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     }
  50     if (!memcmp(magic_version_2_0, buf, length)) {
  51         return 2;
  52     }
  53     return 0;
  54 }
  55
  56 static int cloop_open(BlockDriverState *bs, int flags)
  57 {
  58     BDRVCloopState *s = bs->opaque;
  59     uint32_t offsets_size, max_compressed_block_size = 1, i;
  60
  61     bs->read_only = 1;
  62
  63     /* read header */
  64     if (bdrv_pread(bs->file, 128, &s->block_size, 4) < 4) {
  65         goto cloop_close;
  66     }
  67     s->block_size = be32_to_cpu(s->block_size);
  68
  69     if (bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4) < 4) {
  70         goto cloop_close;
  71     }
  72     s->n_blocks = be32_to_cpu(s->n_blocks);
  73
  74     /* read offsets */
  75     offsets_size = s->n_blocks * sizeof(uint64_t);
  76     s->offsets = g_malloc(offsets_size);
  77     if (bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size) <
  78             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
  91     /* initialize zlib engine */
  92     s->compressed_block = g_malloc(max_compressed_block_size + 1);
  93     s->uncompressed_block = g_malloc(s->block_size);
  94     if (inflateInit(&s->zstream) != Z_OK) {
  95         goto cloop_close;
  96     }
  97     s->current_block = s->n_blocks;
  98
  99     s->sectors_per_block = s->block_size/512;
 100     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 101     qemu_co_mutex_init(&s->lock);
 102     return 0;
 103
 104 cloop_close:
 105     return -1;
 106 }
 107
 108 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 109 {
 110     BDRVCloopState *s = bs->opaque;
 111
 112     if (s->current_block != block_num) {
 113         int ret;
 114         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 115
 116         ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
 117                          bytes);
 118         if (ret != bytes) {
 119             return -1;
 120         }
 121
 122         s->zstream.next_in = s->compressed_block;
 123         s->zstream.avail_in = bytes;
 124         s->zstream.next_out = s->uncompressed_block;
 125         s->zstream.avail_out = s->block_size;
 126         ret = inflateReset(&s->zstream);
 127         if (ret != Z_OK) {
 128             return -1;
 129         }
 130         ret = inflate(&s->zstream, Z_FINISH);
 131         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 132             return -1;
 133         }
 134
 135         s->current_block = block_num;
 136     }
 137     return 0;
 138 }
 139
 140 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 141                     uint8_t *buf, int nb_sectors)
 142 {
 143     BDRVCloopState *s = bs->opaque;
 144     int i;
 145
 146     for (i = 0; i < nb_sectors; i++) {
 147         uint32_t sector_offset_in_block =
 148             ((sector_num + i) % s->sectors_per_block),
 149             block_num = (sector_num + i) / s->sectors_per_block;
 150         if (cloop_read_block(bs, block_num) != 0) {
 151             return -1;
 152         }
 153         memcpy(buf + i * 512,
 154             s->uncompressed_block + sector_offset_in_block * 512, 512);
 155     }
 156     return 0;
 157 }
 158
 159 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
 160                                       uint8_t *buf, int nb_sectors)
 161 {
 162     int ret;
 163     BDRVCloopState *s = bs->opaque;
 164     qemu_co_mutex_lock(&s->lock);
 165     ret = cloop_read(bs, sector_num, buf, nb_sectors);
 166     qemu_co_mutex_unlock(&s->lock);
 167     return ret;
 168 }
 169
 170 static void cloop_close(BlockDriverState *bs)
 171 {
 172     BDRVCloopState *s = bs->opaque;
 173     if (s->n_blocks > 0) {
 174         g_free(s->offsets);
 175     }
 176     g_free(s->compressed_block);
 177     g_free(s->uncompressed_block);
 178     inflateEnd(&s->zstream);
 179 }
 180
 181 static BlockDriver bdrv_cloop = {
 182     .format_name    = "cloop",
 183     .instance_size  = sizeof(BDRVCloopState),
 184     .bdrv_probe     = cloop_probe,
 185     .bdrv_open      = cloop_open,
 186     .bdrv_read      = cloop_co_read,
 187     .bdrv_close     = cloop_close,
 188 };
 189
 190 static void bdrv_cloop_init(void)
 191 {
 192     bdrv_register(&bdrv_cloop);
 193 }
 194
 195 block_init(bdrv_cloop_init);