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 "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               /* 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, &buffer, 8);
  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, &buffer, 4);
  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 UDIG: /* zero */
 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 UDRW:    /* uncompressed */
 203     case UDIG:    /* zeroes */
 204     case UDZO:    /* zlib */
 205         return true;
 206     case UDBZ:    /* bzip2 */
 207         return !!dmg_uncompress_bz2;
 208     case ULFO:    /* lzfse */
 209         return !!dmg_uncompress_lzfse;
 210     default:
 211         return false;
 212     }
 213 }
 214
 215 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 216                                uint8_t *buffer, uint32_t count)
 217 {
 218     uint32_t type, i;
 219     int ret;
 220     size_t new_size;
 221     uint32_t chunk_count;
 222     int64_t offset = 0;
 223     uint64_t data_offset;
 224     uint64_t in_offset = ds->data_fork_offset;
 225     uint64_t out_offset;
 226
 227     type = buff_read_uint32(buffer, offset);
 228     /* skip data that is not a valid MISH block (invalid magic or too small) */
 229     if (type != 0x6d697368 || count < 244) {
 230         /* assume success for now */
 231         return 0;
 232     }
 233
 234     /* chunk offsets are relative to this sector number */
 235     out_offset = buff_read_uint64(buffer, offset + 8);
 236
 237     /* location in data fork for (compressed) blob (in bytes) */
 238     data_offset = buff_read_uint64(buffer, offset + 0x18);
 239     in_offset += data_offset;
 240
 241     /* move to begin of chunk entries */
 242     offset += 204;
 243
 244     chunk_count = (count - 204) / 40;
 245     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 246     s->types = g_realloc(s->types, new_size / 2);
 247     s->offsets = g_realloc(s->offsets, new_size);
 248     s->lengths = g_realloc(s->lengths, new_size);
 249     s->sectors = g_realloc(s->sectors, new_size);
 250     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 251
 252     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 253         s->types[i] = buff_read_uint32(buffer, offset);
 254         if (!dmg_is_known_block_type(s->types[i])) {
 255             chunk_count--;
 256             i--;
 257             offset += 40;
 258             continue;
 259         }
 260
 261         /* sector number */
 262         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 263         s->sectors[i] += out_offset;
 264
 265         /* sector count */
 266         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 267
 268         /* all-zeroes sector (type 2) does not need to be "uncompressed" and can
 269          * therefore be unbounded. */
 270         if (s->types[i] != 2 && 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     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
 436     if (ret < 0) {
 437         return ret;
 438     }
 439
 440     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 441                                false, errp);
 442     if (!bs->file) {
 443         return -EINVAL;
 444     }
 445
 446     block_module_load_one("dmg-bz2");
 447     block_module_load_one("dmg-lzfse");
 448
 449     s->n_chunks = 0;
 450     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 451     /* used by dmg_read_mish_block to keep track of the current I/O position */
 452     ds.data_fork_offset = 0;
 453     ds.max_compressed_size = 1;
 454     ds.max_sectors_per_chunk = 1;
 455
 456     /* locate the UDIF trailer */
 457     offset = dmg_find_koly_offset(bs->file, errp);
 458     if (offset < 0) {
 459         ret = offset;
 460         goto fail;
 461     }
 462
 463     /* offset of data fork (DataForkOffset) */
 464     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 465     if (ret < 0) {
 466         goto fail;
 467     } else if (ds.data_fork_offset > offset) {
 468         ret = -EINVAL;
 469         goto fail;
 470     }
 471
 472     /* offset of resource fork (RsrcForkOffset) */
 473     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 474     if (ret < 0) {
 475         goto fail;
 476     }
 477     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 478     if (ret < 0) {
 479         goto fail;
 480     }
 481     if (rsrc_fork_offset >= offset ||
 482         rsrc_fork_length > offset - rsrc_fork_offset) {
 483         ret = -EINVAL;
 484         goto fail;
 485     }
 486     /* offset of property list (XMLOffset) */
 487     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 488     if (ret < 0) {
 489         goto fail;
 490     }
 491     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 492     if (ret < 0) {
 493         goto fail;
 494     }
 495     if (plist_xml_offset >= offset ||
 496         plist_xml_length > offset - plist_xml_offset) {
 497         ret = -EINVAL;
 498         goto fail;
 499     }
 500     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 501     if (ret < 0) {
 502         goto fail;
 503     }
 504     if (bs->total_sectors < 0) {
 505         ret = -EINVAL;
 506         goto fail;
 507     }
 508     if (rsrc_fork_length != 0) {
 509         ret = dmg_read_resource_fork(bs, &ds,
 510                                      rsrc_fork_offset, rsrc_fork_length);
 511         if (ret < 0) {
 512             goto fail;
 513         }
 514     } else if (plist_xml_length != 0) {
 515         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 516         if (ret < 0) {
 517             goto fail;
 518         }
 519     } else {
 520         ret = -EINVAL;
 521         goto fail;
 522     }
 523
 524     /* initialize zlib engine */
 525     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 526                                               ds.max_compressed_size + 1);
 527     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 528                                                 512 * ds.max_sectors_per_chunk);
 529     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 530         ret = -ENOMEM;
 531         goto fail;
 532     }
 533
 534     if (inflateInit(&s->zstream) != Z_OK) {
 535         ret = -EINVAL;
 536         goto fail;
 537     }
 538
 539     s->current_chunk = s->n_chunks;
 540
 541     qemu_co_mutex_init(&s->lock);
 542     return 0;
 543
 544 fail:
 545     g_free(s->types);
 546     g_free(s->offsets);
 547     g_free(s->lengths);
 548     g_free(s->sectors);
 549     g_free(s->sectorcounts);
 550     qemu_vfree(s->compressed_chunk);
 551     qemu_vfree(s->uncompressed_chunk);
 552     return ret;
 553 }
 554
 555 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 556 {
 557     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 558 }
 559
 560 static inline int is_sector_in_chunk(BDRVDMGState* s,
 561                 uint32_t chunk_num, uint64_t sector_num)
 562 {
 563     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 564             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 565         return 0;
 566     } else {
 567         return -1;
 568     }
 569 }
 570
 571 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 572 {
 573     /* binary search */
 574     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 575     while (chunk1 != chunk2) {
 576         chunk3 = (chunk1 + chunk2) / 2;
 577         if (s->sectors[chunk3] > sector_num) {
 578             chunk2 = chunk3;
 579         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 580             return chunk3;
 581         } else {
 582             chunk1 = chunk3;
 583         }
 584     }
 585     return s->n_chunks; /* error */
 586 }
 587
 588 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 589 {
 590     BDRVDMGState *s = bs->opaque;
 591
 592     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 593         int ret;
 594         uint32_t chunk = search_chunk(s, sector_num);
 595
 596         if (chunk >= s->n_chunks) {
 597             return -1;
 598         }
 599
 600         s->current_chunk = s->n_chunks;
 601         switch (s->types[chunk]) { /* block entry type */
 602         case UDZO: { /* zlib compressed */
 603             /* we need to buffer, because only the chunk as whole can be
 604              * inflated. */
 605             ret = bdrv_pread(bs->file, s->offsets[chunk],
 606                              s->compressed_chunk, s->lengths[chunk]);
 607             if (ret != s->lengths[chunk]) {
 608                 return -1;
 609             }
 610
 611             s->zstream.next_in = s->compressed_chunk;
 612             s->zstream.avail_in = s->lengths[chunk];
 613             s->zstream.next_out = s->uncompressed_chunk;
 614             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 615             ret = inflateReset(&s->zstream);
 616             if (ret != Z_OK) {
 617                 return -1;
 618             }
 619             ret = inflate(&s->zstream, Z_FINISH);
 620             if (ret != Z_STREAM_END ||
 621                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 622                 return -1;
 623             }
 624             break; }
 625         case UDBZ: /* bzip2 compressed */
 626             if (!dmg_uncompress_bz2) {
 627                 break;
 628             }
 629             /* we need to buffer, because only the chunk as whole can be
 630              * inflated. */
 631             ret = bdrv_pread(bs->file, s->offsets[chunk],
 632                              s->compressed_chunk, s->lengths[chunk]);
 633             if (ret != s->lengths[chunk]) {
 634                 return -1;
 635             }
 636
 637             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
 638                                      (unsigned int) s->lengths[chunk],
 639                                      (char *)s->uncompressed_chunk,
 640                                      (unsigned int)
 641                                          (512 * s->sectorcounts[chunk]));
 642             if (ret < 0) {
 643                 return ret;
 644             }
 645             break;
 646         case ULFO:
 647             if (!dmg_uncompress_lzfse) {
 648                 break;
 649             }
 650             /* we need to buffer, because only the chunk as whole can be
 651              * inflated. */
 652             ret = bdrv_pread(bs->file, s->offsets[chunk],
 653                              s->compressed_chunk, s->lengths[chunk]);
 654             if (ret != s->lengths[chunk]) {
 655                 return -1;
 656             }
 657
 658             ret = dmg_uncompress_lzfse((char *)s->compressed_chunk,
 659                                        (unsigned int) s->lengths[chunk],
 660                                        (char *)s->uncompressed_chunk,
 661                                        (unsigned int)
 662                                            (512 * s->sectorcounts[chunk]));
 663             if (ret < 0) {
 664                 return ret;
 665             }
 666             break;
 667         case UDRW: /* copy */
 668             ret = bdrv_pread(bs->file, s->offsets[chunk],
 669                              s->uncompressed_chunk, s->lengths[chunk]);
 670             if (ret != s->lengths[chunk]) {
 671                 return -1;
 672             }
 673             break;
 674         case UDIG: /* zero */
 675             /* see dmg_read, it is treated specially. No buffer needs to be
 676              * pre-filled, the zeroes can be set directly. */
 677             break;
 678         }
 679         s->current_chunk = chunk;
 680     }
 681     return 0;
 682 }
 683
 684 static int coroutine_fn
 685 dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 686               QEMUIOVector *qiov, int flags)
 687 {
 688     BDRVDMGState *s = bs->opaque;
 689     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 690     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 691     int ret, i;
 692
 693     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 694     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 695
 696     qemu_co_mutex_lock(&s->lock);
 697
 698     for (i = 0; i < nb_sectors; i++) {
 699         uint32_t sector_offset_in_chunk;
 700         void *data;
 701
 702         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 703             ret = -EIO;
 704             goto fail;
 705         }
 706         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 707          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 708          * section. dmg_read_chunk is called to find s->current_chunk */
 709         if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
 710             qemu_iovec_memset(qiov, i * 512, 0, 512);
 711             continue;
 712         }
 713         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 714         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 715         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 716     }
 717
 718     ret = 0;
 719 fail:
 720     qemu_co_mutex_unlock(&s->lock);
 721     return ret;
 722 }
 723
 724 static void dmg_close(BlockDriverState *bs)
 725 {
 726     BDRVDMGState *s = bs->opaque;
 727
 728     g_free(s->types);
 729     g_free(s->offsets);
 730     g_free(s->lengths);
 731     g_free(s->sectors);
 732     g_free(s->sectorcounts);
 733     qemu_vfree(s->compressed_chunk);
 734     qemu_vfree(s->uncompressed_chunk);
 735
 736     inflateEnd(&s->zstream);
 737 }
 738
 739 static BlockDriver bdrv_dmg = {
 740     .format_name    = "dmg",
 741     .instance_size  = sizeof(BDRVDMGState),
 742     .bdrv_probe     = dmg_probe,
 743     .bdrv_open      = dmg_open,
 744     .bdrv_refresh_limits = dmg_refresh_limits,
 745     .bdrv_child_perm     = bdrv_format_default_perms,
 746     .bdrv_co_preadv = dmg_co_preadv,
 747     .bdrv_close     = dmg_close,
 748 };
 749
 750 static void bdrv_dmg_init(void)
 751 {
 752     bdrv_register(&bdrv_dmg);
 753 }
 754
 755 block_init(bdrv_dmg_init);