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, QDict *options, int flags,
  57                       Error **errp)
  58 {
  59     BDRVCloopState *s = bs->opaque;
  60     uint32_t offsets_size, max_compressed_block_size = 1, i;
  61     int ret;
  62
  63     bs->read_only = 1;
  64
  65     /* read header */
  66     ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
  67     if (ret < 0) {
  68         return ret;
  69     }
  70     s->block_size = be32_to_cpu(s->block_size);
  71
  72     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
  73     if (ret < 0) {
  74         return ret;
  75     }
  76     s->n_blocks = be32_to_cpu(s->n_blocks);
  77
  78     /* read offsets */
  79     offsets_size = s->n_blocks * sizeof(uint64_t);
  80     s->offsets = g_malloc(offsets_size);
  81
  82     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
  83     if (ret < 0) {
  84         goto fail;
  85     }
  86
  87     for(i=0;i<s->n_blocks;i++) {
  88         s->offsets[i] = be64_to_cpu(s->offsets[i]);
  89         if (i > 0) {
  90             uint32_t size = s->offsets[i] - s->offsets[i - 1];
  91             if (size > max_compressed_block_size) {
  92                 max_compressed_block_size = size;
  93             }
  94         }
  95     }
  96
  97     /* initialize zlib engine */
  98     s->compressed_block = g_malloc(max_compressed_block_size + 1);
  99     s->uncompressed_block = g_malloc(s->block_size);
 100     if (inflateInit(&s->zstream) != Z_OK) {
 101         ret = -EINVAL;
 102         goto fail;
 103     }
 104     s->current_block = s->n_blocks;
 105
 106     s->sectors_per_block = s->block_size/512;
 107     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 108     qemu_co_mutex_init(&s->lock);
 109     return 0;
 110
 111 fail:
 112     g_free(s->offsets);
 113     g_free(s->compressed_block);
 114     g_free(s->uncompressed_block);
 115     return ret;
 116 }
 117
 118 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 119 {
 120     BDRVCloopState *s = bs->opaque;
 121
 122     if (s->current_block != block_num) {
 123         int ret;
 124         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 125
 126         ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
 127                          bytes);
 128         if (ret != bytes) {
 129             return -1;
 130         }
 131
 132         s->zstream.next_in = s->compressed_block;
 133         s->zstream.avail_in = bytes;
 134         s->zstream.next_out = s->uncompressed_block;
 135         s->zstream.avail_out = s->block_size;
 136         ret = inflateReset(&s->zstream);
 137         if (ret != Z_OK) {
 138             return -1;
 139         }
 140         ret = inflate(&s->zstream, Z_FINISH);
 141         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 142             return -1;
 143         }
 144
 145         s->current_block = block_num;
 146     }
 147     return 0;
 148 }
 149
 150 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 151                     uint8_t *buf, int nb_sectors)
 152 {
 153     BDRVCloopState *s = bs->opaque;
 154     int i;
 155
 156     for (i = 0; i < nb_sectors; i++) {
 157         uint32_t sector_offset_in_block =
 158             ((sector_num + i) % s->sectors_per_block),
 159             block_num = (sector_num + i) / s->sectors_per_block;
 160         if (cloop_read_block(bs, block_num) != 0) {
 161             return -1;
 162         }
 163         memcpy(buf + i * 512,
 164             s->uncompressed_block + sector_offset_in_block * 512, 512);
 165     }
 166     return 0;
 167 }
 168
 169 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
 170                                       uint8_t *buf, int nb_sectors)
 171 {
 172     int ret;
 173     BDRVCloopState *s = bs->opaque;
 174     qemu_co_mutex_lock(&s->lock);
 175     ret = cloop_read(bs, sector_num, buf, nb_sectors);
 176     qemu_co_mutex_unlock(&s->lock);
 177     return ret;
 178 }
 179
 180 static void cloop_close(BlockDriverState *bs)
 181 {
 182     BDRVCloopState *s = bs->opaque;
 183     if (s->n_blocks > 0) {
 184         g_free(s->offsets);
 185     }
 186     g_free(s->compressed_block);
 187     g_free(s->uncompressed_block);
 188     inflateEnd(&s->zstream);
 189 }
 190
 191 static BlockDriver bdrv_cloop = {
 192     .format_name    = "cloop",
 193     .instance_size  = sizeof(BDRVCloopState),
 194     .bdrv_probe     = cloop_probe,
 195     .bdrv_open      = cloop_open,
 196     .bdrv_read      = cloop_co_read,
 197     .bdrv_close     = cloop_close,
 198 };
 199
 200 static void bdrv_cloop_init(void)
 201 {
 202     bdrv_register(&bdrv_cloop);
 203 }
 204
 205 block_init(bdrv_cloop_init);