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 "dmg.h"
  31
  32 int (*dmg_uncompress_bz2)(char *next_in, unsigned int avail_in,
  33                           char *next_out, unsigned int avail_out);
  34
  35 int (*dmg_uncompress_lzfse)(char *next_in, unsigned int avail_in,
  36                             char *next_out, unsigned int avail_out);
  37
  38 enum {
  39     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  40      * or truncating when converting to 32-bit types
  41      */
  42     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  43     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  44 };
  45
  46 enum {
  47     /* DMG Block Type */
  48     UDZE = 0, /* Zeroes */
  49     UDRW,     /* RAW type */
  50     UDIG,     /* Ignore */
  51     UDCO = 0x80000004,
  52     UDZO,
  53     UDBZ,
  54     ULFO,
  55     UDCM = 0x7ffffffe, /* Comments */
  56     UDLE = 0xffffffff  /* Last Entry */
  57 };
  58
  59 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  60 {
  61     int len;
  62
  63     if (!filename) {
  64         return 0;
  65     }
  66
  67     len = strlen(filename);
  68     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  69         return 2;
  70     }
  71     return 0;
  72 }
  73
  74 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  75 {
  76     uint64_t buffer;
  77     int ret;
  78
  79     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  80     if (ret < 0) {
  81         return ret;
  82     }
  83
  84     *result = be64_to_cpu(buffer);
  85     return 0;
  86 }
  87
  88 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  89 {
  90     uint32_t buffer;
  91     int ret;
  92
  93     ret = bdrv_pread(bs->file, offset, &buffer, 4);
  94     if (ret < 0) {
  95         return ret;
  96     }
  97
  98     *result = be32_to_cpu(buffer);
  99     return 0;
 100 }
 101
 102 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 103 {
 104     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 105 }
 106
 107 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 108 {
 109     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 110 }
 111
 112 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 113  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 114  */
 115 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 116                                   uint32_t *max_compressed_size,
 117                                   uint32_t *max_sectors_per_chunk)
 118 {
 119     uint32_t compressed_size = 0;
 120     uint32_t uncompressed_sectors = 0;
 121
 122     switch (s->types[chunk]) {
 123     case UDZO: /* zlib compressed */
 124     case UDBZ: /* bzip2 compressed */
 125     case ULFO: /* lzfse compressed */
 126         compressed_size = s->lengths[chunk];
 127         uncompressed_sectors = s->sectorcounts[chunk];
 128         break;
 129     case UDRW: /* copy */
 130         uncompressed_sectors = DIV_ROUND_UP(s->lengths[chunk], 512);
 131         break;
 132     case UDZE: /* zero */
 133     case UDIG: /* ignore */
 134         /* as the all-zeroes block may be large, it is treated specially: the
 135          * sector is not copied from a large buffer, a simple memset is used
 136          * instead. Therefore uncompressed_sectors does not need to be set. */
 137         break;
 138     }
 139
 140     if (compressed_size > *max_compressed_size) {
 141         *max_compressed_size = compressed_size;
 142     }
 143     if (uncompressed_sectors > *max_sectors_per_chunk) {
 144         *max_sectors_per_chunk = uncompressed_sectors;
 145     }
 146 }
 147
 148 static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
 149 {
 150     BlockDriverState *file_bs = file->bs;
 151     int64_t length;
 152     int64_t offset = 0;
 153     uint8_t buffer[515];
 154     int i, ret;
 155
 156     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 157      * dmg images can have odd sizes, try to look for the "koly" magic which
 158      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 159      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 160      * the last sector (search space: 515 bytes) */
 161     length = bdrv_getlength(file_bs);
 162     if (length < 0) {
 163         error_setg_errno(errp, -length,
 164             "Failed to get file size while reading UDIF trailer");
 165         return length;
 166     } else if (length < 512) {
 167         error_setg(errp, "dmg file must be at least 512 bytes long");
 168         return -EINVAL;
 169     }
 170     if (length > 511 + 512) {
 171         offset = length - 511 - 512;
 172     }
 173     length = length < 515 ? length : 515;
 174     ret = bdrv_pread(file, offset, buffer, length);
 175     if (ret < 0) {
 176         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 177         return ret;
 178     }
 179     for (i = 0; i < length - 3; i++) {
 180         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 181             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 182             return offset + i;
 183         }
 184     }
 185     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 186     return -EINVAL;
 187 }
 188
 189 /* used when building the sector table */
 190 typedef struct DmgHeaderState {
 191     /* used internally by dmg_read_mish_block to remember offsets of blocks
 192      * across calls */
 193     uint64_t data_fork_offset;
 194     /* exported for dmg_open */
 195     uint32_t max_compressed_size;
 196     uint32_t max_sectors_per_chunk;
 197 } DmgHeaderState;
 198
 199 static bool dmg_is_known_block_type(uint32_t entry_type)
 200 {
 201     switch (entry_type) {
 202     case UDZE:    /* zeros */
 203     case UDRW:    /* uncompressed */
 204     case UDIG:    /* ignore */
 205     case UDZO:    /* zlib */
 206         return true;
 207     case UDBZ:    /* bzip2 */
 208         return !!dmg_uncompress_bz2;
 209     case ULFO:    /* lzfse */
 210         return !!dmg_uncompress_lzfse;
 211     default:
 212         return false;
 213     }
 214 }
 215
 216 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 217                                uint8_t *buffer, uint32_t count)
 218 {
 219     uint32_t type, i;
 220     int ret;
 221     size_t new_size;
 222     uint32_t chunk_count;
 223     int64_t offset = 0;
 224     uint64_t data_offset;
 225     uint64_t in_offset = ds->data_fork_offset;
 226     uint64_t out_offset;
 227
 228     type = buff_read_uint32(buffer, offset);
 229     /* skip data that is not a valid MISH block (invalid magic or too small) */
 230     if (type != 0x6d697368 || count < 244) {
 231         /* assume success for now */
 232         return 0;
 233     }
 234
 235     /* chunk offsets are relative to this sector number */
 236     out_offset = buff_read_uint64(buffer, offset + 8);
 237
 238     /* location in data fork for (compressed) blob (in bytes) */
 239     data_offset = buff_read_uint64(buffer, offset + 0x18);
 240     in_offset += data_offset;
 241
 242     /* move to begin of chunk entries */
 243     offset += 204;
 244
 245     chunk_count = (count - 204) / 40;
 246     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 247     s->types = g_realloc(s->types, new_size / 2);
 248     s->offsets = g_realloc(s->offsets, new_size);
 249     s->lengths = g_realloc(s->lengths, new_size);
 250     s->sectors = g_realloc(s->sectors, new_size);
 251     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 252
 253     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 254         s->types[i] = buff_read_uint32(buffer, offset);
 255         if (!dmg_is_known_block_type(s->types[i])) {
 256             chunk_count--;
 257             i--;
 258             offset += 40;
 259             continue;
 260         }
 261
 262         /* sector number */
 263         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 264         s->sectors[i] += out_offset;
 265
 266         /* sector count */
 267         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 268
 269         /* all-zeroes sector (type UDZE and UDIG) does not need to be
 270          * "uncompressed" and can therefore be unbounded. */
 271         if (s->types[i] != UDZE && s->types[i] != UDIG
 272             && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 273             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 274                          " is larger than max (%u)",
 275                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 276             ret = -EINVAL;
 277             goto fail;
 278         }
 279
 280         /* offset in (compressed) data fork */
 281         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 282         s->offsets[i] += in_offset;
 283
 284         /* length in (compressed) data fork */
 285         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 286
 287         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 288             error_report("length %" PRIu64 " for chunk %" PRIu32
 289                          " is larger than max (%u)",
 290                          s->lengths[i], i, DMG_LENGTHS_MAX);
 291             ret = -EINVAL;
 292             goto fail;
 293         }
 294
 295         update_max_chunk_size(s, i, &ds->max_compressed_size,
 296                               &ds->max_sectors_per_chunk);
 297         offset += 40;
 298     }
 299     s->n_chunks += chunk_count;
 300     return 0;
 301
 302 fail:
 303     return ret;
 304 }
 305
 306 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 307                                   uint64_t info_begin, uint64_t info_length)
 308 {
 309     BDRVDMGState *s = bs->opaque;
 310     int ret;
 311     uint32_t count, rsrc_data_offset;
 312     uint8_t *buffer = NULL;
 313     uint64_t info_end;
 314     uint64_t offset;
 315
 316     /* read offset from begin of resource fork (info_begin) to resource data */
 317     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 318     if (ret < 0) {
 319         goto fail;
 320     } else if (rsrc_data_offset > info_length) {
 321         ret = -EINVAL;
 322         goto fail;
 323     }
 324
 325     /* read length of resource data */
 326     ret = read_uint32(bs, info_begin + 8, &count);
 327     if (ret < 0) {
 328         goto fail;
 329     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 330         ret = -EINVAL;
 331         goto fail;
 332     }
 333
 334     /* begin of resource data (consisting of one or more resources) */
 335     offset = info_begin + rsrc_data_offset;
 336
 337     /* end of resource data (there is possibly a following resource map
 338      * which will be ignored). */
 339     info_end = offset + count;
 340
 341     /* read offsets (mish blocks) from one or more resources in resource data */
 342     while (offset < info_end) {
 343         /* size of following resource */
 344         ret = read_uint32(bs, offset, &count);
 345         if (ret < 0) {
 346             goto fail;
 347         } else if (count == 0 || count > info_end - offset) {
 348             ret = -EINVAL;
 349             goto fail;
 350         }
 351         offset += 4;
 352
 353         buffer = g_realloc(buffer, count);
 354         ret = bdrv_pread(bs->file, offset, buffer, count);
 355         if (ret < 0) {
 356             goto fail;
 357         }
 358
 359         ret = dmg_read_mish_block(s, ds, buffer, count);
 360         if (ret < 0) {
 361             goto fail;
 362         }
 363         /* advance offset by size of resource */
 364         offset += count;
 365     }
 366     ret = 0;
 367
 368 fail:
 369     g_free(buffer);
 370     return ret;
 371 }
 372
 373 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 374                               uint64_t info_begin, uint64_t info_length)
 375 {
 376     BDRVDMGState *s = bs->opaque;
 377     int ret;
 378     uint8_t *buffer = NULL;
 379     char *data_begin, *data_end;
 380
 381     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 382      * safe upper cap on the data length. A test sample had a XML length of
 383      * about 1 MiB. */
 384     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 385         ret = -EINVAL;
 386         goto fail;
 387     }
 388
 389     buffer = g_malloc(info_length + 1);
 390     buffer[info_length] = '\0';
 391     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 392     if (ret != info_length) {
 393         ret = -EINVAL;
 394         goto fail;
 395     }
 396
 397     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 398      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 399      * and line feeds. */
 400     data_end = (char *)buffer;
 401     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 402         guchar *mish;
 403         gsize out_len = 0;
 404
 405         data_begin += 6;
 406         data_end = strstr(data_begin, "</data>");
 407         /* malformed XML? */
 408         if (data_end == NULL) {
 409             ret = -EINVAL;
 410             goto fail;
 411         }
 412         *data_end++ = '\0';
 413         mish = g_base64_decode(data_begin, &out_len);
 414         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 415         g_free(mish);
 416         if (ret < 0) {
 417             goto fail;
 418         }
 419     }
 420     ret = 0;
 421
 422 fail:
 423     g_free(buffer);
 424     return ret;
 425 }
 426
 427 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 428                     Error **errp)
 429 {
 430     BDRVDMGState *s = bs->opaque;
 431     DmgHeaderState ds;
 432     uint64_t rsrc_fork_offset, rsrc_fork_length;
 433     uint64_t plist_xml_offset, plist_xml_length;
 434     int64_t offset;
 435     int ret;
 436
 437     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
 438     if (ret < 0) {
 439         return ret;
 440     }
 441
 442     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
 443                                BDRV_CHILD_IMAGE, false, errp);
 444     if (!bs->file) {
 445         return -EINVAL;
 446     }
 447
 448     block_module_load_one("dmg-bz2");
 449     block_module_load_one("dmg-lzfse");
 450
 451     s->n_chunks = 0;
 452     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 453     /* used by dmg_read_mish_block to keep track of the current I/O position */
 454     ds.data_fork_offset = 0;
 455     ds.max_compressed_size = 1;
 456     ds.max_sectors_per_chunk = 1;
 457
 458     /* locate the UDIF trailer */
 459     offset = dmg_find_koly_offset(bs->file, errp);
 460     if (offset < 0) {
 461         ret = offset;
 462         goto fail;
 463     }
 464
 465     /* offset of data fork (DataForkOffset) */
 466     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 467     if (ret < 0) {
 468         goto fail;
 469     } else if (ds.data_fork_offset > offset) {
 470         ret = -EINVAL;
 471         goto fail;
 472     }
 473
 474     /* offset of resource fork (RsrcForkOffset) */
 475     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 476     if (ret < 0) {
 477         goto fail;
 478     }
 479     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 480     if (ret < 0) {
 481         goto fail;
 482     }
 483     if (rsrc_fork_offset >= offset ||
 484         rsrc_fork_length > offset - rsrc_fork_offset) {
 485         ret = -EINVAL;
 486         goto fail;
 487     }
 488     /* offset of property list (XMLOffset) */
 489     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 490     if (ret < 0) {
 491         goto fail;
 492     }
 493     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 494     if (ret < 0) {
 495         goto fail;
 496     }
 497     if (plist_xml_offset >= offset ||
 498         plist_xml_length > offset - plist_xml_offset) {
 499         ret = -EINVAL;
 500         goto fail;
 501     }
 502     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 503     if (ret < 0) {
 504         goto fail;
 505     }
 506     if (bs->total_sectors < 0) {
 507         ret = -EINVAL;
 508         goto fail;
 509     }
 510     if (rsrc_fork_length != 0) {
 511         ret = dmg_read_resource_fork(bs, &ds,
 512                                      rsrc_fork_offset, rsrc_fork_length);
 513         if (ret < 0) {
 514             goto fail;
 515         }
 516     } else if (plist_xml_length != 0) {
 517         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 518         if (ret < 0) {
 519             goto fail;
 520         }
 521     } else {
 522         ret = -EINVAL;
 523         goto fail;
 524     }
 525
 526     /* initialize zlib engine */
 527     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 528                                               ds.max_compressed_size + 1);
 529     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 530                                                 512 * ds.max_sectors_per_chunk);
 531     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 532         ret = -ENOMEM;
 533         goto fail;
 534     }
 535
 536     if (inflateInit(&s->zstream) != Z_OK) {
 537         ret = -EINVAL;
 538         goto fail;
 539     }
 540
 541     s->current_chunk = s->n_chunks;
 542
 543     qemu_co_mutex_init(&s->lock);
 544     return 0;
 545
 546 fail:
 547     g_free(s->types);
 548     g_free(s->offsets);
 549     g_free(s->lengths);
 550     g_free(s->sectors);
 551     g_free(s->sectorcounts);
 552     qemu_vfree(s->compressed_chunk);
 553     qemu_vfree(s->uncompressed_chunk);
 554     return ret;
 555 }
 556
 557 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 558 {
 559     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 560 }
 561
 562 static inline int is_sector_in_chunk(BDRVDMGState* s,
 563                 uint32_t chunk_num, uint64_t sector_num)
 564 {
 565     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 566             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 567         return 0;
 568     } else {
 569         return -1;
 570     }
 571 }
 572
 573 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 574 {
 575     /* binary search */
 576     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 577     while (chunk1 <= chunk2) {
 578         chunk3 = (chunk1 + chunk2) / 2;
 579         if (s->sectors[chunk3] > sector_num) {
 580             if (chunk3 == 0) {
 581                 goto err;
 582             }
 583             chunk2 = chunk3 - 1;
 584         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 585             return chunk3;
 586         } else {
 587             chunk1 = chunk3 + 1;
 588         }
 589     }
 590 err:
 591     return s->n_chunks; /* error */
 592 }
 593
 594 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 595 {
 596     BDRVDMGState *s = bs->opaque;
 597
 598     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 599         int ret;
 600         uint32_t chunk = search_chunk(s, sector_num);
 601
 602         if (chunk >= s->n_chunks) {
 603             return -1;
 604         }
 605
 606         s->current_chunk = s->n_chunks;
 607         switch (s->types[chunk]) { /* block entry type */
 608         case UDZO: { /* zlib compressed */
 609             /* we need to buffer, because only the chunk as whole can be
 610              * inflated. */
 611             ret = bdrv_pread(bs->file, s->offsets[chunk],
 612                              s->compressed_chunk, s->lengths[chunk]);
 613             if (ret != s->lengths[chunk]) {
 614                 return -1;
 615             }
 616
 617             s->zstream.next_in = s->compressed_chunk;
 618             s->zstream.avail_in = s->lengths[chunk];
 619             s->zstream.next_out = s->uncompressed_chunk;
 620             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 621             ret = inflateReset(&s->zstream);
 622             if (ret != Z_OK) {
 623                 return -1;
 624             }
 625             ret = inflate(&s->zstream, Z_FINISH);
 626             if (ret != Z_STREAM_END ||
 627                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 628                 return -1;
 629             }
 630             break; }
 631         case UDBZ: /* bzip2 compressed */
 632             if (!dmg_uncompress_bz2) {
 633                 break;
 634             }
 635             /* we need to buffer, because only the chunk as whole can be
 636              * inflated. */
 637             ret = bdrv_pread(bs->file, s->offsets[chunk],
 638                              s->compressed_chunk, s->lengths[chunk]);
 639             if (ret != s->lengths[chunk]) {
 640                 return -1;
 641             }
 642
 643             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
 644                                      (unsigned int) s->lengths[chunk],
 645                                      (char *)s->uncompressed_chunk,
 646                                      (unsigned int)
 647                                          (512 * s->sectorcounts[chunk]));
 648             if (ret < 0) {
 649                 return ret;
 650             }
 651             break;
 652         case ULFO:
 653             if (!dmg_uncompress_lzfse) {
 654                 break;
 655             }
 656             /* we need to buffer, because only the chunk as whole can be
 657              * inflated. */
 658             ret = bdrv_pread(bs->file, s->offsets[chunk],
 659                              s->compressed_chunk, s->lengths[chunk]);
 660             if (ret != s->lengths[chunk]) {
 661                 return -1;
 662             }
 663
 664             ret = dmg_uncompress_lzfse((char *)s->compressed_chunk,
 665                                        (unsigned int) s->lengths[chunk],
 666                                        (char *)s->uncompressed_chunk,
 667                                        (unsigned int)
 668                                            (512 * s->sectorcounts[chunk]));
 669             if (ret < 0) {
 670                 return ret;
 671             }
 672             break;
 673         case UDRW: /* copy */
 674             ret = bdrv_pread(bs->file, s->offsets[chunk],
 675                              s->uncompressed_chunk, s->lengths[chunk]);
 676             if (ret != s->lengths[chunk]) {
 677                 return -1;
 678             }
 679             break;
 680         case UDZE: /* zeros */
 681         case UDIG: /* ignore */
 682             /* see dmg_read, it is treated specially. No buffer needs to be
 683              * pre-filled, the zeroes can be set directly. */
 684             break;
 685         }
 686         s->current_chunk = chunk;
 687     }
 688     return 0;
 689 }
 690
 691 static int coroutine_fn
 692 dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 693               QEMUIOVector *qiov, int flags)
 694 {
 695     BDRVDMGState *s = bs->opaque;
 696     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 697     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 698     int ret, i;
 699
 700     assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 701     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 702
 703     qemu_co_mutex_lock(&s->lock);
 704
 705     for (i = 0; i < nb_sectors; i++) {
 706         uint32_t sector_offset_in_chunk;
 707         void *data;
 708
 709         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 710             ret = -EIO;
 711             goto fail;
 712         }
 713         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 714          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 715          * section. dmg_read_chunk is called to find s->current_chunk */
 716         if (s->types[s->current_chunk] == UDZE
 717             || s->types[s->current_chunk] == UDIG) { /* all zeroes block entry */
 718             qemu_iovec_memset(qiov, i * 512, 0, 512);
 719             continue;
 720         }
 721         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 722         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 723         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 724     }
 725
 726     ret = 0;
 727 fail:
 728     qemu_co_mutex_unlock(&s->lock);
 729     return ret;
 730 }
 731
 732 static void dmg_close(BlockDriverState *bs)
 733 {
 734     BDRVDMGState *s = bs->opaque;
 735
 736     g_free(s->types);
 737     g_free(s->offsets);
 738     g_free(s->lengths);
 739     g_free(s->sectors);
 740     g_free(s->sectorcounts);
 741     qemu_vfree(s->compressed_chunk);
 742     qemu_vfree(s->uncompressed_chunk);
 743
 744     inflateEnd(&s->zstream);
 745 }
 746
 747 static BlockDriver bdrv_dmg = {
 748     .format_name    = "dmg",
 749     .instance_size  = sizeof(BDRVDMGState),
 750     .bdrv_probe     = dmg_probe,
 751     .bdrv_open      = dmg_open,
 752     .bdrv_refresh_limits = dmg_refresh_limits,
 753     .bdrv_child_perm     = bdrv_default_perms,
 754     .bdrv_co_preadv = dmg_co_preadv,
 755     .bdrv_close     = dmg_close,
 756     .is_format      = true,
 757 };
 758
 759 static void bdrv_dmg_init(void)
 760 {
 761     bdrv_register(&bdrv_dmg);
 762 }
 763
 764 block_init(bdrv_dmg_init);