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     CoMutex lock;
  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, int flags)
  55 {
  56     BDRVCloopState *s = bs->opaque;
  57     uint32_t offsets_size,max_compressed_block_size=1,i;
  58
  59     bs->read_only = 1;
  60
  61     /* read header */
  62     if (bdrv_pread(bs->file, 128, &s->block_size, 4) < 4) {
  63         goto cloop_close;
  64     }
  65     s->block_size = be32_to_cpu(s->block_size);
  66
  67     if (bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4) < 4) {
  68         goto cloop_close;
  69     }
  70     s->n_blocks = be32_to_cpu(s->n_blocks);
  71
  72     /* read offsets */
  73     offsets_size = s->n_blocks * sizeof(uint64_t);
  74     s->offsets = g_malloc(offsets_size);
  75     if (bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size) <
  76             offsets_size) {
  77         goto cloop_close;
  78     }
  79     for(i=0;i<s->n_blocks;i++) {
  80         s->offsets[i]=be64_to_cpu(s->offsets[i]);
  81         if(i>0) {
  82             uint32_t size=s->offsets[i]-s->offsets[i-1];
  83             if(size>max_compressed_block_size)
  84                 max_compressed_block_size=size;
  85         }
  86     }
  87
  88     /* initialize zlib engine */
  89     s->compressed_block = g_malloc(max_compressed_block_size+1);
  90     s->uncompressed_block = g_malloc(s->block_size);
  91     if(inflateInit(&s->zstream) != Z_OK)
  92         goto cloop_close;
  93     s->current_block=s->n_blocks;
  94
  95     s->sectors_per_block = s->block_size/512;
  96     bs->total_sectors = s->n_blocks*s->sectors_per_block;
  97     qemu_co_mutex_init(&s->lock);
  98     return 0;
  99
 100 cloop_close:
 101     return -1;
 102 }
 103
 104 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 105 {
 106     BDRVCloopState *s = bs->opaque;
 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 = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
 113                          bytes);
 114         if (ret != bytes)
 115             return -1;
 116
 117         s->zstream.next_in = s->compressed_block;
 118         s->zstream.avail_in = bytes;
 119         s->zstream.next_out = s->uncompressed_block;
 120         s->zstream.avail_out = s->block_size;
 121         ret = inflateReset(&s->zstream);
 122         if(ret != Z_OK)
 123             return -1;
 124         ret = inflate(&s->zstream, Z_FINISH);
 125         if(ret != Z_STREAM_END || s->zstream.total_out != s->block_size)
 126             return -1;
 127
 128         s->current_block = block_num;
 129     }
 130     return 0;
 131 }
 132
 133 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 134                     uint8_t *buf, int nb_sectors)
 135 {
 136     BDRVCloopState *s = bs->opaque;
 137     int i;
 138
 139     for(i=0;i<nb_sectors;i++) {
 140         uint32_t sector_offset_in_block=((sector_num+i)%s->sectors_per_block),
 141             block_num=(sector_num+i)/s->sectors_per_block;
 142         if(cloop_read_block(bs, block_num) != 0)
 143             return -1;
 144         memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);
 145     }
 146     return 0;
 147 }
 148
 149 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
 150                                       uint8_t *buf, int nb_sectors)
 151 {
 152     int ret;
 153     BDRVCloopState *s = bs->opaque;
 154     qemu_co_mutex_lock(&s->lock);
 155     ret = cloop_read(bs, sector_num, buf, nb_sectors);
 156     qemu_co_mutex_unlock(&s->lock);
 157     return ret;
 158 }
 159
 160 static void cloop_close(BlockDriverState *bs)
 161 {
 162     BDRVCloopState *s = bs->opaque;
 163     if(s->n_blocks>0)
 164         free(s->offsets);
 165     free(s->compressed_block);
 166     free(s->uncompressed_block);
 167     inflateEnd(&s->zstream);
 168 }
 169
 170 static BlockDriver bdrv_cloop = {
 171     .format_name        = "cloop",
 172     .instance_size      = sizeof(BDRVCloopState),
 173     .bdrv_probe         = cloop_probe,
 174     .bdrv_open          = cloop_open,
 175     .bdrv_read          = cloop_co_read,
 176     .bdrv_close         = cloop_close,
 177 };
 178
 179 static void bdrv_cloop_init(void)
 180 {
 181     bdrv_register(&bdrv_cloop);
 182 }
 183
 184 block_init(bdrv_cloop_init);