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/block_int.h"
  26 #include "qemu/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     int ret;
  61
  62     bs->read_only = 1;
  63
  64     /* read header */
  65     ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
  66     if (ret < 0) {
  67         return ret;
  68     }
  69     s->block_size = be32_to_cpu(s->block_size);
  70
  71     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
  72     if (ret < 0) {
  73         return ret;
  74     }
  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 = g_malloc(offsets_size);
  80
  81     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
  82     if (ret < 0) {
  83         goto fail;
  84     }
  85
  86     for(i=0;i<s->n_blocks;i++) {
  87         s->offsets[i] = be64_to_cpu(s->offsets[i]);
  88         if (i > 0) {
  89             uint32_t size = s->offsets[i] - s->offsets[i - 1];
  90             if (size > max_compressed_block_size) {
  91                 max_compressed_block_size = size;
  92             }
  93         }
  94     }
  95
  96     /* initialize zlib engine */
  97     s->compressed_block = g_malloc(max_compressed_block_size + 1);
  98     s->uncompressed_block = g_malloc(s->block_size);
  99     if (inflateInit(&s->zstream) != Z_OK) {
 100         ret = -EINVAL;
 101         goto fail;
 102     }
 103     s->current_block = s->n_blocks;
 104
 105     s->sectors_per_block = s->block_size/512;
 106     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 107     qemu_co_mutex_init(&s->lock);
 108     return 0;
 109
 110 fail:
 111     g_free(s->offsets);
 112     g_free(s->compressed_block);
 113     g_free(s->uncompressed_block);
 114     return ret;
 115 }
 116
 117 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 118 {
 119     BDRVCloopState *s = bs->opaque;
 120
 121     if (s->current_block != block_num) {
 122         int ret;
 123         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 124
 125         ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
 126                          bytes);
 127         if (ret != bytes) {
 128             return -1;
 129         }
 130
 131         s->zstream.next_in = s->compressed_block;
 132         s->zstream.avail_in = bytes;
 133         s->zstream.next_out = s->uncompressed_block;
 134         s->zstream.avail_out = s->block_size;
 135         ret = inflateReset(&s->zstream);
 136         if (ret != Z_OK) {
 137             return -1;
 138         }
 139         ret = inflate(&s->zstream, Z_FINISH);
 140         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 141             return -1;
 142         }
 143
 144         s->current_block = block_num;
 145     }
 146     return 0;
 147 }
 148
 149 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 150                     uint8_t *buf, int nb_sectors)
 151 {
 152     BDRVCloopState *s = bs->opaque;
 153     int i;
 154
 155     for (i = 0; i < nb_sectors; i++) {
 156         uint32_t sector_offset_in_block =
 157             ((sector_num + i) % s->sectors_per_block),
 158             block_num = (sector_num + i) / s->sectors_per_block;
 159         if (cloop_read_block(bs, block_num) != 0) {
 160             return -1;
 161         }
 162         memcpy(buf + i * 512,
 163             s->uncompressed_block + sector_offset_in_block * 512, 512);
 164     }
 165     return 0;
 166 }
 167
 168 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
 169                                       uint8_t *buf, int nb_sectors)
 170 {
 171     int ret;
 172     BDRVCloopState *s = bs->opaque;
 173     qemu_co_mutex_lock(&s->lock);
 174     ret = cloop_read(bs, sector_num, buf, nb_sectors);
 175     qemu_co_mutex_unlock(&s->lock);
 176     return ret;
 177 }
 178
 179 static void cloop_close(BlockDriverState *bs)
 180 {
 181     BDRVCloopState *s = bs->opaque;
 182     if (s->n_blocks > 0) {
 183         g_free(s->offsets);
 184     }
 185     g_free(s->compressed_block);
 186     g_free(s->uncompressed_block);
 187     inflateEnd(&s->zstream);
 188 }
 189
 190 static BlockDriver bdrv_cloop = {
 191     .format_name    = "cloop",
 192     .instance_size  = sizeof(BDRVCloopState),
 193     .bdrv_probe     = cloop_probe,
 194     .bdrv_open      = cloop_open,
 195     .bdrv_read      = cloop_co_read,
 196     .bdrv_close     = cloop_close,
 197 };
 198
 199 static void bdrv_cloop_init(void)
 200 {
 201     bdrv_register(&bdrv_cloop);
 202 }
 203
 204 block_init(bdrv_cloop_init);