tor-browser

gfxFontUtils.cpp (64317B)

---

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "gfxFontUtils.h"
#include "gfxFontEntry.h"
#include "gfxFontVariations.h"
#include "gfxUtils.h"

#include "nsServiceManagerUtils.h"

#include "mozilla/Preferences.h"
#include "mozilla/BinarySearch.h"
#include "mozilla/Sprintf.h"

#include "nsCOMPtr.h"
#include "nsIUUIDGenerator.h"
#include "mozilla/Encoding.h"

#include "mozilla/ServoStyleSet.h"
#include "mozilla/dom/WorkerCommon.h"

#include "mozilla/Logging.h"
#include "mozilla/Base64.h"

#ifdef XP_DARWIN
#  include <CoreFoundation/CoreFoundation.h>
#endif

#define LOG(log, args) MOZ_LOG(gfxPlatform::GetLog(log), LogLevel::Debug, args)

#define UNICODE_BMP_LIMIT 0x10000

using namespace mozilla;

#pragma pack(1)

typedef struct {
 AutoSwap_PRUint16 format;
 AutoSwap_PRUint16 reserved;
 AutoSwap_PRUint32 length;
 AutoSwap_PRUint32 language;
 AutoSwap_PRUint32 startCharCode;
 AutoSwap_PRUint32 numChars;
} Format10CmapHeader;

typedef struct {
 AutoSwap_PRUint16 format;
 AutoSwap_PRUint16 reserved;
 AutoSwap_PRUint32 length;
 AutoSwap_PRUint32 language;
 AutoSwap_PRUint32 numGroups;
} Format12CmapHeader;

typedef struct {
 AutoSwap_PRUint32 startCharCode;
 AutoSwap_PRUint32 endCharCode;
 AutoSwap_PRUint32 startGlyphId;
} Format12Group;

#pragma pack()

void gfxSparseBitSet::Dump(const char* aPrefix, eGfxLog aWhichLog) const {
 uint32_t numBlocks = mBlockIndex.Length();

 for (uint32_t b = 0; b < numBlocks; b++) {
   if (mBlockIndex[b] == NO_BLOCK) {
     continue;
   }
   const Block* block = &mBlocks[mBlockIndex[b]];
   const int BUFSIZE = 256;
   char outStr[BUFSIZE];
   int index = 0;
   index += snprintf(&outStr[index], BUFSIZE - index, "%s u+%6.6x [", aPrefix,
                     (b * BLOCK_SIZE_BITS));
   for (int i = 0; i < 32; i += 4) {
     for (int j = i; j < i + 4; j++) {
       uint8_t bits = block->mBits[j];
       uint8_t flip1 = ((bits & 0xaa) >> 1) | ((bits & 0x55) << 1);
       uint8_t flip2 = ((flip1 & 0xcc) >> 2) | ((flip1 & 0x33) << 2);
       uint8_t flipped = ((flip2 & 0xf0) >> 4) | ((flip2 & 0x0f) << 4);

       index += snprintf(&outStr[index], BUFSIZE - index, "%2.2x", flipped);
     }
     if (i + 4 != 32) index += snprintf(&outStr[index], BUFSIZE - index, " ");
   }
   (void)snprintf(&outStr[index], BUFSIZE - index, "]");
   LOG(aWhichLog, ("%s", outStr));
 }
}

nsresult gfxFontUtils::ReadCMAPTableFormat10(const uint8_t* aBuf,
                                            uint32_t aLength,
                                            gfxSparseBitSet& aCharacterMap) {
 // Ensure table is large enough that we can safely read the header
 NS_ENSURE_TRUE(aLength >= sizeof(Format10CmapHeader),
                NS_ERROR_GFX_CMAP_MALFORMED);

 // Sanity-check header fields
 const Format10CmapHeader* cmap10 =
     reinterpret_cast<const Format10CmapHeader*>(aBuf);
 NS_ENSURE_TRUE(uint16_t(cmap10->format) == 10, NS_ERROR_GFX_CMAP_MALFORMED);
 NS_ENSURE_TRUE(uint16_t(cmap10->reserved) == 0, NS_ERROR_GFX_CMAP_MALFORMED);

 uint32_t tablelen = cmap10->length;
 NS_ENSURE_TRUE(tablelen >= sizeof(Format10CmapHeader) && tablelen <= aLength,
                NS_ERROR_GFX_CMAP_MALFORMED);

 NS_ENSURE_TRUE(cmap10->language == 0, NS_ERROR_GFX_CMAP_MALFORMED);

 uint32_t numChars = cmap10->numChars;
 NS_ENSURE_TRUE(
     tablelen == sizeof(Format10CmapHeader) + numChars * sizeof(uint16_t),
     NS_ERROR_GFX_CMAP_MALFORMED);

 uint32_t charCode = cmap10->startCharCode;
 NS_ENSURE_TRUE(charCode <= CMAP_MAX_CODEPOINT &&
                    charCode + numChars <= CMAP_MAX_CODEPOINT,
                NS_ERROR_GFX_CMAP_MALFORMED);

 // glyphs[] array immediately follows the subtable header
 const AutoSwap_PRUint16* glyphs =
     reinterpret_cast<const AutoSwap_PRUint16*>(cmap10 + 1);

 for (uint32_t i = 0; i < numChars; ++i) {
   if (uint16_t(*glyphs) != 0) {
     aCharacterMap.set(charCode);
   }
   ++charCode;
   ++glyphs;
 }

 aCharacterMap.Compact();

 return NS_OK;
}

nsresult gfxFontUtils::ReadCMAPTableFormat12or13(
   const uint8_t* aBuf, uint32_t aLength, gfxSparseBitSet& aCharacterMap) {
 // Format 13 has the same structure as format 12, the only difference is
 // the interpretation of the glyphID field. So we can share the code here
 // that reads the table and just records character coverage.

 // Ensure table is large enough that we can safely read the header
 NS_ENSURE_TRUE(aLength >= sizeof(Format12CmapHeader),
                NS_ERROR_GFX_CMAP_MALFORMED);

 // Sanity-check header fields
 const Format12CmapHeader* cmap12 =
     reinterpret_cast<const Format12CmapHeader*>(aBuf);
 NS_ENSURE_TRUE(
     uint16_t(cmap12->format) == 12 || uint16_t(cmap12->format) == 13,
     NS_ERROR_GFX_CMAP_MALFORMED);
 NS_ENSURE_TRUE(uint16_t(cmap12->reserved) == 0, NS_ERROR_GFX_CMAP_MALFORMED);

 uint32_t tablelen = cmap12->length;
 NS_ENSURE_TRUE(tablelen >= sizeof(Format12CmapHeader) && tablelen <= aLength,
                NS_ERROR_GFX_CMAP_MALFORMED);

 NS_ENSURE_TRUE(cmap12->language == 0, NS_ERROR_GFX_CMAP_MALFORMED);

 // Check that the table is large enough for the group array
 const uint32_t numGroups = cmap12->numGroups;
 NS_ENSURE_TRUE(
     (tablelen - sizeof(Format12CmapHeader)) / sizeof(Format12Group) >=
         numGroups,
     NS_ERROR_GFX_CMAP_MALFORMED);

 // The array of groups immediately follows the subtable header.
 const Format12Group* group =
     reinterpret_cast<const Format12Group*>(aBuf + sizeof(Format12CmapHeader));

 // Check that groups are in correct order and do not overlap,
 // and record character coverage in aCharacterMap.
 uint32_t prevEndCharCode = 0;
 for (uint32_t i = 0; i < numGroups; i++, group++) {
   uint32_t startCharCode = group->startCharCode;
   const uint32_t endCharCode = group->endCharCode;
   NS_ENSURE_TRUE((prevEndCharCode < startCharCode || i == 0) &&
                      startCharCode <= endCharCode &&
                      endCharCode <= CMAP_MAX_CODEPOINT,
                  NS_ERROR_GFX_CMAP_MALFORMED);
   // don't include a character that maps to glyph ID 0 (.notdef)
   if (group->startGlyphId == 0) {
     startCharCode++;
   }
   if (startCharCode <= endCharCode) {
     aCharacterMap.SetRange(startCharCode, endCharCode);
   }
   prevEndCharCode = endCharCode;
 }

 aCharacterMap.Compact();

 return NS_OK;
}

nsresult gfxFontUtils::ReadCMAPTableFormat4(const uint8_t* aBuf,
                                           uint32_t aLength,
                                           gfxSparseBitSet& aCharacterMap,
                                           bool aIsSymbolFont) {
 enum {
   OffsetFormat = 0,
   OffsetLength = 2,
   OffsetLanguage = 4,
   OffsetSegCountX2 = 6
 };

 NS_ENSURE_TRUE(ReadShortAt(aBuf, OffsetFormat) == 4,
                NS_ERROR_GFX_CMAP_MALFORMED);
 uint16_t tablelen = ReadShortAt(aBuf, OffsetLength);
 NS_ENSURE_TRUE(tablelen <= aLength, NS_ERROR_GFX_CMAP_MALFORMED);
 NS_ENSURE_TRUE(tablelen > 16, NS_ERROR_GFX_CMAP_MALFORMED);

 // This field should normally (except for Mac platform subtables) be zero
 // according to the OT spec, but some buggy fonts have lang = 1 (which would
 // be English for MacOS). E.g. Arial Narrow Bold, v. 1.1 (Tiger), Arial
 // Unicode MS (see bug 530614). So accept either zero or one here; the error
 // should be harmless.
 NS_ENSURE_TRUE((ReadShortAt(aBuf, OffsetLanguage) & 0xfffe) == 0,
                NS_ERROR_GFX_CMAP_MALFORMED);

 uint16_t segCountX2 = ReadShortAt(aBuf, OffsetSegCountX2);
 NS_ENSURE_TRUE(tablelen >= 16 + (segCountX2 * 4),
                NS_ERROR_GFX_CMAP_MALFORMED);

 const uint16_t segCount = segCountX2 / 2;

 const uint16_t* endCounts = reinterpret_cast<const uint16_t*>(aBuf + 14);
 const uint16_t* startCounts =
     endCounts + 1 /* skip one uint16_t for reservedPad */ + segCount;
 const uint16_t* idDeltas = startCounts + segCount;
 const uint16_t* idRangeOffsets = idDeltas + segCount;
 uint16_t prevEndCount = 0;
 for (uint16_t i = 0; i < segCount; i++) {
   const uint16_t endCount = ReadShortAt16(endCounts, i);
   const uint16_t startCount = ReadShortAt16(startCounts, i);
   const uint16_t idRangeOffset = ReadShortAt16(idRangeOffsets, i);

   // sanity-check range
   // This permits ranges to overlap by 1 character, which is strictly
   // incorrect but occurs in Baskerville on OS X 10.7 (see bug 689087),
   // and appears to be harmless in practice
   NS_ENSURE_TRUE(startCount >= prevEndCount && startCount <= endCount,
                  NS_ERROR_GFX_CMAP_MALFORMED);
   prevEndCount = endCount;

   if (idRangeOffset == 0) {
     // figure out if there's a code in the range that would map to
     // glyph ID 0 (.notdef); if so, we need to skip setting that
     // character code in the map
     const uint16_t skipCode = 65536 - ReadShortAt16(idDeltas, i);
     if (startCount < skipCode) {
       aCharacterMap.SetRange(startCount,
                              std::min<uint16_t>(skipCode - 1, endCount));
     }
     if (skipCode < endCount) {
       aCharacterMap.SetRange(std::max<uint16_t>(startCount, skipCode + 1),
                              endCount);
     }
   } else {
     // Unused: self-documenting.
     // const uint16_t idDelta = ReadShortAt16(idDeltas, i);
     for (uint32_t c = startCount; c <= endCount; ++c) {
       if (c == 0xFFFF) break;

       const uint16_t* gdata =
           (idRangeOffset / 2 + (c - startCount) + &idRangeOffsets[i]);

       NS_ENSURE_TRUE(
           (uint8_t*)gdata > aBuf && (uint8_t*)gdata < aBuf + aLength,
           NS_ERROR_GFX_CMAP_MALFORMED);

       // make sure we have a glyph
       if (*gdata != 0) {
         // The glyph index at this point is:
         uint16_t glyph = ReadShortAt16(idDeltas, i) + *gdata;
         if (glyph) {
           aCharacterMap.set(c);
         }
       }
     }
   }
 }

 if (aIsSymbolFont) {
   // For fonts with "MS Symbol" encoding, we duplicate character mappings in
   // the U+F0xx range down to U+00xx codepoints, so as to support fonts such
   // as Wingdings.
   // Note that if the font actually has cmap coverage for the U+00xx range
   // (either duplicating the PUA codepoints or mapping to separate glyphs),
   // this will not affect it.
   for (uint32_t c = 0x0020; c <= 0x00ff; ++c) {
     if (aCharacterMap.test(0xf000 + c)) {
       aCharacterMap.set(c);
     }
   }
 }

 aCharacterMap.Compact();

 return NS_OK;
}

nsresult gfxFontUtils::ReadCMAPTableFormat14(const uint8_t* aBuf,
                                            uint32_t aLength,
                                            const uint8_t*& aTable) {
 enum {
   OffsetFormat = 0,
   OffsetTableLength = 2,
   OffsetNumVarSelectorRecords = 6,
   OffsetVarSelectorRecords = 10,

   SizeOfVarSelectorRecord = 11,
   VSRecOffsetVarSelector = 0,
   VSRecOffsetDefUVSOffset = 3,
   VSRecOffsetNonDefUVSOffset = 7,

   SizeOfDefUVSTable = 4,
   DefUVSOffsetStartUnicodeValue = 0,
   DefUVSOffsetAdditionalCount = 3,

   SizeOfNonDefUVSTable = 5,
   NonDefUVSOffsetUnicodeValue = 0,
   NonDefUVSOffsetGlyphID = 3
 };
 NS_ENSURE_TRUE(aLength >= OffsetVarSelectorRecords,
                NS_ERROR_GFX_CMAP_MALFORMED);

 NS_ENSURE_TRUE(ReadShortAt(aBuf, OffsetFormat) == 14,
                NS_ERROR_GFX_CMAP_MALFORMED);

 uint32_t tablelen = ReadLongAt(aBuf, OffsetTableLength);
 NS_ENSURE_TRUE(tablelen <= aLength, NS_ERROR_GFX_CMAP_MALFORMED);
 NS_ENSURE_TRUE(tablelen >= OffsetVarSelectorRecords,
                NS_ERROR_GFX_CMAP_MALFORMED);

 const uint32_t numVarSelectorRecords =
     ReadLongAt(aBuf, OffsetNumVarSelectorRecords);
 NS_ENSURE_TRUE(
     (tablelen - OffsetVarSelectorRecords) / SizeOfVarSelectorRecord >=
         numVarSelectorRecords,
     NS_ERROR_GFX_CMAP_MALFORMED);

 const uint8_t* records = aBuf + OffsetVarSelectorRecords;
 for (uint32_t i = 0; i < numVarSelectorRecords;
      i++, records += SizeOfVarSelectorRecord) {
   const uint32_t varSelector = ReadUint24At(records, VSRecOffsetVarSelector);
   const uint32_t defUVSOffset = ReadLongAt(records, VSRecOffsetDefUVSOffset);
   const uint32_t nonDefUVSOffset =
       ReadLongAt(records, VSRecOffsetNonDefUVSOffset);
   NS_ENSURE_TRUE(varSelector <= CMAP_MAX_CODEPOINT &&
                      defUVSOffset <= tablelen - 4 &&
                      nonDefUVSOffset <= tablelen - 4,
                  NS_ERROR_GFX_CMAP_MALFORMED);

   if (defUVSOffset) {
     const uint32_t numUnicodeValueRanges = ReadLongAt(aBuf, defUVSOffset);
     NS_ENSURE_TRUE((tablelen - defUVSOffset) / SizeOfDefUVSTable >=
                        numUnicodeValueRanges,
                    NS_ERROR_GFX_CMAP_MALFORMED);
     const uint8_t* tables = aBuf + defUVSOffset + 4;
     uint32_t prevEndUnicode = 0;
     for (uint32_t j = 0; j < numUnicodeValueRanges;
          j++, tables += SizeOfDefUVSTable) {
       const uint32_t startUnicode =
           ReadUint24At(tables, DefUVSOffsetStartUnicodeValue);
       const uint32_t endUnicode =
           startUnicode + tables[DefUVSOffsetAdditionalCount];
       NS_ENSURE_TRUE((prevEndUnicode < startUnicode || j == 0) &&
                          endUnicode <= CMAP_MAX_CODEPOINT,
                      NS_ERROR_GFX_CMAP_MALFORMED);
       prevEndUnicode = endUnicode;
     }
   }

   if (nonDefUVSOffset) {
     const uint32_t numUVSMappings = ReadLongAt(aBuf, nonDefUVSOffset);
     NS_ENSURE_TRUE(
         (tablelen - nonDefUVSOffset) / SizeOfNonDefUVSTable >= numUVSMappings,
         NS_ERROR_GFX_CMAP_MALFORMED);
     const uint8_t* tables = aBuf + nonDefUVSOffset + 4;
     uint32_t prevUnicode = 0;
     for (uint32_t j = 0; j < numUVSMappings;
          j++, tables += SizeOfNonDefUVSTable) {
       const uint32_t unicodeValue =
           ReadUint24At(tables, NonDefUVSOffsetUnicodeValue);
       NS_ENSURE_TRUE((prevUnicode < unicodeValue || j == 0) &&
                          unicodeValue <= CMAP_MAX_CODEPOINT,
                      NS_ERROR_GFX_CMAP_MALFORMED);
       prevUnicode = unicodeValue;
     }
   }
 }

 uint8_t* table = new uint8_t[tablelen];
 memcpy(table, aBuf, tablelen);

 aTable = static_cast<const uint8_t*>(table);

 return NS_OK;
}

// For fonts with two format-4 tables, the first one (Unicode platform) is
// preferred on the Mac; on other platforms we allow the Microsoft-platform
// subtable to replace it.

#if defined(XP_MACOSX)
#  define acceptableFormat4(p, e, k)                                         \
   (((p) == PLATFORM_ID_MICROSOFT && (e) == EncodingIDMicrosoft && !(k)) || \
    ((p) == PLATFORM_ID_UNICODE))

#  define acceptableUCS4Encoding(p, e, k)           \
   (((p) == PLATFORM_ID_MICROSOFT &&               \
     (e) == EncodingIDUCS4ForMicrosoftPlatform) && \
        (k) != 12 ||                               \
    ((p) == PLATFORM_ID_UNICODE && ((e) != EncodingIDUVSForUnicodePlatform)))
#else
#  define acceptableFormat4(p, e, k)                                 \
   (((p) == PLATFORM_ID_MICROSOFT && (e) == EncodingIDMicrosoft) || \
    ((p) == PLATFORM_ID_UNICODE))

#  define acceptableUCS4Encoding(p, e, k) \
   ((p) == PLATFORM_ID_MICROSOFT && (e) == EncodingIDUCS4ForMicrosoftPlatform)
#endif

#define acceptablePlatform(p) \
 ((p) == PLATFORM_ID_UNICODE || (p) == PLATFORM_ID_MICROSOFT)
#define isSymbol(p, e) ((p) == PLATFORM_ID_MICROSOFT && (e) == EncodingIDSymbol)
#define isUVSEncoding(p, e) \
 ((p) == PLATFORM_ID_UNICODE && (e) == EncodingIDUVSForUnicodePlatform)

uint32_t gfxFontUtils::FindPreferredSubtable(const uint8_t* aBuf,
                                            uint32_t aBufLength,
                                            uint32_t* aTableOffset,
                                            uint32_t* aUVSTableOffset,
                                            bool* aIsSymbolFont) {
 enum {
   OffsetVersion = 0,
   OffsetNumTables = 2,
   SizeOfHeader = 4,

   TableOffsetPlatformID = 0,
   TableOffsetEncodingID = 2,
   TableOffsetOffset = 4,
   SizeOfTable = 8,

   SubtableOffsetFormat = 0
 };
 enum {
   EncodingIDSymbol = 0,
   EncodingIDMicrosoft = 1,
   EncodingIDDefaultForUnicodePlatform = 0,
   EncodingIDUCS4ForUnicodePlatform = 3,
   EncodingIDUVSForUnicodePlatform = 5,
   EncodingIDUCS4ForMicrosoftPlatform = 10
 };

 if (aUVSTableOffset) {
   *aUVSTableOffset = 0;
 }
 if (aIsSymbolFont) {
   *aIsSymbolFont = false;
 }

 if (!aBuf || aBufLength < SizeOfHeader) {
   // cmap table is missing, or too small to contain header fields!
   return 0;
 }

 // uint16_t version = ReadShortAt(aBuf, OffsetVersion); // Unused:
 // self-documenting.
 uint16_t numTables = ReadShortAt(aBuf, OffsetNumTables);
 if (aBufLength < uint32_t(SizeOfHeader + numTables * SizeOfTable)) {
   return 0;
 }

 // save the format we want here
 uint32_t keepFormat = 0;

 const uint8_t* table = aBuf + SizeOfHeader;
 for (uint16_t i = 0; i < numTables; ++i, table += SizeOfTable) {
   const uint16_t platformID = ReadShortAt(table, TableOffsetPlatformID);
   if (!acceptablePlatform(platformID)) continue;

   const uint16_t encodingID = ReadShortAt(table, TableOffsetEncodingID);
   const uint32_t offset = ReadLongAt(table, TableOffsetOffset);
   if (aBufLength - 2 < offset) {
     // this subtable is not valid - beyond end of buffer
     return 0;
   }

   const uint8_t* subtable = aBuf + offset;
   const uint16_t format = ReadShortAt(subtable, SubtableOffsetFormat);

   if (isSymbol(platformID, encodingID)) {
     keepFormat = format;
     *aTableOffset = offset;
     if (aIsSymbolFont) {
       *aIsSymbolFont = true;
     }
     break;
   } else if (format == 4 &&
              acceptableFormat4(platformID, encodingID, keepFormat)) {
     keepFormat = format;
     *aTableOffset = offset;
   } else if ((format == 10 || format == 12 || format == 13) &&
              acceptableUCS4Encoding(platformID, encodingID, keepFormat)) {
     keepFormat = format;
     *aTableOffset = offset;
     if (platformID > PLATFORM_ID_UNICODE || !aUVSTableOffset ||
         *aUVSTableOffset) {
       break;  // we don't want to try anything else when this format is
               // available.
     }
   } else if (format == 14 && isUVSEncoding(platformID, encodingID) &&
              aUVSTableOffset) {
     *aUVSTableOffset = offset;
     if (keepFormat == 10 || keepFormat == 12) {
       break;
     }
   }
 }

 return keepFormat;
}

nsresult gfxFontUtils::ReadCMAP(const uint8_t* aBuf, uint32_t aBufLength,
                               gfxSparseBitSet& aCharacterMap,
                               uint32_t& aUVSOffset) {
 uint32_t offset;
 bool isSymbolFont;
 uint32_t format = FindPreferredSubtable(aBuf, aBufLength, &offset,
                                         &aUVSOffset, &isSymbolFont);

 switch (format) {
   case 4:
     return ReadCMAPTableFormat4(aBuf + offset, aBufLength - offset,
                                 aCharacterMap, isSymbolFont);

   case 10:
     return ReadCMAPTableFormat10(aBuf + offset, aBufLength - offset,
                                  aCharacterMap);

   case 12:
   case 13:
     return ReadCMAPTableFormat12or13(aBuf + offset, aBufLength - offset,
                                      aCharacterMap);

   default:
     break;
 }

 return NS_ERROR_FAILURE;
}

#pragma pack(1)

typedef struct {
 AutoSwap_PRUint16 format;
 AutoSwap_PRUint16 length;
 AutoSwap_PRUint16 language;
 AutoSwap_PRUint16 segCountX2;
 AutoSwap_PRUint16 searchRange;
 AutoSwap_PRUint16 entrySelector;
 AutoSwap_PRUint16 rangeShift;

 AutoSwap_PRUint16 arrays[1];
} Format4Cmap;

typedef struct Format14Cmap {
 AutoSwap_PRUint16 format;
 AutoSwap_PRUint32 length;
 AutoSwap_PRUint32 numVarSelectorRecords;

 typedef struct {
   AutoSwap_PRUint24 varSelector;
   AutoSwap_PRUint32 defaultUVSOffset;
   AutoSwap_PRUint32 nonDefaultUVSOffset;
 } VarSelectorRecord;

 VarSelectorRecord varSelectorRecords[1];
} Format14Cmap;

typedef struct DefUVSTable {
 AutoSwap_PRUint32 numUnicodeValueRanges;

 typedef struct {
   AutoSwap_PRUint24 startUnicodeValue;
   uint8_t additionalCount;
 } UnicodeRange;

 UnicodeRange ranges[1];
} DefUVSTable;

typedef struct UnicodeRangeComparator {
 explicit UnicodeRangeComparator(uint32_t aTarget) : mTarget(aTarget) {}
 int operator()(std::pair<uint32_t, uint32_t> aVal) const {
   if (mTarget < aVal.first) {
     return -1;
   }
   if (mTarget > aVal.second) {
     return 1;
   }
   return 0;
 }
 const uint32_t mTarget;
} UnicodeRangeComparator;

typedef struct NonDefUVSTable {
 AutoSwap_PRUint32 numUVSMappings;

 typedef struct {
   AutoSwap_PRUint24 unicodeValue;
   AutoSwap_PRUint16 glyphID;
 } UVSMapping;

 UVSMapping uvsMappings[1];
} NonDefUVSTable;

#pragma pack()

uint32_t gfxFontUtils::MapCharToGlyphFormat4(const uint8_t* aBuf,
                                            uint32_t aLength, char16_t aCh) {
 const Format4Cmap* cmap4 = reinterpret_cast<const Format4Cmap*>(aBuf);

 uint16_t segCount = (uint16_t)(cmap4->segCountX2) / 2;

 const AutoSwap_PRUint16* endCodes = &cmap4->arrays[0];
 const AutoSwap_PRUint16* startCodes = &cmap4->arrays[segCount + 1];
 const AutoSwap_PRUint16* idDelta = &startCodes[segCount];
 const AutoSwap_PRUint16* idRangeOffset = &idDelta[segCount];

 // Sanity-check that the fixed-size arrays don't exceed the buffer.
 const uint8_t* const limit = aBuf + aLength;
 if ((const uint8_t*)(&idRangeOffset[segCount]) > limit) {
   return 0;  // broken font, just bail out safely
 }

 // For most efficient binary search, we want to work on a range of segment
 // indexes that is a power of 2 so that we can always halve it by shifting.
 // So we find the largest power of 2 that is <= segCount.
 // We will offset this range by segOffset so as to reach the end
 // of the table, provided that doesn't put us beyond the target
 // value from the outset.
 uint32_t powerOf2 = mozilla::FindHighestBit(segCount);
 uint32_t segOffset = segCount - powerOf2;
 uint32_t idx = 0;

 if (uint16_t(startCodes[segOffset]) <= aCh) {
   idx = segOffset;
 }

 // Repeatedly halve the size of the range until we find the target group
 while (powerOf2 > 1) {
   powerOf2 >>= 1;
   if (uint16_t(startCodes[idx + powerOf2]) <= aCh) {
     idx += powerOf2;
   }
 }

 if (aCh >= uint16_t(startCodes[idx]) && aCh <= uint16_t(endCodes[idx])) {
   uint16_t result;
   if (uint16_t(idRangeOffset[idx]) == 0) {
     result = aCh;
   } else {
     uint16_t offset = aCh - uint16_t(startCodes[idx]);
     const AutoSwap_PRUint16* glyphIndexTable =
         (const AutoSwap_PRUint16*)((const char*)&idRangeOffset[idx] +
                                    uint16_t(idRangeOffset[idx]));
     if ((const uint8_t*)(glyphIndexTable + offset + 1) > limit) {
       return 0;  // broken font, just bail out safely
     }
     result = glyphIndexTable[offset];
   }

   // Note that this is unsigned 16-bit arithmetic, and may wrap around
   // (which is required behavior per spec)
   result += uint16_t(idDelta[idx]);
   return result;
 }

 return 0;
}

uint32_t gfxFontUtils::MapCharToGlyphFormat10(const uint8_t* aBuf,
                                             uint32_t aCh) {
 const Format10CmapHeader* cmap10 =
     reinterpret_cast<const Format10CmapHeader*>(aBuf);

 uint32_t startChar = cmap10->startCharCode;
 uint32_t numChars = cmap10->numChars;

 if (aCh < startChar || aCh >= startChar + numChars) {
   return 0;
 }

 const AutoSwap_PRUint16* glyphs =
     reinterpret_cast<const AutoSwap_PRUint16*>(cmap10 + 1);

 uint16_t glyph = glyphs[aCh - startChar];
 return glyph;
}

uint32_t gfxFontUtils::MapCharToGlyphFormat12or13(const uint8_t* aBuf,
                                                 uint32_t aCh) {
 // The only difference between formats 12 and 13 is the interpretation of
 // the glyphId field. So the code here uses the same "Format12" structures,
 // etc., to handle both subtable formats.

 const Format12CmapHeader* cmap12 =
     reinterpret_cast<const Format12CmapHeader*>(aBuf);

 // We know that numGroups is within range for the subtable size
 // because it was checked by ReadCMAPTableFormat12or13.
 uint32_t numGroups = cmap12->numGroups;

 // The array of groups immediately follows the subtable header.
 const Format12Group* groups =
     reinterpret_cast<const Format12Group*>(aBuf + sizeof(Format12CmapHeader));

 // For most efficient binary search, we want to work on a range that
 // is a power of 2 so that we can always halve it by shifting.
 // So we find the largest power of 2 that is <= numGroups.
 // We will offset this range by rangeOffset so as to reach the end
 // of the table, provided that doesn't put us beyond the target
 // value from the outset.
 uint32_t powerOf2 = mozilla::FindHighestBit(numGroups);
 uint32_t rangeOffset = numGroups - powerOf2;
 uint32_t range = 0;
 uint32_t startCharCode;

 if (groups[rangeOffset].startCharCode <= aCh) {
   range = rangeOffset;
 }

 // Repeatedly halve the size of the range until we find the target group
 while (powerOf2 > 1) {
   powerOf2 >>= 1;
   if (groups[range + powerOf2].startCharCode <= aCh) {
     range += powerOf2;
   }
 }

 // Check if the character is actually present in the range and return
 // the corresponding glyph ID. Here is where formats 12 and 13 interpret
 // the startGlyphId (12) or glyphId (13) field differently
 startCharCode = groups[range].startCharCode;
 if (startCharCode <= aCh && groups[range].endCharCode >= aCh) {
   return uint16_t(cmap12->format) == 12
              ? uint16_t(groups[range].startGlyphId) + aCh - startCharCode
              : uint16_t(groups[range].startGlyphId);
 }

 // Else it's not present, so return the .notdef glyph
 return 0;
}

namespace {

struct Format14CmapWrapper {
 const Format14Cmap& mCmap14;
 explicit Format14CmapWrapper(const Format14Cmap& cmap14) : mCmap14(cmap14) {}
 uint32_t operator[](size_t index) const {
   return mCmap14.varSelectorRecords[index].varSelector;
 }
};

struct DefUVSTableWrapper {
 const DefUVSTable& mTable;
 explicit DefUVSTableWrapper(const DefUVSTable& table) : mTable(table) {}
 std::pair<uint32_t, uint32_t> operator[](size_t index) const {
   const auto& range = mTable.ranges[index];
   return std::make_pair(range.startUnicodeValue,
                         range.startUnicodeValue + range.additionalCount);
 }
};

struct NonDefUVSTableWrapper {
 const NonDefUVSTable& mTable;
 explicit NonDefUVSTableWrapper(const NonDefUVSTable& table) : mTable(table) {}
 uint32_t operator[](size_t index) const {
   return mTable.uvsMappings[index].unicodeValue;
 }
};

}  // namespace

uint16_t gfxFontUtils::MapUVSToGlyphFormat14(const uint8_t* aBuf, uint32_t aCh,
                                            uint32_t aVS) {
 using mozilla::BinarySearch;
 const Format14Cmap* cmap14 = reinterpret_cast<const Format14Cmap*>(aBuf);

 size_t index;
 if (!BinarySearch(Format14CmapWrapper(*cmap14), 0,
                   cmap14->numVarSelectorRecords, aVS, &index)) {
   return 0;
 }

 const uint32_t nonDefUVSOffset =
     cmap14->varSelectorRecords[index].nonDefaultUVSOffset;
 if (!nonDefUVSOffset) {
   return 0;
 }

 const NonDefUVSTable* table =
     reinterpret_cast<const NonDefUVSTable*>(aBuf + nonDefUVSOffset);

 if (BinarySearch(NonDefUVSTableWrapper(*table), 0, table->numUVSMappings, aCh,
                  &index)) {
   return table->uvsMappings[index].glyphID;
 }

 return 0;
}

bool gfxFontUtils::IsDefaultUVSSequence(const uint8_t* aBuf, uint32_t aCh,
                                       uint32_t aVS) {
 using mozilla::BinarySearch;
 const Format14Cmap* cmap14 = reinterpret_cast<const Format14Cmap*>(aBuf);

 size_t index;
 if (!BinarySearch(Format14CmapWrapper(*cmap14), 0,
                   cmap14->numVarSelectorRecords, aVS, &index)) {
   return false;
 }

 const uint32_t defUVSOffset =
     cmap14->varSelectorRecords[index].defaultUVSOffset;
 if (!defUVSOffset) {
   return false;
 }

 const DefUVSTable* table =
     reinterpret_cast<const DefUVSTable*>(aBuf + defUVSOffset);

 if (BinarySearchIf(DefUVSTableWrapper(*table), 0,
                    table->numUnicodeValueRanges, UnicodeRangeComparator(aCh),
                    &index)) {
   return true;
 }

 return false;
}

uint32_t gfxFontUtils::MapCharToGlyph(const uint8_t* aCmapBuf,
                                     uint32_t aBufLength, uint32_t aUnicode,
                                     uint32_t aVarSelector) {
 uint32_t offset, uvsOffset;
 bool isSymbolFont;
 uint32_t format = FindPreferredSubtable(aCmapBuf, aBufLength, &offset,
                                         &uvsOffset, &isSymbolFont);

 uint32_t gid;
 switch (format) {
   case 4:
     gid = aUnicode < UNICODE_BMP_LIMIT
               ? MapCharToGlyphFormat4(aCmapBuf + offset, aBufLength - offset,
                                       char16_t(aUnicode))
               : 0;
     if (!gid && isSymbolFont) {
       if (auto pua = MapLegacySymbolFontCharToPUA(aUnicode)) {
         gid = MapCharToGlyphFormat4(aCmapBuf + offset, aBufLength - offset,
                                     pua);
       }
     }
     break;
   case 10:
     gid = MapCharToGlyphFormat10(aCmapBuf + offset, aUnicode);
     break;
   case 12:
   case 13:
     gid = MapCharToGlyphFormat12or13(aCmapBuf + offset, aUnicode);
     break;
   default:
     NS_WARNING("unsupported cmap format, glyphs will be missing");
     gid = 0;
 }

 if (aVarSelector && uvsOffset && gid) {
   uint32_t varGID = gfxFontUtils::MapUVSToGlyphFormat14(
       aCmapBuf + uvsOffset, aUnicode, aVarSelector);
   if (!varGID) {
     aUnicode = gfxFontUtils::GetUVSFallback(aUnicode, aVarSelector);
     if (aUnicode) {
       switch (format) {
         case 4:
           if (aUnicode < UNICODE_BMP_LIMIT) {
             varGID = MapCharToGlyphFormat4(
                 aCmapBuf + offset, aBufLength - offset, char16_t(aUnicode));
           }
           break;
         case 10:
           varGID = MapCharToGlyphFormat10(aCmapBuf + offset, aUnicode);
           break;
         case 12:
         case 13:
           varGID = MapCharToGlyphFormat12or13(aCmapBuf + offset, aUnicode);
           break;
       }
     }
   }
   if (varGID) {
     gid = varGID;
   }

   // else the variation sequence was not supported, use default mapping
   // of the character code alone
 }

 return gid;
}

void gfxFontUtils::ParseFontList(const nsACString& aFamilyList,
                                nsTArray<nsCString>& aFontList) {
 const char kComma = ',';

 // append each font name to the list
 nsAutoCString fontname;
 const char *p, *p_end;
 aFamilyList.BeginReading(p);
 aFamilyList.EndReading(p_end);

 while (p < p_end) {
   const char* nameStart = p;
   while (++p != p_end && *p != kComma) /* nothing */
     ;

   // pull out a single name and clean out leading/trailing whitespace
   fontname = Substring(nameStart, p);
   fontname.CompressWhitespace(true, true);

   // append it to the list if it's not empty
   if (!fontname.IsEmpty()) {
     aFontList.AppendElement(fontname);
   }
   ++p;
 }
}

void gfxFontUtils::GetPrefsFontList(const char* aPrefName,
                                   nsTArray<nsCString>& aFontList) {
 aFontList.Clear();

 nsAutoCString fontlistValue;
 nsresult rv = Preferences::GetCString(aPrefName, fontlistValue);
 if (NS_FAILED(rv)) {
   return;
 }

 ParseFontList(fontlistValue, aFontList);
}

// produce a unique font name that is (1) a valid Postscript name and (2) less
// than 31 characters in length.  Using AddFontMemResourceEx on Windows fails
// for names longer than 30 characters in length.

constexpr uint32_t MAX_B64_LEN = 32;

nsresult gfxFontUtils::MakeUniqueUserFontName(nsAString& aName) {
 nsCOMPtr<nsIUUIDGenerator> uuidgen =
     do_GetService("@mozilla.org/uuid-generator;1");
 NS_ENSURE_TRUE(uuidgen, NS_ERROR_OUT_OF_MEMORY);

 nsID guid;

 NS_ASSERTION(sizeof(guid) * 2 <= MAX_B64_LEN, "size of nsID has changed!");

 nsresult rv = uuidgen->GenerateUUIDInPlace(&guid);
 NS_ENSURE_SUCCESS(rv, rv);

 char guidB64[MAX_B64_LEN];

 if (NS_FAILED(mozilla::Base64Encode(reinterpret_cast<char*>(&guid),
                                     sizeof(guid), guidB64)))
   return NS_ERROR_FAILURE;

 // all b64 characters except for '/' are allowed in Postscript names, so
 // convert / ==> -
 char* p;
 for (p = guidB64; *p; p++) {
   if (*p == '/') *p = '-';
 }

 aName.AssignLiteral(u"uf");
 aName.AppendASCII(guidB64);
 return NS_OK;
}

// TrueType/OpenType table handling code

// need byte aligned structs
#pragma pack(1)

// name table stores set of name record structures, followed by
// large block containing all the strings.  name record offset and length
// indicates the offset and length within that block.
// http://www.microsoft.com/typography/otspec/name.htm
struct NameRecordData {
 uint32_t offset;
 uint32_t length;
};

#pragma pack()

static bool IsValidSFNTVersion(uint32_t version) {
 // normally 0x00010000, CFF-style OT fonts == 'OTTO' and Apple TT fonts =
 // 'true' 'typ1' is also possible for old Type 1 fonts in a SFNT container but
 // not supported
 return version == 0x10000 || version == TRUETYPE_TAG('O', 'T', 'T', 'O') ||
        version == TRUETYPE_TAG('t', 'r', 'u', 'e');
}

gfxUserFontType gfxFontUtils::DetermineFontDataType(const uint8_t* aFontData,
                                                   uint32_t aFontDataLength) {
 // test for OpenType font data
 // problem: EOT-Lite with 0x10000 length will look like TrueType!
 if (aFontDataLength >= sizeof(SFNTHeader)) {
   const SFNTHeader* sfntHeader =
       reinterpret_cast<const SFNTHeader*>(aFontData);
   uint32_t sfntVersion = sfntHeader->sfntVersion;
   if (IsValidSFNTVersion(sfntVersion)) {
     return GFX_USERFONT_OPENTYPE;
   }
 }

 // test for WOFF or WOFF2
 if (aFontDataLength >= sizeof(AutoSwap_PRUint32)) {
   const AutoSwap_PRUint32* version =
       reinterpret_cast<const AutoSwap_PRUint32*>(aFontData);
   if (uint32_t(*version) == TRUETYPE_TAG('w', 'O', 'F', 'F')) {
     return GFX_USERFONT_WOFF;
   }
   if (uint32_t(*version) == TRUETYPE_TAG('w', 'O', 'F', '2')) {
     return GFX_USERFONT_WOFF2;
   }
 }

 // tests for other formats here

 return GFX_USERFONT_UNKNOWN;
}

static int DirEntryCmp(const void* aKey, const void* aItem) {
 int32_t tag = *static_cast<const int32_t*>(aKey);
 const TableDirEntry* entry = static_cast<const TableDirEntry*>(aItem);
 return tag - int32_t(entry->tag);
}

/* static */
TableDirEntry* gfxFontUtils::FindTableDirEntry(const void* aFontData,
                                              uint32_t aTableTag) {
 const SFNTHeader* header = reinterpret_cast<const SFNTHeader*>(aFontData);
 const TableDirEntry* dir = reinterpret_cast<const TableDirEntry*>(header + 1);
 return static_cast<TableDirEntry*>(
     bsearch(&aTableTag, dir, uint16_t(header->numTables),
             sizeof(TableDirEntry), DirEntryCmp));
}

/* static */
hb_blob_t* gfxFontUtils::GetTableFromFontData(const void* aFontData,
                                             uint32_t aTableTag) {
 const TableDirEntry* dir = FindTableDirEntry(aFontData, aTableTag);
 if (dir) {
   return hb_blob_create(
       reinterpret_cast<const char*>(aFontData) + dir->offset, dir->length,
       HB_MEMORY_MODE_READONLY, nullptr, nullptr);
 }
 return nullptr;
}

nsresult gfxFontUtils::RenameFont(const nsAString& aName,
                                 const uint8_t* aFontData,
                                 uint32_t aFontDataLength,
                                 FallibleTArray<uint8_t>* aNewFont) {
 NS_ASSERTION(aNewFont, "null font data array");

 uint64_t dataLength(aFontDataLength);

 // new name table
 static const uint32_t neededNameIDs[] = {NAME_ID_FAMILY, NAME_ID_STYLE,
                                          NAME_ID_UNIQUE, NAME_ID_FULL,
                                          NAME_ID_POSTSCRIPT};

 // calculate new name table size
 uint16_t nameCount = std::size(neededNameIDs);

 // leave room for null-terminator
 uint32_t nameStrLength = (aName.Length() + 1) * sizeof(char16_t);
 if (nameStrLength > 65535) {
   // The name length _in bytes_ must fit in an unsigned short field;
   // therefore, a name longer than this cannot be used.
   return NS_ERROR_FAILURE;
 }

 // round name table size up to 4-byte multiple
 uint32_t nameTableSize =
     (sizeof(NameHeader) + sizeof(NameRecord) * nameCount + nameStrLength +
      3) &
     ~3;

 if (dataLength + nameTableSize > UINT32_MAX) return NS_ERROR_FAILURE;

 // bug 505386 - need to handle unpadded font length
 uint32_t paddedFontDataSize = (aFontDataLength + 3) & ~3;
 uint32_t adjFontDataSize = paddedFontDataSize + nameTableSize;

 // create new buffer: old font data plus new name table
 if (!aNewFont->AppendElements(adjFontDataSize, fallible))
   return NS_ERROR_OUT_OF_MEMORY;

 // copy the old font data
 uint8_t* newFontData = reinterpret_cast<uint8_t*>(aNewFont->Elements());

 // null the last four bytes in case the font length is not a multiple of 4
 memset(newFontData + aFontDataLength, 0,
        paddedFontDataSize - aFontDataLength);

 // copy font data
 memcpy(newFontData, aFontData, aFontDataLength);

 // null out the last 4 bytes for checksum calculations
 memset(newFontData + adjFontDataSize - 4, 0, 4);

 NameHeader* nameHeader =
     reinterpret_cast<NameHeader*>(newFontData + paddedFontDataSize);

 // -- name header
 nameHeader->format = 0;
 nameHeader->count = nameCount;
 nameHeader->stringOffset =
     sizeof(NameHeader) + nameCount * sizeof(NameRecord);

 // -- name records
 uint32_t i;
 NameRecord* nameRecord = reinterpret_cast<NameRecord*>(nameHeader + 1);

 for (i = 0; i < nameCount; i++, nameRecord++) {
   nameRecord->platformID = PLATFORM_ID_MICROSOFT;
   nameRecord->encodingID = ENCODING_ID_MICROSOFT_UNICODEBMP;
   nameRecord->languageID = LANG_ID_MICROSOFT_EN_US;
   nameRecord->nameID = neededNameIDs[i];
   nameRecord->offset = 0;
   nameRecord->length = nameStrLength;
 }

 // -- string data, located after the name records, stored in big-endian form
 char16_t* strData = reinterpret_cast<char16_t*>(nameRecord);

 mozilla::NativeEndian::copyAndSwapToBigEndian(strData, aName.BeginReading(),
                                               aName.Length());
 strData[aName.Length()] = 0;  // add null termination

 // adjust name table header to point to the new name table
 SFNTHeader* sfntHeader = reinterpret_cast<SFNTHeader*>(newFontData);

 // table directory entries begin immediately following SFNT header
 TableDirEntry* dirEntry =
     FindTableDirEntry(newFontData, TRUETYPE_TAG('n', 'a', 'm', 'e'));
 // function only called if font validates, so this should always be true
 MOZ_ASSERT(dirEntry, "attempt to rename font with no name table");

 uint32_t numTables = sfntHeader->numTables;

 // note: dirEntry now points to 'name' table record

 // recalculate name table checksum
 uint32_t checkSum = 0;
 AutoSwap_PRUint32* nameData =
     reinterpret_cast<AutoSwap_PRUint32*>(nameHeader);
 AutoSwap_PRUint32* nameDataEnd = nameData + (nameTableSize >> 2);

 while (nameData < nameDataEnd) checkSum = checkSum + *nameData++;

 // adjust name table entry to point to new name table
 dirEntry->offset = paddedFontDataSize;
 dirEntry->length = nameTableSize;
 dirEntry->checkSum = checkSum;

 // fix up checksums
 uint32_t checksum = 0;

 // checksum for font = (checksum of header) + (checksum of tables)
 uint32_t headerLen = sizeof(SFNTHeader) + sizeof(TableDirEntry) * numTables;
 const AutoSwap_PRUint32* headerData =
     reinterpret_cast<const AutoSwap_PRUint32*>(newFontData);

 // header length is in bytes, checksum calculated in longwords
 for (i = 0; i < (headerLen >> 2); i++, headerData++) {
   checksum += *headerData;
 }

 uint32_t headOffset = 0;
 dirEntry = reinterpret_cast<TableDirEntry*>(newFontData + sizeof(SFNTHeader));

 for (i = 0; i < numTables; i++, dirEntry++) {
   if (dirEntry->tag == TRUETYPE_TAG('h', 'e', 'a', 'd')) {
     headOffset = dirEntry->offset;
   }
   checksum += dirEntry->checkSum;
 }

 NS_ASSERTION(headOffset != 0, "no head table for font");

 HeadTable* headData = reinterpret_cast<HeadTable*>(newFontData + headOffset);

 headData->checkSumAdjustment = HeadTable::HEAD_CHECKSUM_CALC_CONST - checksum;

 return NS_OK;
}

// This is only called after the basic validity of the downloaded sfnt
// data has been checked, so it should never fail to find the name table
// (though it might fail to read it, if memory isn't available);
// other checks here are just for extra paranoia.
nsresult gfxFontUtils::GetFullNameFromSFNT(const uint8_t* aFontData,
                                          uint32_t aLength,
                                          nsACString& aFullName) {
 aFullName = "(MISSING NAME)";  // should always get replaced

 const TableDirEntry* dirEntry =
     FindTableDirEntry(aFontData, TRUETYPE_TAG('n', 'a', 'm', 'e'));

 // should never fail, as we're only called after font validation succeeded
 NS_ENSURE_TRUE(dirEntry, NS_ERROR_NOT_AVAILABLE);

 uint32_t len = dirEntry->length;
 NS_ENSURE_TRUE(aLength > len && aLength - len >= dirEntry->offset,
                NS_ERROR_UNEXPECTED);

 AutoHBBlob nameBlob(hb_blob_create((const char*)aFontData + dirEntry->offset,
                                    len, HB_MEMORY_MODE_READONLY, nullptr,
                                    nullptr));
 nsresult rv = GetFullNameFromTable(nameBlob, aFullName);

 return rv;
}

nsresult gfxFontUtils::GetFullNameFromTable(hb_blob_t* aNameTable,
                                           nsACString& aFullName) {
 nsAutoCString name;
 nsresult rv = gfxFontUtils::ReadCanonicalName(
     aNameTable, gfxFontUtils::NAME_ID_FULL, name);
 if (NS_SUCCEEDED(rv) && !name.IsEmpty()) {
   aFullName = name;
   return NS_OK;
 }
 rv = gfxFontUtils::ReadCanonicalName(aNameTable, gfxFontUtils::NAME_ID_FAMILY,
                                      name);
 if (NS_SUCCEEDED(rv) && !name.IsEmpty()) {
   nsAutoCString styleName;
   rv = gfxFontUtils::ReadCanonicalName(
       aNameTable, gfxFontUtils::NAME_ID_STYLE, styleName);
   if (NS_SUCCEEDED(rv) && !styleName.IsEmpty()) {
     name.Append(' ');
     name.Append(styleName);
     aFullName = name;
   }
   return NS_OK;
 }

 return NS_ERROR_NOT_AVAILABLE;
}

nsresult gfxFontUtils::GetFamilyNameFromTable(hb_blob_t* aNameTable,
                                             nsACString& aFamilyName) {
 nsAutoCString name;
 nsresult rv = gfxFontUtils::ReadCanonicalName(
     aNameTable, gfxFontUtils::NAME_ID_FAMILY, name);
 if (NS_SUCCEEDED(rv) && !name.IsEmpty()) {
   aFamilyName = name;
   return NS_OK;
 }
 return NS_ERROR_NOT_AVAILABLE;
}

enum {
#if defined(XP_MACOSX)
 CANONICAL_LANG_ID = gfxFontUtils::LANG_ID_MAC_ENGLISH,
 PLATFORM_ID = gfxFontUtils::PLATFORM_ID_MAC
#else
 CANONICAL_LANG_ID = gfxFontUtils::LANG_ID_MICROSOFT_EN_US,
 PLATFORM_ID = gfxFontUtils::PLATFORM_ID_MICROSOFT
#endif
};

nsresult gfxFontUtils::ReadNames(const char* aNameData, uint32_t aDataLen,
                                uint32_t aNameID, int32_t aPlatformID,
                                nsTArray<nsCString>& aNames) {
 return ReadNames(aNameData, aDataLen, aNameID, LANG_ALL, aPlatformID, aNames);
}

nsresult gfxFontUtils::ReadCanonicalName(hb_blob_t* aNameTable,
                                        uint32_t aNameID, nsCString& aName) {
 uint32_t nameTableLen;
 const char* nameTable = hb_blob_get_data(aNameTable, &nameTableLen);
 return ReadCanonicalName(nameTable, nameTableLen, aNameID, aName);
}

nsresult gfxFontUtils::ReadCanonicalName(const char* aNameData,
                                        uint32_t aDataLen, uint32_t aNameID,
                                        nsCString& aName) {
 nsresult rv;

 nsTArray<nsCString> names;

 // first, look for the English name (this will succeed 99% of the time)
 rv = ReadNames(aNameData, aDataLen, aNameID, CANONICAL_LANG_ID, PLATFORM_ID,
                names);
 NS_ENSURE_SUCCESS(rv, rv);

 // otherwise, grab names for all languages
 if (names.Length() == 0) {
   rv = ReadNames(aNameData, aDataLen, aNameID, LANG_ALL, PLATFORM_ID, names);
   NS_ENSURE_SUCCESS(rv, rv);
 }

#if defined(XP_MACOSX)
 // may be dealing with font that only has Microsoft name entries
 if (names.Length() == 0) {
   rv = ReadNames(aNameData, aDataLen, aNameID, LANG_ID_MICROSOFT_EN_US,
                  PLATFORM_ID_MICROSOFT, names);
   NS_ENSURE_SUCCESS(rv, rv);

   // getting really desperate now, take anything!
   if (names.Length() == 0) {
     rv = ReadNames(aNameData, aDataLen, aNameID, LANG_ALL,
                    PLATFORM_ID_MICROSOFT, names);
     NS_ENSURE_SUCCESS(rv, rv);
   }
 }
#endif

 // return the first name (99.9% of the time names will
 // contain a single English name)
 if (names.Length()) {
   aName.Assign(names[0]);
   return NS_OK;
 }

 return NS_ERROR_FAILURE;
}

// Charsets to use for decoding Mac platform font names.
// This table is sorted by {encoding, language}, with the wildcard "ANY" being
// greater than any defined values for each field; we use a binary search on
// both fields, and fall back to matching only encoding if necessary

// Some "redundant" entries for specific combinations are included such as
// encoding=roman, lang=english, in order that common entries will be found
// on the first search.

const uint16_t ANY = 0xffff;
MOZ_RUNINIT const gfxFontUtils::MacFontNameCharsetMapping
   gfxFontUtils::gMacFontNameCharsets[] = {
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_ENGLISH, MACINTOSH_ENCODING},
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_ICELANDIC, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_TURKISH, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_POLISH, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_ROMANIAN, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_CZECH, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ROMAN, LANG_ID_MAC_SLOVAK, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ROMAN, ANY, MACINTOSH_ENCODING},
       {ENCODING_ID_MAC_JAPANESE, LANG_ID_MAC_JAPANESE, SHIFT_JIS_ENCODING},
       {ENCODING_ID_MAC_JAPANESE, ANY, SHIFT_JIS_ENCODING},
       {ENCODING_ID_MAC_TRAD_CHINESE, LANG_ID_MAC_TRAD_CHINESE, BIG5_ENCODING},
       {ENCODING_ID_MAC_TRAD_CHINESE, ANY, BIG5_ENCODING},
       {ENCODING_ID_MAC_KOREAN, LANG_ID_MAC_KOREAN, EUC_KR_ENCODING},
       {ENCODING_ID_MAC_KOREAN, ANY, EUC_KR_ENCODING},
       {ENCODING_ID_MAC_ARABIC, LANG_ID_MAC_ARABIC, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ARABIC, LANG_ID_MAC_URDU, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ARABIC, LANG_ID_MAC_FARSI, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_ARABIC, ANY, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_HEBREW, LANG_ID_MAC_HEBREW, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_HEBREW, ANY, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_GREEK, ANY, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_CYRILLIC, ANY, X_MAC_CYRILLIC_ENCODING},
       {ENCODING_ID_MAC_DEVANAGARI, ANY, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_GURMUKHI, ANY, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_GUJARATI, ANY, X_USER_DEFINED_ENCODING},
       {ENCODING_ID_MAC_SIMP_CHINESE, LANG_ID_MAC_SIMP_CHINESE,
        GB18030_ENCODING},
       {ENCODING_ID_MAC_SIMP_CHINESE, ANY, GB18030_ENCODING}};

MOZ_RUNINIT const Encoding* gfxFontUtils::gISOFontNameCharsets[] = {
   /* 0 */ WINDOWS_1252_ENCODING, /* US-ASCII */
   /* 1 */ nullptr, /* spec says "ISO 10646" but does not specify encoding
                       form! */
   /* 2 */ WINDOWS_1252_ENCODING /* ISO-8859-1 */
};

MOZ_RUNINIT const Encoding* gfxFontUtils::gMSFontNameCharsets[] = {
   /* [0] ENCODING_ID_MICROSOFT_SYMBOL */ UTF_16BE_ENCODING,
   /* [1] ENCODING_ID_MICROSOFT_UNICODEBMP */ UTF_16BE_ENCODING,
   /* [2] ENCODING_ID_MICROSOFT_SHIFTJIS */ SHIFT_JIS_ENCODING,
   /* [3] ENCODING_ID_MICROSOFT_PRC */ nullptr,
   /* [4] ENCODING_ID_MICROSOFT_BIG5 */ BIG5_ENCODING,
   /* [5] ENCODING_ID_MICROSOFT_WANSUNG */ nullptr,
   /* [6] ENCODING_ID_MICROSOFT_JOHAB */ nullptr,
   /* [7] reserved */ nullptr,
   /* [8] reserved */ nullptr,
   /* [9] reserved */ nullptr,
   /*[10] ENCODING_ID_MICROSOFT_UNICODEFULL */ UTF_16BE_ENCODING};

struct MacCharsetMappingComparator {
 typedef gfxFontUtils::MacFontNameCharsetMapping MacFontNameCharsetMapping;
 const MacFontNameCharsetMapping& mSearchValue;
 explicit MacCharsetMappingComparator(
     const MacFontNameCharsetMapping& aSearchValue)
     : mSearchValue(aSearchValue) {}
 int operator()(const MacFontNameCharsetMapping& aEntry) const {
   if (mSearchValue < aEntry) {
     return -1;
   }
   if (aEntry < mSearchValue) {
     return 1;
   }
   return 0;
 }
};

// Return the Encoding object we should use to decode a font name
// given the name table attributes.
// Special return values:
//    X_USER_DEFINED_ENCODING  One of Mac legacy encodings that is not a part
//                             of Encoding Standard
//    nullptr                  unknown charset, do not attempt conversion
const Encoding* gfxFontUtils::GetCharsetForFontName(uint16_t aPlatform,
                                                   uint16_t aScript,
                                                   uint16_t aLanguage) {
 switch (aPlatform) {
   case PLATFORM_ID_UNICODE:
     return UTF_16BE_ENCODING;

   case PLATFORM_ID_MAC: {
     MacFontNameCharsetMapping searchValue = {aScript, aLanguage, nullptr};
     for (uint32_t i = 0; i < 2; ++i) {
       size_t idx;
       if (BinarySearchIf(gMacFontNameCharsets, 0,
                          std::size(gMacFontNameCharsets),
                          MacCharsetMappingComparator(searchValue), &idx)) {
         return gMacFontNameCharsets[idx].mEncoding;
       }

       // no match, so try again finding one in any language
       searchValue.mLanguage = ANY;
     }
   } break;

   case PLATFORM_ID_ISO:
     if (aScript < std::size(gISOFontNameCharsets)) {
       return gISOFontNameCharsets[aScript];
     }
     break;

   case PLATFORM_ID_MICROSOFT:
     if (aScript < std::size(gMSFontNameCharsets)) {
       return gMSFontNameCharsets[aScript];
     }
     break;
 }

 return nullptr;
}

template <int N>
static bool StartsWith(const nsACString& string, const char (&prefix)[N]) {
 if (N - 1 > string.Length()) {
   return false;
 }
 return memcmp(string.Data(), prefix, N - 1) == 0;
}

// convert a raw name from the name table to an nsString, if possible;
// return value indicates whether conversion succeeded
bool gfxFontUtils::DecodeFontName(const char* aNameData, int32_t aByteLen,
                                 uint32_t aPlatformCode, uint32_t aScriptCode,
                                 uint32_t aLangCode, nsACString& aName) {
 if (aByteLen <= 0) {
   NS_WARNING("empty font name");
   aName.SetLength(0);
   return true;
 }

 auto encoding = GetCharsetForFontName(aPlatformCode, aScriptCode, aLangCode);

 if (!encoding) {
   // nullptr -> unknown charset
#ifdef DEBUG
   char warnBuf[128];
   if (aByteLen > 64) aByteLen = 64;
   SprintfLiteral(warnBuf,
                  "skipping font name, unknown charset %d:%d:%d for <%.*s>",
                  aPlatformCode, aScriptCode, aLangCode, aByteLen, aNameData);
   NS_WARNING(warnBuf);
#endif
   return false;
 }

 if (encoding == X_USER_DEFINED_ENCODING) {
#ifdef XP_DARWIN
   // Special case for macOS only: support legacy Mac encodings
   // that aren't part of the Encoding Standard.
   if (aPlatformCode == PLATFORM_ID_MAC) {
     CFStringRef str =
         CFStringCreateWithBytes(kCFAllocatorDefault, (const UInt8*)aNameData,
                                 aByteLen, aScriptCode, false);
     if (str) {
       CFIndex length = CFStringGetLength(str);
       nsAutoString name16;
       name16.SetLength(length);
       CFStringGetCharacters(str, CFRangeMake(0, length),
                             (UniChar*)name16.BeginWriting());
       CFRelease(str);
       CopyUTF16toUTF8(name16, aName);
       return true;
     }
   }
#endif
   NS_WARNING("failed to get the decoder for a font name string");
   return false;
 }

 auto rv = encoding->DecodeWithoutBOMHandling(
     nsDependentCSubstring(aNameData, aByteLen), aName);
 return NS_SUCCEEDED(rv);
}

nsresult gfxFontUtils::ReadNames(const char* aNameData, uint32_t aDataLen,
                                uint32_t aNameID, int32_t aLangID,
                                int32_t aPlatformID,
                                nsTArray<nsCString>& aNames) {
 NS_ASSERTION(aDataLen != 0, "null name table");

 if (!aDataLen) {
   return NS_ERROR_FAILURE;
 }

 // -- name table data
 const NameHeader* nameHeader = reinterpret_cast<const NameHeader*>(aNameData);

 uint32_t nameCount = nameHeader->count;

 // -- sanity check the number of name records
 if (uint64_t(nameCount) * sizeof(NameRecord) > aDataLen) {
   NS_WARNING("invalid font (name table data)");
   return NS_ERROR_FAILURE;
 }

 // -- iterate through name records
 const NameRecord* nameRecord =
     reinterpret_cast<const NameRecord*>(aNameData + sizeof(NameHeader));
 uint64_t nameStringsBase = uint64_t(nameHeader->stringOffset);

 uint32_t i;
 for (i = 0; i < nameCount; i++, nameRecord++) {
   uint32_t platformID;

   // skip over unwanted nameID's
   if (uint32_t(nameRecord->nameID) != aNameID) {
     continue;
   }

   // skip over unwanted platform data
   platformID = nameRecord->platformID;
   if (aPlatformID != PLATFORM_ALL && platformID != uint32_t(aPlatformID)) {
     continue;
   }

   // skip over unwanted languages
   if (aLangID != LANG_ALL &&
       uint32_t(nameRecord->languageID) != uint32_t(aLangID)) {
     continue;
   }

   // add name to names array

   // -- calculate string location
   uint32_t namelen = nameRecord->length;
   uint32_t nameoff =
       nameRecord->offset;  // offset from base of string storage

   if (nameStringsBase + uint64_t(nameoff) + uint64_t(namelen) > aDataLen) {
     NS_WARNING("invalid font (name table strings)");
     return NS_ERROR_FAILURE;
   }

   // -- decode if necessary and make nsString
   nsAutoCString name;

   DecodeFontName(aNameData + nameStringsBase + nameoff, namelen, platformID,
                  uint32_t(nameRecord->encodingID),
                  uint32_t(nameRecord->languageID), name);

   uint32_t k, numNames;
   bool foundName = false;

   numNames = aNames.Length();
   for (k = 0; k < numNames; k++) {
     if (name.Equals(aNames[k])) {
       foundName = true;
       break;
     }
   }

   if (!foundName) aNames.AppendElement(name);
 }

 return NS_OK;
}

void gfxFontUtils::GetVariationData(
   gfxFontEntry* aFontEntry, nsTArray<gfxFontVariationAxis>* aAxes,
   nsTArray<gfxFontVariationInstance>* aInstances) {
 MOZ_ASSERT(!aAxes || aAxes->IsEmpty());
 MOZ_ASSERT(!aInstances || aInstances->IsEmpty());

 if (!aFontEntry->HasVariations()) {
   return;
 }

 // Some platforms don't offer a simple API to return the list of instances,
 // so we have to interpret the 'fvar' table ourselves.

 // https://www.microsoft.com/typography/otspec/fvar.htm#fvarHeader
 struct FvarHeader {
   AutoSwap_PRUint16 majorVersion;
   AutoSwap_PRUint16 minorVersion;
   AutoSwap_PRUint16 axesArrayOffset;
   AutoSwap_PRUint16 reserved;
   AutoSwap_PRUint16 axisCount;
   AutoSwap_PRUint16 axisSize;
   AutoSwap_PRUint16 instanceCount;
   AutoSwap_PRUint16 instanceSize;
 };

 // https://www.microsoft.com/typography/otspec/fvar.htm#variationAxisRecord
 struct AxisRecord {
   AutoSwap_PRUint32 axisTag;
   AutoSwap_PRInt32 minValue;
   AutoSwap_PRInt32 defaultValue;
   AutoSwap_PRInt32 maxValue;
   AutoSwap_PRUint16 flags;
   AutoSwap_PRUint16 axisNameID;
 };
 const uint16_t HIDDEN_AXIS = 0x0001;  // AxisRecord flags value

 // https://www.microsoft.com/typography/otspec/fvar.htm#instanceRecord
 struct InstanceRecord {
   AutoSwap_PRUint16 subfamilyNameID;
   AutoSwap_PRUint16 flags;
   AutoSwap_PRInt32 coordinates[1];  // variable-size array [axisCount]
   // The variable-length 'coordinates' array may be followed by an
   // optional extra field 'postScriptNameID'. We can't directly
   // represent this in the struct, because its offset varies depending
   // on the number of axes present.
   // (Not currently used by our code here anyhow.)
   //  AutoSwap_PRUint16 postScriptNameID;
 };

 // Load the two font tables we need as harfbuzz blobs; if either is absent,
 // just bail out.
 AutoHBBlob fvarTable(
     aFontEntry->GetFontTable(TRUETYPE_TAG('f', 'v', 'a', 'r')));
 AutoHBBlob nameTable(
     aFontEntry->GetFontTable(TRUETYPE_TAG('n', 'a', 'm', 'e')));
 if (!fvarTable || !nameTable) {
   return;
 }
 unsigned int len;
 const char* data = hb_blob_get_data(fvarTable, &len);
 if (len < sizeof(FvarHeader)) {
   return;
 }
 // Read the fields of the table header; bail out if it looks broken.
 auto fvar = reinterpret_cast<const FvarHeader*>(data);
 if (uint16_t(fvar->majorVersion) != 1 || uint16_t(fvar->minorVersion) != 0 ||
     uint16_t(fvar->reserved) != 2) {
   return;
 }
 uint16_t axisCount = fvar->axisCount;
 uint16_t axisSize = fvar->axisSize;
 uint16_t instanceCount = fvar->instanceCount;
 uint16_t instanceSize = fvar->instanceSize;
 if (axisCount ==
         0 ||  // no axes?
               // https://www.microsoft.com/typography/otspec/fvar.htm#axisSize
     axisSize != 20 ||  // required value for current table version
     // https://www.microsoft.com/typography/otspec/fvar.htm#instanceSize
     (instanceSize != axisCount * sizeof(int32_t) + 4 &&
      instanceSize != axisCount * sizeof(int32_t) + 6)) {
   return;
 }
 // Check that axis array will not exceed table size
 uint16_t axesOffset = fvar->axesArrayOffset;
 if (axesOffset + uint32_t(axisCount) * axisSize > len) {
   return;
 }
 // Get pointer to the array of axis records
 auto axes = reinterpret_cast<const AxisRecord*>(data + axesOffset);
 // Get address of instance array, and check it doesn't overflow table size.
 // https://www.microsoft.com/typography/otspec/fvar.htm#axisAndInstanceArrays
 auto instData = data + axesOffset + axisCount * axisSize;
 if (instData + uint32_t(instanceCount) * instanceSize > data + len) {
   return;
 }
 if (aInstances) {
   aInstances->SetCapacity(instanceCount);
   for (unsigned i = 0; i < instanceCount; ++i, instData += instanceSize) {
     // Typed pointer to the current instance record, to read its fields.
     auto inst = reinterpret_cast<const InstanceRecord*>(instData);
     // Pointer to the coordinates array within the instance record.
     // This array has axisCount elements, and is included in instanceSize
     // (which depends on axisCount, and was validated above) so we know
     // access to coords[j] below will not be outside the table bounds.
     auto coords = &inst->coordinates[0];
     gfxFontVariationInstance instance;
     uint16_t nameID = inst->subfamilyNameID;
     nsresult rv = ReadCanonicalName(nameTable, nameID, instance.mName);
     if (NS_FAILED(rv)) {
       // If no name was available for the instance, ignore it.
       continue;
     }
     instance.mValues.SetCapacity(axisCount);
     for (unsigned j = 0; j < axisCount; ++j) {
       gfxFontVariationValue value = {axes[j].axisTag,
                                      int32_t(coords[j]) / 65536.0f};
       instance.mValues.AppendElement(value);
     }
     aInstances->AppendElement(std::move(instance));
   }
 }
 if (aAxes) {
   aAxes->SetCapacity(axisCount);
   for (unsigned i = 0; i < axisCount; ++i) {
     if (uint16_t(axes[i].flags) & HIDDEN_AXIS) {
       continue;
     }
     gfxFontVariationAxis axis;
     axis.mTag = axes[i].axisTag;
     uint16_t nameID = axes[i].axisNameID;
     nsresult rv = ReadCanonicalName(nameTable, nameID, axis.mName);
     if (NS_FAILED(rv)) {
       axis.mName.Truncate(0);
     }
     // Convert values from 16.16 fixed-point to float
     axis.mMinValue = int32_t(axes[i].minValue) / 65536.0f;
     axis.mDefaultValue = int32_t(axes[i].defaultValue) / 65536.0f;
     axis.mMaxValue = int32_t(axes[i].maxValue) / 65536.0f;
     aAxes->AppendElement(axis);
   }
 }
}

void gfxFontUtils::ReadOtherFamilyNamesForFace(
   const nsACString& aFamilyName, const char* aNameData, uint32_t aDataLength,
   nsTArray<nsCString>& aOtherFamilyNames, bool useFullName) {
 const NameHeader* nameHeader = reinterpret_cast<const NameHeader*>(aNameData);

 uint32_t nameCount = nameHeader->count;
 if (nameCount * sizeof(NameRecord) > aDataLength) {
   NS_WARNING("invalid font (name records)");
   return;
 }

 const NameRecord* nameRecord =
     reinterpret_cast<const NameRecord*>(aNameData + sizeof(NameHeader));
 uint32_t stringsBase = uint32_t(nameHeader->stringOffset);

 for (uint32_t i = 0; i < nameCount; i++, nameRecord++) {
   uint32_t nameLen = nameRecord->length;
   uint32_t nameOff =
       nameRecord->offset;  // offset from base of string storage

   if (stringsBase + nameOff + nameLen > aDataLength) {
     NS_WARNING("invalid font (name table strings)");
     return;
   }

   uint16_t nameID = nameRecord->nameID;
   if ((useFullName && nameID == NAME_ID_FULL) ||
       (!useFullName &&
        (nameID == NAME_ID_FAMILY || nameID == NAME_ID_PREFERRED_FAMILY))) {
     nsAutoCString otherFamilyName;
     bool ok = DecodeFontName(
         aNameData + stringsBase + nameOff, nameLen,
         uint32_t(nameRecord->platformID), uint32_t(nameRecord->encodingID),
         uint32_t(nameRecord->languageID), otherFamilyName);
     // add if not same as canonical family name
     if (ok && otherFamilyName != aFamilyName &&
         !aOtherFamilyNames.Contains(otherFamilyName)) {
       aOtherFamilyNames.AppendElement(otherFamilyName);
     }
   }
 }
}

#ifdef XP_WIN

/* static */
bool gfxFontUtils::IsCffFont(const uint8_t* aFontData) {
 // this is only called after aFontData has passed basic validation,
 // so we know there is enough data present to allow us to read the version!
 const SFNTHeader* sfntHeader = reinterpret_cast<const SFNTHeader*>(aFontData);
 return (sfntHeader->sfntVersion == TRUETYPE_TAG('O', 'T', 'T', 'O'));
}

#endif

/* static */ bool gfxFontUtils::IsInServoTraversal() {
 if (NS_IsMainThread()) {
   return ServoStyleSet::IsInServoTraversal();
 }

 if (dom::GetCurrentThreadWorkerPrivate()) {
   return false;
 }

 // The only permissible threads are the main thread, the worker thread, the
 // servo threads. If the latter, we must be traversing.
 bool traversing = ServoStyleSet::IsInServoTraversal();
 MOZ_ASSERT(traversing);
 return traversing;
}

/* static */ ServoStyleSet* gfxFontUtils::CurrentServoStyleSet() {
 // If we are on a worker thread, we must not check for the current set since
 // the main/servo threads may be busy in parallel.
 if (dom::GetCurrentThreadWorkerPrivate()) {
   return nullptr;
 }

 return ServoStyleSet::Current();
}

#ifdef DEBUG
/* static */ void gfxFontUtils::AssertSafeThreadOrServoFontMetricsLocked() {
 if (!dom::GetCurrentThreadWorkerPrivate()) {
   AssertIsMainThreadOrServoFontMetricsLocked();
 }
}
#endif

#undef acceptablePlatform
#undef isSymbol
#undef isUVSEncoding
#undef LOG
#undef LOG_ENABLED