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(lseek(s->fd,128,SEEK_SET)<0) {
  66 cloop_close:
  67         close(s->fd);
  68         return -1;
  69     }
  70     if(read(s->fd,&s->block_size,4)<4)
  71         goto cloop_close;
  72     s->block_size=be32_to_cpu(s->block_size);
  73     if(read(s->fd,&s->n_blocks,4)<4)
  74         goto cloop_close;
  75     s->n_blocks=be32_to_cpu(s->n_blocks);
  76
  77     /* read offsets */
  78     offsets_size=s->n_blocks*sizeof(uint64_t);
  79     s->offsets=(uint64_t*)qemu_malloc(offsets_size);
  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     s->compressed_block = qemu_malloc(max_compressed_block_size+1);
  93     s->uncompressed_block = qemu_malloc(s->block_size);
  94     if(inflateInit(&s->zstream) != Z_OK)
  95         goto cloop_close;
  96     s->current_block=s->n_blocks;
  97
  98     s->sectors_per_block = s->block_size/512;
  99     bs->total_sectors = s->n_blocks*s->sectors_per_block;
 100     return 0;
 101 }
 102
 103 static inline int cloop_read_block(BDRVCloopState *s,int block_num)
 104 {
 105     if(s->current_block != block_num) {
 106         int ret;
 107         uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
 108
 109         lseek(s->fd, s->offsets[block_num], SEEK_SET);
 110         ret = read(s->fd, s->compressed_block, bytes);
 111         if (ret != bytes)
 112             return -1;
 113
 114         s->zstream.next_in = s->compressed_block;
 115         s->zstream.avail_in = bytes;
 116         s->zstream.next_out = s->uncompressed_block;
 117         s->zstream.avail_out = s->block_size;
 118         ret = inflateReset(&s->zstream);
 119         if(ret != Z_OK)
 120             return -1;
 121         ret = inflate(&s->zstream, Z_FINISH);
 122         if(ret != Z_STREAM_END || s->zstream.total_out != s->block_size)
 123             return -1;
 124
 125         s->current_block = block_num;
 126     }
 127     return 0;
 128 }
 129
 130 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 131                     uint8_t *buf, int nb_sectors)
 132 {
 133     BDRVCloopState *s = bs->opaque;
 134     int i;
 135
 136     for(i=0;i<nb_sectors;i++) {
 137         uint32_t sector_offset_in_block=((sector_num+i)%s->sectors_per_block),
 138             block_num=(sector_num+i)/s->sectors_per_block;
 139         if(cloop_read_block(s, block_num) != 0)
 140             return -1;
 141         memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);
 142     }
 143     return 0;
 144 }
 145
 146 static void cloop_close(BlockDriverState *bs)
 147 {
 148     BDRVCloopState *s = bs->opaque;
 149     close(s->fd);
 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);