 118         s->zstream.next_out = s->uncompressed_block;
 119         s->zstream.avail_out = s->block_size;
 120         ret = inflateReset(&s->zstream);
 121         if(ret != Z_OK)
 122             return -1;
 123         ret = inflate(&s->zstream, Z_FINISH);
 124         if(ret != Z_STREAM_END || s->zstream.total_out != s->block_size)
 125             return -1;
 126
 127         s->current_block = block_num;
 128     }
 129     return 0;
 130 }
 131
 132 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 133                     uint8_t *buf, int nb_sectors)
 134 {
 135     BDRVCloopState *s = bs->opaque;
 136     int i;
 137
 138     for(i=0;i<nb_sectors;i++) {
 139         uint32_t sector_offset_in_block=((sector_num+i)%s->sectors_per_block),
 140             block_num=(sector_num+i)/s->sectors_per_block;
 141         if(cloop_read_block(s, block_num) != 0)
 142             return -1;
 143         memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);
 144     }
 145     return 0;
 146 }
 147
 148 static void cloop_close(BlockDriverState *bs)
 149 {
 150     BDRVCloopState *s = bs->opaque;
 151     close(s->fd);
 152     if(s->n_blocks>0)
 153         free(s->offsets);
 154     free(s->compressed_block);
 155     free(s->uncompressed_block);
 156     inflateEnd(&s->zstream);
 157 }
 158
 159 static BlockDriver bdrv_cloop = {
 160     .format_name        = "cloop",
 161     .instance_size      = sizeof(BDRVCloopState),
 162     .bdrv_probe         = cloop_probe,
 163     .bdrv_file_open     = cloop_open,
 164     .bdrv_read          = cloop_read,
 165     .bdrv_close         = cloop_close,
 166 };
 167
 168 static void bdrv_cloop_init(void)
 169 {
 170     bdrv_register(&bdrv_cloop);
 171 }
 172
 173 block_init(bdrv_cloop_init);