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 /* Increase max chunk sizes, if necessary.  This function is used to calculate
 104  * the buffer sizes needed for compressed/uncompressed chunk I/O.
 105  */
 106 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
 107                                   uint32_t *max_compressed_size,
 108                                   uint32_t *max_sectors_per_chunk)
 109 {
 110     uint32_t compressed_size = 0;
 111     uint32_t uncompressed_sectors = 0;
 112
 113     switch (s->types[chunk]) {
 114     case 0x80000005: /* zlib compressed */
 115         compressed_size = s->lengths[chunk];
 116         uncompressed_sectors = s->sectorcounts[chunk];
 117         break;
 118     case 1: /* copy */
 119         uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
 120         break;
 121     case 2: /* zero */
 122         uncompressed_sectors = s->sectorcounts[chunk];
 123         break;
 124     }
 125
 126     if (compressed_size > *max_compressed_size) {
 127         *max_compressed_size = compressed_size;
 128     }
 129     if (uncompressed_sectors > *max_sectors_per_chunk) {
 130         *max_sectors_per_chunk = uncompressed_sectors;
 131     }
 132 }
 133
 134 static int64_t dmg_find_koly_offset(BlockDriverState *file_bs, Error **errp)
 135 {
 136     int64_t length;
 137     int64_t offset = 0;
 138     uint8_t buffer[515];
 139     int i, ret;
 140
 141     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
 142      * dmg images can have odd sizes, try to look for the "koly" magic which
 143      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
 144      * in the last 511 bytes of the second-last sector or the first 4 bytes of
 145      * the last sector (search space: 515 bytes) */
 146     length = bdrv_getlength(file_bs);
 147     if (length < 0) {
 148         error_setg_errno(errp, -length,
 149             "Failed to get file size while reading UDIF trailer");
 150         return length;
 151     } else if (length < 512) {
 152         error_setg(errp, "dmg file must be at least 512 bytes long");
 153         return -EINVAL;
 154     }
 155     if (length > 511 + 512) {
 156         offset = length - 511 - 512;
 157     }
 158     length = length < 515 ? length : 515;
 159     ret = bdrv_pread(file_bs, offset, buffer, length);
 160     if (ret < 0) {
 161         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
 162         return ret;
 163     }
 164     for (i = 0; i < length - 3; i++) {
 165         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
 166             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
 167             return offset + i;
 168         }
 169     }
 170     error_setg(errp, "Could not locate UDIF trailer in dmg file");
 171     return -EINVAL;
 172 }
 173
 174 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
 175                     Error **errp)
 176 {
 177     BDRVDMGState *s = bs->opaque;
 178     uint64_t info_begin, info_end, last_in_offset, last_out_offset;
 179     uint32_t count, tmp;
 180     uint32_t max_compressed_size = 1, max_sectors_per_chunk = 1, i;
 181     int64_t offset;
 182     int ret;
 183
 184     bs->read_only = 1;
 185     s->n_chunks = 0;
 186     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 187
 188     /* locate the UDIF trailer */
 189     offset = dmg_find_koly_offset(bs->file, errp);
 190     if (offset < 0) {
 191         ret = offset;
 192         goto fail;
 193     }
 194
 195     ret = read_uint64(bs, offset + 0x28, &info_begin);
 196     if (ret < 0) {
 197         goto fail;
 198     } else if (info_begin == 0) {
 199         ret = -EINVAL;
 200         goto fail;
 201     }
 202
 203     ret = read_uint32(bs, info_begin, &tmp);
 204     if (ret < 0) {
 205         goto fail;
 206     } else if (tmp != 0x100) {
 207         ret = -EINVAL;
 208         goto fail;
 209     }
 210
 211     ret = read_uint32(bs, info_begin + 4, &count);
 212     if (ret < 0) {
 213         goto fail;
 214     } else if (count == 0) {
 215         ret = -EINVAL;
 216         goto fail;
 217     }
 218     info_end = info_begin + count;
 219
 220     offset = info_begin + 0x100;
 221
 222     /* read offsets */
 223     last_in_offset = last_out_offset = 0;
 224     while (offset < info_end) {
 225         uint32_t type;
 226
 227         ret = read_uint32(bs, offset, &count);
 228         if (ret < 0) {
 229             goto fail;
 230         } else if (count == 0) {
 231             ret = -EINVAL;
 232             goto fail;
 233         }
 234         offset += 4;
 235
 236         ret = read_uint32(bs, offset, &type);
 237         if (ret < 0) {
 238             goto fail;
 239         }
 240
 241         if (type == 0x6d697368 && count >= 244) {
 242             size_t new_size;
 243             uint32_t chunk_count;
 244
 245             offset += 4;
 246             offset += 200;
 247
 248             chunk_count = (count - 204) / 40;
 249             new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 250             s->types = g_realloc(s->types, new_size / 2);
 251             s->offsets = g_realloc(s->offsets, new_size);
 252             s->lengths = g_realloc(s->lengths, new_size);
 253             s->sectors = g_realloc(s->sectors, new_size);
 254             s->sectorcounts = g_realloc(s->sectorcounts, new_size);
 255
 256             for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
 257                 ret = read_uint32(bs, offset, &s->types[i]);
 258                 if (ret < 0) {
 259                     goto fail;
 260                 }
 261                 offset += 4;
 262                 if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
 263                     s->types[i] != 2) {
 264                     if (s->types[i] == 0xffffffff && i > 0) {
 265                         last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
 266                         last_out_offset = s->sectors[i - 1] +
 267                                           s->sectorcounts[i - 1];
 268                     }
 269                     chunk_count--;
 270                     i--;
 271                     offset += 36;
 272                     continue;
 273                 }
 274                 offset += 4;
 275
 276                 ret = read_uint64(bs, offset, &s->sectors[i]);
 277                 if (ret < 0) {
 278                     goto fail;
 279                 }
 280                 s->sectors[i] += last_out_offset;
 281                 offset += 8;
 282
 283                 ret = read_uint64(bs, offset, &s->sectorcounts[i]);
 284                 if (ret < 0) {
 285                     goto fail;
 286                 }
 287                 offset += 8;
 288
 289                 if (s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
 290                     error_report("sector count %" PRIu64 " for chunk %" PRIu32
 291                                  " is larger than max (%u)",
 292                                  s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
 293                     ret = -EINVAL;
 294                     goto fail;
 295                 }
 296
 297                 ret = read_uint64(bs, offset, &s->offsets[i]);
 298                 if (ret < 0) {
 299                     goto fail;
 300                 }
 301                 s->offsets[i] += last_in_offset;
 302                 offset += 8;
 303
 304                 ret = read_uint64(bs, offset, &s->lengths[i]);
 305                 if (ret < 0) {
 306                     goto fail;
 307                 }
 308                 offset += 8;
 309
 310                 if (s->lengths[i] > DMG_LENGTHS_MAX) {
 311                     error_report("length %" PRIu64 " for chunk %" PRIu32
 312                                  " is larger than max (%u)",
 313                                  s->lengths[i], i, DMG_LENGTHS_MAX);
 314                     ret = -EINVAL;
 315                     goto fail;
 316                 }
 317
 318                 update_max_chunk_size(s, i, &max_compressed_size,
 319                                       &max_sectors_per_chunk);
 320             }
 321             s->n_chunks += chunk_count;
 322         }
 323     }
 324
 325     /* initialize zlib engine */
 326     s->compressed_chunk = qemu_try_blockalign(bs->file,
 327                                               max_compressed_size + 1);
 328     s->uncompressed_chunk = qemu_try_blockalign(bs->file,
 329                                                 512 * max_sectors_per_chunk);
 330     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
 331         ret = -ENOMEM;
 332         goto fail;
 333     }
 334
 335     if (inflateInit(&s->zstream) != Z_OK) {
 336         ret = -EINVAL;
 337         goto fail;
 338     }
 339
 340     s->current_chunk = s->n_chunks;
 341
 342     qemu_co_mutex_init(&s->lock);
 343     return 0;
 344
 345 fail:
 346     g_free(s->types);
 347     g_free(s->offsets);
 348     g_free(s->lengths);
 349     g_free(s->sectors);
 350     g_free(s->sectorcounts);
 351     qemu_vfree(s->compressed_chunk);
 352     qemu_vfree(s->uncompressed_chunk);
 353     return ret;
 354 }
 355
 356 static inline int is_sector_in_chunk(BDRVDMGState* s,
 357                 uint32_t chunk_num, uint64_t sector_num)
 358 {
 359     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
 360             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
 361         return 0;
 362     } else {
 363         return -1;
 364     }
 365 }
 366
 367 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
 368 {
 369     /* binary search */
 370     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
 371     while (chunk1 != chunk2) {
 372         chunk3 = (chunk1 + chunk2) / 2;
 373         if (s->sectors[chunk3] > sector_num) {
 374             chunk2 = chunk3;
 375         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
 376             return chunk3;
 377         } else {
 378             chunk1 = chunk3;
 379         }
 380     }
 381     return s->n_chunks; /* error */
 382 }
 383
 384 static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
 385 {
 386     BDRVDMGState *s = bs->opaque;
 387
 388     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
 389         int ret;
 390         uint32_t chunk = search_chunk(s, sector_num);
 391
 392         if (chunk >= s->n_chunks) {
 393             return -1;
 394         }
 395
 396         s->current_chunk = s->n_chunks;
 397         switch (s->types[chunk]) {
 398         case 0x80000005: { /* zlib compressed */
 399             /* we need to buffer, because only the chunk as whole can be
 400              * inflated. */
 401             ret = bdrv_pread(bs->file, s->offsets[chunk],
 402                              s->compressed_chunk, s->lengths[chunk]);
 403             if (ret != s->lengths[chunk]) {
 404                 return -1;
 405             }
 406
 407             s->zstream.next_in = s->compressed_chunk;
 408             s->zstream.avail_in = s->lengths[chunk];
 409             s->zstream.next_out = s->uncompressed_chunk;
 410             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
 411             ret = inflateReset(&s->zstream);
 412             if (ret != Z_OK) {
 413                 return -1;
 414             }
 415             ret = inflate(&s->zstream, Z_FINISH);
 416             if (ret != Z_STREAM_END ||
 417                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
 418                 return -1;
 419             }
 420             break; }
 421         case 1: /* copy */
 422             ret = bdrv_pread(bs->file, s->offsets[chunk],
 423                              s->uncompressed_chunk, s->lengths[chunk]);
 424             if (ret != s->lengths[chunk]) {
 425                 return -1;
 426             }
 427             break;
 428         case 2: /* zero */
 429             memset(s->uncompressed_chunk, 0, 512 * s->sectorcounts[chunk]);
 430             break;
 431         }
 432         s->current_chunk = chunk;
 433     }
 434     return 0;
 435 }
 436
 437 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
 438                     uint8_t *buf, int nb_sectors)
 439 {
 440     BDRVDMGState *s = bs->opaque;
 441     int i;
 442
 443     for (i = 0; i < nb_sectors; i++) {
 444         uint32_t sector_offset_in_chunk;
 445         if (dmg_read_chunk(bs, sector_num + i) != 0) {
 446             return -1;
 447         }
 448         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
 449         memcpy(buf + i * 512,
 450                s->uncompressed_chunk + sector_offset_in_chunk * 512, 512);
 451     }
 452     return 0;
 453 }
 454
 455 static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
 456                                     uint8_t *buf, int nb_sectors)
 457 {
 458     int ret;
 459     BDRVDMGState *s = bs->opaque;
 460     qemu_co_mutex_lock(&s->lock);
 461     ret = dmg_read(bs, sector_num, buf, nb_sectors);
 462     qemu_co_mutex_unlock(&s->lock);
 463     return ret;
 464 }
 465
 466 static void dmg_close(BlockDriverState *bs)
 467 {
 468     BDRVDMGState *s = bs->opaque;
 469
 470     g_free(s->types);
 471     g_free(s->offsets);
 472     g_free(s->lengths);
 473     g_free(s->sectors);
 474     g_free(s->sectorcounts);
 475     qemu_vfree(s->compressed_chunk);
 476     qemu_vfree(s->uncompressed_chunk);
 477
 478     inflateEnd(&s->zstream);
 479 }
 480
 481 static BlockDriver bdrv_dmg = {
 482     .format_name    = "dmg",
 483     .instance_size  = sizeof(BDRVDMGState),
 484     .bdrv_probe     = dmg_probe,
 485     .bdrv_open      = dmg_open,
 486     .bdrv_read      = dmg_co_read,
 487     .bdrv_close     = dmg_close,
 488 };
 489
 490 static void bdrv_dmg_init(void)
 491 {
 492     bdrv_register(&bdrv_dmg);
 493 }
 494
 495 block_init(bdrv_dmg_init);