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/osdep.h"
  25 #include "qemu-common.h"
  26 #include "block/block_int.h"
  27 #include "qemu/module.h"
  28 #include <zlib.h>
  29
  30 /* Maximum compressed block size */
  31 #define MAX_BLOCK_SIZE (64 * 1024 * 1024)
  32
  33 typedef struct BDRVCloopState {
  34     CoMutex lock;
  35     uint32_t block_size;
  36     uint32_t n_blocks;
  37     uint64_t *offsets;
  38     uint32_t sectors_per_block;
  39     uint32_t current_block;
  40     uint8_t *compressed_block;
  41     uint8_t *uncompressed_block;
  42     z_stream zstream;
  43 } BDRVCloopState;
  44
  45 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
  46 {
  47     const char *magic_version_2_0 = "#!/bin/sh\n"
  48         "#V2.0 Format\n"
  49         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
  50     int length = strlen(magic_version_2_0);
  51     if (length > buf_size) {
  52         length = buf_size;
  53     }
  54     if (!memcmp(magic_version_2_0, buf, length)) {
  55         return 2;
  56     }
  57     return 0;
  58 }
  59
  60 static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
  61                       Error **errp)
  62 {
  63     BDRVCloopState *s = bs->opaque;
  64     uint32_t offsets_size, max_compressed_block_size = 1, i;
  65     int ret;
  66
  67     bs->read_only = 1;
  68
  69     /* read header */
  70     ret = bdrv_pread(bs->file->bs, 128, &s->block_size, 4);
  71     if (ret < 0) {
  72         return ret;
  73     }
  74     s->block_size = be32_to_cpu(s->block_size);
  75     if (s->block_size % 512) {
  76         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  77                    s->block_size);
  78         return -EINVAL;
  79     }
  80     if (s->block_size == 0) {
  81         error_setg(errp, "block_size cannot be zero");
  82         return -EINVAL;
  83     }
  84
  85     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
  86      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
  87      * need a buffer this big.
  88      */
  89     if (s->block_size > MAX_BLOCK_SIZE) {
  90         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
  91                    s->block_size,
  92                    MAX_BLOCK_SIZE / (1024 * 1024));
  93         return -EINVAL;
  94     }
  95
  96     ret = bdrv_pread(bs->file->bs, 128 + 4, &s->n_blocks, 4);
  97     if (ret < 0) {
  98         return ret;
  99     }
 100     s->n_blocks = be32_to_cpu(s->n_blocks);
 101
 102     /* read offsets */
 103     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 104         /* Prevent integer overflow */
 105         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 106                    s->n_blocks,
 107                    (UINT32_MAX - 1) / sizeof(uint64_t));
 108         return -EINVAL;
 109     }
 110     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 111     if (offsets_size > 512 * 1024 * 1024) {
 112         /* Prevent ridiculous offsets_size which causes memory allocation to
 113          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 114          * offsets[] limit supports 16 TB images at 256 KB block size.
 115          */
 116         error_setg(errp, "image requires too many offsets, "
 117                    "try increasing block size");
 118         return -EINVAL;
 119     }
 120
 121     s->offsets = g_try_malloc(offsets_size);
 122     if (s->offsets == NULL) {
 123         error_setg(errp, "Could not allocate offsets table");
 124         return -ENOMEM;
 125     }
 126
 127     ret = bdrv_pread(bs->file->bs, 128 + 4 + 4, s->offsets, offsets_size);
 128     if (ret < 0) {
 129         goto fail;
 130     }
 131
 132     for (i = 0; i < s->n_blocks + 1; i++) {
 133         uint64_t size;
 134
 135         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 136         if (i == 0) {
 137             continue;
 138         }
 139
 140         if (s->offsets[i] < s->offsets[i - 1]) {
 141             error_setg(errp, "offsets not monotonically increasing at "
 142                        "index %" PRIu32 ", image file is corrupt", i);
 143             ret = -EINVAL;
 144             goto fail;
 145         }
 146
 147         size = s->offsets[i] - s->offsets[i - 1];
 148
 149         /* Compressed blocks should be smaller than the uncompressed block size
 150          * but maybe compression performed poorly so the compressed block is
 151          * actually bigger.  Clamp down on unrealistic values to prevent
 152          * ridiculous s->compressed_block allocation.
 153          */
 154         if (size > 2 * MAX_BLOCK_SIZE) {
 155             error_setg(errp, "invalid compressed block size at index %" PRIu32
 156                        ", image file is corrupt", i);
 157             ret = -EINVAL;
 158             goto fail;
 159         }
 160
 161         if (size > max_compressed_block_size) {
 162             max_compressed_block_size = size;
 163         }
 164     }
 165
 166     /* initialize zlib engine */
 167     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 168     if (s->compressed_block == NULL) {
 169         error_setg(errp, "Could not allocate compressed_block");
 170         ret = -ENOMEM;
 171         goto fail;
 172     }
 173
 174     s->uncompressed_block = g_try_malloc(s->block_size);
 175     if (s->uncompressed_block == NULL) {
 176         error_setg(errp, "Could not allocate uncompressed_block");
 177         ret = -ENOMEM;
 178         goto fail;
 179     }
 180
 181     if (inflateInit(&s->zstream) != Z_OK) {
 182         ret = -EINVAL;
 183         goto fail;
 184     }
 185     s->current_block = s->n_blocks;
 186
 187     s->sectors_per_block = s->block_size/512;
 188     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 189     qemu_co_mutex_init(&s->lock);
 190     return 0;
 191
 192 fail:
 193     g_free(s->offsets);
 194     g_free(s->compressed_block);
 195     g_free(s->uncompressed_block);
 196     return ret;
 197 }
 198
 199 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 200 {
 201     BDRVCloopState *s = bs->opaque;
 202
 203     if (s->current_block != block_num) {
 204         int ret;
 205         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 206
 207         ret = bdrv_pread(bs->file->bs, s->offsets[block_num],
 208                          s->compressed_block, bytes);
 209         if (ret != bytes) {
 210             return -1;
 211         }
 212
 213         s->zstream.next_in = s->compressed_block;
 214         s->zstream.avail_in = bytes;
 215         s->zstream.next_out = s->uncompressed_block;
 216         s->zstream.avail_out = s->block_size;
 217         ret = inflateReset(&s->zstream);
 218         if (ret != Z_OK) {
 219             return -1;
 220         }
 221         ret = inflate(&s->zstream, Z_FINISH);
 222         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 223             return -1;
 224         }
 225
 226         s->current_block = block_num;
 227     }
 228     return 0;
 229 }
 230
 231 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 232                     uint8_t *buf, int nb_sectors)
 233 {
 234     BDRVCloopState *s = bs->opaque;
 235     int i;
 236
 237     for (i = 0; i < nb_sectors; i++) {
 238         uint32_t sector_offset_in_block =
 239             ((sector_num + i) % s->sectors_per_block),
 240             block_num = (sector_num + i) / s->sectors_per_block;
 241         if (cloop_read_block(bs, block_num) != 0) {
 242             return -1;
 243         }
 244         memcpy(buf + i * 512,
 245             s->uncompressed_block + sector_offset_in_block * 512, 512);
 246     }
 247     return 0;
 248 }
 249
 250 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
 251                                       uint8_t *buf, int nb_sectors)
 252 {
 253     int ret;
 254     BDRVCloopState *s = bs->opaque;
 255     qemu_co_mutex_lock(&s->lock);
 256     ret = cloop_read(bs, sector_num, buf, nb_sectors);
 257     qemu_co_mutex_unlock(&s->lock);
 258     return ret;
 259 }
 260
 261 static void cloop_close(BlockDriverState *bs)
 262 {
 263     BDRVCloopState *s = bs->opaque;
 264     g_free(s->offsets);
 265     g_free(s->compressed_block);
 266     g_free(s->uncompressed_block);
 267     inflateEnd(&s->zstream);
 268 }
 269
 270 static BlockDriver bdrv_cloop = {
 271     .format_name    = "cloop",
 272     .instance_size  = sizeof(BDRVCloopState),
 273     .bdrv_probe     = cloop_probe,
 274     .bdrv_open      = cloop_open,
 275     .bdrv_read      = cloop_co_read,
 276     .bdrv_close     = cloop_close,
 277 };
 278
 279 static void bdrv_cloop_init(void)
 280 {
 281     bdrv_register(&bdrv_cloop);
 282 }
 283
 284 block_init(bdrv_cloop_init);