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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "SFNTData.h"
#include <algorithm>
#include <numeric>
#include "BigEndianInts.h"
#include "Logging.h"
#include "mozilla/HashFunctions.h"
#include "mozilla/Span.h"
namespace mozilla {
namespace gfx {
#define TRUETYPE_TAG(a, b, c, d) ((a) << 24 | (b) << 16 | (c) << 8 | (d))
#pragma pack(push, 1)
struct TTCHeader {
BigEndianUint32 ttcTag; // Always 'ttcf'
BigEndianUint32 version; // Fixed, 0x00010000
BigEndianUint32 numFonts;
};
struct OffsetTable {
BigEndianUint32 sfntVersion; // Fixed, 0x00010000 for version 1.0.
BigEndianUint16 numTables;
BigEndianUint16 searchRange; // (Maximum power of 2 <= numTables) x 16.
BigEndianUint16 entrySelector; // Log2(maximum power of 2 <= numTables).
BigEndianUint16 rangeShift; // NumTables x 16-searchRange.
};
struct TableDirEntry {
BigEndianUint32 tag; // 4 -byte identifier.
BigEndianUint32 checkSum; // CheckSum for this table.
BigEndianUint32 offset; // Offset from beginning of TrueType font file.
BigEndianUint32 length; // Length of this table.
friend bool operator<(const TableDirEntry& lhs, const uint32_t aTag) {
return lhs.tag < aTag;
}
};
#pragma pack(pop)
class SFNTData::Font {
public:
Font(const OffsetTable* aOffsetTable, const uint8_t* aFontData,
uint32_t aDataLength)
: mFontData(aFontData),
mFirstDirEntry(
reinterpret_cast<const TableDirEntry*>(aOffsetTable + 1)),
mEndOfDirEntries(mFirstDirEntry + aOffsetTable->numTables),
mDataLength(aDataLength) {}
Span<const uint8_t> GetHeadTableBytes() const {
const TableDirEntry* dirEntry =
GetDirEntry(TRUETYPE_TAG('h', 'e', 'a', 'd'));
if (!dirEntry) {
gfxWarning() << "Head table entry not found.";
return {};
}
return {mFontData + dirEntry->offset, dirEntry->length};
}
private:
const TableDirEntry* GetDirEntry(const uint32_t aTag) const {
const TableDirEntry* foundDirEntry =
std::lower_bound(mFirstDirEntry, mEndOfDirEntries, aTag);
if (foundDirEntry == mEndOfDirEntries || foundDirEntry->tag != aTag) {
gfxWarning() << "Font data does not contain tag.";
return nullptr;
}
if (mDataLength < (foundDirEntry->offset + foundDirEntry->length)) {
gfxWarning() << "Font data too short to contain table.";
return nullptr;
}
return foundDirEntry;
}
const uint8_t* mFontData;
const TableDirEntry* mFirstDirEntry;
const TableDirEntry* mEndOfDirEntries;
uint32_t mDataLength;
};
/* static */
UniquePtr<SFNTData> SFNTData::Create(const uint8_t* aFontData,
uint32_t aDataLength) {
MOZ_ASSERT(aFontData);
// Check to see if this is a font collection.
if (aDataLength < sizeof(TTCHeader)) {
gfxWarning() << "Font data too short.";
return nullptr;
}
const TTCHeader* ttcHeader = reinterpret_cast<const TTCHeader*>(aFontData);
if (ttcHeader->ttcTag == TRUETYPE_TAG('t', 't', 'c', 'f')) {
uint32_t numFonts = ttcHeader->numFonts;
if (aDataLength <
sizeof(TTCHeader) + (numFonts * sizeof(BigEndianUint32))) {
gfxWarning() << "Font data too short to contain full TTC Header.";
return nullptr;
}
UniquePtr<SFNTData> sfntData(new SFNTData);
const BigEndianUint32* offset =
reinterpret_cast<const BigEndianUint32*>(aFontData + sizeof(TTCHeader));
const BigEndianUint32* endOfOffsets = offset + numFonts;
while (offset != endOfOffsets) {
if (!sfntData->AddFont(aFontData, aDataLength, *offset)) {
return nullptr;
}
++offset;
}
return sfntData;
}
UniquePtr<SFNTData> sfntData(new SFNTData);
if (!sfntData->AddFont(aFontData, aDataLength, 0)) {
return nullptr;
}
return sfntData;
}
/* static */
uint64_t SFNTData::GetUniqueKey(const uint8_t* aFontData, uint32_t aDataLength,
uint32_t aVarDataSize, const void* aVarData) {
uint64_t hash = 0;
UniquePtr<SFNTData> sfntData = SFNTData::Create(aFontData, aDataLength);
if (sfntData) {
hash = sfntData->HashHeadTables();
} else {
gfxWarning() << "Failed to create SFNTData from data, hashing whole font.";
hash = HashBytes(aFontData, aDataLength);
}
if (aVarDataSize) {
hash = AddToHash(hash, HashBytes(aVarData, aVarDataSize));
}
return hash << 32 | aDataLength;
}
SFNTData::~SFNTData() {
for (size_t i = 0; i < mFonts.length(); ++i) {
delete mFonts[i];
}
}
bool SFNTData::AddFont(const uint8_t* aFontData, uint32_t aDataLength,
uint32_t aOffset) {
uint32_t remainingLength = aDataLength - aOffset;
if (remainingLength < sizeof(OffsetTable)) {
gfxWarning() << "Font data too short to contain OffsetTable " << aOffset;
return false;
}
const OffsetTable* offsetTable =
reinterpret_cast<const OffsetTable*>(aFontData + aOffset);
if (remainingLength <
sizeof(OffsetTable) + (offsetTable->numTables * sizeof(TableDirEntry))) {
gfxWarning() << "Font data too short to contain tables.";
return false;
}
return mFonts.append(new Font(offsetTable, aFontData, aDataLength));
}
uint32_t SFNTData::HashHeadTables() {
uint32_t headTableHash = std::accumulate(
mFonts.begin(), mFonts.end(), 0U, [](uint32_t hash, Font* font) {
Span<const uint8_t> headBytes = font->GetHeadTableBytes();
return AddToHash(hash, HashBytes(headBytes.data(), headBytes.size()));
});
return headTableHash;
}
} // namespace gfx
} // namespace mozilla