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/osdep.h"
  25 #include "qapi/error.h"
  26 #include "qemu-common.h"
  27 #include "block/block_int.h"
  28 #include "qemu/bswap.h"
  29 #include "qemu/error-report.h"
  30 #include "qemu/module.h"
  31 #include <zlib.h>
  32 #ifdef CONFIG_BZIP2
  33 #include <bzlib.h>
  34 #endif
  35
  36 enum {
  37     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  38      * or truncating when converting to 32-bit types
  39      */
  40     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  41     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  42 };
  43
  44 typedef struct BDRVDMGState {
  45     CoMutex lock;
  46     /* each chunk contains a certain number of sectors,
  47      * offsets[i] is the offset in the .dmg file,
  48      * lengths[i] is the length of the compressed chunk,
  49      * sectors[i] is the sector beginning at offsets[i],
  50      * sectorcounts[i] is the number of sectors in that chunk,
  51      * the sectors array is ordered
  52      * 0<=i<n_chunks */
  53
  54     uint32_t n_chunks;
  55     uint32_t* types;
  56     uint64_t* offsets;
  57     uint64_t* lengths;
  58     uint64_t* sectors;
  59     uint64_t* sectorcounts;
  60     uint32_t current_chunk;
  61     uint8_t *compressed_chunk;
  62     uint8_t *uncompressed_chunk;
  63     z_stream zstream;
  64 #ifdef CONFIG_BZIP2
  65     bz_stream bzstream;
  66 #endif
  67 } BDRVDMGState;
  68
  69 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  70 {
  71     int len;
  72
  73     if (!filename) {
  74         return 0;
  75     }
  76
  77     len = strlen(filename);
  78     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  79         return 2;
  80     }
  81     return 0;
  82 }
  83
  84 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  85 {
  86     uint64_t buffer;
  87     int ret;
  88
  89     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  90     if (ret < 0) {
  91         return ret;
  92     }
  93
  94     *result = be64_to_cpu(buffer);
  95     return 0;
  96 }
  97
  98 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  99 {
 100     uint32_t buffer;
 101     int ret;
 102
 103     ret = bdrv_pread(bs->file, offset, &buffer, 4);
 104     if (ret < 0) {
 105         return ret;
 106     }
 107
 108     *result = be32_to_cpu(buffer);
 109     return 0;
 110 }
 111
 112 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 113 {
 114     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 115 }
 116
 117 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 118 {
 119     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 120 }
 121
 122 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 123  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 124  */
 125 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 126                                   uint32_t *max_compressed_size,
 127                                   uint32_t *max_sectors_per_chunk)
 128 {
 129     uint32_t compressed_size = 0;
 130     uint32_t uncompressed_sectors = 0;
 131
 132     switch (s->types[chunk]) {
 133     case 0x80000005: /* zlib compressed */
 134     case 0x80000006: /* bzip2 compressed */
 135         compressed_size = s->lengths[chunk];
 136         uncompressed_sectors = s->sectorcounts[chunk];
 137         break;
 138     case 1: /* copy */
 139         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 140         break;
 141     case 2: /* zero */
 142         /* as the all-zeroes block may be large, it is treated specially: the
 143          * sector is not copied from a large buffer, a simple memset is used
 144          * instead. Therefore uncompressed_sectors does not need to be set. */
 145         break;
 146     }
 147
 148     if (compressed_size > *max_compressed_size) {
 149         *max_compressed_size = compressed_size;
 150     }
 151     if (uncompressed_sectors > *max_sectors_per_chunk) {
 152         *max_sectors_per_chunk = uncompressed_sectors;
 153     }
 154 }
 155
 156 static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
 157 {
 158     BlockDriverState *file_bs = file->bs;
 159     int64_t length;
 160     int64_t offset = 0;
 161     uint8_t buffer[515];
 162     int i, ret;
 163
 164     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 165      * dmg images can have odd sizes, try to look for the "koly" magic which
 166      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 167      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 168      * the last sector (search space: 515 bytes) */
 169     length = bdrv_getlength(file_bs);
 170     if (length < 0) {
 171         error_setg_errno(errp, -length,
 172             "Failed to get file size while reading UDIF trailer");
 173         return length;
 174     } else if (length < 512) {
 175         error_setg(errp, "dmg file must be at least 512 bytes long");
 176         return -EINVAL;
 177     }
 178     if (length > 511 + 512) {
 179         offset = length - 511 - 512;
 180     }
 181     length = length < 515 ? length : 515;
 182     ret = bdrv_pread(file, offset, buffer, length);
 183     if (ret < 0) {
 184         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 185         return ret;
 186     }
 187     for (i = 0; i < length - 3; i++) {
 188         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 189             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 190             return offset + i;
 191         }
 192     }
 193     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 194     return -EINVAL;
 195 }
 196
 197 /* used when building the sector table */
 198 typedef struct DmgHeaderState {
 199     /* used internally by dmg_read_mish_block to remember offsets of blocks
 200      * across calls */
 201     uint64_t data_fork_offset;
 202     /* exported for dmg_open */
 203     uint32_t max_compressed_size;
 204     uint32_t max_sectors_per_chunk;
 205 } DmgHeaderState;
 206
 207 static bool dmg_is_known_block_type(uint32_t entry_type)
 208 {
 209     switch (entry_type) {
 210     case 0x00000001:    /* uncompressed */
 211     case 0x00000002:    /* zeroes */
 212     case 0x80000005:    /* zlib */
 213 #ifdef CONFIG_BZIP2
 214     case 0x80000006:    /* bzip2 */
 215 #endif
 216         return true;
 217     default:
 218         return false;
 219     }
 220 }
 221
 222 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 223                                uint8_t *buffer, uint32_t count)
 224 {
 225     uint32_t type, i;
 226     int ret;
 227     size_t new_size;
 228     uint32_t chunk_count;
 229     int64_t offset = 0;
 230     uint64_t data_offset;
 231     uint64_t in_offset = ds->data_fork_offset;
 232     uint64_t out_offset;
 233
 234     type = buff_read_uint32(buffer, offset);
 235     /* skip data that is not a valid MISH block (invalid magic or too small) */
 236     if (type != 0x6d697368 || count < 244) {
 237         /* assume success for now */
 238         return 0;
 239     }
 240
 241     /* chunk offsets are relative to this sector number */
 242     out_offset = buff_read_uint64(buffer, offset + 8);
 243
 244     /* location in data fork for (compressed) blob (in bytes) */
 245     data_offset = buff_read_uint64(buffer, offset + 0x18);
 246     in_offset += data_offset;
 247
 248     /* move to begin of chunk entries */
 249     offset += 204;
 250
 251     chunk_count = (count - 204) / 40;
 252     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 253     s->types = g_realloc(s->types, new_size / 2);
 254     s->offsets = g_realloc(s->offsets, new_size);
 255     s->lengths = g_realloc(s->lengths, new_size);
 256     s->sectors = g_realloc(s->sectors, new_size);
 257     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 258
 259     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 260         s->types[i] = buff_read_uint32(buffer, offset);
 261         if (!dmg_is_known_block_type(s->types[i])) {
 262             chunk_count--;
 263             i--;
 264             offset += 40;
 265             continue;
 266         }
 267
 268         /* sector number */
 269         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 270         s->sectors[i] += out_offset;
 271
 272         /* sector count */
 273         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 274
 275         /* all-zeroes sector (type 2) does not need to be "uncompressed" and can
 276          * therefore be unbounded. */
 277         if (s->types[i] != 2 && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 278             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 279                          " is larger than max (%u)",
 280                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 281             ret = -EINVAL;
 282             goto fail;
 283         }
 284
 285         /* offset in (compressed) data fork */
 286         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 287         s->offsets[i] += in_offset;
 288
 289         /* length in (compressed) data fork */
 290         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 291
 292         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 293             error_report("length %" PRIu64 " for chunk %" PRIu32
 294                          " is larger than max (%u)",
 295                          s->lengths[i], i, DMG_LENGTHS_MAX);
 296             ret = -EINVAL;
 297             goto fail;
 298         }
 299
 300         update_max_chunk_size(s, i, &ds->max_compressed_size,
 301                               &ds->max_sectors_per_chunk);
 302         offset += 40;
 303     }
 304     s->n_chunks += chunk_count;
 305     return 0;
 306
 307 fail:
 308     return ret;
 309 }
 310
 311 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 312                                   uint64_t info_begin, uint64_t info_length)
 313 {
 314     BDRVDMGState *s = bs->opaque;
 315     int ret;
 316     uint32_t count, rsrc_data_offset;
 317     uint8_t *buffer = NULL;
 318     uint64_t info_end;
 319     uint64_t offset;
 320
 321     /* read offset from begin of resource fork (info_begin) to resource data */
 322     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 323     if (ret < 0) {
 324         goto fail;
 325     } else if (rsrc_data_offset > info_length) {
 326         ret = -EINVAL;
 327         goto fail;
 328     }
 329
 330     /* read length of resource data */
 331     ret = read_uint32(bs, info_begin + 8, &count);
 332     if (ret < 0) {
 333         goto fail;
 334     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 335         ret = -EINVAL;
 336         goto fail;
 337     }
 338
 339     /* begin of resource data (consisting of one or more resources) */
 340     offset = info_begin + rsrc_data_offset;
 341
 342     /* end of resource data (there is possibly a following resource map
 343      * which will be ignored). */
 344     info_end = offset + count;
 345
 346     /* read offsets (mish blocks) from one or more resources in resource data */
 347     while (offset < info_end) {
 348         /* size of following resource */
 349         ret = read_uint32(bs, offset, &count);
 350         if (ret < 0) {
 351             goto fail;
 352         } else if (count == 0 || count > info_end - offset) {
 353             ret = -EINVAL;
 354             goto fail;
 355         }
 356         offset += 4;
 357
 358         buffer = g_realloc(buffer, count);
 359         ret = bdrv_pread(bs->file, offset, buffer, count);
 360         if (ret < 0) {
 361             goto fail;
 362         }
 363
 364         ret = dmg_read_mish_block(s, ds, buffer, count);
 365         if (ret < 0) {
 366             goto fail;
 367         }
 368         /* advance offset by size of resource */
 369         offset += count;
 370     }
 371     ret = 0;
 372
 373 fail:
 374     g_free(buffer);
 375     return ret;
 376 }
 377
 378 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 379                               uint64_t info_begin, uint64_t info_length)
 380 {
 381     BDRVDMGState *s = bs->opaque;
 382     int ret;
 383     uint8_t *buffer = NULL;
 384     char *data_begin, *data_end;
 385
 386     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 387      * safe upper cap on the data length. A test sample had a XML length of
 388      * about 1 MiB. */
 389     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 390         ret = -EINVAL;
 391         goto fail;
 392     }
 393
 394     buffer = g_malloc(info_length + 1);
 395     buffer[info_length] = '\0';
 396     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 397     if (ret != info_length) {
 398         ret = -EINVAL;
 399         goto fail;
 400     }
 401
 402     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 403      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 404      * and line feeds. */
 405     data_end = (char *)buffer;
 406     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 407         guchar *mish;
 408         gsize out_len = 0;
 409
 410         data_begin += 6;
 411         data_end = strstr(data_begin, "</data>");
 412         /* malformed XML? */
 413         if (data_end == NULL) {
 414             ret = -EINVAL;
 415             goto fail;
 416         }
 417         *data_end++ = '\0';
 418         mish = g_base64_decode(data_begin, &out_len);
 419         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 420         g_free(mish);
 421         if (ret < 0) {
 422             goto fail;
 423         }
 424     }
 425     ret = 0;
 426
 427 fail:
 428     g_free(buffer);
 429     return ret;
 430 }
 431
 432 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 433                     Error **errp)
 434 {
 435     BDRVDMGState *s = bs->opaque;
 436     DmgHeaderState ds;
 437     uint64_t rsrc_fork_offset, rsrc_fork_length;
 438     uint64_t plist_xml_offset, plist_xml_length;
 439     int64_t offset;
 440     int ret;
 441
 442     bs->read_only = true;
 443
 444     s->n_chunks = 0;
 445     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 446     /* used by dmg_read_mish_block to keep track of the current I/O position */
 447     ds.data_fork_offset = 0;
 448     ds.max_compressed_size = 1;
 449     ds.max_sectors_per_chunk = 1;
 450
 451     /* locate the UDIF trailer */
 452     offset = dmg_find_koly_offset(bs->file, errp);
 453     if (offset < 0) {
 454         ret = offset;
 455         goto fail;
 456     }
 457
 458     /* offset of data fork (DataForkOffset) */
 459     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 460     if (ret < 0) {
 461         goto fail;
 462     } else if (ds.data_fork_offset > offset) {
 463         ret = -EINVAL;
 464         goto fail;
 465     }
 466
 467     /* offset of resource fork (RsrcForkOffset) */
 468     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 469     if (ret < 0) {
 470         goto fail;
 471     }
 472     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 473     if (ret < 0) {
 474         goto fail;
 475     }
 476     if (rsrc_fork_offset >= offset ||
 477         rsrc_fork_length > offset - rsrc_fork_offset) {
 478         ret = -EINVAL;
 479         goto fail;
 480     }
 481     /* offset of property list (XMLOffset) */
 482     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 483     if (ret < 0) {
 484         goto fail;
 485     }
 486     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 487     if (ret < 0) {
 488         goto fail;
 489     }
 490     if (plist_xml_offset >= offset ||
 491         plist_xml_length > offset - plist_xml_offset) {
 492         ret = -EINVAL;
 493         goto fail;
 494     }
 495     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 496     if (ret < 0) {
 497         goto fail;
 498     }
 499     if (bs->total_sectors < 0) {
 500         ret = -EINVAL;
 501         goto fail;
 502     }
 503     if (rsrc_fork_length != 0) {
 504         ret = dmg_read_resource_fork(bs, &ds,
 505                                      rsrc_fork_offset, rsrc_fork_length);
 506         if (ret < 0) {
 507             goto fail;
 508         }
 509     } else if (plist_xml_length != 0) {
 510         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 511         if (ret < 0) {
 512             goto fail;
 513         }
 514     } else {
 515         ret = -EINVAL;
 516         goto fail;
 517     }
 518
 519     /* initialize zlib engine */
 520     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 521                                               ds.max_compressed_size + 1);
 522     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 523                                                 512 * ds.max_sectors_per_chunk);
 524     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 525         ret = -ENOMEM;
 526         goto fail;
 527     }
 528
 529     if (inflateInit(&s->zstream) != Z_OK) {
 530         ret = -EINVAL;
 531         goto fail;
 532     }
 533
 534     s->current_chunk = s->n_chunks;
 535
 536     qemu_co_mutex_init(&s->lock);
 537     return 0;
 538
 539 fail:
 540     g_free(s->types);
 541     g_free(s->offsets);
 542     g_free(s->lengths);
 543     g_free(s->sectors);
 544     g_free(s->sectorcounts);
 545     qemu_vfree(s->compressed_chunk);
 546     qemu_vfree(s->uncompressed_chunk);
 547     return ret;
 548 }
 549
 550 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 551 {
 552     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 553 }
 554
 555 static inline int is_sector_in_chunk(BDRVDMGState* s,
 556                 uint32_t chunk_num, uint64_t sector_num)
 557 {
 558     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 559             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 560         return 0;
 561     } else {
 562         return -1;
 563     }
 564 }
 565
 566 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 567 {
 568     /* binary search */
 569     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 570     while (chunk1 != chunk2) {
 571         chunk3 = (chunk1 + chunk2) / 2;
 572         if (s->sectors[chunk3] > sector_num) {
 573             chunk2 = chunk3;
 574         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 575             return chunk3;
 576         } else {
 577             chunk1 = chunk3;
 578         }
 579     }
 580     return s->n_chunks; /* error */
 581 }
 582
 583 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 584 {
 585     BDRVDMGState *s = bs->opaque;
 586
 587     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 588         int ret;
 589         uint32_t chunk = search_chunk(s, sector_num);
 590 #ifdef CONFIG_BZIP2
 591         uint64_t total_out;
 592 #endif
 593
 594         if (chunk >= s->n_chunks) {
 595             return -1;
 596         }
 597
 598         s->current_chunk = s->n_chunks;
 599         switch (s->types[chunk]) { /* block entry type */
 600         case 0x80000005: { /* zlib compressed */
 601             /* we need to buffer, because only the chunk as whole can be
 602              * inflated. */
 603             ret = bdrv_pread(bs->file, s->offsets[chunk],
 604                              s->compressed_chunk, s->lengths[chunk]);
 605             if (ret != s->lengths[chunk]) {
 606                 return -1;
 607             }
 608
 609             s->zstream.next_in = s->compressed_chunk;
 610             s->zstream.avail_in = s->lengths[chunk];
 611             s->zstream.next_out = s->uncompressed_chunk;
 612             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 613             ret = inflateReset(&s->zstream);
 614             if (ret != Z_OK) {
 615                 return -1;
 616             }
 617             ret = inflate(&s->zstream, Z_FINISH);
 618             if (ret != Z_STREAM_END ||
 619                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 620                 return -1;
 621             }
 622             break; }
 623 #ifdef CONFIG_BZIP2
 624         case 0x80000006: /* bzip2 compressed */
 625             /* we need to buffer, because only the chunk as whole can be
 626              * inflated. */
 627             ret = bdrv_pread(bs->file, s->offsets[chunk],
 628                              s->compressed_chunk, s->lengths[chunk]);
 629             if (ret != s->lengths[chunk]) {
 630                 return -1;
 631             }
 632
 633             ret = BZ2_bzDecompressInit(&s->bzstream, 0, 0);
 634             if (ret != BZ_OK) {
 635                 return -1;
 636             }
 637             s->bzstream.next_in = (char *)s->compressed_chunk;
 638             s->bzstream.avail_in = (unsigned int) s->lengths[chunk];
 639             s->bzstream.next_out = (char *)s->uncompressed_chunk;
 640             s->bzstream.avail_out = (unsigned int) 512 * s->sectorcounts[chunk];
 641             ret = BZ2_bzDecompress(&s->bzstream);
 642             total_out = ((uint64_t)s->bzstream.total_out_hi32 << 32) +
 643                         s->bzstream.total_out_lo32;
 644             BZ2_bzDecompressEnd(&s->bzstream);
 645             if (ret != BZ_STREAM_END ||
 646                 total_out != 512 * s->sectorcounts[chunk]) {
 647                 return -1;
 648             }
 649             break;
 650 #endif /* CONFIG_BZIP2 */
 651         case 1: /* copy */
 652             ret = bdrv_pread(bs->file, s->offsets[chunk],
 653                              s->uncompressed_chunk, s->lengths[chunk]);
 654             if (ret != s->lengths[chunk]) {
 655                 return -1;
 656             }
 657             break;
 658         case 2: /* zero */
 659             /* see dmg_read, it is treated specially. No buffer needs to be
 660              * pre-filled, the zeroes can be set directly. */
 661             break;
 662         }
 663         s->current_chunk = chunk;
 664     }
 665     return 0;
 666 }
 667
 668 static int coroutine_fn
 669 dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 670               QEMUIOVector *qiov, int flags)
 671 {
 672     BDRVDMGState *s = bs->opaque;
 673     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 674     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 675     int ret, i;
 676
 677     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 678     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 679
 680     qemu_co_mutex_lock(&s->lock);
 681
 682     for (i = 0; i < nb_sectors; i++) {
 683         uint32_t sector_offset_in_chunk;
 684         void *data;
 685
 686         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 687             ret = -EIO;
 688             goto fail;
 689         }
 690         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 691          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 692          * section. dmg_read_chunk is called to find s->current_chunk */
 693         if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
 694             qemu_iovec_memset(qiov, i * 512, 0, 512);
 695             continue;
 696         }
 697         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 698         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 699         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 700     }
 701
 702     ret = 0;
 703 fail:
 704     qemu_co_mutex_unlock(&s->lock);
 705     return ret;
 706 }
 707
 708 static void dmg_close(BlockDriverState *bs)
 709 {
 710     BDRVDMGState *s = bs->opaque;
 711
 712     g_free(s->types);
 713     g_free(s->offsets);
 714     g_free(s->lengths);
 715     g_free(s->sectors);
 716     g_free(s->sectorcounts);
 717     qemu_vfree(s->compressed_chunk);
 718     qemu_vfree(s->uncompressed_chunk);
 719
 720     inflateEnd(&s->zstream);
 721 }
 722
 723 static BlockDriver bdrv_dmg = {
 724     .format_name    = "dmg",
 725     .instance_size  = sizeof(BDRVDMGState),
 726     .bdrv_probe     = dmg_probe,
 727     .bdrv_open      = dmg_open,
 728     .bdrv_refresh_limits = dmg_refresh_limits,
 729     .bdrv_co_preadv = dmg_co_preadv,
 730     .bdrv_close     = dmg_close,
 731 };
 732
 733 static void bdrv_dmg_init(void)
 734 {
 735     bdrv_register(&bdrv_dmg);
 736 }
 737
 738 block_init(bdrv_dmg_init);