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 "block/block_int.h"
  27 #include "qemu/bswap.h"
  28 #include "qemu/error-report.h"
  29 #include "qemu/module.h"
  30 #include "qemu/memalign.h"
  31 #include "dmg.h"
  32
  33 int (*dmg_uncompress_bz2)(char *next_in, unsigned int avail_in,
  34                           char *next_out, unsigned int avail_out);
  35
  36 int (*dmg_uncompress_lzfse)(char *next_in, unsigned int avail_in,
  37                             char *next_out, unsigned int avail_out);
  38
  39 enum {
  40     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  41      * or truncating when converting to 32-bit types
  42      */
  43     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  44     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  45 };
  46
  47 enum {
  48     /* DMG Block Type */
  49     UDZE = 0, /* Zeroes */
  50     UDRW,     /* RAW type */
  51     UDIG,     /* Ignore */
  52     UDCO = 0x80000004,
  53     UDZO,
  54     UDBZ,
  55     ULFO,
  56     UDCM = 0x7ffffffe, /* Comments */
  57     UDLE = 0xffffffff  /* Last Entry */
  58 };
  59
  60 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  61 {
  62     int len;
  63
  64     if (!filename) {
  65         return 0;
  66     }
  67
  68     len = strlen(filename);
  69     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  70         return 2;
  71     }
  72     return 0;
  73 }
  74
  75 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  76 {
  77     uint64_t buffer;
  78     int ret;
  79
  80     ret = bdrv_pread(bs->file, offset, 8, &buffer, 0);
  81     if (ret < 0) {
  82         return ret;
  83     }
  84
  85     *result = be64_to_cpu(buffer);
  86     return 0;
  87 }
  88
  89 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  90 {
  91     uint32_t buffer;
  92     int ret;
  93
  94     ret = bdrv_pread(bs->file, offset, 4, &buffer, 0);
  95     if (ret < 0) {
  96         return ret;
  97     }
  98
  99     *result = be32_to_cpu(buffer);
 100     return 0;
 101 }
 102
 103 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 104 {
 105     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 106 }
 107
 108 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 109 {
 110     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 111 }
 112
 113 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 114  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 115  */
 116 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 117                                   uint32_t *max_compressed_size,
 118                                   uint32_t *max_sectors_per_chunk)
 119 {
 120     uint32_t compressed_size = 0;
 121     uint32_t uncompressed_sectors = 0;
 122
 123     switch (s->types[chunk]) {
 124     case UDZO: /* zlib compressed */
 125     case UDBZ: /* bzip2 compressed */
 126     case ULFO: /* lzfse compressed */
 127         compressed_size = s->lengths[chunk];
 128         uncompressed_sectors = s->sectorcounts[chunk];
 129         break;
 130     case UDRW: /* copy */
 131         uncompressed_sectors = DIV_ROUND_UP(s->lengths[chunk], 512);
 132         break;
 133     case UDZE: /* zero */
 134     case UDIG: /* ignore */
 135         /* as the all-zeroes block may be large, it is treated specially: the
 136          * sector is not copied from a large buffer, a simple memset is used
 137          * instead. Therefore uncompressed_sectors does not need to be set. */
 138         break;
 139     }
 140
 141     if (compressed_size > *max_compressed_size) {
 142         *max_compressed_size = compressed_size;
 143     }
 144     if (uncompressed_sectors > *max_sectors_per_chunk) {
 145         *max_sectors_per_chunk = uncompressed_sectors;
 146     }
 147 }
 148
 149 static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
 150 {
 151     BlockDriverState *file_bs = file->bs;
 152     int64_t length;
 153     int64_t offset = 0;
 154     uint8_t buffer[515];
 155     int i, ret;
 156
 157     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 158      * dmg images can have odd sizes, try to look for the "koly" magic which
 159      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 160      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 161      * the last sector (search space: 515 bytes) */
 162     length = bdrv_getlength(file_bs);
 163     if (length < 0) {
 164         error_setg_errno(errp, -length,
 165             "Failed to get file size while reading UDIF trailer");
 166         return length;
 167     } else if (length < 512) {
 168         error_setg(errp, "dmg file must be at least 512 bytes long");
 169         return -EINVAL;
 170     }
 171     if (length > 511 + 512) {
 172         offset = length - 511 - 512;
 173     }
 174     length = length < 515 ? length : 515;
 175     ret = bdrv_pread(file, offset, length, buffer, 0);
 176     if (ret < 0) {
 177         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 178         return ret;
 179     }
 180     for (i = 0; i < length - 3; i++) {
 181         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 182             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 183             return offset + i;
 184         }
 185     }
 186     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 187     return -EINVAL;
 188 }
 189
 190 /* used when building the sector table */
 191 typedef struct DmgHeaderState {
 192     /* used internally by dmg_read_mish_block to remember offsets of blocks
 193      * across calls */
 194     uint64_t data_fork_offset;
 195     /* exported for dmg_open */
 196     uint32_t max_compressed_size;
 197     uint32_t max_sectors_per_chunk;
 198 } DmgHeaderState;
 199
 200 static bool dmg_is_known_block_type(uint32_t entry_type)
 201 {
 202     switch (entry_type) {
 203     case UDZE:    /* zeros */
 204     case UDRW:    /* uncompressed */
 205     case UDIG:    /* ignore */
 206     case UDZO:    /* zlib */
 207         return true;
 208     case UDBZ:    /* bzip2 */
 209         return !!dmg_uncompress_bz2;
 210     case ULFO:    /* lzfse */
 211         return !!dmg_uncompress_lzfse;
 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             switch (s->types[i]) {
 258             case UDBZ:
 259                 warn_report_once("dmg-bzip2 module is missing, accessing bzip2 "
 260                                  "compressed blocks will result in I/O errors");
 261                 break;
 262             case ULFO:
 263                 warn_report_once("dmg-lzfse module is missing, accessing lzfse "
 264                                  "compressed blocks will result in I/O errors");
 265                 break;
 266             case UDCM:
 267             case UDLE:
 268                 /* Comments and last entry can be ignored without problems */
 269                 break;
 270             default:
 271                 warn_report_once("Image contains chunks of unknown type %x, "
 272                                  "accessing them will result in I/O errors",
 273                                  s->types[i]);
 274                 break;
 275             }
 276             chunk_count--;
 277             i--;
 278             offset += 40;
 279             continue;
 280         }
 281
 282         /* sector number */
 283         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 284         s->sectors[i] += out_offset;
 285
 286         /* sector count */
 287         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 288
 289         /* all-zeroes sector (type UDZE and UDIG) does not need to be
 290          * "uncompressed" and can therefore be unbounded. */
 291         if (s->types[i] != UDZE && s->types[i] != UDIG
 292             && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 293             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 294                          " is larger than max (%u)",
 295                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 296             ret = -EINVAL;
 297             goto fail;
 298         }
 299
 300         /* offset in (compressed) data fork */
 301         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 302         s->offsets[i] += in_offset;
 303
 304         /* length in (compressed) data fork */
 305         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 306
 307         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 308             error_report("length %" PRIu64 " for chunk %" PRIu32
 309                          " is larger than max (%u)",
 310                          s->lengths[i], i, DMG_LENGTHS_MAX);
 311             ret = -EINVAL;
 312             goto fail;
 313         }
 314
 315         update_max_chunk_size(s, i, &ds->max_compressed_size,
 316                               &ds->max_sectors_per_chunk);
 317         offset += 40;
 318     }
 319     s->n_chunks += chunk_count;
 320     return 0;
 321
 322 fail:
 323     return ret;
 324 }
 325
 326 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 327                                   uint64_t info_begin, uint64_t info_length)
 328 {
 329     BDRVDMGState *s = bs->opaque;
 330     int ret;
 331     uint32_t count, rsrc_data_offset;
 332     uint8_t *buffer = NULL;
 333     uint64_t info_end;
 334     uint64_t offset;
 335
 336     /* read offset from begin of resource fork (info_begin) to resource data */
 337     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 338     if (ret < 0) {
 339         goto fail;
 340     } else if (rsrc_data_offset > info_length) {
 341         ret = -EINVAL;
 342         goto fail;
 343     }
 344
 345     /* read length of resource data */
 346     ret = read_uint32(bs, info_begin + 8, &count);
 347     if (ret < 0) {
 348         goto fail;
 349     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 350         ret = -EINVAL;
 351         goto fail;
 352     }
 353
 354     /* begin of resource data (consisting of one or more resources) */
 355     offset = info_begin + rsrc_data_offset;
 356
 357     /* end of resource data (there is possibly a following resource map
 358      * which will be ignored). */
 359     info_end = offset + count;
 360
 361     /* read offsets (mish blocks) from one or more resources in resource data */
 362     while (offset < info_end) {
 363         /* size of following resource */
 364         ret = read_uint32(bs, offset, &count);
 365         if (ret < 0) {
 366             goto fail;
 367         } else if (count == 0 || count > info_end - offset) {
 368             ret = -EINVAL;
 369             goto fail;
 370         }
 371         offset += 4;
 372
 373         buffer = g_realloc(buffer, count);
 374         ret = bdrv_pread(bs->file, offset, count, buffer, 0);
 375         if (ret < 0) {
 376             goto fail;
 377         }
 378
 379         ret = dmg_read_mish_block(s, ds, buffer, count);
 380         if (ret < 0) {
 381             goto fail;
 382         }
 383         /* advance offset by size of resource */
 384         offset += count;
 385     }
 386     ret = 0;
 387
 388 fail:
 389     g_free(buffer);
 390     return ret;
 391 }
 392
 393 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 394                               uint64_t info_begin, uint64_t info_length)
 395 {
 396     BDRVDMGState *s = bs->opaque;
 397     int ret;
 398     uint8_t *buffer = NULL;
 399     char *data_begin, *data_end;
 400
 401     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 402      * safe upper cap on the data length. A test sample had a XML length of
 403      * about 1 MiB. */
 404     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 405         ret = -EINVAL;
 406         goto fail;
 407     }
 408
 409     buffer = g_malloc(info_length + 1);
 410     buffer[info_length] = '\0';
 411     ret = bdrv_pread(bs->file, info_begin, info_length, buffer, 0);
 412     if (ret < 0) {
 413         ret = -EINVAL;
 414         goto fail;
 415     }
 416
 417     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 418      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 419      * and line feeds. */
 420     data_end = (char *)buffer;
 421     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 422         guchar *mish;
 423         gsize out_len = 0;
 424
 425         data_begin += 6;
 426         data_end = strstr(data_begin, "</data>");
 427         /* malformed XML? */
 428         if (data_end == NULL) {
 429             ret = -EINVAL;
 430             goto fail;
 431         }
 432         *data_end++ = '\0';
 433         mish = g_base64_decode(data_begin, &out_len);
 434         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 435         g_free(mish);
 436         if (ret < 0) {
 437             goto fail;
 438         }
 439     }
 440     ret = 0;
 441
 442 fail:
 443     g_free(buffer);
 444     return ret;
 445 }
 446
 447 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 448                     Error **errp)
 449 {
 450     BDRVDMGState *s = bs->opaque;
 451     DmgHeaderState ds;
 452     uint64_t rsrc_fork_offset, rsrc_fork_length;
 453     uint64_t plist_xml_offset, plist_xml_length;
 454     int64_t offset;
 455     int ret;
 456
 457     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
 458     if (ret < 0) {
 459         return ret;
 460     }
 461
 462     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
 463     if (ret < 0) {
 464         return ret;
 465     }
 466     /*
 467      * NB: if uncompress submodules are absent,
 468      * ie block_module_load return value == 0, the function pointers
 469      * dmg_uncompress_bz2 and dmg_uncompress_lzfse will be NULL.
 470      */
 471     if (block_module_load("dmg-bz2", errp) < 0) {
 472         return -EINVAL;
 473     }
 474     if (block_module_load("dmg-lzfse", errp) < 0) {
 475         return -EINVAL;
 476     }
 477
 478     s->n_chunks = 0;
 479     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 480     /* used by dmg_read_mish_block to keep track of the current I/O position */
 481     ds.data_fork_offset = 0;
 482     ds.max_compressed_size = 1;
 483     ds.max_sectors_per_chunk = 1;
 484
 485     /* locate the UDIF trailer */
 486     offset = dmg_find_koly_offset(bs->file, errp);
 487     if (offset < 0) {
 488         ret = offset;
 489         goto fail;
 490     }
 491
 492     /* offset of data fork (DataForkOffset) */
 493     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 494     if (ret < 0) {
 495         goto fail;
 496     } else if (ds.data_fork_offset > offset) {
 497         ret = -EINVAL;
 498         goto fail;
 499     }
 500
 501     /* offset of resource fork (RsrcForkOffset) */
 502     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 503     if (ret < 0) {
 504         goto fail;
 505     }
 506     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 507     if (ret < 0) {
 508         goto fail;
 509     }
 510     if (rsrc_fork_offset >= offset ||
 511         rsrc_fork_length > offset - rsrc_fork_offset) {
 512         ret = -EINVAL;
 513         goto fail;
 514     }
 515     /* offset of property list (XMLOffset) */
 516     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 517     if (ret < 0) {
 518         goto fail;
 519     }
 520     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 521     if (ret < 0) {
 522         goto fail;
 523     }
 524     if (plist_xml_offset >= offset ||
 525         plist_xml_length > offset - plist_xml_offset) {
 526         ret = -EINVAL;
 527         goto fail;
 528     }
 529     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 530     if (ret < 0) {
 531         goto fail;
 532     }
 533     if (bs->total_sectors < 0) {
 534         ret = -EINVAL;
 535         goto fail;
 536     }
 537     if (rsrc_fork_length != 0) {
 538         ret = dmg_read_resource_fork(bs, &ds,
 539                                      rsrc_fork_offset, rsrc_fork_length);
 540         if (ret < 0) {
 541             goto fail;
 542         }
 543     } else if (plist_xml_length != 0) {
 544         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 545         if (ret < 0) {
 546             goto fail;
 547         }
 548     } else {
 549         ret = -EINVAL;
 550         goto fail;
 551     }
 552
 553     /* initialize zlib engine */
 554     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 555                                               ds.max_compressed_size + 1);
 556     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 557                                                 512 * ds.max_sectors_per_chunk);
 558     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 559         ret = -ENOMEM;
 560         goto fail;
 561     }
 562
 563     if (inflateInit(&s->zstream) != Z_OK) {
 564         ret = -EINVAL;
 565         goto fail;
 566     }
 567
 568     s->current_chunk = s->n_chunks;
 569
 570     qemu_co_mutex_init(&s->lock);
 571     return 0;
 572
 573 fail:
 574     g_free(s->types);
 575     g_free(s->offsets);
 576     g_free(s->lengths);
 577     g_free(s->sectors);
 578     g_free(s->sectorcounts);
 579     qemu_vfree(s->compressed_chunk);
 580     qemu_vfree(s->uncompressed_chunk);
 581     return ret;
 582 }
 583
 584 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 585 {
 586     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 587 }
 588
 589 static inline int is_sector_in_chunk(BDRVDMGState *s,
 590                 uint32_t chunk_num, uint64_t sector_num)
 591 {
 592     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 593             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 594         return 0;
 595     } else {
 596         return -1;
 597     }
 598 }
 599
 600 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 601 {
 602     /* binary search */
 603     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 604     while (chunk1 <= chunk2) {
 605         chunk3 = (chunk1 + chunk2) / 2;
 606         if (s->sectors[chunk3] > sector_num) {
 607             if (chunk3 == 0) {
 608                 goto err;
 609             }
 610             chunk2 = chunk3 - 1;
 611         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 612             return chunk3;
 613         } else {
 614             chunk1 = chunk3 + 1;
 615         }
 616     }
 617 err:
 618     return s->n_chunks; /* error */
 619 }
 620
 621 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 622 {
 623     BDRVDMGState *s = bs->opaque;
 624
 625     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 626         int ret;
 627         uint32_t chunk = search_chunk(s, sector_num);
 628
 629         if (chunk >= s->n_chunks) {
 630             return -1;
 631         }
 632
 633         s->current_chunk = s->n_chunks;
 634         switch (s->types[chunk]) { /* block entry type */
 635         case UDZO: { /* zlib compressed */
 636             /* we need to buffer, because only the chunk as whole can be
 637              * inflated. */
 638             ret = bdrv_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
 639                              s->compressed_chunk, 0);
 640             if (ret < 0) {
 641                 return -1;
 642             }
 643
 644             s->zstream.next_in = s->compressed_chunk;
 645             s->zstream.avail_in = s->lengths[chunk];
 646             s->zstream.next_out = s->uncompressed_chunk;
 647             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 648             ret = inflateReset(&s->zstream);
 649             if (ret != Z_OK) {
 650                 return -1;
 651             }
 652             ret = inflate(&s->zstream, Z_FINISH);
 653             if (ret != Z_STREAM_END ||
 654                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 655                 return -1;
 656             }
 657             break; }
 658         case UDBZ: /* bzip2 compressed */
 659             if (!dmg_uncompress_bz2) {
 660                 break;
 661             }
 662             /* we need to buffer, because only the chunk as whole can be
 663              * inflated. */
 664             ret = bdrv_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
 665                              s->compressed_chunk, 0);
 666             if (ret < 0) {
 667                 return -1;
 668             }
 669
 670             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
 671                                      (unsigned int) s->lengths[chunk],
 672                                      (char *)s->uncompressed_chunk,
 673                                      (unsigned int)
 674                                          (512 * s->sectorcounts[chunk]));
 675             if (ret < 0) {
 676                 return ret;
 677             }
 678             break;
 679         case ULFO:
 680             if (!dmg_uncompress_lzfse) {
 681                 break;
 682             }
 683             /* we need to buffer, because only the chunk as whole can be
 684              * inflated. */
 685             ret = bdrv_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
 686                              s->compressed_chunk, 0);
 687             if (ret < 0) {
 688                 return -1;
 689             }
 690
 691             ret = dmg_uncompress_lzfse((char *)s->compressed_chunk,
 692                                        (unsigned int) s->lengths[chunk],
 693                                        (char *)s->uncompressed_chunk,
 694                                        (unsigned int)
 695                                            (512 * s->sectorcounts[chunk]));
 696             if (ret < 0) {
 697                 return ret;
 698             }
 699             break;
 700         case UDRW: /* copy */
 701             ret = bdrv_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
 702                              s->uncompressed_chunk, 0);
 703             if (ret < 0) {
 704                 return -1;
 705             }
 706             break;
 707         case UDZE: /* zeros */
 708         case UDIG: /* ignore */
 709             /* see dmg_read, it is treated specially. No buffer needs to be
 710              * pre-filled, the zeroes can be set directly. */
 711             break;
 712         }
 713         s->current_chunk = chunk;
 714     }
 715     return 0;
 716 }
 717
 718 static int coroutine_fn
 719 dmg_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 720               QEMUIOVector *qiov, BdrvRequestFlags flags)
 721 {
 722     BDRVDMGState *s = bs->opaque;
 723     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 724     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 725     int ret, i;
 726
 727     assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 728     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 729
 730     qemu_co_mutex_lock(&s->lock);
 731
 732     for (i = 0; i < nb_sectors; i++) {
 733         uint32_t sector_offset_in_chunk;
 734         void *data;
 735
 736         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 737             ret = -EIO;
 738             goto fail;
 739         }
 740         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 741          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 742          * section. dmg_read_chunk is called to find s->current_chunk */
 743         if (s->types[s->current_chunk] == UDZE
 744             || s->types[s->current_chunk] == UDIG) { /* all zeroes block entry */
 745             qemu_iovec_memset(qiov, i * 512, 0, 512);
 746             continue;
 747         }
 748         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 749         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 750         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 751     }
 752
 753     ret = 0;
 754 fail:
 755     qemu_co_mutex_unlock(&s->lock);
 756     return ret;
 757 }
 758
 759 static void dmg_close(BlockDriverState *bs)
 760 {
 761     BDRVDMGState *s = bs->opaque;
 762
 763     g_free(s->types);
 764     g_free(s->offsets);
 765     g_free(s->lengths);
 766     g_free(s->sectors);
 767     g_free(s->sectorcounts);
 768     qemu_vfree(s->compressed_chunk);
 769     qemu_vfree(s->uncompressed_chunk);
 770
 771     inflateEnd(&s->zstream);
 772 }
 773
 774 static BlockDriver bdrv_dmg = {
 775     .format_name    = "dmg",
 776     .instance_size  = sizeof(BDRVDMGState),
 777     .bdrv_probe     = dmg_probe,
 778     .bdrv_open      = dmg_open,
 779     .bdrv_refresh_limits = dmg_refresh_limits,
 780     .bdrv_child_perm     = bdrv_default_perms,
 781     .bdrv_co_preadv = dmg_co_preadv,
 782     .bdrv_close     = dmg_close,
 783     .is_format      = true,
 784 };
 785
 786 static void bdrv_dmg_init(void)
 787 {
 788     bdrv_register(&bdrv_dmg);
 789 }
 790
 791 block_init(bdrv_dmg_init);