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-common.h"
  25 #include "block/block_int.h"
  26 #include "qemu/bswap.h"
  27 #include "qemu/module.h"
  28 #include <zlib.h>
  29 #include <glib.h>
  30
  31 enum {
  32     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  33      * or truncating when converting to 32-bit types
  34      */
  35     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  36     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  37 };
  38
  39 typedef struct BDRVDMGState {
  40     CoMutex lock;
  41     /* each chunk contains a certain number of sectors,
  42      * offsets[i] is the offset in the .dmg file,
  43      * lengths[i] is the length of the compressed chunk,
  44      * sectors[i] is the sector beginning at offsets[i],
  45      * sectorcounts[i] is the number of sectors in that chunk,
  46      * the sectors array is ordered
  47      * 0<=i<n_chunks */
  48
  49     uint32_t n_chunks;
  50     uint32_t* types;
  51     uint64_t* offsets;
  52     uint64_t* lengths;
  53     uint64_t* sectors;
  54     uint64_t* sectorcounts;
  55     uint32_t current_chunk;
  56     uint8_t *compressed_chunk;
  57     uint8_t *uncompressed_chunk;
  58     z_stream zstream;
  59 } BDRVDMGState;
  60
  61 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  62 {
  63     int len;
  64
  65     if (!filename) {
  66         return 0;
  67     }
  68
  69     len = strlen(filename);
  70     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  71         return 2;
  72     }
  73     return 0;
  74 }
  75
  76 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  77 {
  78     uint64_t buffer;
  79     int ret;
  80
  81     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  82     if (ret < 0) {
  83         return ret;
  84     }
  85
  86     *result = be64_to_cpu(buffer);
  87     return 0;
  88 }
  89
  90 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  91 {
  92     uint32_t buffer;
  93     int ret;
  94
  95     ret = bdrv_pread(bs->file, offset, &buffer, 4);
  96     if (ret < 0) {
  97         return ret;
  98     }
  99
 100     *result = be32_to_cpu(buffer);
 101     return 0;
 102 }
 103
 104 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 105 {
 106     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 107 }
 108
 109 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 110 {
 111     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 112 }
 113
 114 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 115  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 116  */
 117 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 118                                   uint32_t *max_compressed_size,
 119                                   uint32_t *max_sectors_per_chunk)
 120 {
 121     uint32_t compressed_size = 0;
 122     uint32_t uncompressed_sectors = 0;
 123
 124     switch (s->types[chunk]) {
 125     case 0x80000005: /* zlib compressed */
 126         compressed_size = s->lengths[chunk];
 127         uncompressed_sectors = s->sectorcounts[chunk];
 128         break;
 129     case 1: /* copy */
 130         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 131         break;
 132     case 2: /* zero */
 133         uncompressed_sectors = s->sectorcounts[chunk];
 134         break;
 135     }
 136
 137     if (compressed_size > *max_compressed_size) {
 138         *max_compressed_size = compressed_size;
 139     }
 140     if (uncompressed_sectors > *max_sectors_per_chunk) {
 141         *max_sectors_per_chunk = uncompressed_sectors;
 142     }
 143 }
 144
 145 static int64_t dmg_find_koly_offset(BlockDriverState *file_bs, Error **errp)
 146 {
 147     int64_t length;
 148     int64_t offset = 0;
 149     uint8_t buffer[515];
 150     int i, ret;
 151
 152     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 153      * dmg images can have odd sizes, try to look for the "koly" magic which
 154      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 155      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 156      * the last sector (search space: 515 bytes) */
 157     length = bdrv_getlength(file_bs);
 158     if (length < 0) {
 159         error_setg_errno(errp, -length,
 160             "Failed to get file size while reading UDIF trailer");
 161         return length;
 162     } else if (length < 512) {
 163         error_setg(errp, "dmg file must be at least 512 bytes long");
 164         return -EINVAL;
 165     }
 166     if (length > 511 + 512) {
 167         offset = length - 511 - 512;
 168     }
 169     length = length < 515 ? length : 515;
 170     ret = bdrv_pread(file_bs, offset, buffer, length);
 171     if (ret < 0) {
 172         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 173         return ret;
 174     }
 175     for (i = 0; i < length - 3; i++) {
 176         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 177             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 178             return offset + i;
 179         }
 180     }
 181     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 182     return -EINVAL;
 183 }
 184
 185 /* used when building the sector table */
 186 typedef struct DmgHeaderState {
 187     /* used internally by dmg_read_mish_block to remember offsets of blocks
 188      * across calls */
 189     uint64_t last_in_offset;
 190     uint64_t last_out_offset;
 191     /* exported for dmg_open */
 192     uint32_t max_compressed_size;
 193     uint32_t max_sectors_per_chunk;
 194 } DmgHeaderState;
 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
 205     type = buff_read_uint32(buffer, offset);
 206     /* skip data that is not a valid MISH block (invalid magic or too small) */
 207     if (type != 0x6d697368 || count < 244) {
 208         /* assume success for now */
 209         return 0;
 210     }
 211
 212     offset += 4;
 213     offset += 200;
 214
 215     chunk_count = (count - 204) / 40;
 216     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 217     s->types = g_realloc(s->types, new_size / 2);
 218     s->offsets = g_realloc(s->offsets, new_size);
 219     s->lengths = g_realloc(s->lengths, new_size);
 220     s->sectors = g_realloc(s->sectors, new_size);
 221     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 222
 223     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 224         s->types[i] = buff_read_uint32(buffer, offset);
 225         offset += 4;
 226         if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
 227             s->types[i] != 2) {
 228             if (s->types[i] == 0xffffffff && i > 0) {
 229                 ds->last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
 230                 ds->last_out_offset = s->sectors[i - 1] +
 231                                       s->sectorcounts[i - 1];
 232             }
 233             chunk_count--;
 234             i--;
 235             offset += 36;
 236             continue;
 237         }
 238         offset += 4;
 239
 240         s->sectors[i] = buff_read_uint64(buffer, offset);
 241         s->sectors[i] += ds->last_out_offset;
 242         offset += 8;
 243
 244         s->sectorcounts[i] = buff_read_uint64(buffer, offset);
 245         offset += 8;
 246
 247         if (s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 248             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 249                          " is larger than max (%u)",
 250                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 251             ret = -EINVAL;
 252             goto fail;
 253         }
 254
 255         s->offsets[i] = buff_read_uint64(buffer, offset);
 256         s->offsets[i] += ds->last_in_offset;
 257         offset += 8;
 258
 259         s->lengths[i] = buff_read_uint64(buffer, offset);
 260         offset += 8;
 261
 262         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 263             error_report("length %" PRIu64 " for chunk %" PRIu32
 264                          " is larger than max (%u)",
 265                          s->lengths[i], i, DMG_LENGTHS_MAX);
 266             ret = -EINVAL;
 267             goto fail;
 268         }
 269
 270         update_max_chunk_size(s, i, &ds->max_compressed_size,
 271                               &ds->max_sectors_per_chunk);
 272     }
 273     s->n_chunks += chunk_count;
 274     return 0;
 275
 276 fail:
 277     return ret;
 278 }
 279
 280 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 281                                   uint64_t info_begin, uint64_t info_length)
 282 {
 283     BDRVDMGState *s = bs->opaque;
 284     int ret;
 285     uint32_t count, rsrc_data_offset;
 286     uint8_t *buffer = NULL;
 287     uint64_t info_end;
 288     uint64_t offset;
 289
 290     /* read offset from begin of resource fork (info_begin) to resource data */
 291     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 292     if (ret < 0) {
 293         goto fail;
 294     } else if (rsrc_data_offset > info_length) {
 295         ret = -EINVAL;
 296         goto fail;
 297     }
 298
 299     /* read length of resource data */
 300     ret = read_uint32(bs, info_begin + 8, &count);
 301     if (ret < 0) {
 302         goto fail;
 303     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 304         ret = -EINVAL;
 305         goto fail;
 306     }
 307
 308     /* begin of resource data (consisting of one or more resources) */
 309     offset = info_begin + rsrc_data_offset;
 310
 311     /* end of resource data (there is possibly a following resource map
 312      * which will be ignored). */
 313     info_end = offset + count;
 314
 315     /* read offsets (mish blocks) from one or more resources in resource data */
 316     while (offset < info_end) {
 317         /* size of following resource */
 318         ret = read_uint32(bs, offset, &count);
 319         if (ret < 0) {
 320             goto fail;
 321         } else if (count == 0 || count > info_end - offset) {
 322             ret = -EINVAL;
 323             goto fail;
 324         }
 325         offset += 4;
 326
 327         buffer = g_realloc(buffer, count);
 328         ret = bdrv_pread(bs->file, offset, buffer, count);
 329         if (ret < 0) {
 330             goto fail;
 331         }
 332
 333         ret = dmg_read_mish_block(s, ds, buffer, count);
 334         if (ret < 0) {
 335             goto fail;
 336         }
 337         /* advance offset by size of resource */
 338         offset += count;
 339     }
 340     ret = 0;
 341
 342 fail:
 343     g_free(buffer);
 344     return ret;
 345 }
 346
 347 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
 348                               uint64_t info_begin, uint64_t info_length)
 349 {
 350     BDRVDMGState *s = bs->opaque;
 351     int ret;
 352     uint8_t *buffer = NULL;
 353     char *data_begin, *data_end;
 354
 355     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
 356      * safe upper cap on the data length. A test sample had a XML length of
 357      * about 1 MiB. */
 358     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
 359         ret = -EINVAL;
 360         goto fail;
 361     }
 362
 363     buffer = g_malloc(info_length + 1);
 364     buffer[info_length] = '\0';
 365     ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
 366     if (ret != info_length) {
 367         ret = -EINVAL;
 368         goto fail;
 369     }
 370
 371     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
 372      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
 373      * and line feeds. */
 374     data_end = (char *)buffer;
 375     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
 376         guchar *mish;
 377         gsize out_len = 0;
 378
 379         data_begin += 6;
 380         data_end = strstr(data_begin, "</data>");
 381         /* malformed XML? */
 382         if (data_end == NULL) {
 383             ret = -EINVAL;
 384             goto fail;
 385         }
 386         *data_end++ = '\0';
 387         mish = g_base64_decode(data_begin, &out_len);
 388         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
 389         g_free(mish);
 390         if (ret < 0) {
 391             goto fail;
 392         }
 393     }
 394     ret = 0;
 395
 396 fail:
 397     g_free(buffer);
 398     return ret;
 399 }
 400
 401 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 402                     Error **errp)
 403 {
 404     BDRVDMGState *s = bs->opaque;
 405     DmgHeaderState ds;
 406     uint64_t rsrc_fork_offset, rsrc_fork_length;
 407     uint64_t plist_xml_offset, plist_xml_length;
 408     int64_t offset;
 409     int ret;
 410
 411     bs->read_only = 1;
 412     s->n_chunks = 0;
 413     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 414     /* used by dmg_read_mish_block to keep track of the current I/O position */
 415     ds.last_in_offset = 0;
 416     ds.last_out_offset = 0;
 417     ds.max_compressed_size = 1;
 418     ds.max_sectors_per_chunk = 1;
 419
 420     /* locate the UDIF trailer */
 421     offset = dmg_find_koly_offset(bs->file, errp);
 422     if (offset < 0) {
 423         ret = offset;
 424         goto fail;
 425     }
 426
 427     /* offset of resource fork (RsrcForkOffset) */
 428     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 429     if (ret < 0) {
 430         goto fail;
 431     }
 432     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 433     if (ret < 0) {
 434         goto fail;
 435     }
 436     if (rsrc_fork_offset >= offset ||
 437         rsrc_fork_length > offset - rsrc_fork_offset) {
 438         ret = -EINVAL;
 439         goto fail;
 440     }
 441     /* offset of property list (XMLOffset) */
 442     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
 443     if (ret < 0) {
 444         goto fail;
 445     }
 446     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
 447     if (ret < 0) {
 448         goto fail;
 449     }
 450     if (plist_xml_offset >= offset ||
 451         plist_xml_length > offset - plist_xml_offset) {
 452         ret = -EINVAL;
 453         goto fail;
 454     }
 455     if (rsrc_fork_length != 0) {
 456         ret = dmg_read_resource_fork(bs, &ds,
 457                                      rsrc_fork_offset, rsrc_fork_length);
 458         if (ret < 0) {
 459             goto fail;
 460         }
 461     } else if (plist_xml_length != 0) {
 462         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
 463         if (ret < 0) {
 464             goto fail;
 465         }
 466     } else {
 467         ret = -EINVAL;
 468         goto fail;
 469     }
 470
 471     /* initialize zlib engine */
 472     s->compressed_chunk = qemu_try_blockalign(bs->file,
 473                                               ds.max_compressed_size + 1);
 474     s->uncompressed_chunk = qemu_try_blockalign(bs->file,
 475                                                 512 * ds.max_sectors_per_chunk);
 476     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 477         ret = -ENOMEM;
 478         goto fail;
 479     }
 480
 481     if (inflateInit(&s->zstream) != Z_OK) {
 482         ret = -EINVAL;
 483         goto fail;
 484     }
 485
 486     s->current_chunk = s->n_chunks;
 487
 488     qemu_co_mutex_init(&s->lock);
 489     return 0;
 490
 491 fail:
 492     g_free(s->types);
 493     g_free(s->offsets);
 494     g_free(s->lengths);
 495     g_free(s->sectors);
 496     g_free(s->sectorcounts);
 497     qemu_vfree(s->compressed_chunk);
 498     qemu_vfree(s->uncompressed_chunk);
 499     return ret;
 500 }
 501
 502 static inline int is_sector_in_chunk(BDRVDMGState* s,
 503                 uint32_t chunk_num, uint64_t sector_num)
 504 {
 505     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 506             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 507         return 0;
 508     } else {
 509         return -1;
 510     }
 511 }
 512
 513 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 514 {
 515     /* binary search */
 516     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 517     while (chunk1 != chunk2) {
 518         chunk3 = (chunk1 + chunk2) / 2;
 519         if (s->sectors[chunk3] > sector_num) {
 520             chunk2 = chunk3;
 521         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 522             return chunk3;
 523         } else {
 524             chunk1 = chunk3;
 525         }
 526     }
 527     return s->n_chunks; /* error */
 528 }
 529
 530 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 531 {
 532     BDRVDMGState *s = bs->opaque;
 533
 534     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 535         int ret;
 536         uint32_t chunk = search_chunk(s, sector_num);
 537
 538         if (chunk >= s->n_chunks) {
 539             return -1;
 540         }
 541
 542         s->current_chunk = s->n_chunks;
 543         switch (s->types[chunk]) {
 544         case 0x80000005: { /* zlib compressed */
 545             /* we need to buffer, because only the chunk as whole can be
 546              * inflated. */
 547             ret = bdrv_pread(bs->file, s->offsets[chunk],
 548                              s->compressed_chunk, s->lengths[chunk]);
 549             if (ret != s->lengths[chunk]) {
 550                 return -1;
 551             }
 552
 553             s->zstream.next_in = s->compressed_chunk;
 554             s->zstream.avail_in = s->lengths[chunk];
 555             s->zstream.next_out = s->uncompressed_chunk;
 556             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 557             ret = inflateReset(&s->zstream);
 558             if (ret != Z_OK) {
 559                 return -1;
 560             }
 561             ret = inflate(&s->zstream, Z_FINISH);
 562             if (ret != Z_STREAM_END ||
 563                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 564                 return -1;
 565             }
 566             break; }
 567         case 1: /* copy */
 568             ret = bdrv_pread(bs->file, s->offsets[chunk],
 569                              s->uncompressed_chunk, s->lengths[chunk]);
 570             if (ret != s->lengths[chunk]) {
 571                 return -1;
 572             }
 573             break;
 574         case 2: /* zero */
 575             memset(s->uncompressed_chunk, 0, 512 * s->sectorcounts[chunk]);
 576             break;
 577         }
 578         s->current_chunk = chunk;
 579     }
 580     return 0;
 581 }
 582
 583 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
 584                     uint8_t *buf, int nb_sectors)
 585 {
 586     BDRVDMGState *s = bs->opaque;
 587     int i;
 588
 589     for (i = 0; i < nb_sectors; i++) {
 590         uint32_t sector_offset_in_chunk;
 591         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 592             return -1;
 593         }
 594         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 595         memcpy(buf + i * 512,
 596                s->uncompressed_chunk + sector_offset_in_chunk * 512, 512);
 597     }
 598     return 0;
 599 }
 600
 601 static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
 602                                     uint8_t *buf, int nb_sectors)
 603 {
 604     int ret;
 605     BDRVDMGState *s = bs->opaque;
 606     qemu_co_mutex_lock(&s->lock);
 607     ret = dmg_read(bs, sector_num, buf, nb_sectors);
 608     qemu_co_mutex_unlock(&s->lock);
 609     return ret;
 610 }
 611
 612 static void dmg_close(BlockDriverState *bs)
 613 {
 614     BDRVDMGState *s = bs->opaque;
 615
 616     g_free(s->types);
 617     g_free(s->offsets);
 618     g_free(s->lengths);
 619     g_free(s->sectors);
 620     g_free(s->sectorcounts);
 621     qemu_vfree(s->compressed_chunk);
 622     qemu_vfree(s->uncompressed_chunk);
 623
 624     inflateEnd(&s->zstream);
 625 }
 626
 627 static BlockDriver bdrv_dmg = {
 628     .format_name    = "dmg",
 629     .instance_size  = sizeof(BDRVDMGState),
 630     .bdrv_probe     = dmg_probe,
 631     .bdrv_open      = dmg_open,
 632     .bdrv_read      = dmg_co_read,
 633     .bdrv_close     = dmg_close,
 634 };
 635
 636 static void bdrv_dmg_init(void)
 637 {
 638     bdrv_register(&bdrv_dmg);
 639 }
 640
 641 block_init(bdrv_dmg_init);