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
  30 enum {
  31     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
  32      * or truncating when converting to 32-bit types
  33      */
  34     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
  35     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
  36 };
  37
  38 typedef struct BDRVDMGState {
  39     CoMutex lock;
  40     /* each chunk contains a certain number of sectors,
  41      * offsets[i] is the offset in the .dmg file,
  42      * lengths[i] is the length of the compressed chunk,
  43      * sectors[i] is the sector beginning at offsets[i],
  44      * sectorcounts[i] is the number of sectors in that chunk,
  45      * the sectors array is ordered
  46      * 0<=i<n_chunks */
  47
  48     uint32_t n_chunks;
  49     uint32_t* types;
  50     uint64_t* offsets;
  51     uint64_t* lengths;
  52     uint64_t* sectors;
  53     uint64_t* sectorcounts;
  54     uint32_t current_chunk;
  55     uint8_t *compressed_chunk;
  56     uint8_t *uncompressed_chunk;
  57     z_stream zstream;
  58 } BDRVDMGState;
  59
  60 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
  61 {
  62     int len;
  63
  64     if (!filename) {
  65         return 0;
  66     }
  67
  68     len = strlen(filename);
  69     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
  70         return 2;
  71     }
  72     return 0;
  73 }
  74
  75 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
  76 {
  77     uint64_t buffer;
  78     int ret;
  79
  80     ret = bdrv_pread(bs->file, offset, &buffer, 8);
  81     if (ret < 0) {
  82         return ret;
  83     }
  84
  85     *result = be64_to_cpu(buffer);
  86     return 0;
  87 }
  88
  89 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
  90 {
  91     uint32_t buffer;
  92     int ret;
  93
  94     ret = bdrv_pread(bs->file, offset, &buffer, 4);
  95     if (ret < 0) {
  96         return ret;
  97     }
  98
  99     *result = be32_to_cpu(buffer);
 100     return 0;
 101 }
 102
 103 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
 104 {
 105     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
 106 }
 107
 108 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
 109 {
 110     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
 111 }
 112
 113 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 114  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 115  */
 116 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 117                                   uint32_t *max_compressed_size,
 118                                   uint32_t *max_sectors_per_chunk)
 119 {
 120     uint32_t compressed_size = 0;
 121     uint32_t uncompressed_sectors = 0;
 122
 123     switch (s->types[chunk]) {
 124     case 0x80000005: /* zlib compressed */
 125         compressed_size = s->lengths[chunk];
 126         uncompressed_sectors = s->sectorcounts[chunk];
 127         break;
 128     case 1: /* copy */
 129         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 130         break;
 131     case 2: /* zero */
 132         uncompressed_sectors = s->sectorcounts[chunk];
 133         break;
 134     }
 135
 136     if (compressed_size > *max_compressed_size) {
 137         *max_compressed_size = compressed_size;
 138     }
 139     if (uncompressed_sectors > *max_sectors_per_chunk) {
 140         *max_sectors_per_chunk = uncompressed_sectors;
 141     }
 142 }
 143
 144 static int64_t dmg_find_koly_offset(BlockDriverState *file_bs, Error **errp)
 145 {
 146     int64_t length;
 147     int64_t offset = 0;
 148     uint8_t buffer[515];
 149     int i, ret;
 150
 151     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 152      * dmg images can have odd sizes, try to look for the "koly" magic which
 153      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 154      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 155      * the last sector (search space: 515 bytes) */
 156     length = bdrv_getlength(file_bs);
 157     if (length < 0) {
 158         error_setg_errno(errp, -length,
 159             "Failed to get file size while reading UDIF trailer");
 160         return length;
 161     } else if (length < 512) {
 162         error_setg(errp, "dmg file must be at least 512 bytes long");
 163         return -EINVAL;
 164     }
 165     if (length > 511 + 512) {
 166         offset = length - 511 - 512;
 167     }
 168     length = length < 515 ? length : 515;
 169     ret = bdrv_pread(file_bs, offset, buffer, length);
 170     if (ret < 0) {
 171         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 172         return ret;
 173     }
 174     for (i = 0; i < length - 3; i++) {
 175         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 176             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 177             return offset + i;
 178         }
 179     }
 180     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 181     return -EINVAL;
 182 }
 183
 184 /* used when building the sector table */
 185 typedef struct DmgHeaderState {
 186     /* used internally by dmg_read_mish_block to remember offsets of blocks
 187      * across calls */
 188     uint64_t last_in_offset;
 189     uint64_t last_out_offset;
 190     /* exported for dmg_open */
 191     uint32_t max_compressed_size;
 192     uint32_t max_sectors_per_chunk;
 193 } DmgHeaderState;
 194
 195 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
 196                                uint8_t *buffer, uint32_t count)
 197 {
 198     uint32_t type, i;
 199     int ret;
 200     size_t new_size;
 201     uint32_t chunk_count;
 202     int64_t offset = 0;
 203
 204     type = buff_read_uint32(buffer, offset);
 205     /* skip data that is not a valid MISH block (invalid magic or too small) */
 206     if (type != 0x6d697368 || count < 244) {
 207         /* assume success for now */
 208         return 0;
 209     }
 210
 211     offset += 4;
 212     offset += 200;
 213
 214     chunk_count = (count - 204) / 40;
 215     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 216     s->types = g_realloc(s->types, new_size / 2);
 217     s->offsets = g_realloc(s->offsets, new_size);
 218     s->lengths = g_realloc(s->lengths, new_size);
 219     s->sectors = g_realloc(s->sectors, new_size);
 220     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 221
 222     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 223         s->types[i] = buff_read_uint32(buffer, offset);
 224         offset += 4;
 225         if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
 226             s->types[i] != 2) {
 227             if (s->types[i] == 0xffffffff && i > 0) {
 228                 ds->last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
 229                 ds->last_out_offset = s->sectors[i - 1] +
 230                                       s->sectorcounts[i - 1];
 231             }
 232             chunk_count--;
 233             i--;
 234             offset += 36;
 235             continue;
 236         }
 237         offset += 4;
 238
 239         s->sectors[i] = buff_read_uint64(buffer, offset);
 240         s->sectors[i] += ds->last_out_offset;
 241         offset += 8;
 242
 243         s->sectorcounts[i] = buff_read_uint64(buffer, offset);
 244         offset += 8;
 245
 246         if (s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 247             error_report("sector count %" PRIu64 " for chunk %" PRIu32
 248                          " is larger than max (%u)",
 249                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 250             ret = -EINVAL;
 251             goto fail;
 252         }
 253
 254         s->offsets[i] = buff_read_uint64(buffer, offset);
 255         s->offsets[i] += ds->last_in_offset;
 256         offset += 8;
 257
 258         s->lengths[i] = buff_read_uint64(buffer, offset);
 259         offset += 8;
 260
 261         if (s->lengths[i] > DMG_LENGTHS_MAX) {
 262             error_report("length %" PRIu64 " for chunk %" PRIu32
 263                          " is larger than max (%u)",
 264                          s->lengths[i], i, DMG_LENGTHS_MAX);
 265             ret = -EINVAL;
 266             goto fail;
 267         }
 268
 269         update_max_chunk_size(s, i, &ds->max_compressed_size,
 270                               &ds->max_sectors_per_chunk);
 271     }
 272     s->n_chunks += chunk_count;
 273     return 0;
 274
 275 fail:
 276     return ret;
 277 }
 278
 279 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
 280                                   uint64_t info_begin, uint64_t info_length)
 281 {
 282     BDRVDMGState *s = bs->opaque;
 283     int ret;
 284     uint32_t count, rsrc_data_offset;
 285     uint8_t *buffer = NULL;
 286     uint64_t info_end;
 287     uint64_t offset;
 288
 289     /* read offset from begin of resource fork (info_begin) to resource data */
 290     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
 291     if (ret < 0) {
 292         goto fail;
 293     } else if (rsrc_data_offset > info_length) {
 294         ret = -EINVAL;
 295         goto fail;
 296     }
 297
 298     /* read length of resource data */
 299     ret = read_uint32(bs, info_begin + 8, &count);
 300     if (ret < 0) {
 301         goto fail;
 302     } else if (count == 0 || rsrc_data_offset + count > info_length) {
 303         ret = -EINVAL;
 304         goto fail;
 305     }
 306
 307     /* begin of resource data (consisting of one or more resources) */
 308     offset = info_begin + rsrc_data_offset;
 309
 310     /* end of resource data (there is possibly a following resource map
 311      * which will be ignored). */
 312     info_end = offset + count;
 313
 314     /* read offsets (mish blocks) from one or more resources in resource data */
 315     while (offset < info_end) {
 316         /* size of following resource */
 317         ret = read_uint32(bs, offset, &count);
 318         if (ret < 0) {
 319             goto fail;
 320         } else if (count == 0) {
 321             ret = -EINVAL;
 322             goto fail;
 323         }
 324         offset += 4;
 325
 326         buffer = g_realloc(buffer, count);
 327         ret = bdrv_pread(bs->file, offset, buffer, count);
 328         if (ret < 0) {
 329             goto fail;
 330         }
 331
 332         ret = dmg_read_mish_block(s, ds, buffer, count);
 333         if (ret < 0) {
 334             goto fail;
 335         }
 336         /* advance offset by size of resource */
 337         offset += count;
 338     }
 339     ret = 0;
 340
 341 fail:
 342     g_free(buffer);
 343     return ret;
 344 }
 345
 346 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 347                     Error **errp)
 348 {
 349     BDRVDMGState *s = bs->opaque;
 350     DmgHeaderState ds;
 351     uint64_t rsrc_fork_offset, rsrc_fork_length;
 352     int64_t offset;
 353     int ret;
 354
 355     bs->read_only = 1;
 356     s->n_chunks = 0;
 357     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 358     /* used by dmg_read_mish_block to keep track of the current I/O position */
 359     ds.last_in_offset = 0;
 360     ds.last_out_offset = 0;
 361     ds.max_compressed_size = 1;
 362     ds.max_sectors_per_chunk = 1;
 363
 364     /* locate the UDIF trailer */
 365     offset = dmg_find_koly_offset(bs->file, errp);
 366     if (offset < 0) {
 367         ret = offset;
 368         goto fail;
 369     }
 370
 371     /* offset of resource fork (RsrcForkOffset) */
 372     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
 373     if (ret < 0) {
 374         goto fail;
 375     }
 376     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
 377     if (ret < 0) {
 378         goto fail;
 379     }
 380     if (rsrc_fork_length != 0) {
 381         ret = dmg_read_resource_fork(bs, &ds,
 382                                      rsrc_fork_offset, rsrc_fork_length);
 383         if (ret < 0) {
 384             goto fail;
 385         }
 386     } else {
 387         ret = -EINVAL;
 388         goto fail;
 389     }
 390
 391     /* initialize zlib engine */
 392     s->compressed_chunk = qemu_try_blockalign(bs->file,
 393                                               ds.max_compressed_size + 1);
 394     s->uncompressed_chunk = qemu_try_blockalign(bs->file,
 395                                                 512 * ds.max_sectors_per_chunk);
 396     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 397         ret = -ENOMEM;
 398         goto fail;
 399     }
 400
 401     if (inflateInit(&s->zstream) != Z_OK) {
 402         ret = -EINVAL;
 403         goto fail;
 404     }
 405
 406     s->current_chunk = s->n_chunks;
 407
 408     qemu_co_mutex_init(&s->lock);
 409     return 0;
 410
 411 fail:
 412     g_free(s->types);
 413     g_free(s->offsets);
 414     g_free(s->lengths);
 415     g_free(s->sectors);
 416     g_free(s->sectorcounts);
 417     qemu_vfree(s->compressed_chunk);
 418     qemu_vfree(s->uncompressed_chunk);
 419     return ret;
 420 }
 421
 422 static inline int is_sector_in_chunk(BDRVDMGState* s,
 423                 uint32_t chunk_num, uint64_t sector_num)
 424 {
 425     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 426             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 427         return 0;
 428     } else {
 429         return -1;
 430     }
 431 }
 432
 433 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 434 {
 435     /* binary search */
 436     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 437     while (chunk1 != chunk2) {
 438         chunk3 = (chunk1 + chunk2) / 2;
 439         if (s->sectors[chunk3] > sector_num) {
 440             chunk2 = chunk3;
 441         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 442             return chunk3;
 443         } else {
 444             chunk1 = chunk3;
 445         }
 446     }
 447     return s->n_chunks; /* error */
 448 }
 449
 450 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 451 {
 452     BDRVDMGState *s = bs->opaque;
 453
 454     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 455         int ret;
 456         uint32_t chunk = search_chunk(s, sector_num);
 457
 458         if (chunk >= s->n_chunks) {
 459             return -1;
 460         }
 461
 462         s->current_chunk = s->n_chunks;
 463         switch (s->types[chunk]) {
 464         case 0x80000005: { /* zlib compressed */
 465             /* we need to buffer, because only the chunk as whole can be
 466              * inflated. */
 467             ret = bdrv_pread(bs->file, s->offsets[chunk],
 468                              s->compressed_chunk, s->lengths[chunk]);
 469             if (ret != s->lengths[chunk]) {
 470                 return -1;
 471             }
 472
 473             s->zstream.next_in = s->compressed_chunk;
 474             s->zstream.avail_in = s->lengths[chunk];
 475             s->zstream.next_out = s->uncompressed_chunk;
 476             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 477             ret = inflateReset(&s->zstream);
 478             if (ret != Z_OK) {
 479                 return -1;
 480             }
 481             ret = inflate(&s->zstream, Z_FINISH);
 482             if (ret != Z_STREAM_END ||
 483                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 484                 return -1;
 485             }
 486             break; }
 487         case 1: /* copy */
 488             ret = bdrv_pread(bs->file, s->offsets[chunk],
 489                              s->uncompressed_chunk, s->lengths[chunk]);
 490             if (ret != s->lengths[chunk]) {
 491                 return -1;
 492             }
 493             break;
 494         case 2: /* zero */
 495             memset(s->uncompressed_chunk, 0, 512 * s->sectorcounts[chunk]);
 496             break;
 497         }
 498         s->current_chunk = chunk;
 499     }
 500     return 0;
 501 }
 502
 503 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
 504                     uint8_t *buf, int nb_sectors)
 505 {
 506     BDRVDMGState *s = bs->opaque;
 507     int i;
 508
 509     for (i = 0; i < nb_sectors; i++) {
 510         uint32_t sector_offset_in_chunk;
 511         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 512             return -1;
 513         }
 514         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 515         memcpy(buf + i * 512,
 516                s->uncompressed_chunk + sector_offset_in_chunk * 512, 512);
 517     }
 518     return 0;
 519 }
 520
 521 static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
 522                                     uint8_t *buf, int nb_sectors)
 523 {
 524     int ret;
 525     BDRVDMGState *s = bs->opaque;
 526     qemu_co_mutex_lock(&s->lock);
 527     ret = dmg_read(bs, sector_num, buf, nb_sectors);
 528     qemu_co_mutex_unlock(&s->lock);
 529     return ret;
 530 }
 531
 532 static void dmg_close(BlockDriverState *bs)
 533 {
 534     BDRVDMGState *s = bs->opaque;
 535
 536     g_free(s->types);
 537     g_free(s->offsets);
 538     g_free(s->lengths);
 539     g_free(s->sectors);
 540     g_free(s->sectorcounts);
 541     qemu_vfree(s->compressed_chunk);
 542     qemu_vfree(s->uncompressed_chunk);
 543
 544     inflateEnd(&s->zstream);
 545 }
 546
 547 static BlockDriver bdrv_dmg = {
 548     .format_name    = "dmg",
 549     .instance_size  = sizeof(BDRVDMGState),
 550     .bdrv_probe     = dmg_probe,
 551     .bdrv_open      = dmg_open,
 552     .bdrv_read      = dmg_co_read,
 553     .bdrv_close     = dmg_close,
 554 };
 555
 556 static void bdrv_dmg_init(void)
 557 {
 558     bdrv_register(&bdrv_dmg);
 559 }
 560
 561 block_init(bdrv_dmg_init);