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 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  48 {
  49     int len;
  50
  51     if (!filename) {
  52         return 0;
  53     }
  54
  55     len = strlen(filename);
  56     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  57         return 2;
  58     }
  59     return 0;
  60 }
  61
  62 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  63 {
  64     uint64_t buffer;
  65     int ret;
  66
  67     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  68     if (ret < 0) {
  69         return ret;
  70     }
  71
  72     *result = be64_to_cpu(buffer);
  73     return 0;
  74 }
  75
  76 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  77 {
  78     uint32_t buffer;
  79     int ret;
  80
  81     ret = bdrv_pread(bs->file, offset, &buffer, 4);
  82     if (ret < 0) {
  83         return ret;
  84     }
  85
  86     *result = be32_to_cpu(buffer);
  87     return 0;
  88 }
  89
  90 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
  91 {
  92     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
  93 }
  94
  95 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
  96 {
  97     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
  98 }
  99
 100 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 101  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 102  */
 103 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 104                                   uint32_t *max_compressed_size,
 105                                   uint32_t *max_sectors_per_chunk)
 106 {
 107     uint32_t compressed_size = 0;
 108     uint32_t uncompressed_sectors = 0;
 109
 110     switch (s->types[chunk]) {
 111     case 0x80000005: /* zlib compressed */
 112     case 0x80000006: /* bzip2 compressed */
 113     case 0x80000007: /* lzfse compressed */
 114         compressed_size = s->lengths[chunk];
 115         uncompressed_sectors = s->sectorcounts[chunk];
 116         break;
 117     case 1: /* copy */
 118         uncompressed_sectors = DIV_ROUND_UP(s->lengths[chunk], 512);
 119         break;
 120     case 2: /* zero */
 121         /* as the all-zeroes block may be large, it is treated specially: the
 122          * sector is not copied from a large buffer, a simple memset is used
 123          * instead. Therefore uncompressed_sectors does not need to be set. */
 124         break;
 125     }
 126
 127     if (compressed_size > *max_compressed_size) {
 128         *max_compressed_size = compressed_size;
 129     }
 130     if (uncompressed_sectors > *max_sectors_per_chunk) {
 131         *max_sectors_per_chunk = uncompressed_sectors;
 132     }
 133 }
 134
 135 static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
 136 {
 137     BlockDriverState *file_bs = file->bs;
 138     int64_t length;
 139     int64_t offset = 0;
 140     uint8_t buffer[515];
 141     int i, ret;
 142
 143     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 144      * dmg images can have odd sizes, try to look for the "koly" magic which
 145      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 146      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 147      * the last sector (search space: 515 bytes) */
 148     length = bdrv_getlength(file_bs);
 149     if (length < 0) {
 150         error_setg_errno(errp, -length,
 151             "Failed to get file size while reading UDIF trailer");
 152         return length;
 153     } else if (length < 512) {
 154         error_setg(errp, "dmg file must be at least 512 bytes long");
 155         return -EINVAL;
 156     }
 157     if (length > 511 + 512) {
 158         offset = length - 511 - 512;
 159     }
 160     length = length < 515 ? length : 515;
 161     ret = bdrv_pread(file, offset, buffer, length);
 162     if (ret < 0) {
 163         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 164         return ret;
 165     }
 166     for (i = 0; i < length - 3; i++) {
 167         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 168             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 169             return offset + i;
 170         }
 171     }
 172     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 173     return -EINVAL;
 174 }
 175
 176 /* used when building the sector table */
 177 typedef struct DmgHeaderState {
 178     /* used internally by dmg_read_mish_block to remember offsets of blocks
 179      * across calls */
 180     uint64_t data_fork_offset;
 181     /* exported for dmg_open */
 182     uint32_t max_compressed_size;
 183     uint32_t max_sectors_per_chunk;
 184 } DmgHeaderState;
 185
 186 static bool dmg_is_known_block_type(uint32_t entry_type)
 187 {
 188     switch (entry_type) {
 189     case 0x00000001:    /* uncompressed */
 190     case 0x00000002:    /* zeroes */
 191     case 0x80000005:    /* zlib */
 192         return true;
 193     case 0x80000006:    /* bzip2 */
 194         return !!dmg_uncompress_bz2;
 195     case 0x80000007:    /* lzfse */
 196         return !!dmg_uncompress_lzfse;
 197     default:
 198         return false;
 199     }
 200 }
 201
 202 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 203                                uint8_t *buffer, uint32_t count)
 204 {
 205     uint32_t type, i;
 206     int ret;
 207     size_t new_size;
 208     uint32_t chunk_count;
 209     int64_t offset = 0;
 210     uint64_t data_offset;
 211     uint64_t in_offset = ds->data_fork_offset;
 212     uint64_t out_offset;
 213
 214     type = buff_read_uint32(buffer, offset);
 215     /* skip data that is not a valid MISH block (invalid magic or too small) */
 216     if (type != 0x6d697368 || count < 244) {
 217         /* assume success for now */
 218         return 0;
 219     }
 220
 221     /* chunk offsets are relative to this sector number */
 222     out_offset = buff_read_uint64(buffer, offset + 8);
 223
 224     /* location in data fork for (compressed) blob (in bytes) */
 225     data_offset = buff_read_uint64(buffer, offset + 0x18);
 226     in_offset += data_offset;
 227
 228     /* move to begin of chunk entries */
 229     offset += 204;
 230
 231     chunk_count = (count - 204) / 40;
 232     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 233     s->types = g_realloc(s->types, new_size / 2);
 234     s->offsets = g_realloc(s->offsets, new_size);
 235     s->lengths = g_realloc(s->lengths, new_size);
 236     s->sectors = g_realloc(s->sectors, new_size);
 237     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 238
 239     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 240         s->types[i] = buff_read_uint32(buffer, offset);
 241         if (!dmg_is_known_block_type(s->types[i])) {
 242             chunk_count--;
 243             i--;
 244             offset += 40;
 245             continue;
 246         }
 247
 248         /* sector number */
 249         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 250         s->sectors[i] += out_offset;
 251
 252         /* sector count */
 253         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 254
 255         /* all-zeroes sector (type 2) does not need to be "uncompressed" and can
 256          * therefore be unbounded. */
 257         if (s->types[i] != 2 && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 258             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 259                          " is larger than max (%u)",
 260                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 261             ret = -EINVAL;
 262             goto fail;
 263         }
 264
 265         /* offset in (compressed) data fork */
 266         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 267         s->offsets[i] += in_offset;
 268
 269         /* length in (compressed) data fork */
 270         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 271
 272         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 273             error_report("length %" PRIu64 " for chunk %" PRIu32
 274                          " is larger than max (%u)",
 275                          s->lengths[i], i, DMG_LENGTHS_MAX);
 276             ret = -EINVAL;
 277             goto fail;
 278         }
 279
 280         update_max_chunk_size(s, i, &ds->max_compressed_size,
 281                               &ds->max_sectors_per_chunk);
 282         offset += 40;
 283     }
 284     s->n_chunks += chunk_count;
 285     return 0;
 286
 287 fail:
 288     return ret;
 289 }
 290
 291 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 292                                   uint64_t info_begin, uint64_t info_length)
 293 {
 294     BDRVDMGState *s = bs->opaque;
 295     int ret;
 296     uint32_t count, rsrc_data_offset;
 297     uint8_t *buffer = NULL;
 298     uint64_t info_end;
 299     uint64_t offset;
 300
 301     /* read offset from begin of resource fork (info_begin) to resource data */
 302     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 303     if (ret < 0) {
 304         goto fail;
 305     } else if (rsrc_data_offset > info_length) {
 306         ret = -EINVAL;
 307         goto fail;
 308     }
 309
 310     /* read length of resource data */
 311     ret = read_uint32(bs, info_begin + 8, &count);
 312     if (ret < 0) {
 313         goto fail;
 314     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 315         ret = -EINVAL;
 316         goto fail;
 317     }
 318
 319     /* begin of resource data (consisting of one or more resources) */
 320     offset = info_begin + rsrc_data_offset;
 321
 322     /* end of resource data (there is possibly a following resource map
 323      * which will be ignored). */
 324     info_end = offset + count;
 325
 326     /* read offsets (mish blocks) from one or more resources in resource data */
 327     while (offset < info_end) {
 328         /* size of following resource */
 329         ret = read_uint32(bs, offset, &count);
 330         if (ret < 0) {
 331             goto fail;
 332         } else if (count == 0 || count > info_end - offset) {
 333             ret = -EINVAL;
 334             goto fail;
 335         }
 336         offset += 4;
 337
 338         buffer = g_realloc(buffer, count);
 339         ret = bdrv_pread(bs->file, offset, buffer, count);
 340         if (ret < 0) {
 341             goto fail;
 342         }
 343
 344         ret = dmg_read_mish_block(s, ds, buffer, count);
 345         if (ret < 0) {
 346             goto fail;
 347         }
 348         /* advance offset by size of resource */
 349         offset += count;
 350     }
 351     ret = 0;
 352
 353 fail:
 354     g_free(buffer);
 355     return ret;
 356 }
 357
 358 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 359                               uint64_t info_begin, uint64_t info_length)
 360 {
 361     BDRVDMGState *s = bs->opaque;
 362     int ret;
 363     uint8_t *buffer = NULL;
 364     char *data_begin, *data_end;
 365
 366     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 367      * safe upper cap on the data length. A test sample had a XML length of
 368      * about 1 MiB. */
 369     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 370         ret = -EINVAL;
 371         goto fail;
 372     }
 373
 374     buffer = g_malloc(info_length + 1);
 375     buffer[info_length] = '\0';
 376     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 377     if (ret != info_length) {
 378         ret = -EINVAL;
 379         goto fail;
 380     }
 381
 382     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 383      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 384      * and line feeds. */
 385     data_end = (char *)buffer;
 386     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 387         guchar *mish;
 388         gsize out_len = 0;
 389
 390         data_begin += 6;
 391         data_end = strstr(data_begin, "</data>");
 392         /* malformed XML? */
 393         if (data_end == NULL) {
 394             ret = -EINVAL;
 395             goto fail;
 396         }
 397         *data_end++ = '\0';
 398         mish = g_base64_decode(data_begin, &out_len);
 399         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 400         g_free(mish);
 401         if (ret < 0) {
 402             goto fail;
 403         }
 404     }
 405     ret = 0;
 406
 407 fail:
 408     g_free(buffer);
 409     return ret;
 410 }
 411
 412 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 413                     Error **errp)
 414 {
 415     BDRVDMGState *s = bs->opaque;
 416     DmgHeaderState ds;
 417     uint64_t rsrc_fork_offset, rsrc_fork_length;
 418     uint64_t plist_xml_offset, plist_xml_length;
 419     int64_t offset;
 420     int ret;
 421
 422     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
 423     if (ret < 0) {
 424         return ret;
 425     }
 426
 427     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 428                                false, errp);
 429     if (!bs->file) {
 430         return -EINVAL;
 431     }
 432
 433     block_module_load_one("dmg-bz2");
 434     block_module_load_one("dmg-lzfse");
 435
 436     s->n_chunks = 0;
 437     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 438     /* used by dmg_read_mish_block to keep track of the current I/O position */
 439     ds.data_fork_offset = 0;
 440     ds.max_compressed_size = 1;
 441     ds.max_sectors_per_chunk = 1;
 442
 443     /* locate the UDIF trailer */
 444     offset = dmg_find_koly_offset(bs->file, errp);
 445     if (offset < 0) {
 446         ret = offset;
 447         goto fail;
 448     }
 449
 450     /* offset of data fork (DataForkOffset) */
 451     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 452     if (ret < 0) {
 453         goto fail;
 454     } else if (ds.data_fork_offset > offset) {
 455         ret = -EINVAL;
 456         goto fail;
 457     }
 458
 459     /* offset of resource fork (RsrcForkOffset) */
 460     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 461     if (ret < 0) {
 462         goto fail;
 463     }
 464     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 465     if (ret < 0) {
 466         goto fail;
 467     }
 468     if (rsrc_fork_offset >= offset ||
 469         rsrc_fork_length > offset - rsrc_fork_offset) {
 470         ret = -EINVAL;
 471         goto fail;
 472     }
 473     /* offset of property list (XMLOffset) */
 474     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 475     if (ret < 0) {
 476         goto fail;
 477     }
 478     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 479     if (ret < 0) {
 480         goto fail;
 481     }
 482     if (plist_xml_offset >= offset ||
 483         plist_xml_length > offset - plist_xml_offset) {
 484         ret = -EINVAL;
 485         goto fail;
 486     }
 487     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 488     if (ret < 0) {
 489         goto fail;
 490     }
 491     if (bs->total_sectors < 0) {
 492         ret = -EINVAL;
 493         goto fail;
 494     }
 495     if (rsrc_fork_length != 0) {
 496         ret = dmg_read_resource_fork(bs, &ds,
 497                                      rsrc_fork_offset, rsrc_fork_length);
 498         if (ret < 0) {
 499             goto fail;
 500         }
 501     } else if (plist_xml_length != 0) {
 502         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 503         if (ret < 0) {
 504             goto fail;
 505         }
 506     } else {
 507         ret = -EINVAL;
 508         goto fail;
 509     }
 510
 511     /* initialize zlib engine */
 512     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 513                                               ds.max_compressed_size + 1);
 514     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 515                                                 512 * ds.max_sectors_per_chunk);
 516     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 517         ret = -ENOMEM;
 518         goto fail;
 519     }
 520
 521     if (inflateInit(&s->zstream) != Z_OK) {
 522         ret = -EINVAL;
 523         goto fail;
 524     }
 525
 526     s->current_chunk = s->n_chunks;
 527
 528     qemu_co_mutex_init(&s->lock);
 529     return 0;
 530
 531 fail:
 532     g_free(s->types);
 533     g_free(s->offsets);
 534     g_free(s->lengths);
 535     g_free(s->sectors);
 536     g_free(s->sectorcounts);
 537     qemu_vfree(s->compressed_chunk);
 538     qemu_vfree(s->uncompressed_chunk);
 539     return ret;
 540 }
 541
 542 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
 543 {
 544     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 545 }
 546
 547 static inline int is_sector_in_chunk(BDRVDMGState* s,
 548                 uint32_t chunk_num, uint64_t sector_num)
 549 {
 550     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 551             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 552         return 0;
 553     } else {
 554         return -1;
 555     }
 556 }
 557
 558 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 559 {
 560     /* binary search */
 561     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 562     while (chunk1 != chunk2) {
 563         chunk3 = (chunk1 + chunk2) / 2;
 564         if (s->sectors[chunk3] > sector_num) {
 565             chunk2 = chunk3;
 566         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 567             return chunk3;
 568         } else {
 569             chunk1 = chunk3;
 570         }
 571     }
 572     return s->n_chunks; /* error */
 573 }
 574
 575 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 576 {
 577     BDRVDMGState *s = bs->opaque;
 578
 579     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 580         int ret;
 581         uint32_t chunk = search_chunk(s, sector_num);
 582
 583         if (chunk >= s->n_chunks) {
 584             return -1;
 585         }
 586
 587         s->current_chunk = s->n_chunks;
 588         switch (s->types[chunk]) { /* block entry type */
 589         case 0x80000005: { /* zlib compressed */
 590             /* we need to buffer, because only the chunk as whole can be
 591              * inflated. */
 592             ret = bdrv_pread(bs->file, s->offsets[chunk],
 593                              s->compressed_chunk, s->lengths[chunk]);
 594             if (ret != s->lengths[chunk]) {
 595                 return -1;
 596             }
 597
 598             s->zstream.next_in = s->compressed_chunk;
 599             s->zstream.avail_in = s->lengths[chunk];
 600             s->zstream.next_out = s->uncompressed_chunk;
 601             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 602             ret = inflateReset(&s->zstream);
 603             if (ret != Z_OK) {
 604                 return -1;
 605             }
 606             ret = inflate(&s->zstream, Z_FINISH);
 607             if (ret != Z_STREAM_END ||
 608                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 609                 return -1;
 610             }
 611             break; }
 612         case 0x80000006: /* bzip2 compressed */
 613             if (!dmg_uncompress_bz2) {
 614                 break;
 615             }
 616             /* we need to buffer, because only the chunk as whole can be
 617              * inflated. */
 618             ret = bdrv_pread(bs->file, s->offsets[chunk],
 619                              s->compressed_chunk, s->lengths[chunk]);
 620             if (ret != s->lengths[chunk]) {
 621                 return -1;
 622             }
 623
 624             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
 625                                      (unsigned int) s->lengths[chunk],
 626                                      (char *)s->uncompressed_chunk,
 627                                      (unsigned int)
 628                                          (512 * s->sectorcounts[chunk]));
 629             if (ret < 0) {
 630                 return ret;
 631             }
 632             break;
 633         case 0x80000007:
 634             if (!dmg_uncompress_lzfse) {
 635                 break;
 636             }
 637             /* we need to buffer, because only the chunk as whole can be
 638              * inflated. */
 639             ret = bdrv_pread(bs->file, s->offsets[chunk],
 640                              s->compressed_chunk, s->lengths[chunk]);
 641             if (ret != s->lengths[chunk]) {
 642                 return -1;
 643             }
 644
 645             ret = dmg_uncompress_lzfse((char *)s->compressed_chunk,
 646                                        (unsigned int) s->lengths[chunk],
 647                                        (char *)s->uncompressed_chunk,
 648                                        (unsigned int)
 649                                            (512 * s->sectorcounts[chunk]));
 650             if (ret < 0) {
 651                 return ret;
 652             }
 653             break;
 654         case 1: /* copy */
 655             ret = bdrv_pread(bs->file, s->offsets[chunk],
 656                              s->uncompressed_chunk, s->lengths[chunk]);
 657             if (ret != s->lengths[chunk]) {
 658                 return -1;
 659             }
 660             break;
 661         case 2: /* zero */
 662             /* see dmg_read, it is treated specially. No buffer needs to be
 663              * pre-filled, the zeroes can be set directly. */
 664             break;
 665         }
 666         s->current_chunk = chunk;
 667     }
 668     return 0;
 669 }
 670
 671 static int coroutine_fn
 672 dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 673               QEMUIOVector *qiov, int flags)
 674 {
 675     BDRVDMGState *s = bs->opaque;
 676     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 677     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 678     int ret, i;
 679
 680     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 681     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 682
 683     qemu_co_mutex_lock(&s->lock);
 684
 685     for (i = 0; i < nb_sectors; i++) {
 686         uint32_t sector_offset_in_chunk;
 687         void *data;
 688
 689         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 690             ret = -EIO;
 691             goto fail;
 692         }
 693         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 694          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 695          * section. dmg_read_chunk is called to find s->current_chunk */
 696         if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
 697             qemu_iovec_memset(qiov, i * 512, 0, 512);
 698             continue;
 699         }
 700         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 701         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 702         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 703     }
 704
 705     ret = 0;
 706 fail:
 707     qemu_co_mutex_unlock(&s->lock);
 708     return ret;
 709 }
 710
 711 static void dmg_close(BlockDriverState *bs)
 712 {
 713     BDRVDMGState *s = bs->opaque;
 714
 715     g_free(s->types);
 716     g_free(s->offsets);
 717     g_free(s->lengths);
 718     g_free(s->sectors);
 719     g_free(s->sectorcounts);
 720     qemu_vfree(s->compressed_chunk);
 721     qemu_vfree(s->uncompressed_chunk);
 722
 723     inflateEnd(&s->zstream);
 724 }
 725
 726 static BlockDriver bdrv_dmg = {
 727     .format_name    = "dmg",
 728     .instance_size  = sizeof(BDRVDMGState),
 729     .bdrv_probe     = dmg_probe,
 730     .bdrv_open      = dmg_open,
 731     .bdrv_refresh_limits = dmg_refresh_limits,
 732     .bdrv_child_perm     = bdrv_format_default_perms,
 733     .bdrv_co_preadv = dmg_co_preadv,
 734     .bdrv_close     = dmg_close,
 735 };
 736
 737 static void bdrv_dmg_init(void)
 738 {
 739     bdrv_register(&bdrv_dmg);
 740 }
 741
 742 block_init(bdrv_dmg_init);