block/dmg.c

   1 /*
   2  * QEMU Block driver for DMG 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/bswap.h"
  27 #include "qemu/module.h"
  28 #include <zlib.h>
  29 #ifdef CONFIG_BZIP2
  30 #include <bzlib.h>
  31 #endif
  32 #include <glib.h>
  33
  34 enum {
  35     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  36      * or truncating when converting to 32-bit types
  37      */
  38     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  39     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  40 };
  41
  42 typedef struct BDRVDMGState {
  43     CoMutex lock;
  44     /* each chunk contains a certain number of sectors,
  45      * offsets[i] is the offset in the .dmg file,
  46      * lengths[i] is the length of the compressed chunk,
  47      * sectors[i] is the sector beginning at offsets[i],
  48      * sectorcounts[i] is the number of sectors in that chunk,
  49      * the sectors array is ordered
  50      * 0<=i<n_chunks */
  51
  52     uint32_t n_chunks;
  53     uint32_t* types;
  54     uint64_t* offsets;
  55     uint64_t* lengths;
  56     uint64_t* sectors;
  57     uint64_t* sectorcounts;
  58     uint32_t current_chunk;
  59     uint8_t *compressed_chunk;
  60     uint8_t *uncompressed_chunk;
  61     z_stream zstream;
  62 #ifdef CONFIG_BZIP2
  63     bz_stream bzstream;
  64 #endif
  65 } BDRVDMGState;
  66
  67 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  68 {
  69     int len;
  70
  71     if (!filename) {
  72         return 0;
  73     }
  74
  75     len = strlen(filename);
  76     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  77         return 2;
  78     }
  79     return 0;
  80 }
  81
  82 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  83 {
  84     uint64_t buffer;
  85     int ret;
  86
  87     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  88     if (ret < 0) {
  89         return ret;
  90     }
  91
  92     *result = be64_to_cpu(buffer);
  93     return 0;
  94 }
  95
  96 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  97 {
  98     uint32_t buffer;
  99     int ret;
 100
 101     ret = bdrv_pread(bs->file, offset, &buffer, 4);
 102     if (ret < 0) {
 103         return ret;
 104     }
 105
 106     *result = be32_to_cpu(buffer);
 107     return 0;
 108 }
 109
 110 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 111 {
 112     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 113 }
 114
 115 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 116 {
 117     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 118 }
 119
 120 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 121  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 122  */
 123 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 124                                   uint32_t *max_compressed_size,
 125                                   uint32_t *max_sectors_per_chunk)
 126 {
 127     uint32_t compressed_size = 0;
 128     uint32_t uncompressed_sectors = 0;
 129
 130     switch (s->types[chunk]) {
 131     case 0x80000005: /* zlib compressed */
 132     case 0x80000006: /* bzip2 compressed */
 133         compressed_size = s->lengths[chunk];
 134         uncompressed_sectors = s->sectorcounts[chunk];
 135         break;
 136     case 1: /* copy */
 137         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 138         break;
 139     case 2: /* zero */
 140         uncompressed_sectors = s->sectorcounts[chunk];
 141         break;
 142     }
 143
 144     if (compressed_size > *max_compressed_size) {
 145         *max_compressed_size = compressed_size;
 146     }
 147     if (uncompressed_sectors > *max_sectors_per_chunk) {
 148         *max_sectors_per_chunk = uncompressed_sectors;
 149     }
 150 }
 151
 152 static int64_t dmg_find_koly_offset(BlockDriverState *file_bs, Error **errp)
 153 {
 154     int64_t length;
 155     int64_t offset = 0;
 156     uint8_t buffer[515];
 157     int i, ret;
 158
 159     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 160      * dmg images can have odd sizes, try to look for the "koly" magic which
 161      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 162      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 163      * the last sector (search space: 515 bytes) */
 164     length = bdrv_getlength(file_bs);
 165     if (length < 0) {
 166         error_setg_errno(errp, -length,
 167             "Failed to get file size while reading UDIF trailer");
 168         return length;
 169     } else if (length < 512) {
 170         error_setg(errp, "dmg file must be at least 512 bytes long");
 171         return -EINVAL;
 172     }
 173     if (length > 511 + 512) {
 174         offset = length - 511 - 512;
 175     }
 176     length = length < 515 ? length : 515;
 177     ret = bdrv_pread(file_bs, offset, buffer, length);
 178     if (ret < 0) {
 179         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 180         return ret;
 181     }
 182     for (i = 0; i < length - 3; i++) {
 183         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 184             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 185             return offset + i;
 186         }
 187     }
 188     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 189     return -EINVAL;
 190 }
 191
 192 /* used when building the sector table */
 193 typedef struct DmgHeaderState {
 194     /* used internally by dmg_read_mish_block to remember offsets of blocks
 195      * across calls */
 196     uint64_t data_fork_offset;
 197     /* exported for dmg_open */
 198     uint32_t max_compressed_size;
 199     uint32_t max_sectors_per_chunk;
 200 } DmgHeaderState;
 201
 202 static bool dmg_is_known_block_type(uint32_t entry_type)
 203 {
 204     switch (entry_type) {
 205     case 0x00000001:    /* uncompressed */
 206     case 0x00000002:    /* zeroes */
 207     case 0x80000005:    /* zlib */
 208 #ifdef CONFIG_BZIP2
 209     case 0x80000006:    /* bzip2 */
 210 #endif
 211         return true;
 212     default:
 213         return false;
 214     }
 215 }
 216
 217 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 218                                uint8_t *buffer, uint32_t count)
 219 {
 220     uint32_t type, i;
 221     int ret;
 222     size_t new_size;
 223     uint32_t chunk_count;
 224     int64_t offset = 0;
 225     uint64_t data_offset;
 226     uint64_t in_offset = ds->data_fork_offset;
 227     uint64_t out_offset;
 228
 229     type = buff_read_uint32(buffer, offset);
 230     /* skip data that is not a valid MISH block (invalid magic or too small) */
 231     if (type != 0x6d697368 || count < 244) {
 232         /* assume success for now */
 233         return 0;
 234     }
 235
 236     /* chunk offsets are relative to this sector number */
 237     out_offset = buff_read_uint64(buffer, offset + 8);
 238
 239     /* location in data fork for (compressed) blob (in bytes) */
 240     data_offset = buff_read_uint64(buffer, offset + 0x18);
 241     in_offset += data_offset;
 242
 243     /* move to begin of chunk entries */
 244     offset += 204;
 245
 246     chunk_count = (count - 204) / 40;
 247     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 248     s->types = g_realloc(s->types, new_size / 2);
 249     s->offsets = g_realloc(s->offsets, new_size);
 250     s->lengths = g_realloc(s->lengths, new_size);
 251     s->sectors = g_realloc(s->sectors, new_size);
 252     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 253
 254     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 255         s->types[i] = buff_read_uint32(buffer, offset);
 256         if (!dmg_is_known_block_type(s->types[i])) {
 257             chunk_count--;
 258             i--;
 259             offset += 40;
 260             continue;
 261         }
 262
 263         /* sector number */
 264         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 265         s->sectors[i] += out_offset;
 266
 267         /* sector count */
 268         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 269
 270         if (s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 271             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 272                          " is larger than max (%u)",
 273                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 274             ret = -EINVAL;
 275             goto fail;
 276         }
 277
 278         /* offset in (compressed) data fork */
 279         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 280         s->offsets[i] += in_offset;
 281
 282         /* length in (compressed) data fork */
 283         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 284
 285         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 286             error_report("length %" PRIu64 " for chunk %" PRIu32
 287                          " is larger than max (%u)",
 288                          s->lengths[i], i, DMG_LENGTHS_MAX);
 289             ret = -EINVAL;
 290             goto fail;
 291         }
 292
 293         update_max_chunk_size(s, i, &ds->max_compressed_size,
 294                               &ds->max_sectors_per_chunk);
 295         offset += 40;
 296     }
 297     s->n_chunks += chunk_count;
 298     return 0;
 299
 300 fail:
 301     return ret;
 302 }
 303
 304 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 305                                   uint64_t info_begin, uint64_t info_length)
 306 {
 307     BDRVDMGState *s = bs->opaque;
 308     int ret;
 309     uint32_t count, rsrc_data_offset;
 310     uint8_t *buffer = NULL;
 311     uint64_t info_end;
 312     uint64_t offset;
 313
 314     /* read offset from begin of resource fork (info_begin) to resource data */
 315     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 316     if (ret < 0) {
 317         goto fail;
 318     } else if (rsrc_data_offset > info_length) {
 319         ret = -EINVAL;
 320         goto fail;
 321     }
 322
 323     /* read length of resource data */
 324     ret = read_uint32(bs, info_begin + 8, &count);
 325     if (ret < 0) {
 326         goto fail;
 327     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 328         ret = -EINVAL;
 329         goto fail;
 330     }
 331
 332     /* begin of resource data (consisting of one or more resources) */
 333     offset = info_begin + rsrc_data_offset;
 334
 335     /* end of resource data (there is possibly a following resource map
 336      * which will be ignored). */
 337     info_end = offset + count;
 338
 339     /* read offsets (mish blocks) from one or more resources in resource data */
 340     while (offset < info_end) {
 341         /* size of following resource */
 342         ret = read_uint32(bs, offset, &count);
 343         if (ret < 0) {
 344             goto fail;
 345         } else if (count == 0 || count > info_end - offset) {
 346             ret = -EINVAL;
 347             goto fail;
 348         }
 349         offset += 4;
 350
 351         buffer = g_realloc(buffer, count);
 352         ret = bdrv_pread(bs->file, offset, buffer, count);
 353         if (ret < 0) {
 354             goto fail;
 355         }
 356
 357         ret = dmg_read_mish_block(s, ds, buffer, count);
 358         if (ret < 0) {
 359             goto fail;
 360         }
 361         /* advance offset by size of resource */
 362         offset += count;
 363     }
 364     ret = 0;
 365
 366 fail:
 367     g_free(buffer);
 368     return ret;
 369 }
 370
 371 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 372                               uint64_t info_begin, uint64_t info_length)
 373 {
 374     BDRVDMGState *s = bs->opaque;
 375     int ret;
 376     uint8_t *buffer = NULL;
 377     char *data_begin, *data_end;
 378
 379     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 380      * safe upper cap on the data length. A test sample had a XML length of
 381      * about 1 MiB. */
 382     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 383         ret = -EINVAL;
 384         goto fail;
 385     }
 386
 387     buffer = g_malloc(info_length + 1);
 388     buffer[info_length] = '\0';
 389     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 390     if (ret != info_length) {
 391         ret = -EINVAL;
 392         goto fail;
 393     }
 394
 395     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 396      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 397      * and line feeds. */
 398     data_end = (char *)buffer;
 399     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 400         guchar *mish;
 401         gsize out_len = 0;
 402
 403         data_begin += 6;
 404         data_end = strstr(data_begin, "</data>");
 405         /* malformed XML? */
 406         if (data_end == NULL) {
 407             ret = -EINVAL;
 408             goto fail;
 409         }
 410         *data_end++ = '\0';
 411         mish = g_base64_decode(data_begin, &out_len);
 412         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 413         g_free(mish);
 414         if (ret < 0) {
 415             goto fail;
 416         }
 417     }
 418     ret = 0;
 419
 420 fail:
 421     g_free(buffer);
 422     return ret;
 423 }
 424
 425 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 426                     Error **errp)
 427 {
 428     BDRVDMGState *s = bs->opaque;
 429     DmgHeaderState ds;
 430     uint64_t rsrc_fork_offset, rsrc_fork_length;
 431     uint64_t plist_xml_offset, plist_xml_length;
 432     int64_t offset;
 433     int ret;
 434
 435     bs->read_only = 1;
 436     s->n_chunks = 0;
 437     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 438     /* used by dmg_read_mish_block to keep track of the current I/O position */
 439     ds.data_fork_offset = 0;
 440     ds.max_compressed_size = 1;
 441     ds.max_sectors_per_chunk = 1;
 442
 443     /* locate the UDIF trailer */
 444     offset = dmg_find_koly_offset(bs->file, errp);
 445     if (offset < 0) {
 446         ret = offset;
 447         goto fail;
 448     }
 449
 450     /* offset of data fork (DataForkOffset) */
 451     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 452     if (ret < 0) {
 453         goto fail;
 454     } else if (ds.data_fork_offset > offset) {
 455         ret = -EINVAL;
 456         goto fail;
 457     }
 458
 459     /* offset of resource fork (RsrcForkOffset) */
 460     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 461     if (ret < 0) {
 462         goto fail;
 463     }
 464     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 465     if (ret < 0) {
 466         goto fail;
 467     }
 468     if (rsrc_fork_offset >= offset ||
 469         rsrc_fork_length > offset - rsrc_fork_offset) {
 470         ret = -EINVAL;
 471         goto fail;
 472     }
 473     /* offset of property list (XMLOffset) */
 474     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 475     if (ret < 0) {
 476         goto fail;
 477     }
 478     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 479     if (ret < 0) {
 480         goto fail;
 481     }
 482     if (plist_xml_offset >= offset ||
 483         plist_xml_length > offset - plist_xml_offset) {
 484         ret = -EINVAL;
 485         goto fail;
 486     }
 487     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 488     if (ret < 0) {
 489         goto fail;
 490     }
 491     if (bs->total_sectors < 0) {
 492         ret = -EINVAL;
 493         goto fail;
 494     }
 495     if (rsrc_fork_length != 0) {
 496         ret = dmg_read_resource_fork(bs, &ds,
 497                                      rsrc_fork_offset, rsrc_fork_length);
 498         if (ret < 0) {
 499             goto fail;
 500         }
 501     } else if (plist_xml_length != 0) {
 502         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 503         if (ret < 0) {
 504             goto fail;
 505         }
 506     } else {
 507         ret = -EINVAL;
 508         goto fail;
 509     }
 510
 511     /* initialize zlib engine */
 512     s->compressed_chunk = qemu_try_blockalign(bs->file,
 513                                               ds.max_compressed_size + 1);
 514     s->uncompressed_chunk = qemu_try_blockalign(bs->file,
 515                                                 512 * ds.max_sectors_per_chunk);
 516     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 517         ret = -ENOMEM;
 518         goto fail;
 519     }
 520
 521     if (inflateInit(&s->zstream) != Z_OK) {
 522         ret = -EINVAL;
 523         goto fail;
 524     }
 525
 526     s->current_chunk = s->n_chunks;
 527
 528     qemu_co_mutex_init(&s->lock);
 529     return 0;
 530
 531 fail:
 532     g_free(s->types);
 533     g_free(s->offsets);
 534     g_free(s->lengths);
 535     g_free(s->sectors);
 536     g_free(s->sectorcounts);
 537     qemu_vfree(s->compressed_chunk);
 538     qemu_vfree(s->uncompressed_chunk);
 539     return ret;
 540 }
 541
 542 static inline int is_sector_in_chunk(BDRVDMGState* s,
 543                 uint32_t chunk_num, uint64_t sector_num)
 544 {
 545     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 546             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 547         return 0;
 548     } else {
 549         return -1;
 550     }
 551 }
 552
 553 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 554 {
 555     /* binary search */
 556     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 557     while (chunk1 != chunk2) {
 558         chunk3 = (chunk1 + chunk2) / 2;
 559         if (s->sectors[chunk3] > sector_num) {
 560             chunk2 = chunk3;
 561         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 562             return chunk3;
 563         } else {
 564             chunk1 = chunk3;
 565         }
 566     }
 567     return s->n_chunks; /* error */
 568 }
 569
 570 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 571 {
 572     BDRVDMGState *s = bs->opaque;
 573
 574     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 575         int ret;
 576         uint32_t chunk = search_chunk(s, sector_num);
 577 #ifdef CONFIG_BZIP2
 578         uint64_t total_out;
 579 #endif
 580
 581         if (chunk >= s->n_chunks) {
 582             return -1;
 583         }
 584
 585         s->current_chunk = s->n_chunks;
 586         switch (s->types[chunk]) { /* block entry type */
 587         case 0x80000005: { /* zlib compressed */
 588             /* we need to buffer, because only the chunk as whole can be
 589              * inflated. */
 590             ret = bdrv_pread(bs->file, s->offsets[chunk],
 591                              s->compressed_chunk, s->lengths[chunk]);
 592             if (ret != s->lengths[chunk]) {
 593                 return -1;
 594             }
 595
 596             s->zstream.next_in = s->compressed_chunk;
 597             s->zstream.avail_in = s->lengths[chunk];
 598             s->zstream.next_out = s->uncompressed_chunk;
 599             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 600             ret = inflateReset(&s->zstream);
 601             if (ret != Z_OK) {
 602                 return -1;
 603             }
 604             ret = inflate(&s->zstream, Z_FINISH);
 605             if (ret != Z_STREAM_END ||
 606                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 607                 return -1;
 608             }
 609             break; }
 610 #ifdef CONFIG_BZIP2
 611         case 0x80000006: /* bzip2 compressed */
 612             /* we need to buffer, because only the chunk as whole can be
 613              * inflated. */
 614             ret = bdrv_pread(bs->file, s->offsets[chunk],
 615                              s->compressed_chunk, s->lengths[chunk]);
 616             if (ret != s->lengths[chunk]) {
 617                 return -1;
 618             }
 619
 620             ret = BZ2_bzDecompressInit(&s->bzstream, 0, 0);
 621             if (ret != BZ_OK) {
 622                 return -1;
 623             }
 624             s->bzstream.next_in = (char *)s->compressed_chunk;
 625             s->bzstream.avail_in = (unsigned int) s->lengths[chunk];
 626             s->bzstream.next_out = (char *)s->uncompressed_chunk;
 627             s->bzstream.avail_out = (unsigned int) 512 * s->sectorcounts[chunk];
 628             ret = BZ2_bzDecompress(&s->bzstream);
 629             total_out = ((uint64_t)s->bzstream.total_out_hi32 << 32) +
 630                         s->bzstream.total_out_lo32;
 631             BZ2_bzDecompressEnd(&s->bzstream);
 632             if (ret != BZ_STREAM_END ||
 633                 total_out != 512 * s->sectorcounts[chunk]) {
 634                 return -1;
 635             }
 636             break;
 637 #endif /* CONFIG_BZIP2 */
 638         case 1: /* copy */
 639             ret = bdrv_pread(bs->file, s->offsets[chunk],
 640                              s->uncompressed_chunk, s->lengths[chunk]);
 641             if (ret != s->lengths[chunk]) {
 642                 return -1;
 643             }
 644             break;
 645         case 2: /* zero */
 646             memset(s->uncompressed_chunk, 0, 512 * s->sectorcounts[chunk]);
 647             break;
 648         }
 649         s->current_chunk = chunk;
 650     }
 651     return 0;
 652 }
 653
 654 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
 655                     uint8_t *buf, int nb_sectors)
 656 {
 657     BDRVDMGState *s = bs->opaque;
 658     int i;
 659
 660     for (i = 0; i < nb_sectors; i++) {
 661         uint32_t sector_offset_in_chunk;
 662         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 663             return -1;
 664         }
 665         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 666         memcpy(buf + i * 512,
 667                s->uncompressed_chunk + sector_offset_in_chunk * 512, 512);
 668     }
 669     return 0;
 670 }
 671
 672 static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
 673                                     uint8_t *buf, int nb_sectors)
 674 {
 675     int ret;
 676     BDRVDMGState *s = bs->opaque;
 677     qemu_co_mutex_lock(&s->lock);
 678     ret = dmg_read(bs, sector_num, buf, nb_sectors);
 679     qemu_co_mutex_unlock(&s->lock);
 680     return ret;
 681 }
 682
 683 static void dmg_close(BlockDriverState *bs)
 684 {
 685     BDRVDMGState *s = bs->opaque;
 686
 687     g_free(s->types);
 688     g_free(s->offsets);
 689     g_free(s->lengths);
 690     g_free(s->sectors);
 691     g_free(s->sectorcounts);
 692     qemu_vfree(s->compressed_chunk);
 693     qemu_vfree(s->uncompressed_chunk);
 694
 695     inflateEnd(&s->zstream);
 696 }
 697
 698 static BlockDriver bdrv_dmg = {
 699     .format_name    = "dmg",
 700     .instance_size  = sizeof(BDRVDMGState),
 701     .bdrv_probe     = dmg_probe,
 702     .bdrv_open      = dmg_open,
 703     .bdrv_read      = dmg_co_read,
 704     .bdrv_close     = dmg_close,
 705 };
 706
 707 static void bdrv_dmg_init(void)
 708 {
 709     bdrv_register(&bdrv_dmg);
 710 }
 711
 712 block_init(bdrv_dmg_init);