qemu/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 <zlib.h>
  27
  28 typedef struct BDRVCloopState {
  29     int fd;
  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, const char *filename, int flags)
  54 {
  55     BDRVCloopState *s = bs->opaque;
  56     uint32_t offsets_size,max_compressed_block_size=1,i;
  57
  58     s->fd = open(filename, O_RDONLY | O_BINARY);
  59     if (s->fd < 0)
  60         return -errno;
  61     bs->read_only = 1;
  62
  63     /* read header */
  64     if(lseek(s->fd,128,SEEK_SET)<0) {
  65 cloop_close:
  66         close(s->fd);
  67         return -1;
  68     }
  69     if(read(s->fd,&s->block_size,4)<4)
  70         goto cloop_close;
  71     s->block_size=be32_to_cpu(s->block_size);
  72     if(read(s->fd,&s->n_blocks,4)<4)
  73         goto cloop_close;
  74     s->n_blocks=be32_to_cpu(s->n_blocks);
  75
  76     /* read offsets */
  77     offsets_size=s->n_blocks*sizeof(uint64_t);
  78     if(!(s->offsets=(uint64_t*)malloc(offsets_size)))
  79         goto cloop_close;
  80     if(read(s->fd,s->offsets,offsets_size)<offsets_size)
  81         goto cloop_close;
  82     for(i=0;i<s->n_blocks;i++) {
  83         s->offsets[i]=be64_to_cpu(s->offsets[i]);
  84         if(i>0) {
  85             uint32_t size=s->offsets[i]-s->offsets[i-1];
  86             if(size>max_compressed_block_size)
  87                 max_compressed_block_size=size;
  88         }
  89     }
  90
  91     /* initialize zlib engine */
  92     if(!(s->compressed_block = malloc(max_compressed_block_size+1)))
  93         goto cloop_close;
  94     if(!(s->uncompressed_block = malloc(s->block_size)))
  95         goto cloop_close;
  96     if(inflateInit(&s->zstream) != Z_OK)
  97         goto cloop_close;
  98     s->current_block=s->n_blocks;
  99
 100     s->sectors_per_block = s->block_size/512;
 101     bs->total_sectors = s->n_blocks*s->sectors_per_block;
 102     return 0;
 103 }
 104
 105 static inline int cloop_read_block(BDRVCloopState *s,int block_num)
 106 {
 107     if(s->current_block != block_num) {
 108         int ret;
 109         uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
 110
 111         lseek(s->fd, s->offsets[block_num], SEEK_SET);
 112         ret = read(s->fd, s->compressed_block, bytes);
 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 BlockDriver bdrv_cloop = {
 160     "cloop",
 161     sizeof(BDRVCloopState),
 162     cloop_probe,
 163     cloop_open,
 164     cloop_read,
 165     NULL,
 166     cloop_close,
 167 };
 168
 169