DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (fce0b326cd31)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074
// Copyright (c) 2009-2017 The OTS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cmap.h"

#include <algorithm>
#include <set>
#include <utility>
#include <vector>

#include "maxp.h"
#include "os2.h"

// cmap - Character To Glyph Index Mapping Table
// http://www.microsoft.com/typography/otspec/cmap.htm

namespace {

struct CMAPSubtableHeader {
  uint16_t platform;
  uint16_t encoding;
  uint32_t offset;
  uint16_t format;
  uint32_t length;
  uint32_t language;
};

struct Subtable314Range {
  uint16_t start_range;
  uint16_t end_range;
  int16_t id_delta;
  uint16_t id_range_offset;
  uint32_t id_range_offset_offset;
};

// Glyph array size for the Mac Roman (format 0) table.
const size_t kFormat0ArraySize = 256;

// The upper limit of the Unicode code point.
const uint32_t kUnicodeUpperLimit = 0x10FFFF;

// The maximum number of UVS records (See below).
const uint32_t kMaxCMAPSelectorRecords = 259;
// The range of UVSes are:
//   0x180B-0x180D (3 code points)
//   0xFE00-0xFE0F (16 code points)
//   0xE0100-0xE01EF (240 code points)
const uint32_t kMongolianVSStart = 0x180B;
const uint32_t kMongolianVSEnd = 0x180D;
const uint32_t kVSStart = 0xFE00;
const uint32_t kVSEnd = 0xFE0F;
const uint32_t kIVSStart = 0xE0100;
const uint32_t kIVSEnd = 0xE01EF;
const uint32_t kUVSUpperLimit = 0xFFFFFF;

} // namespace

namespace ots {

// Parses Format 4 tables
bool OpenTypeCMAP::ParseFormat4(int platform, int encoding,
              const uint8_t *data, size_t length, uint16_t num_glyphs) {
  ots::Buffer subtable(data, length);

  // 0.3.4, 3.0.4 or 3.1.4 subtables are complex and, rather than expanding the
  // whole thing and recompacting it, we validate it and include it verbatim
  // in the output.

  OpenTypeOS2 *os2 = static_cast<OpenTypeOS2*>(
      GetFont()->GetTypedTable(OTS_TAG_OS2));
  if (!os2) {
    return Error("Required OS/2 table missing");
  }

  if (!subtable.Skip(4)) {
    return Error("Can't read 4 bytes at start of cmap format 4 subtable");
  }
  uint16_t language = 0;
  if (!subtable.ReadU16(&language)) {
    return Error("Can't read language");
  }
  if (language) {
    // Platform ID 3 (windows) subtables should have language '0'.
    return Error("Languages should be 0 (%d)", language);
  }

  uint16_t segcountx2, search_range, entry_selector, range_shift;
  segcountx2 = search_range = entry_selector = range_shift = 0;
  if (!subtable.ReadU16(&segcountx2) ||
      !subtable.ReadU16(&search_range) ||
      !subtable.ReadU16(&entry_selector) ||
      !subtable.ReadU16(&range_shift)) {
    return Error("Failed to read subcmap structure");
  }

  if (segcountx2 & 1 || search_range & 1) {
    return Error("Bad subcmap structure");
  }
  const uint16_t segcount = segcountx2 >> 1;
  // There must be at least one segment according the spec.
  if (segcount < 1) {
    return Error("Segcount < 1 (%d)", segcount);
  }

  // log2segcount is the maximal x s.t. 2^x < segcount
  unsigned log2segcount = 0;
  while (1u << (log2segcount + 1) <= segcount) {
    log2segcount++;
  }

  const uint16_t expected_search_range = 2 * 1u << log2segcount;
  if (expected_search_range != search_range) {
    return Error("expected search range != search range (%d != %d)", expected_search_range, search_range);
  }

  if (entry_selector != log2segcount) {
    return Error("entry selector != log2(segement count) (%d != %d)", entry_selector, log2segcount);
  }

  const uint16_t expected_range_shift = segcountx2 - search_range;
  if (range_shift != expected_range_shift) {
    return Error("unexpected range shift (%d != %d)", range_shift, expected_range_shift);
  }

  std::vector<Subtable314Range> ranges(segcount);

  for (unsigned i = 0; i < segcount; ++i) {
    if (!subtable.ReadU16(&ranges[i].end_range)) {
      return Error("Failed to read segment %d", i);
    }
  }

  uint16_t padding;
  if (!subtable.ReadU16(&padding)) {
    return Error("Failed to read cmap subtable segment padding");
  }
  if (padding) {
    return Error("Non zero cmap subtable segment padding (%d)", padding);
  }

  for (unsigned i = 0; i < segcount; ++i) {
    if (!subtable.ReadU16(&ranges[i].start_range)) {
      return Error("Failed to read segment start range %d", i);
    }
  }
  for (unsigned i = 0; i < segcount; ++i) {
    if (!subtable.ReadS16(&ranges[i].id_delta)) {
      return Error("Failed to read segment delta %d", i);
    }
  }
  for (unsigned i = 0; i < segcount; ++i) {
    ranges[i].id_range_offset_offset = subtable.offset();
    if (!subtable.ReadU16(&ranges[i].id_range_offset)) {
      return Error("Failed to read segment range offset %d", i);
    }

    if (ranges[i].id_range_offset & 1) {
      // Some font generators seem to put 65535 on id_range_offset
      // for 0xFFFF-0xFFFF range.
      // (e.g., many fonts in http://www.princexml.com/fonts/)
      if (i == segcount - 1u) {
        Warning("bad id_range_offset");
        ranges[i].id_range_offset = 0;
        // The id_range_offset value in the transcoded font will not change
        // since this table is not actually "transcoded" yet.
      } else {
        return Error("Bad segment offset (%d)", ranges[i].id_range_offset);
      }
    }
  }

  // ranges must be ascending order, based on the end_code. Ranges may not
  // overlap.
  for (unsigned i = 1; i < segcount; ++i) {
    if ((i == segcount - 1u) &&
        (ranges[i - 1].start_range == 0xffff) &&
        (ranges[i - 1].end_range == 0xffff) &&
        (ranges[i].start_range == 0xffff) &&
        (ranges[i].end_range == 0xffff)) {
      // Some fonts (e.g., Germania.ttf) have multiple 0xffff terminators.
      // We'll accept them as an exception.
      Warning("multiple 0xffff terminators found");
      continue;
    }

    // Note: some Linux fonts (e.g., LucidaSansOblique.ttf, bsmi00lp.ttf) have
    // unsorted table...
    if (ranges[i].end_range <= ranges[i - 1].end_range) {
      return Error("Out of order end range (%d <= %d)", ranges[i].end_range, ranges[i-1].end_range);
    }
    if (ranges[i].start_range <= ranges[i - 1].end_range) {
      return Error("out of order start range (%d <= %d)", ranges[i].start_range, ranges[i-1].end_range);
    }

    // On many fonts, the value of {first, last}_char_index are incorrect.
    // Fix them.
    if (os2->table.first_char_index != 0xFFFF &&
        ranges[i].start_range != 0xFFFF &&
        os2->table.first_char_index > ranges[i].start_range) {
      os2->table.first_char_index = ranges[i].start_range;
    }
    if (os2->table.last_char_index != 0xFFFF &&
        ranges[i].end_range != 0xFFFF &&
        os2->table.last_char_index < ranges[i].end_range) {
      os2->table.last_char_index = ranges[i].end_range;
    }
  }

  // The last range must end at 0xffff
  if (ranges[segcount - 1].start_range != 0xffff || ranges[segcount - 1].end_range != 0xffff) {
    return Error("Final segment start and end must be 0xFFFF (0x%04X-0x%04X)",
                           ranges[segcount - 1].start_range, ranges[segcount - 1].end_range);
  }

  // A format 4 CMAP subtable is complex. To be safe we simulate a lookup of
  // each code-point defined in the table and make sure that they are all valid
  // glyphs and that we don't access anything out-of-bounds.
  for (unsigned i = 0; i < segcount; ++i) {
    for (unsigned cp = ranges[i].start_range; cp <= ranges[i].end_range; ++cp) {
      const uint16_t code_point = static_cast<uint16_t>(cp);
      if (ranges[i].id_range_offset == 0) {
        // this is explictly allowed to overflow in the spec
        const uint16_t glyph = code_point + ranges[i].id_delta;
        if (glyph >= num_glyphs) {
          return Error("Range glyph reference too high (%d > %d)", glyph, num_glyphs - 1);
        }
      } else {
        const uint16_t range_delta = code_point - ranges[i].start_range;
        // this might seem odd, but it's true. The offset is relative to the
        // location of the offset value itself.
        const uint32_t glyph_id_offset = ranges[i].id_range_offset_offset +
                                         ranges[i].id_range_offset +
                                         range_delta * 2;
        // We need to be able to access a 16-bit value from this offset
        if (glyph_id_offset + 1 >= length) {
          return Error("bad glyph id offset (%d > %ld)", glyph_id_offset, length);
        }
        uint16_t glyph;
        std::memcpy(&glyph, data + glyph_id_offset, 2);
        glyph = ots_ntohs(glyph);
        if (glyph >= num_glyphs) {
          return Error("Range glyph reference too high (%d > %d)", glyph, num_glyphs - 1);
        }
      }
    }
  }

  // We accept the table.
  // TODO(yusukes): transcode the subtable.
  if (platform == 3 && encoding == 0) {
    this->subtable_3_0_4_data = data;
    this->subtable_3_0_4_length = length;
  } else if (platform == 3 && encoding == 1) {
    this->subtable_3_1_4_data = data;
    this->subtable_3_1_4_length = length;
  } else if (platform == 0 && encoding == 3) {
    this->subtable_0_3_4_data = data;
    this->subtable_0_3_4_length = length;
  } else {
    return Error("Unknown cmap subtable type (platform=%d, encoding=%d)", platform, encoding);
  }

  return true;
}

bool OpenTypeCMAP::Parse31012(const uint8_t *data, size_t length,
                              uint16_t num_glyphs) {
  ots::Buffer subtable(data, length);

  // Format 12 tables are simple. We parse these and fully serialise them
  // later.

  if (!subtable.Skip(8)) {
    return Error("failed to skip the first 8 bytes of format 12 subtable");
  }
  uint32_t language = 0;
  if (!subtable.ReadU32(&language)) {
    return Error("can't read format 12 subtable language");
  }
  if (language) {
    return Error("format 12 subtable language should be zero (%d)", language);
  }

  uint32_t num_groups = 0;
  if (!subtable.ReadU32(&num_groups)) {
    return Error("can't read number of format 12 subtable groups");
  }
  if (num_groups == 0 || subtable.remaining() / 12 < num_groups) {
    return Error("Bad format 12 subtable group count %d", num_groups);
  }

  std::vector<ots::OpenTypeCMAPSubtableRange> &groups
      = this->subtable_3_10_12;
  groups.resize(num_groups);

  for (unsigned i = 0; i < num_groups; ++i) {
    if (!subtable.ReadU32(&groups[i].start_range) ||
        !subtable.ReadU32(&groups[i].end_range) ||
        !subtable.ReadU32(&groups[i].start_glyph_id)) {
      return Error("can't read format 12 subtable group");
    }

    if (groups[i].start_range > kUnicodeUpperLimit ||
        groups[i].end_range > kUnicodeUpperLimit ||
        groups[i].start_glyph_id > 0xFFFF) {
      return Error("bad format 12 subtable group (startCharCode=0x%4X, endCharCode=0x%4X, startGlyphID=%d)",
                             groups[i].start_range, groups[i].end_range, groups[i].start_glyph_id);
    }

    // We assert that the glyph value is within range. Because of the range
    // limits, above, we don't need to worry about overflow.
    if (groups[i].end_range < groups[i].start_range) {
      return Error("format 12 subtable group endCharCode before startCharCode (0x%4X < 0x%4X)",
                             groups[i].end_range, groups[i].start_range);
    }
    if ((groups[i].end_range - groups[i].start_range) +
        groups[i].start_glyph_id > num_glyphs) {
      return Error("bad format 12 subtable group startGlyphID (%d)", groups[i].start_glyph_id);
    }
  }

  // the groups must be sorted by start code and may not overlap
  for (unsigned i = 1; i < num_groups; ++i) {
    if (groups[i].start_range <= groups[i - 1].start_range) {
      return Error("out of order format 12 subtable group (startCharCode=0x%4X <= startCharCode=0x%4X of previous group)",
                             groups[i].start_range, groups[i-1].start_range);
    }
    if (groups[i].start_range <= groups[i - 1].end_range) {
      return Error("overlapping format 12 subtable groups (startCharCode=0x%4X <= endCharCode=0x%4X of previous group)",
                             groups[i].start_range, groups[i-1].end_range);
    }
  }

  return true;
}

bool OpenTypeCMAP::Parse31013(const uint8_t *data, size_t length,
                              uint16_t num_glyphs) {
  ots::Buffer subtable(data, length);

  // Format 13 tables are simple. We parse these and fully serialise them
  // later.

  if (!subtable.Skip(8)) {
    return Error("Bad cmap subtable length");
  }
  uint32_t language = 0;
  if (!subtable.ReadU32(&language)) {
    return Error("Can't read cmap subtable language");
  }
  if (language) {
    return Error("Cmap subtable language should be zero but is %d", language);
  }

  uint32_t num_groups = 0;
  if (!subtable.ReadU32(&num_groups)) {
    return Error("Can't read number of groups in a cmap subtable");
  }

  // We limit the number of groups in the same way as in 3.10.12 tables. See
  // the comment there in
  if (num_groups == 0 || subtable.remaining() / 12 < num_groups) {
    return Error("Bad format 13 subtable group count %d", num_groups);
  }

  std::vector<ots::OpenTypeCMAPSubtableRange> &groups = this->subtable_3_10_13;
  groups.resize(num_groups);

  for (unsigned i = 0; i < num_groups; ++i) {
    if (!subtable.ReadU32(&groups[i].start_range) ||
        !subtable.ReadU32(&groups[i].end_range) ||
        !subtable.ReadU32(&groups[i].start_glyph_id)) {
      return Error("Can't read subrange structure in a cmap subtable");
    }

    // We conservatively limit all of the values to protect some parsers from
    // overflows
    if (groups[i].start_range > kUnicodeUpperLimit ||
        groups[i].end_range > kUnicodeUpperLimit ||
        groups[i].start_glyph_id > 0xFFFF) {
      return Error("Bad subrange with start_range=%d, end_range=%d, start_glyph_id=%d", groups[i].start_range, groups[i].end_range, groups[i].start_glyph_id);
    }

    if (groups[i].start_glyph_id >= num_glyphs) {
      return Error("Subrange starting glyph id too high (%d > %d)", groups[i].start_glyph_id, num_glyphs);
    }
  }

  // the groups must be sorted by start code and may not overlap
  for (unsigned i = 1; i < num_groups; ++i) {
    if (groups[i].start_range <= groups[i - 1].start_range) {
      return Error("Overlapping subrange starts (%d >= %d)", groups[i]. start_range, groups[i-1].start_range);
    }
    if (groups[i].start_range <= groups[i - 1].end_range) {
      return Error("Overlapping subranges (%d <= %d)", groups[i].start_range, groups[i-1].end_range);
    }
  }

  return true;
}

bool OpenTypeCMAP::Parse0514(const uint8_t *data, size_t length,
                             uint16_t num_glyphs) {
  // Unicode Variation Selector table
  ots::Buffer subtable(data, length);

  // Format 14 tables are simple. We parse these and fully serialise them
  // later.

  // Skip format (USHORT) and length (ULONG)
  if (!subtable.Skip(6)) {
    return Error("Can't read start of cmap subtable");
  }

  uint32_t num_records = 0;
  if (!subtable.ReadU32(&num_records)) {
    return Error("Can't read number of records in cmap subtable");
  }
  if (num_records == 0 || num_records > kMaxCMAPSelectorRecords) {
    return Error("Bad format 14 subtable records count %d", num_records);
  }

  std::vector<ots::OpenTypeCMAPSubtableVSRecord>& records
      = this->subtable_0_5_14;
  records.resize(num_records);

  for (unsigned i = 0; i < num_records; ++i) {
    if (!subtable.ReadU24(&records[i].var_selector) ||
        !subtable.ReadU32(&records[i].default_offset) ||
        !subtable.ReadU32(&records[i].non_default_offset)) {
      return Error("Can't read record structure of record %d in cmap subtale", i);
    }
    // Checks the value of variation selector
    if (!((records[i].var_selector >= kMongolianVSStart &&
           records[i].var_selector <= kMongolianVSEnd) ||
          (records[i].var_selector >= kVSStart &&
           records[i].var_selector <= kVSEnd) ||
          (records[i].var_selector >= kIVSStart &&
           records[i].var_selector <= kIVSEnd))) {
      return Error("Bad record variation selector (%04X) in record %i", records[i].var_selector, i);
    }
    if (i > 0 &&
        records[i-1].var_selector >= records[i].var_selector) {
      return Error("Out of order variation selector (%04X >= %04X) in record %d", records[i-1].var_selector, records[i].var_selector, i);
    }

    // Checks offsets
    if (!records[i].default_offset && !records[i].non_default_offset) {
      return Error("No default aoffset in variation selector record %d", i);
    }
    if (records[i].default_offset &&
        records[i].default_offset >= length) {
      return Error("Default offset too high (%d >= %ld) in record %d", records[i].default_offset, length, i);
    }
    if (records[i].non_default_offset &&
        records[i].non_default_offset >= length) {
      return Error("Non default offset too high (%d >= %ld) in record %d", records[i].non_default_offset, length, i);
    }
  }

  for (unsigned i = 0; i < num_records; ++i) {
    // Checks default UVS table
    if (records[i].default_offset) {
      subtable.set_offset(records[i].default_offset);
      uint32_t num_ranges = 0;
      if (!subtable.ReadU32(&num_ranges)) {
        return Error("Can't read number of ranges in record %d", i);
      }
      if (num_ranges == 0 || subtable.remaining() / 4 < num_ranges) {
        return Error("Bad number of ranges (%d) in record %d", num_ranges, i);
      }

      uint32_t last_unicode_value = 0;
      std::vector<ots::OpenTypeCMAPSubtableVSRange>& ranges
          = records[i].ranges;
      ranges.resize(num_ranges);

      for (unsigned j = 0; j < num_ranges; ++j) {
        if (!subtable.ReadU24(&ranges[j].unicode_value) ||
            !subtable.ReadU8(&ranges[j].additional_count)) {
          return Error("Can't read range info in variation selector record %d", i);
        }
        const uint32_t check_value =
            ranges[j].unicode_value + ranges[j].additional_count;
        if (ranges[j].unicode_value == 0 ||
            ranges[j].unicode_value > kUnicodeUpperLimit ||
            check_value > kUVSUpperLimit ||
            (last_unicode_value &&
             ranges[j].unicode_value <= last_unicode_value)) {
          return Error("Bad Unicode value *%04X) in variation selector range %d record %d", ranges[j].unicode_value, j, i);
        }
        last_unicode_value = check_value;
      }
    }

    // Checks non default UVS table
    if (records[i].non_default_offset) {
      subtable.set_offset(records[i].non_default_offset);
      uint32_t num_mappings = 0;
      if (!subtable.ReadU32(&num_mappings)) {
        return Error("Can't read number of mappings in variation selector record %d", i);
      }
      if (num_mappings == 0 || subtable.remaining() / 5 < num_mappings) {
        return Error("Bad number of mappings (%d) in variation selector record %d", num_mappings, i);
      }

      uint32_t last_unicode_value = 0;
      std::vector<ots::OpenTypeCMAPSubtableVSMapping>& mappings
          = records[i].mappings;
      mappings.resize(num_mappings);

      for (unsigned j = 0; j < num_mappings; ++j) {
        if (!subtable.ReadU24(&mappings[j].unicode_value) ||
            !subtable.ReadU16(&mappings[j].glyph_id)) {
          return Error("Can't read mapping %d in variation selector record %d", j, i);
        }
        if (mappings[j].glyph_id == 0 ||
            mappings[j].unicode_value == 0 ||
            mappings[j].unicode_value > kUnicodeUpperLimit ||
            (last_unicode_value &&
             mappings[j].unicode_value <= last_unicode_value)) {
          return Error("Bad mapping (%04X -> %d) in mapping %d of variation selector %d", mappings[j].unicode_value, mappings[j].glyph_id, j, i);
        }
        last_unicode_value = mappings[j].unicode_value;
      }
    }
  }

  if (subtable.offset() != length) {
    return Error("Bad subtable offset (%ld != %ld)", subtable.offset(), length);
  }
  this->subtable_0_5_14_length = subtable.offset();
  return true;
}

bool OpenTypeCMAP::Parse100(const uint8_t *data, size_t length) {
  // Mac Roman table
  ots::Buffer subtable(data, length);

  if (!subtable.Skip(4)) {
    return Error("Bad cmap subtable");
  }
  uint16_t language = 0;
  if (!subtable.ReadU16(&language)) {
    return Error("Can't read language in cmap subtable");
  }
  if (language) {
    // simsun.ttf has non-zero language id.
    Warning("language id should be zero: %u", language);
  }

  this->subtable_1_0_0.reserve(kFormat0ArraySize);
  for (size_t i = 0; i < kFormat0ArraySize; ++i) {
    uint8_t glyph_id = 0;
    if (!subtable.ReadU8(&glyph_id)) {
      return Error("Can't read glyph id at array[%ld] in cmap subtable", i);
    }
    this->subtable_1_0_0.push_back(glyph_id);
  }

  return true;
}

bool OpenTypeCMAP::Parse(const uint8_t *data, size_t length) {
  Buffer table(data, length);

  uint16_t version = 0;
  uint16_t num_tables = 0;
  if (!table.ReadU16(&version) ||
      !table.ReadU16(&num_tables)) {
    return Error("Can't read structure of cmap");
  }

  if (version != 0) {
    return Error("Non zero cmap version (%d)", version);
  }
  if (!num_tables) {
    return Error("No subtables in cmap!");
  }

  std::vector<CMAPSubtableHeader> subtable_headers;

  // read the subtable headers
  subtable_headers.reserve(num_tables);
  for (unsigned i = 0; i < num_tables; ++i) {
    CMAPSubtableHeader subt;

    if (!table.ReadU16(&subt.platform) ||
        !table.ReadU16(&subt.encoding) ||
        !table.ReadU32(&subt.offset)) {
      return Error("Can't read subtable information cmap subtable %d", i);
    }

    subtable_headers.push_back(subt);
  }

  const size_t data_offset = table.offset();

  // make sure that all the offsets are valid.
  for (unsigned i = 0; i < num_tables; ++i) {
    if (subtable_headers[i].offset > 1024 * 1024 * 1024) {
      return Error("Bad subtable offset in cmap subtable %d", i);
    }
    if (subtable_headers[i].offset < data_offset ||
        subtable_headers[i].offset >= length) {
      return Error("Bad subtable offset (%d) in cmap subtable %d", subtable_headers[i].offset, i);
    }
  }

  // the format of the table is the first couple of bytes in the table. The
  // length of the table is stored in a format-specific way.
  for (unsigned i = 0; i < num_tables; ++i) {
    table.set_offset(subtable_headers[i].offset);
    if (!table.ReadU16(&subtable_headers[i].format)) {
      return Error("Can't read cmap subtable header format %d", i);
    }

    uint16_t len = 0;
    uint16_t lang = 0;
    switch (subtable_headers[i].format) {
      case 0:
      case 4:
        if (!table.ReadU16(&len)) {
          return Error("Can't read cmap subtable %d length", i);
        }
        if (!table.ReadU16(&lang)) {
          return Error("Can't read cmap subtable %d language", i);
        }
        subtable_headers[i].length = len;
        subtable_headers[i].language = lang;
        break;
      case 12:
      case 13:
        if (!table.Skip(2)) {
          return Error("Bad cmap subtable %d structure", i);
        }
        if (!table.ReadU32(&subtable_headers[i].length)) {
          return Error("Can read cmap subtable %d length", i);
        }
        if (!table.ReadU32(&subtable_headers[i].language)) {
          return Error("Can't read cmap subtable %d language", i);
        }
        break;
      case 14:
        if (!table.ReadU32(&subtable_headers[i].length)) {
          return Error("Can't read cmap subtable %d length", i);
        }
        subtable_headers[i].language = 0;
        break;
      default:
        subtable_headers[i].length = 0;
        subtable_headers[i].language = 0;
        break;
    }
  }

  // check if the table is sorted first by platform ID, then by encoding ID.
  for (unsigned i = 1; i < num_tables; ++i) {
    if (subtable_headers[i - 1].platform > subtable_headers[i].platform ||
        (subtable_headers[i - 1].platform == subtable_headers[i].platform &&
         (subtable_headers[i - 1].encoding > subtable_headers[i].encoding ||
          (subtable_headers[i - 1].encoding == subtable_headers[i].encoding &&
           subtable_headers[i - 1].language > subtable_headers[i].language))))
      Warning("subtable %d with platform ID %d, encoding ID %d, language ID %d "
                  "following subtable with platform ID %d, encoding ID %d, language ID %d",
                  i,
                  subtable_headers[i].platform,
                  subtable_headers[i].encoding,
                  subtable_headers[i].language,
                  subtable_headers[i - 1].platform,
                  subtable_headers[i - 1].encoding,
                  subtable_headers[i - 1].language);
  }

  // Now, verify that all the lengths are sane
  for (unsigned i = 0; i < num_tables; ++i) {
    if (!subtable_headers[i].length) continue;
    if (subtable_headers[i].length > 1024 * 1024 * 1024) {
      return Error("Bad cmap subtable %d length", i);
    }
    // We know that both the offset and length are < 1GB, so the following
    // addition doesn't overflow
    const uint32_t end_byte
        = subtable_headers[i].offset + subtable_headers[i].length;
    if (end_byte > length) {
      return Error("Over long cmap subtable %d @ %d for %d", i, subtable_headers[i].offset, subtable_headers[i].length);
    }
  }

  // check that the cmap subtables are not overlapping.
  std::set<std::pair<uint32_t, uint32_t> > uniq_checker;
  std::vector<std::pair<uint32_t, uint8_t> > overlap_checker;
  for (unsigned i = 0; i < num_tables; ++i) {
    const uint32_t end_byte
        = subtable_headers[i].offset + subtable_headers[i].length;

    if (!uniq_checker.insert(std::make_pair(subtable_headers[i].offset,
                                            end_byte)).second) {
      // Sometimes Unicode table and MS table share exactly the same data.
      // We'll allow this.
      continue;
    }
    overlap_checker.push_back(
        std::make_pair(subtable_headers[i].offset,
                       static_cast<uint8_t>(1) /* start */));
    overlap_checker.push_back(
        std::make_pair(end_byte, static_cast<uint8_t>(0) /* end */));
  }
  std::sort(overlap_checker.begin(), overlap_checker.end());
  int overlap_count = 0;
  for (unsigned i = 0; i < overlap_checker.size(); ++i) {
    overlap_count += (overlap_checker[i].second ? 1 : -1);
    if (overlap_count > 1) {
      return Error("Excessive overlap count %d", overlap_count);
    }
  }

  // we grab the number of glyphs in the file from the maxp table to make sure
  // that the character map isn't referencing anything beyound this range.
  OpenTypeMAXP *maxp = static_cast<OpenTypeMAXP*>(
      GetFont()->GetTypedTable(OTS_TAG_MAXP));
  if (!maxp) {
    return Error("No maxp table in font! Needed by cmap.");
  }
  const uint16_t num_glyphs = maxp->num_glyphs;

  // We only support a subset of the possible character map tables. Microsoft
  // 'strongly recommends' that everyone supports the Unicode BMP table with
  // the UCS-4 table for non-BMP glyphs. We'll pass the following subtables:
  //   Platform ID   Encoding ID  Format
  //   0             0            4       (Unicode Default)
  //   0             1            4       (Unicode 1.1)
  //   0             3            4       (Unicode BMP)
  //   0             3            12      (Unicode UCS-4)
  //   0             5            14      (Unicode Variation Sequences)
  //   1             0            0       (Mac Roman)
  //   3             0            4       (MS Symbol)
  //   3             1            4       (MS Unicode BMP)
  //   3             10           12      (MS Unicode UCS-4)
  //   3             10           13      (MS UCS-4 Fallback mapping)
  //
  // Note:
  //  * 0-0-4 and 0-1-4 tables are (usually) written as a 3-1-4 table. If 3-1-4 table
  //    also exists, the 0-0-4 or 0-1-4 tables are ignored.
  //  * Unlike 0-0-4 table, 0-3-4 table is written as a 0-3-4 table.
  //    Some fonts which include 0-5-14 table seems to be required 0-3-4
  //    table. The 0-3-4 table will be wriiten even if 3-1-4 table also exists.
  //  * 0-3-12 table is written as a 3-10-12 table. If 3-10-12 table also
  //    exists, the 0-3-12 table is ignored.
  //

  for (unsigned i = 0; i < num_tables; ++i) {
    if (subtable_headers[i].platform == 0) {
      // Unicode platform

      if ((subtable_headers[i].encoding == 0 || subtable_headers[i].encoding == 1) &&
          (subtable_headers[i].format == 4)) {
        // parse and output the 0-0-4 and 0-1-4 tables as 3-1-4 table. Sometimes the 0-0-4
        // table actually points to MS symbol data and thus should be parsed as
        // 3-0-4 table (e.g., marqueem.ttf and quixotic.ttf). This error will be
        // recovered in ots_cmap_serialise().
        if (!ParseFormat4(3, 1, data + subtable_headers[i].offset,
                      subtable_headers[i].length, num_glyphs)) {
          return Error("Failed to parse format 4 cmap subtable %d", i);
        }
      } else if ((subtable_headers[i].encoding == 3) &&
                 (subtable_headers[i].format == 4)) {
        // parse and output the 0-3-4 table as 0-3-4 table.
        if (!ParseFormat4(0, 3, data + subtable_headers[i].offset,
                      subtable_headers[i].length, num_glyphs)) {
          return Error("Failed to parse format 4 cmap subtable %d", i);
        }
      } else if ((subtable_headers[i].encoding == 3 ||
                  subtable_headers[i].encoding == 4) &&
                 (subtable_headers[i].format == 12)) {
        // parse and output the 0-3-12 or 0-4-12 tables as 3-10-12 table.
        if (!Parse31012(data + subtable_headers[i].offset,
                        subtable_headers[i].length, num_glyphs)) {
          return Error("Failed to parse format 12 cmap subtable %d", i);
        }
      } else if ((subtable_headers[i].encoding == 5) &&
                 (subtable_headers[i].format == 14)) {
        if (!Parse0514(data + subtable_headers[i].offset,
                       subtable_headers[i].length, num_glyphs)) {
          return Error("Failed to parse format 14 cmap subtable %d", i);
        }
      }
    } else if (subtable_headers[i].platform == 1) {
      // Mac platform

      if ((subtable_headers[i].encoding == 0) &&
          (subtable_headers[i].format == 0)) {
        // parse and output the 1-0-0 table.
        if (!Parse100(data + subtable_headers[i].offset,
                      subtable_headers[i].length)) {
          return OTS_FAILURE();
        }
      }
    } else if (subtable_headers[i].platform == 3) {
      // MS platform

      switch (subtable_headers[i].encoding) {
        case 0:
        case 1:
          if (subtable_headers[i].format == 4) {
            // parse 3-0-4 or 3-1-4 table.
            if (!ParseFormat4(subtable_headers[i].platform,
                          subtable_headers[i].encoding,
                          data + subtable_headers[i].offset,
                          subtable_headers[i].length, num_glyphs)) {
              return OTS_FAILURE();
            }
          }
          break;
        case 10:
          if (subtable_headers[i].format == 12) {
            this->subtable_3_10_12.clear();
            if (!Parse31012(data + subtable_headers[i].offset,
                            subtable_headers[i].length, num_glyphs)) {
              return OTS_FAILURE();
            }
          } else if (subtable_headers[i].format == 13) {
            this->subtable_3_10_13.clear();
            if (!Parse31013(data + subtable_headers[i].offset,
                            subtable_headers[i].length, num_glyphs)) {
              return OTS_FAILURE();
            }
          }
          break;
      }
    }
  }

  return true;
}

bool OpenTypeCMAP::Serialize(OTSStream *out) {
  const bool have_034 = this->subtable_0_3_4_data != NULL;
  const bool have_0514 = this->subtable_0_5_14.size() != 0;
  const bool have_100 = this->subtable_1_0_0.size() != 0;
  const bool have_304 = this->subtable_3_0_4_data != NULL;
  // MS Symbol and MS Unicode tables should not co-exist.
  // See the comment above in 0-0-4 parser.
  const bool have_314 = (!have_304) && this->subtable_3_1_4_data;
  const bool have_31012 = this->subtable_3_10_12.size() != 0;
  const bool have_31013 = this->subtable_3_10_13.size() != 0;
  const uint16_t num_subtables = static_cast<uint16_t>(have_034) +
                                 static_cast<uint16_t>(have_0514) +
                                 static_cast<uint16_t>(have_100) +
                                 static_cast<uint16_t>(have_304) +
                                 static_cast<uint16_t>(have_314) +
                                 static_cast<uint16_t>(have_31012) +
                                 static_cast<uint16_t>(have_31013);
  const off_t table_start = out->Tell();

  // Some fonts don't have 3-0-4 MS Symbol nor 3-1-4 Unicode BMP tables
  // (e.g., old fonts for Mac). We don't support them.
  if (!have_304 && !have_314 && !have_034 && !have_31012 && !have_31013) {
    return Error("no supported subtables were found");
  }

  if (!out->WriteU16(0) ||
      !out->WriteU16(num_subtables)) {
    return OTS_FAILURE();
  }

  const off_t record_offset = out->Tell();
  if (!out->Pad(num_subtables * 8)) {
    return OTS_FAILURE();
  }

  const off_t offset_034 = out->Tell();
  if (have_034) {
    if (!out->Write(this->subtable_0_3_4_data,
                    this->subtable_0_3_4_length)) {
      return OTS_FAILURE();
    }
  }

  const off_t offset_0514 = out->Tell();
  if (have_0514) {
    const std::vector<ots::OpenTypeCMAPSubtableVSRecord> &records
        = this->subtable_0_5_14;
    const unsigned num_records = records.size();
    if (!out->WriteU16(14) ||
        !out->WriteU32(this->subtable_0_5_14_length) ||
        !out->WriteU32(num_records)) {
      return OTS_FAILURE();
    }
    for (unsigned i = 0; i < num_records; ++i) {
      if (!out->WriteU24(records[i].var_selector) ||
          !out->WriteU32(records[i].default_offset) ||
          !out->WriteU32(records[i].non_default_offset)) {
        return OTS_FAILURE();
      }
    }
    for (unsigned i = 0; i < num_records; ++i) {
      if (records[i].default_offset) {
        const std::vector<ots::OpenTypeCMAPSubtableVSRange> &ranges
            = records[i].ranges;
        const unsigned num_ranges = ranges.size();
        if (!out->Seek(records[i].default_offset + offset_0514) ||
            !out->WriteU32(num_ranges)) {
          return OTS_FAILURE();
        }
        for (unsigned j = 0; j < num_ranges; ++j) {
          if (!out->WriteU24(ranges[j].unicode_value) ||
              !out->WriteU8(ranges[j].additional_count)) {
            return OTS_FAILURE();
          }
        }
      }
      if (records[i].non_default_offset) {
        const std::vector<ots::OpenTypeCMAPSubtableVSMapping> &mappings
            = records[i].mappings;
        const unsigned num_mappings = mappings.size();
        if (!out->Seek(records[i].non_default_offset + offset_0514) ||
            !out->WriteU32(num_mappings)) {
          return OTS_FAILURE();
        }
        for (unsigned j = 0; j < num_mappings; ++j) {
          if (!out->WriteU24(mappings[j].unicode_value) ||
              !out->WriteU16(mappings[j].glyph_id)) {
            return OTS_FAILURE();
          }
        }
      }
    }
  }

  const off_t offset_100 = out->Tell();
  if (have_100) {
    if (!out->WriteU16(0) ||  // format
        !out->WriteU16(6 + kFormat0ArraySize) ||  // length
        !out->WriteU16(0)) {  // language
      return OTS_FAILURE();
    }
    if (!out->Write(&(this->subtable_1_0_0[0]), kFormat0ArraySize)) {
      return OTS_FAILURE();
    }
  }

  const off_t offset_304 = out->Tell();
  if (have_304) {
    if (!out->Write(this->subtable_3_0_4_data,
                    this->subtable_3_0_4_length)) {
      return OTS_FAILURE();
    }
  }

  const off_t offset_314 = out->Tell();
  if (have_314) {
    if (!out->Write(this->subtable_3_1_4_data,
                    this->subtable_3_1_4_length)) {
      return OTS_FAILURE();
    }
  }

  const off_t offset_31012 = out->Tell();
  if (have_31012) {
    std::vector<OpenTypeCMAPSubtableRange> &groups
        = this->subtable_3_10_12;
    const unsigned num_groups = groups.size();
    if (!out->WriteU16(12) ||
        !out->WriteU16(0) ||
        !out->WriteU32(num_groups * 12 + 16) ||
        !out->WriteU32(0) ||
        !out->WriteU32(num_groups)) {
      return OTS_FAILURE();
    }

    for (unsigned i = 0; i < num_groups; ++i) {
      if (!out->WriteU32(groups[i].start_range) ||
          !out->WriteU32(groups[i].end_range) ||
          !out->WriteU32(groups[i].start_glyph_id)) {
        return OTS_FAILURE();
      }
    }
  }

  const off_t offset_31013 = out->Tell();
  if (have_31013) {
    std::vector<OpenTypeCMAPSubtableRange> &groups
        = this->subtable_3_10_13;
    const unsigned num_groups = groups.size();
    if (!out->WriteU16(13) ||
        !out->WriteU16(0) ||
        !out->WriteU32(num_groups * 12 + 16) ||
        !out->WriteU32(0) ||
        !out->WriteU32(num_groups)) {
      return OTS_FAILURE();
    }

    for (unsigned i = 0; i < num_groups; ++i) {
      if (!out->WriteU32(groups[i].start_range) ||
          !out->WriteU32(groups[i].end_range) ||
          !out->WriteU32(groups[i].start_glyph_id)) {
        return OTS_FAILURE();
      }
    }
  }

  const off_t table_end = out->Tell();

  // Now seek back and write the table of offsets
  if (!out->Seek(record_offset)) {
    return OTS_FAILURE();
  }

  if (have_034) {
    if (!out->WriteU16(0) ||
        !out->WriteU16(3) ||
        !out->WriteU32(offset_034 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (have_0514) {
    if (!out->WriteU16(0) ||
        !out->WriteU16(5) ||
        !out->WriteU32(offset_0514 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (have_100) {
    if (!out->WriteU16(1) ||
        !out->WriteU16(0) ||
        !out->WriteU32(offset_100 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (have_304) {
    if (!out->WriteU16(3) ||
        !out->WriteU16(0) ||
        !out->WriteU32(offset_304 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (have_314) {
    if (!out->WriteU16(3) ||
        !out->WriteU16(1) ||
        !out->WriteU32(offset_314 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (have_31012) {
    if (!out->WriteU16(3) ||
        !out->WriteU16(10) ||
        !out->WriteU32(offset_31012 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (have_31013) {
    if (!out->WriteU16(3) ||
        !out->WriteU16(10) ||
        !out->WriteU32(offset_31013 - table_start)) {
      return OTS_FAILURE();
    }
  }

  if (!out->Seek(table_end)) {
    return OTS_FAILURE();
  }

  return true;
}

}  // namespace ots