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 enum {
  37     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  38      * or truncating when converting to 32-bit types
  39      */
  40     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  41     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  42 };
  43
  44 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  45 {
  46     int len;
  47
  48     if (!filename) {
  49         return 0;
  50     }
  51
  52     len = strlen(filename);
  53     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  54         return 2;
  55     }
  56     return 0;
  57 }
  58
  59 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  60 {
  61     uint64_t buffer;
  62     int ret;
  63
  64     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  65     if (ret < 0) {
  66         return ret;
  67     }
  68
  69     *result = be64_to_cpu(buffer);
  70     return 0;
  71 }
  72
  73 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  74 {
  75     uint32_t buffer;
  76     int ret;
  77
  78     ret = bdrv_pread(bs->file, offset, &buffer, 4);
  79     if (ret < 0) {
  80         return ret;
  81     }
  82
  83     *result = be32_to_cpu(buffer);
  84     return 0;
  85 }
  86
  87 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
  88 {
  89     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
  90 }
  91
  92 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
  93 {
  94     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
  95 }
  96
  97 /* Increase max chunk sizes, if necessary.  This function is used to calculate
  98  * the buffer sizes needed for compressed/uncompressed chunk I/O.
  99  */
 100 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 101                                   uint32_t *max_compressed_size,
 102                                   uint32_t *max_sectors_per_chunk)
 103 {
 104     uint32_t compressed_size = 0;
 105     uint32_t uncompressed_sectors = 0;
 106
 107     switch (s->types[chunk]) {
 108     case 0x80000005: /* zlib compressed */
 109     case 0x80000006: /* bzip2 compressed */
 110         compressed_size = s->lengths[chunk];
 111         uncompressed_sectors = s->sectorcounts[chunk];
 112         break;
 113     case 1: /* copy */
 114         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 115         break;
 116     case 2: /* zero */
 117         /* as the all-zeroes block may be large, it is treated specially: the
 118          * sector is not copied from a large buffer, a simple memset is used
 119          * instead. Therefore uncompressed_sectors does not need to be set. */
 120         break;
 121     }
 122
 123     if (compressed_size > *max_compressed_size) {
 124         *max_compressed_size = compressed_size;
 125     }
 126     if (uncompressed_sectors > *max_sectors_per_chunk) {
 127         *max_sectors_per_chunk = uncompressed_sectors;
 128     }
 129 }
 130
 131 static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
 132 {
 133     BlockDriverState *file_bs = file->bs;
 134     int64_t length;
 135     int64_t offset = 0;
 136     uint8_t buffer[515];
 137     int i, ret;
 138
 139     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 140      * dmg images can have odd sizes, try to look for the "koly" magic which
 141      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 142      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 143      * the last sector (search space: 515 bytes) */
 144     length = bdrv_getlength(file_bs);
 145     if (length < 0) {
 146         error_setg_errno(errp, -length,
 147             "Failed to get file size while reading UDIF trailer");
 148         return length;
 149     } else if (length < 512) {
 150         error_setg(errp, "dmg file must be at least 512 bytes long");
 151         return -EINVAL;
 152     }
 153     if (length > 511 + 512) {
 154         offset = length - 511 - 512;
 155     }
 156     length = length < 515 ? length : 515;
 157     ret = bdrv_pread(file, offset, buffer, length);
 158     if (ret < 0) {
 159         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 160         return ret;
 161     }
 162     for (i = 0; i < length - 3; i++) {
 163         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 164             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 165             return offset + i;
 166         }
 167     }
 168     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 169     return -EINVAL;
 170 }
 171
 172 /* used when building the sector table */
 173 typedef struct DmgHeaderState {
 174     /* used internally by dmg_read_mish_block to remember offsets of blocks
 175      * across calls */
 176     uint64_t data_fork_offset;
 177     /* exported for dmg_open */
 178     uint32_t max_compressed_size;
 179     uint32_t max_sectors_per_chunk;
 180 } DmgHeaderState;
 181
 182 static bool dmg_is_known_block_type(uint32_t entry_type)
 183 {
 184     switch (entry_type) {
 185     case 0x00000001:    /* uncompressed */
 186     case 0x00000002:    /* zeroes */
 187     case 0x80000005:    /* zlib */
 188         return true;
 189     case 0x80000006:    /* bzip2 */
 190         return !!dmg_uncompress_bz2;
 191     default:
 192         return false;
 193     }
 194 }
 195
 196 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 197                                uint8_t *buffer, uint32_t count)
 198 {
 199     uint32_t type, i;
 200     int ret;
 201     size_t new_size;
 202     uint32_t chunk_count;
 203     int64_t offset = 0;
 204     uint64_t data_offset;
 205     uint64_t in_offset = ds->data_fork_offset;
 206     uint64_t out_offset;
 207
 208     type = buff_read_uint32(buffer, offset);
 209     /* skip data that is not a valid MISH block (invalid magic or too small) */
 210     if (type != 0x6d697368 || count < 244) {
 211         /* assume success for now */
 212         return 0;
 213     }
 214
 215     /* chunk offsets are relative to this sector number */
 216     out_offset = buff_read_uint64(buffer, offset + 8);
 217
 218     /* location in data fork for (compressed) blob (in bytes) */
 219     data_offset = buff_read_uint64(buffer, offset + 0x18);
 220     in_offset += data_offset;
 221
 222     /* move to begin of chunk entries */
 223     offset += 204;
 224
 225     chunk_count = (count - 204) / 40;
 226     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 227     s->types = g_realloc(s->types, new_size / 2);
 228     s->offsets = g_realloc(s->offsets, new_size);
 229     s->lengths = g_realloc(s->lengths, new_size);
 230     s->sectors = g_realloc(s->sectors, new_size);
 231     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 232
 233     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 234         s->types[i] = buff_read_uint32(buffer, offset);
 235         if (!dmg_is_known_block_type(s->types[i])) {
 236             chunk_count--;
 237             i--;
 238             offset += 40;
 239             continue;
 240         }
 241
 242         /* sector number */
 243         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 244         s->sectors[i] += out_offset;
 245
 246         /* sector count */
 247         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 248
 249         /* all-zeroes sector (type 2) does not need to be "uncompressed" and can
 250          * therefore be unbounded. */
 251         if (s->types[i] != 2 && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 252             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 253                          " is larger than max (%u)",
 254                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 255             ret = -EINVAL;
 256             goto fail;
 257         }
 258
 259         /* offset in (compressed) data fork */
 260         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 261         s->offsets[i] += in_offset;
 262
 263         /* length in (compressed) data fork */
 264         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 265
 266         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 267             error_report("length %" PRIu64 " for chunk %" PRIu32
 268                          " is larger than max (%u)",
 269                          s->lengths[i], i, DMG_LENGTHS_MAX);
 270             ret = -EINVAL;
 271             goto fail;
 272         }
 273
 274         update_max_chunk_size(s, i, &ds->max_compressed_size,
 275                               &ds->max_sectors_per_chunk);
 276         offset += 40;
 277     }
 278     s->n_chunks += chunk_count;
 279     return 0;
 280
 281 fail:
 282     return ret;
 283 }
 284
 285 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 286                                   uint64_t info_begin, uint64_t info_length)
 287 {
 288     BDRVDMGState *s = bs->opaque;
 289     int ret;
 290     uint32_t count, rsrc_data_offset;
 291     uint8_t *buffer = NULL;
 292     uint64_t info_end;
 293     uint64_t offset;
 294
 295     /* read offset from begin of resource fork (info_begin) to resource data */
 296     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 297     if (ret < 0) {
 298         goto fail;
 299     } else if (rsrc_data_offset > info_length) {
 300         ret = -EINVAL;
 301         goto fail;
 302     }
 303
 304     /* read length of resource data */
 305     ret = read_uint32(bs, info_begin + 8, &count);
 306     if (ret < 0) {
 307         goto fail;
 308     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 309         ret = -EINVAL;
 310         goto fail;
 311     }
 312
 313     /* begin of resource data (consisting of one or more resources) */
 314     offset = info_begin + rsrc_data_offset;
 315
 316     /* end of resource data (there is possibly a following resource map
 317      * which will be ignored). */
 318     info_end = offset + count;
 319
 320     /* read offsets (mish blocks) from one or more resources in resource data */
 321     while (offset < info_end) {
 322         /* size of following resource */
 323         ret = read_uint32(bs, offset, &count);
 324         if (ret < 0) {
 325             goto fail;
 326         } else if (count == 0 || count > info_end - offset) {
 327             ret = -EINVAL;
 328             goto fail;
 329         }
 330         offset += 4;
 331
 332         buffer = g_realloc(buffer, count);
 333         ret = bdrv_pread(bs->file, offset, buffer, count);
 334         if (ret < 0) {
 335             goto fail;
 336         }
 337
 338         ret = dmg_read_mish_block(s, ds, buffer, count);
 339         if (ret < 0) {
 340             goto fail;
 341         }
 342         /* advance offset by size of resource */
 343         offset += count;
 344     }
 345     ret = 0;
 346
 347 fail:
 348     g_free(buffer);
 349     return ret;
 350 }
 351
 352 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 353                               uint64_t info_begin, uint64_t info_length)
 354 {
 355     BDRVDMGState *s = bs->opaque;
 356     int ret;
 357     uint8_t *buffer = NULL;
 358     char *data_begin, *data_end;
 359
 360     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 361      * safe upper cap on the data length. A test sample had a XML length of
 362      * about 1 MiB. */
 363     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 364         ret = -EINVAL;
 365         goto fail;
 366     }
 367
 368     buffer = g_malloc(info_length + 1);
 369     buffer[info_length] = '\0';
 370     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 371     if (ret != info_length) {
 372         ret = -EINVAL;
 373         goto fail;
 374     }
 375
 376     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 377      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 378      * and line feeds. */
 379     data_end = (char *)buffer;
 380     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 381         guchar *mish;
 382         gsize out_len = 0;
 383
 384         data_begin += 6;
 385         data_end = strstr(data_begin, "</data>");
 386         /* malformed XML? */
 387         if (data_end == NULL) {
 388             ret = -EINVAL;
 389             goto fail;
 390         }
 391         *data_end++ = '\0';
 392         mish = g_base64_decode(data_begin, &out_len);
 393         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 394         g_free(mish);
 395         if (ret < 0) {
 396             goto fail;
 397         }
 398     }
 399     ret = 0;
 400
 401 fail:
 402     g_free(buffer);
 403     return ret;
 404 }
 405
 406 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 407                     Error **errp)
 408 {
 409     BDRVDMGState *s = bs->opaque;
 410     DmgHeaderState ds;
 411     uint64_t rsrc_fork_offset, rsrc_fork_length;
 412     uint64_t plist_xml_offset, plist_xml_length;
 413     int64_t offset;
 414     int ret;
 415
 416     block_module_load_one("dmg-bz2");
 417     bs->read_only = true;
 418
 419     s->n_chunks = 0;
 420     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 421     /* used by dmg_read_mish_block to keep track of the current I/O position */
 422     ds.data_fork_offset = 0;
 423     ds.max_compressed_size = 1;
 424     ds.max_sectors_per_chunk = 1;
 425
 426     /* locate the UDIF trailer */
 427     offset = dmg_find_koly_offset(bs->file, errp);
 428     if (offset < 0) {
 429         ret = offset;
 430         goto fail;
 431     }
 432
 433     /* offset of data fork (DataForkOffset) */
 434     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 435     if (ret < 0) {
 436         goto fail;
 437     } else if (ds.data_fork_offset > offset) {
 438         ret = -EINVAL;
 439         goto fail;
 440     }
 441
 442     /* offset of resource fork (RsrcForkOffset) */
 443     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 444     if (ret < 0) {
 445         goto fail;
 446     }
 447     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 448     if (ret < 0) {
 449         goto fail;
 450     }
 451     if (rsrc_fork_offset >= offset ||
 452         rsrc_fork_length > offset - rsrc_fork_offset) {
 453         ret = -EINVAL;
 454         goto fail;
 455     }
 456     /* offset of property list (XMLOffset) */
 457     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 458     if (ret < 0) {
 459         goto fail;
 460     }
 461     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 462     if (ret < 0) {
 463         goto fail;
 464     }
 465     if (plist_xml_offset >= offset ||
 466         plist_xml_length > offset - plist_xml_offset) {
 467         ret = -EINVAL;
 468         goto fail;
 469     }
 470     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 471     if (ret < 0) {
 472         goto fail;
 473     }
 474     if (bs->total_sectors < 0) {
 475         ret = -EINVAL;
 476         goto fail;
 477     }
 478     if (rsrc_fork_length != 0) {
 479         ret = dmg_read_resource_fork(bs, &ds,
 480                                      rsrc_fork_offset, rsrc_fork_length);
 481         if (ret < 0) {
 482             goto fail;
 483         }
 484     } else if (plist_xml_length != 0) {
 485         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 486         if (ret < 0) {
 487             goto fail;
 488         }
 489     } else {
 490         ret = -EINVAL;
 491         goto fail;
 492     }
 493
 494     /* initialize zlib engine */
 495     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 496                                               ds.max_compressed_size + 1);
 497     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 498                                                 512 * ds.max_sectors_per_chunk);
 499     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 500         ret = -ENOMEM;
 501         goto fail;
 502     }
 503
 504     if (inflateInit(&s->zstream) != Z_OK) {
 505         ret = -EINVAL;
 506         goto fail;
 507     }
 508
 509     s->current_chunk = s->n_chunks;
 510
 511     qemu_co_mutex_init(&s->lock);
 512     return 0;
 513
 514 fail:
 515     g_free(s->types);
 516     g_free(s->offsets);
 517     g_free(s->lengths);
 518     g_free(s->sectors);
 519     g_free(s->sectorcounts);
 520     qemu_vfree(s->compressed_chunk);
 521     qemu_vfree(s->uncompressed_chunk);
 522     return ret;
 523 }
 524
 525 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 526 {
 527     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 528 }
 529
 530 static inline int is_sector_in_chunk(BDRVDMGState* s,
 531                 uint32_t chunk_num, uint64_t sector_num)
 532 {
 533     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 534             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 535         return 0;
 536     } else {
 537         return -1;
 538     }
 539 }
 540
 541 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 542 {
 543     /* binary search */
 544     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 545     while (chunk1 != chunk2) {
 546         chunk3 = (chunk1 + chunk2) / 2;
 547         if (s->sectors[chunk3] > sector_num) {
 548             chunk2 = chunk3;
 549         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 550             return chunk3;
 551         } else {
 552             chunk1 = chunk3;
 553         }
 554     }
 555     return s->n_chunks; /* error */
 556 }
 557
 558 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 559 {
 560     BDRVDMGState *s = bs->opaque;
 561
 562     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 563         int ret;
 564         uint32_t chunk = search_chunk(s, sector_num);
 565
 566         if (chunk >= s->n_chunks) {
 567             return -1;
 568         }
 569
 570         s->current_chunk = s->n_chunks;
 571         switch (s->types[chunk]) { /* block entry type */
 572         case 0x80000005: { /* zlib compressed */
 573             /* we need to buffer, because only the chunk as whole can be
 574              * inflated. */
 575             ret = bdrv_pread(bs->file, s->offsets[chunk],
 576                              s->compressed_chunk, s->lengths[chunk]);
 577             if (ret != s->lengths[chunk]) {
 578                 return -1;
 579             }
 580
 581             s->zstream.next_in = s->compressed_chunk;
 582             s->zstream.avail_in = s->lengths[chunk];
 583             s->zstream.next_out = s->uncompressed_chunk;
 584             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 585             ret = inflateReset(&s->zstream);
 586             if (ret != Z_OK) {
 587                 return -1;
 588             }
 589             ret = inflate(&s->zstream, Z_FINISH);
 590             if (ret != Z_STREAM_END ||
 591                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 592                 return -1;
 593             }
 594             break; }
 595         case 0x80000006: /* bzip2 compressed */
 596             if (!dmg_uncompress_bz2) {
 597                 break;
 598             }
 599             /* we need to buffer, because only the chunk as whole can be
 600              * inflated. */
 601             ret = bdrv_pread(bs->file, s->offsets[chunk],
 602                              s->compressed_chunk, s->lengths[chunk]);
 603             if (ret != s->lengths[chunk]) {
 604                 return -1;
 605             }
 606
 607             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
 608                                      (unsigned int) s->lengths[chunk],
 609                                      (char *)s->uncompressed_chunk,
 610                                      (unsigned int)
 611                                          (512 * s->sectorcounts[chunk]));
 612             if (ret < 0) {
 613                 return ret;
 614             }
 615             break;
 616         case 1: /* copy */
 617             ret = bdrv_pread(bs->file, s->offsets[chunk],
 618                              s->uncompressed_chunk, s->lengths[chunk]);
 619             if (ret != s->lengths[chunk]) {
 620                 return -1;
 621             }
 622             break;
 623         case 2: /* zero */
 624             /* see dmg_read, it is treated specially. No buffer needs to be
 625              * pre-filled, the zeroes can be set directly. */
 626             break;
 627         }
 628         s->current_chunk = chunk;
 629     }
 630     return 0;
 631 }
 632
 633 static int coroutine_fn
 634 dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 635               QEMUIOVector *qiov, int flags)
 636 {
 637     BDRVDMGState *s = bs->opaque;
 638     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 639     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 640     int ret, i;
 641
 642     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 643     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 644
 645     qemu_co_mutex_lock(&s->lock);
 646
 647     for (i = 0; i < nb_sectors; i++) {
 648         uint32_t sector_offset_in_chunk;
 649         void *data;
 650
 651         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 652             ret = -EIO;
 653             goto fail;
 654         }
 655         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 656          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 657          * section. dmg_read_chunk is called to find s->current_chunk */
 658         if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
 659             qemu_iovec_memset(qiov, i * 512, 0, 512);
 660             continue;
 661         }
 662         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 663         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 664         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 665     }
 666
 667     ret = 0;
 668 fail:
 669     qemu_co_mutex_unlock(&s->lock);
 670     return ret;
 671 }
 672
 673 static void dmg_close(BlockDriverState *bs)
 674 {
 675     BDRVDMGState *s = bs->opaque;
 676
 677     g_free(s->types);
 678     g_free(s->offsets);
 679     g_free(s->lengths);
 680     g_free(s->sectors);
 681     g_free(s->sectorcounts);
 682     qemu_vfree(s->compressed_chunk);
 683     qemu_vfree(s->uncompressed_chunk);
 684
 685     inflateEnd(&s->zstream);
 686 }
 687
 688 static BlockDriver bdrv_dmg = {
 689     .format_name    = "dmg",
 690     .instance_size  = sizeof(BDRVDMGState),
 691     .bdrv_probe     = dmg_probe,
 692     .bdrv_open      = dmg_open,
 693     .bdrv_refresh_limits = dmg_refresh_limits,
 694     .bdrv_co_preadv = dmg_co_preadv,
 695     .bdrv_close     = dmg_close,
 696 };
 697
 698 static void bdrv_dmg_init(void)
 699 {
 700     bdrv_register(&bdrv_dmg);
 701 }
 702
 703 block_init(bdrv_dmg_init);