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 <zlib.h>
  32 #ifdef CONFIG_BZIP2
  33 #include <bzlib.h>
  34 #endif
  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 typedef struct BDRVDMGState {
  45     CoMutex lock;
  46     /* each chunk contains a certain number of sectors,
  47      * offsets[i] is the offset in the .dmg file,
  48      * lengths[i] is the length of the compressed chunk,
  49      * sectors[i] is the sector beginning at offsets[i],
  50      * sectorcounts[i] is the number of sectors in that chunk,
  51      * the sectors array is ordered
  52      * 0<=i<n_chunks */
  53
  54     uint32_t n_chunks;
  55     uint32_t* types;
  56     uint64_t* offsets;
  57     uint64_t* lengths;
  58     uint64_t* sectors;
  59     uint64_t* sectorcounts;
  60     uint32_t current_chunk;
  61     uint8_t *compressed_chunk;
  62     uint8_t *uncompressed_chunk;
  63     z_stream zstream;
  64 #ifdef CONFIG_BZIP2
  65     bz_stream bzstream;
  66 #endif
  67 } BDRVDMGState;
  68
  69 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  70 {
  71     int len;
  72
  73     if (!filename) {
  74         return 0;
  75     }
  76
  77     len = strlen(filename);
  78     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  79         return 2;
  80     }
  81     return 0;
  82 }
  83
  84 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  85 {
  86     uint64_t buffer;
  87     int ret;
  88
  89     ret = bdrv_pread(bs->file->bs, offset, &buffer, 8);
  90     if (ret < 0) {
  91         return ret;
  92     }
  93
  94     *result = be64_to_cpu(buffer);
  95     return 0;
  96 }
  97
  98 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  99 {
 100     uint32_t buffer;
 101     int ret;
 102
 103     ret = bdrv_pread(bs->file->bs, offset, &buffer, 4);
 104     if (ret < 0) {
 105         return ret;
 106     }
 107
 108     *result = be32_to_cpu(buffer);
 109     return 0;
 110 }
 111
 112 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 113 {
 114     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 115 }
 116
 117 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 118 {
 119     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 120 }
 121
 122 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 123  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 124  */
 125 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 126                                   uint32_t *max_compressed_size,
 127                                   uint32_t *max_sectors_per_chunk)
 128 {
 129     uint32_t compressed_size = 0;
 130     uint32_t uncompressed_sectors = 0;
 131
 132     switch (s->types[chunk]) {
 133     case 0x80000005: /* zlib compressed */
 134     case 0x80000006: /* bzip2 compressed */
 135         compressed_size = s->lengths[chunk];
 136         uncompressed_sectors = s->sectorcounts[chunk];
 137         break;
 138     case 1: /* copy */
 139         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 140         break;
 141     case 2: /* zero */
 142         /* as the all-zeroes block may be large, it is treated specially: the
 143          * sector is not copied from a large buffer, a simple memset is used
 144          * instead. Therefore uncompressed_sectors does not need to be set. */
 145         break;
 146     }
 147
 148     if (compressed_size > *max_compressed_size) {
 149         *max_compressed_size = compressed_size;
 150     }
 151     if (uncompressed_sectors > *max_sectors_per_chunk) {
 152         *max_sectors_per_chunk = uncompressed_sectors;
 153     }
 154 }
 155
 156 static int64_t dmg_find_koly_offset(BlockDriverState *file_bs, Error **errp)
 157 {
 158     int64_t length;
 159     int64_t offset = 0;
 160     uint8_t buffer[515];
 161     int i, ret;
 162
 163     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 164      * dmg images can have odd sizes, try to look for the "koly" magic which
 165      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 166      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 167      * the last sector (search space: 515 bytes) */
 168     length = bdrv_getlength(file_bs);
 169     if (length < 0) {
 170         error_setg_errno(errp, -length,
 171             "Failed to get file size while reading UDIF trailer");
 172         return length;
 173     } else if (length < 512) {
 174         error_setg(errp, "dmg file must be at least 512 bytes long");
 175         return -EINVAL;
 176     }
 177     if (length > 511 + 512) {
 178         offset = length - 511 - 512;
 179     }
 180     length = length < 515 ? length : 515;
 181     ret = bdrv_pread(file_bs, offset, buffer, length);
 182     if (ret < 0) {
 183         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 184         return ret;
 185     }
 186     for (i = 0; i < length - 3; i++) {
 187         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 188             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 189             return offset + i;
 190         }
 191     }
 192     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 193     return -EINVAL;
 194 }
 195
 196 /* used when building the sector table */
 197 typedef struct DmgHeaderState {
 198     /* used internally by dmg_read_mish_block to remember offsets of blocks
 199      * across calls */
 200     uint64_t data_fork_offset;
 201     /* exported for dmg_open */
 202     uint32_t max_compressed_size;
 203     uint32_t max_sectors_per_chunk;
 204 } DmgHeaderState;
 205
 206 static bool dmg_is_known_block_type(uint32_t entry_type)
 207 {
 208     switch (entry_type) {
 209     case 0x00000001:    /* uncompressed */
 210     case 0x00000002:    /* zeroes */
 211     case 0x80000005:    /* zlib */
 212 #ifdef CONFIG_BZIP2
 213     case 0x80000006:    /* bzip2 */
 214 #endif
 215         return true;
 216     default:
 217         return false;
 218     }
 219 }
 220
 221 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 222                                uint8_t *buffer, uint32_t count)
 223 {
 224     uint32_t type, i;
 225     int ret;
 226     size_t new_size;
 227     uint32_t chunk_count;
 228     int64_t offset = 0;
 229     uint64_t data_offset;
 230     uint64_t in_offset = ds->data_fork_offset;
 231     uint64_t out_offset;
 232
 233     type = buff_read_uint32(buffer, offset);
 234     /* skip data that is not a valid MISH block (invalid magic or too small) */
 235     if (type != 0x6d697368 || count < 244) {
 236         /* assume success for now */
 237         return 0;
 238     }
 239
 240     /* chunk offsets are relative to this sector number */
 241     out_offset = buff_read_uint64(buffer, offset + 8);
 242
 243     /* location in data fork for (compressed) blob (in bytes) */
 244     data_offset = buff_read_uint64(buffer, offset + 0x18);
 245     in_offset += data_offset;
 246
 247     /* move to begin of chunk entries */
 248     offset += 204;
 249
 250     chunk_count = (count - 204) / 40;
 251     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 252     s->types = g_realloc(s->types, new_size / 2);
 253     s->offsets = g_realloc(s->offsets, new_size);
 254     s->lengths = g_realloc(s->lengths, new_size);
 255     s->sectors = g_realloc(s->sectors, new_size);
 256     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 257
 258     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 259         s->types[i] = buff_read_uint32(buffer, offset);
 260         if (!dmg_is_known_block_type(s->types[i])) {
 261             chunk_count--;
 262             i--;
 263             offset += 40;
 264             continue;
 265         }
 266
 267         /* sector number */
 268         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
 269         s->sectors[i] += out_offset;
 270
 271         /* sector count */
 272         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
 273
 274         /* all-zeroes sector (type 2) does not need to be "uncompressed" and can
 275          * therefore be unbounded. */
 276         if (s->types[i] != 2 && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 277             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 278                          " is larger than max (%u)",
 279                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 280             ret = -EINVAL;
 281             goto fail;
 282         }
 283
 284         /* offset in (compressed) data fork */
 285         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
 286         s->offsets[i] += in_offset;
 287
 288         /* length in (compressed) data fork */
 289         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
 290
 291         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 292             error_report("length %" PRIu64 " for chunk %" PRIu32
 293                          " is larger than max (%u)",
 294                          s->lengths[i], i, DMG_LENGTHS_MAX);
 295             ret = -EINVAL;
 296             goto fail;
 297         }
 298
 299         update_max_chunk_size(s, i, &ds->max_compressed_size,
 300                               &ds->max_sectors_per_chunk);
 301         offset += 40;
 302     }
 303     s->n_chunks += chunk_count;
 304     return 0;
 305
 306 fail:
 307     return ret;
 308 }
 309
 310 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 311                                   uint64_t info_begin, uint64_t info_length)
 312 {
 313     BDRVDMGState *s = bs->opaque;
 314     int ret;
 315     uint32_t count, rsrc_data_offset;
 316     uint8_t *buffer = NULL;
 317     uint64_t info_end;
 318     uint64_t offset;
 319
 320     /* read offset from begin of resource fork (info_begin) to resource data */
 321     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 322     if (ret < 0) {
 323         goto fail;
 324     } else if (rsrc_data_offset > info_length) {
 325         ret = -EINVAL;
 326         goto fail;
 327     }
 328
 329     /* read length of resource data */
 330     ret = read_uint32(bs, info_begin + 8, &count);
 331     if (ret < 0) {
 332         goto fail;
 333     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 334         ret = -EINVAL;
 335         goto fail;
 336     }
 337
 338     /* begin of resource data (consisting of one or more resources) */
 339     offset = info_begin + rsrc_data_offset;
 340
 341     /* end of resource data (there is possibly a following resource map
 342      * which will be ignored). */
 343     info_end = offset + count;
 344
 345     /* read offsets (mish blocks) from one or more resources in resource data */
 346     while (offset < info_end) {
 347         /* size of following resource */
 348         ret = read_uint32(bs, offset, &count);
 349         if (ret < 0) {
 350             goto fail;
 351         } else if (count == 0 || count > info_end - offset) {
 352             ret = -EINVAL;
 353             goto fail;
 354         }
 355         offset += 4;
 356
 357         buffer = g_realloc(buffer, count);
 358         ret = bdrv_pread(bs->file->bs, offset, buffer, count);
 359         if (ret < 0) {
 360             goto fail;
 361         }
 362
 363         ret = dmg_read_mish_block(s, ds, buffer, count);
 364         if (ret < 0) {
 365             goto fail;
 366         }
 367         /* advance offset by size of resource */
 368         offset += count;
 369     }
 370     ret = 0;
 371
 372 fail:
 373     g_free(buffer);
 374     return ret;
 375 }
 376
 377 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 378                               uint64_t info_begin, uint64_t info_length)
 379 {
 380     BDRVDMGState *s = bs->opaque;
 381     int ret;
 382     uint8_t *buffer = NULL;
 383     char *data_begin, *data_end;
 384
 385     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 386      * safe upper cap on the data length. A test sample had a XML length of
 387      * about 1 MiB. */
 388     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 389         ret = -EINVAL;
 390         goto fail;
 391     }
 392
 393     buffer = g_malloc(info_length + 1);
 394     buffer[info_length] = '\0';
 395     ret = bdrv_pread(bs->file->bs, info_begin, buffer, info_length);
 396     if (ret != info_length) {
 397         ret = -EINVAL;
 398         goto fail;
 399     }
 400
 401     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 402      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 403      * and line feeds. */
 404     data_end = (char *)buffer;
 405     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 406         guchar *mish;
 407         gsize out_len = 0;
 408
 409         data_begin += 6;
 410         data_end = strstr(data_begin, "</data>");
 411         /* malformed XML? */
 412         if (data_end == NULL) {
 413             ret = -EINVAL;
 414             goto fail;
 415         }
 416         *data_end++ = '\0';
 417         mish = g_base64_decode(data_begin, &out_len);
 418         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 419         g_free(mish);
 420         if (ret < 0) {
 421             goto fail;
 422         }
 423     }
 424     ret = 0;
 425
 426 fail:
 427     g_free(buffer);
 428     return ret;
 429 }
 430
 431 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 432                     Error **errp)
 433 {
 434     BDRVDMGState *s = bs->opaque;
 435     DmgHeaderState ds;
 436     uint64_t rsrc_fork_offset, rsrc_fork_length;
 437     uint64_t plist_xml_offset, plist_xml_length;
 438     int64_t offset;
 439     int ret;
 440
 441     bs->read_only = 1;
 442     bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
 443
 444     s->n_chunks = 0;
 445     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 446     /* used by dmg_read_mish_block to keep track of the current I/O position */
 447     ds.data_fork_offset = 0;
 448     ds.max_compressed_size = 1;
 449     ds.max_sectors_per_chunk = 1;
 450
 451     /* locate the UDIF trailer */
 452     offset = dmg_find_koly_offset(bs->file->bs, errp);
 453     if (offset < 0) {
 454         ret = offset;
 455         goto fail;
 456     }
 457
 458     /* offset of data fork (DataForkOffset) */
 459     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
 460     if (ret < 0) {
 461         goto fail;
 462     } else if (ds.data_fork_offset > offset) {
 463         ret = -EINVAL;
 464         goto fail;
 465     }
 466
 467     /* offset of resource fork (RsrcForkOffset) */
 468     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 469     if (ret < 0) {
 470         goto fail;
 471     }
 472     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 473     if (ret < 0) {
 474         goto fail;
 475     }
 476     if (rsrc_fork_offset >= offset ||
 477         rsrc_fork_length > offset - rsrc_fork_offset) {
 478         ret = -EINVAL;
 479         goto fail;
 480     }
 481     /* offset of property list (XMLOffset) */
 482     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 483     if (ret < 0) {
 484         goto fail;
 485     }
 486     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 487     if (ret < 0) {
 488         goto fail;
 489     }
 490     if (plist_xml_offset >= offset ||
 491         plist_xml_length > offset - plist_xml_offset) {
 492         ret = -EINVAL;
 493         goto fail;
 494     }
 495     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
 496     if (ret < 0) {
 497         goto fail;
 498     }
 499     if (bs->total_sectors < 0) {
 500         ret = -EINVAL;
 501         goto fail;
 502     }
 503     if (rsrc_fork_length != 0) {
 504         ret = dmg_read_resource_fork(bs, &ds,
 505                                      rsrc_fork_offset, rsrc_fork_length);
 506         if (ret < 0) {
 507             goto fail;
 508         }
 509     } else if (plist_xml_length != 0) {
 510         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 511         if (ret < 0) {
 512             goto fail;
 513         }
 514     } else {
 515         ret = -EINVAL;
 516         goto fail;
 517     }
 518
 519     /* initialize zlib engine */
 520     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
 521                                               ds.max_compressed_size + 1);
 522     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
 523                                                 512 * ds.max_sectors_per_chunk);
 524     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 525         ret = -ENOMEM;
 526         goto fail;
 527     }
 528
 529     if (inflateInit(&s->zstream) != Z_OK) {
 530         ret = -EINVAL;
 531         goto fail;
 532     }
 533
 534     s->current_chunk = s->n_chunks;
 535
 536     qemu_co_mutex_init(&s->lock);
 537     return 0;
 538
 539 fail:
 540     g_free(s->types);
 541     g_free(s->offsets);
 542     g_free(s->lengths);
 543     g_free(s->sectors);
 544     g_free(s->sectorcounts);
 545     qemu_vfree(s->compressed_chunk);
 546     qemu_vfree(s->uncompressed_chunk);
 547     return ret;
 548 }
 549
 550 static inline int is_sector_in_chunk(BDRVDMGState* s,
 551                 uint32_t chunk_num, uint64_t sector_num)
 552 {
 553     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 554             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 555         return 0;
 556     } else {
 557         return -1;
 558     }
 559 }
 560
 561 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 562 {
 563     /* binary search */
 564     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 565     while (chunk1 != chunk2) {
 566         chunk3 = (chunk1 + chunk2) / 2;
 567         if (s->sectors[chunk3] > sector_num) {
 568             chunk2 = chunk3;
 569         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 570             return chunk3;
 571         } else {
 572             chunk1 = chunk3;
 573         }
 574     }
 575     return s->n_chunks; /* error */
 576 }
 577
 578 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 579 {
 580     BDRVDMGState *s = bs->opaque;
 581
 582     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 583         int ret;
 584         uint32_t chunk = search_chunk(s, sector_num);
 585 #ifdef CONFIG_BZIP2
 586         uint64_t total_out;
 587 #endif
 588
 589         if (chunk >= s->n_chunks) {
 590             return -1;
 591         }
 592
 593         s->current_chunk = s->n_chunks;
 594         switch (s->types[chunk]) { /* block entry type */
 595         case 0x80000005: { /* zlib compressed */
 596             /* we need to buffer, because only the chunk as whole can be
 597              * inflated. */
 598             ret = bdrv_pread(bs->file->bs, s->offsets[chunk],
 599                              s->compressed_chunk, s->lengths[chunk]);
 600             if (ret != s->lengths[chunk]) {
 601                 return -1;
 602             }
 603
 604             s->zstream.next_in = s->compressed_chunk;
 605             s->zstream.avail_in = s->lengths[chunk];
 606             s->zstream.next_out = s->uncompressed_chunk;
 607             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 608             ret = inflateReset(&s->zstream);
 609             if (ret != Z_OK) {
 610                 return -1;
 611             }
 612             ret = inflate(&s->zstream, Z_FINISH);
 613             if (ret != Z_STREAM_END ||
 614                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 615                 return -1;
 616             }
 617             break; }
 618 #ifdef CONFIG_BZIP2
 619         case 0x80000006: /* bzip2 compressed */
 620             /* we need to buffer, because only the chunk as whole can be
 621              * inflated. */
 622             ret = bdrv_pread(bs->file->bs, s->offsets[chunk],
 623                              s->compressed_chunk, s->lengths[chunk]);
 624             if (ret != s->lengths[chunk]) {
 625                 return -1;
 626             }
 627
 628             ret = BZ2_bzDecompressInit(&s->bzstream, 0, 0);
 629             if (ret != BZ_OK) {
 630                 return -1;
 631             }
 632             s->bzstream.next_in = (char *)s->compressed_chunk;
 633             s->bzstream.avail_in = (unsigned int) s->lengths[chunk];
 634             s->bzstream.next_out = (char *)s->uncompressed_chunk;
 635             s->bzstream.avail_out = (unsigned int) 512 * s->sectorcounts[chunk];
 636             ret = BZ2_bzDecompress(&s->bzstream);
 637             total_out = ((uint64_t)s->bzstream.total_out_hi32 << 32) +
 638                         s->bzstream.total_out_lo32;
 639             BZ2_bzDecompressEnd(&s->bzstream);
 640             if (ret != BZ_STREAM_END ||
 641                 total_out != 512 * s->sectorcounts[chunk]) {
 642                 return -1;
 643             }
 644             break;
 645 #endif /* CONFIG_BZIP2 */
 646         case 1: /* copy */
 647             ret = bdrv_pread(bs->file->bs, s->offsets[chunk],
 648                              s->uncompressed_chunk, s->lengths[chunk]);
 649             if (ret != s->lengths[chunk]) {
 650                 return -1;
 651             }
 652             break;
 653         case 2: /* zero */
 654             /* see dmg_read, it is treated specially. No buffer needs to be
 655              * pre-filled, the zeroes can be set directly. */
 656             break;
 657         }
 658         s->current_chunk = chunk;
 659     }
 660     return 0;
 661 }
 662
 663 static int coroutine_fn
 664 dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 665               QEMUIOVector *qiov, int flags)
 666 {
 667     BDRVDMGState *s = bs->opaque;
 668     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 669     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 670     int ret, i;
 671
 672     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 673     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 674
 675     qemu_co_mutex_lock(&s->lock);
 676
 677     for (i = 0; i < nb_sectors; i++) {
 678         uint32_t sector_offset_in_chunk;
 679         void *data;
 680
 681         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 682             ret = -EIO;
 683             goto fail;
 684         }
 685         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
 686          * s->uncompressed_chunk may be too small to cover the large all-zeroes
 687          * section. dmg_read_chunk is called to find s->current_chunk */
 688         if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
 689             qemu_iovec_memset(qiov, i * 512, 0, 512);
 690             continue;
 691         }
 692         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 693         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
 694         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 695     }
 696
 697     ret = 0;
 698 fail:
 699     qemu_co_mutex_unlock(&s->lock);
 700     return ret;
 701 }
 702
 703 static void dmg_close(BlockDriverState *bs)
 704 {
 705     BDRVDMGState *s = bs->opaque;
 706
 707     g_free(s->types);
 708     g_free(s->offsets);
 709     g_free(s->lengths);
 710     g_free(s->sectors);
 711     g_free(s->sectorcounts);
 712     qemu_vfree(s->compressed_chunk);
 713     qemu_vfree(s->uncompressed_chunk);
 714
 715     inflateEnd(&s->zstream);
 716 }
 717
 718 static BlockDriver bdrv_dmg = {
 719     .format_name    = "dmg",
 720     .instance_size  = sizeof(BDRVDMGState),
 721     .bdrv_probe     = dmg_probe,
 722     .bdrv_open      = dmg_open,
 723     .bdrv_co_preadv = dmg_co_preadv,
 724     .bdrv_close     = dmg_close,
 725 };
 726
 727 static void bdrv_dmg_init(void)
 728 {
 729     bdrv_register(&bdrv_dmg);
 730 }
 731
 732 block_init(bdrv_dmg_init);