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, &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 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, buffer, length);
 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             chunk_count--;
 258             i--;
 259             offset += 40;
 260             continue;
 261         }
 262
 263         /* sector number */
 264         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 265         s->sectors[i] += out_offset;
 266
 267         /* sector count */
 268         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 269
 270         /* all-zeroes sector (type UDZE and UDIG) does not need to be
 271          * "uncompressed" and can therefore be unbounded. */
 272         if (s->types[i] != UDZE && s->types[i] != UDIG
 273             && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 274             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 275                          " is larger than max (%u)",
 276                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 277             ret = -EINVAL;
 278             goto fail;
 279         }
 280
 281         /* offset in (compressed) data fork */
 282         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 283         s->offsets[i] += in_offset;
 284
 285         /* length in (compressed) data fork */
 286         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 287
 288         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 289             error_report("length %" PRIu64 " for chunk %" PRIu32
 290                          " is larger than max (%u)",
 291                          s->lengths[i], i, DMG_LENGTHS_MAX);
 292             ret = -EINVAL;
 293             goto fail;
 294         }
 295
 296         update_max_chunk_size(s, i, &ds->max_compressed_size,
 297                               &ds->max_sectors_per_chunk);
 298         offset += 40;
 299     }
 300     s->n_chunks += chunk_count;
 301     return 0;
 302
 303 fail:
 304     return ret;
 305 }
 306
 307 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 308                                   uint64_t info_begin, uint64_t info_length)
 309 {
 310     BDRVDMGState *s = bs->opaque;
 311     int ret;
 312     uint32_t count, rsrc_data_offset;
 313     uint8_t *buffer = NULL;
 314     uint64_t info_end;
 315     uint64_t offset;
 316
 317     /* read offset from begin of resource fork (info_begin) to resource data */
 318     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 319     if (ret < 0) {
 320         goto fail;
 321     } else if (rsrc_data_offset > info_length) {
 322         ret = -EINVAL;
 323         goto fail;
 324     }
 325
 326     /* read length of resource data */
 327     ret = read_uint32(bs, info_begin + 8, &count);
 328     if (ret < 0) {
 329         goto fail;
 330     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 331         ret = -EINVAL;
 332         goto fail;
 333     }
 334
 335     /* begin of resource data (consisting of one or more resources) */
 336     offset = info_begin + rsrc_data_offset;
 337
 338     /* end of resource data (there is possibly a following resource map
 339      * which will be ignored). */
 340     info_end = offset + count;
 341
 342     /* read offsets (mish blocks) from one or more resources in resource data */
 343     while (offset < info_end) {
 344         /* size of following resource */
 345         ret = read_uint32(bs, offset, &count);
 346         if (ret < 0) {
 347             goto fail;
 348         } else if (count == 0 || count > info_end - offset) {
 349             ret = -EINVAL;
 350             goto fail;
 351         }
 352         offset += 4;
 353
 354         buffer = g_realloc(buffer, count);
 355         ret = bdrv_pread(bs->file, offset, buffer, count);
 356         if (ret < 0) {
 357             goto fail;
 358         }
 359
 360         ret = dmg_read_mish_block(s, ds, buffer, count);
 361         if (ret < 0) {
 362             goto fail;
 363         }
 364         /* advance offset by size of resource */
 365         offset += count;
 366     }
 367     ret = 0;
 368
 369 fail:
 370     g_free(buffer);
 371     return ret;
 372 }
 373
 374 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 375                               uint64_t info_begin, uint64_t info_length)
 376 {
 377     BDRVDMGState *s = bs->opaque;
 378     int ret;
 379     uint8_t *buffer = NULL;
 380     char *data_begin, *data_end;
 381
 382     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 383      * safe upper cap on the data length. A test sample had a XML length of
 384      * about 1 MiB. */
 385     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 386         ret = -EINVAL;
 387         goto fail;
 388     }
 389
 390     buffer = g_malloc(info_length + 1);
 391     buffer[info_length] = '\0';
 392     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 393     if (ret != info_length) {
 394         ret = -EINVAL;
 395         goto fail;
 396     }
 397
 398     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 399      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 400      * and line feeds. */
 401     data_end = (char *)buffer;
 402     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 403         guchar *mish;
 404         gsize out_len = 0;
 405
 406         data_begin += 6;
 407         data_end = strstr(data_begin, "</data>");
 408         /* malformed XML? */
 409         if (data_end == NULL) {
 410             ret = -EINVAL;
 411             goto fail;
 412         }
 413         *data_end++ = '\0';
 414         mish = g_base64_decode(data_begin, &out_len);
 415         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 416         g_free(mish);
 417         if (ret < 0) {
 418             goto fail;
 419         }
 420     }
 421     ret = 0;
 422
 423 fail:
 424     g_free(buffer);
 425     return ret;
 426 }
 427
 428 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 429                     Error **errp)
 430 {
 431     BDRVDMGState *s = bs->opaque;
 432     DmgHeaderState ds;
 433     uint64_t rsrc_fork_offset, rsrc_fork_length;
 434     uint64_t plist_xml_offset, plist_xml_length;
 435     int64_t offset;
 436     int ret;
 437
 438     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
 439     if (ret < 0) {
 440         return ret;
 441     }
 442
 443     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
 444                                BDRV_CHILD_IMAGE, false, errp);
 445     if (!bs->file) {
 446         return -EINVAL;
 447     }
 448
 449     block_module_load_one("dmg-bz2");
 450     block_module_load_one("dmg-lzfse");
 451
 452     s->n_chunks = 0;
 453     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 454     /* used by dmg_read_mish_block to keep track of the current I/O position */
 455     ds.data_fork_offset = 0;
 456     ds.max_compressed_size = 1;
 457     ds.max_sectors_per_chunk = 1;
 458
 459     /* locate the UDIF trailer */
 460     offset = dmg_find_koly_offset(bs->file, errp);
 461     if (offset < 0) {
 462         ret = offset;
 463         goto fail;
 464     }
 465
 466     /* offset of data fork (DataForkOffset) */
 467     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 468     if (ret < 0) {
 469         goto fail;
 470     } else if (ds.data_fork_offset > offset) {
 471         ret = -EINVAL;
 472         goto fail;
 473     }
 474
 475     /* offset of resource fork (RsrcForkOffset) */
 476     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 477     if (ret < 0) {
 478         goto fail;
 479     }
 480     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 481     if (ret < 0) {
 482         goto fail;
 483     }
 484     if (rsrc_fork_offset >= offset ||
 485         rsrc_fork_length > offset - rsrc_fork_offset) {
 486         ret = -EINVAL;
 487         goto fail;
 488     }
 489     /* offset of property list (XMLOffset) */
 490     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 491     if (ret < 0) {
 492         goto fail;
 493     }
 494     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 495     if (ret < 0) {
 496         goto fail;
 497     }
 498     if (plist_xml_offset >= offset ||
 499         plist_xml_length > offset - plist_xml_offset) {
 500         ret = -EINVAL;
 501         goto fail;
 502     }
 503     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 504     if (ret < 0) {
 505         goto fail;
 506     }
 507     if (bs->total_sectors < 0) {
 508         ret = -EINVAL;
 509         goto fail;
 510     }
 511     if (rsrc_fork_length != 0) {
 512         ret = dmg_read_resource_fork(bs, &ds,
 513                                      rsrc_fork_offset, rsrc_fork_length);
 514         if (ret < 0) {
 515             goto fail;
 516         }
 517     } else if (plist_xml_length != 0) {
 518         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 519         if (ret < 0) {
 520             goto fail;
 521         }
 522     } else {
 523         ret = -EINVAL;
 524         goto fail;
 525     }
 526
 527     /* initialize zlib engine */
 528     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 529                                               ds.max_compressed_size + 1);
 530     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 531                                                 512 * ds.max_sectors_per_chunk);
 532     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 533         ret = -ENOMEM;
 534         goto fail;
 535     }
 536
 537     if (inflateInit(&s->zstream) != Z_OK) {
 538         ret = -EINVAL;
 539         goto fail;
 540     }
 541
 542     s->current_chunk = s->n_chunks;
 543
 544     qemu_co_mutex_init(&s->lock);
 545     return 0;
 546
 547 fail:
 548     g_free(s->types);
 549     g_free(s->offsets);
 550     g_free(s->lengths);
 551     g_free(s->sectors);
 552     g_free(s->sectorcounts);
 553     qemu_vfree(s->compressed_chunk);
 554     qemu_vfree(s->uncompressed_chunk);
 555     return ret;
 556 }
 557
 558 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 559 {
 560     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 561 }
 562
 563 static inline int is_sector_in_chunk(BDRVDMGState *s,
 564                 uint32_t chunk_num, uint64_t sector_num)
 565 {
 566     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 567             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 568         return 0;
 569     } else {
 570         return -1;
 571     }
 572 }
 573
 574 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 575 {
 576     /* binary search */
 577     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 578     while (chunk1 <= chunk2) {
 579         chunk3 = (chunk1 + chunk2) / 2;
 580         if (s->sectors[chunk3] > sector_num) {
 581             if (chunk3 == 0) {
 582                 goto err;
 583             }
 584             chunk2 = chunk3 - 1;
 585         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 586             return chunk3;
 587         } else {
 588             chunk1 = chunk3 + 1;
 589         }
 590     }
 591 err:
 592     return s->n_chunks; /* error */
 593 }
 594
 595 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 596 {
 597     BDRVDMGState *s = bs->opaque;
 598
 599     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 600         int ret;
 601         uint32_t chunk = search_chunk(s, sector_num);
 602
 603         if (chunk >= s->n_chunks) {
 604             return -1;
 605         }
 606
 607         s->current_chunk = s->n_chunks;
 608         switch (s->types[chunk]) { /* block entry type */
 609         case UDZO: { /* zlib compressed */
 610             /* we need to buffer, because only the chunk as whole can be
 611              * inflated. */
 612             ret = bdrv_pread(bs->file, s->offsets[chunk],
 613                              s->compressed_chunk, s->lengths[chunk]);
 614             if (ret != s->lengths[chunk]) {
 615                 return -1;
 616             }
 617
 618             s->zstream.next_in = s->compressed_chunk;
 619             s->zstream.avail_in = s->lengths[chunk];
 620             s->zstream.next_out = s->uncompressed_chunk;
 621             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 622             ret = inflateReset(&s->zstream);
 623             if (ret != Z_OK) {
 624                 return -1;
 625             }
 626             ret = inflate(&s->zstream, Z_FINISH);
 627             if (ret != Z_STREAM_END ||
 628                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 629                 return -1;
 630             }
 631             break; }
 632         case UDBZ: /* bzip2 compressed */
 633             if (!dmg_uncompress_bz2) {
 634                 break;
 635             }
 636             /* we need to buffer, because only the chunk as whole can be
 637              * inflated. */
 638             ret = bdrv_pread(bs->file, s->offsets[chunk],
 639                              s->compressed_chunk, s->lengths[chunk]);
 640             if (ret != s->lengths[chunk]) {
 641                 return -1;
 642             }
 643
 644             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
 645                                      (unsigned int) s->lengths[chunk],
 646                                      (char *)s->uncompressed_chunk,
 647                                      (unsigned int)
 648                                          (512 * s->sectorcounts[chunk]));
 649             if (ret < 0) {
 650                 return ret;
 651             }
 652             break;
 653         case ULFO:
 654             if (!dmg_uncompress_lzfse) {
 655                 break;
 656             }
 657             /* we need to buffer, because only the chunk as whole can be
 658              * inflated. */
 659             ret = bdrv_pread(bs->file, s->offsets[chunk],
 660                              s->compressed_chunk, s->lengths[chunk]);
 661             if (ret != s->lengths[chunk]) {
 662                 return -1;
 663             }
 664
 665             ret = dmg_uncompress_lzfse((char *)s->compressed_chunk,
 666                                        (unsigned int) s->lengths[chunk],
 667                                        (char *)s->uncompressed_chunk,
 668                                        (unsigned int)
 669                                            (512 * s->sectorcounts[chunk]));
 670             if (ret < 0) {
 671                 return ret;
 672             }
 673             break;
 674         case UDRW: /* copy */
 675             ret = bdrv_pread(bs->file, s->offsets[chunk],
 676                              s->uncompressed_chunk, s->lengths[chunk]);
 677             if (ret != s->lengths[chunk]) {
 678                 return -1;
 679             }
 680             break;
 681         case UDZE: /* zeros */
 682         case UDIG: /* ignore */
 683             /* see dmg_read, it is treated specially. No buffer needs to be
 684              * pre-filled, the zeroes can be set directly. */
 685             break;
 686         }
 687         s->current_chunk = chunk;
 688     }
 689     return 0;
 690 }
 691
 692 static int coroutine_fn
 693 dmg_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 694               QEMUIOVector *qiov, BdrvRequestFlags flags)
 695 {
 696     BDRVDMGState *s = bs->opaque;
 697     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 698     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 699     int ret, i;
 700
 701     assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 702     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 703
 704     qemu_co_mutex_lock(&s->lock);
 705
 706     for (i = 0; i < nb_sectors; i++) {
 707         uint32_t sector_offset_in_chunk;
 708         void *data;
 709
 710         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 711             ret = -EIO;
 712             goto fail;
 713         }
 714         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 715          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 716          * section. dmg_read_chunk is called to find s->current_chunk */
 717         if (s->types[s->current_chunk] == UDZE
 718             || s->types[s->current_chunk] == UDIG) { /* all zeroes block entry */
 719             qemu_iovec_memset(qiov, i * 512, 0, 512);
 720             continue;
 721         }
 722         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 723         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 724         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 725     }
 726
 727     ret = 0;
 728 fail:
 729     qemu_co_mutex_unlock(&s->lock);
 730     return ret;
 731 }
 732
 733 static void dmg_close(BlockDriverState *bs)
 734 {
 735     BDRVDMGState *s = bs->opaque;
 736
 737     g_free(s->types);
 738     g_free(s->offsets);
 739     g_free(s->lengths);
 740     g_free(s->sectors);
 741     g_free(s->sectorcounts);
 742     qemu_vfree(s->compressed_chunk);
 743     qemu_vfree(s->uncompressed_chunk);
 744
 745     inflateEnd(&s->zstream);
 746 }
 747
 748 static BlockDriver bdrv_dmg = {
 749     .format_name    = "dmg",
 750     .instance_size  = sizeof(BDRVDMGState),
 751     .bdrv_probe     = dmg_probe,
 752     .bdrv_open      = dmg_open,
 753     .bdrv_refresh_limits = dmg_refresh_limits,
 754     .bdrv_child_perm     = bdrv_default_perms,
 755     .bdrv_co_preadv = dmg_co_preadv,
 756     .bdrv_close     = dmg_close,
 757     .is_format      = true,
 758 };
 759
 760 static void bdrv_dmg_init(void)
 761 {
 762     bdrv_register(&bdrv_dmg);
 763 }
 764
 765 block_init(bdrv_dmg_init);