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/* -*- 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/. */
#ifndef GFX_OTS_UTILS_H
#define GFX_OTS_UTILS_H
#include "gfxFontUtils.h"
#include "opentype-sanitiser.h"
struct gfxOTSMozAlloc {
void* Grow(void* aPtr, size_t aLength) { return moz_xrealloc(aPtr, aLength); }
void* ShrinkToFit(void* aPtr, size_t aLength) {
return moz_xrealloc(aPtr, aLength);
}
void Free(void* aPtr) { free(aPtr); }
};
// Based on ots::ExpandingMemoryStream from ots-memory-stream.h,
// adapted to use Mozilla allocators and to allow the final
// memory buffer to be adopted by the client.
template <typename AllocT = gfxOTSMozAlloc>
class gfxOTSExpandingMemoryStream : public ots::OTSStream {
public:
// limit output/expansion to 256MB by default
enum { DEFAULT_LIMIT = 256 * 1024 * 1024 };
explicit gfxOTSExpandingMemoryStream(size_t initial,
size_t limit = DEFAULT_LIMIT)
: mLength(initial), mLimit(limit), mOff(0) {
mPtr = mAlloc.Grow(nullptr, mLength);
}
~gfxOTSExpandingMemoryStream() { mAlloc.Free(mPtr); }
size_t size() override { return mLimit; }
// Return the buffer, resized to fit its contents (as it may have been
// over-allocated during growth), and give up ownership of it so the
// caller becomes responsible to call free() when finished with it.
auto forget() {
auto p = mAlloc.ShrinkToFit(mPtr, mOff);
mPtr = nullptr;
return p;
}
bool WriteRaw(const void* data, size_t length) override {
if ((mOff + length > mLength) ||
(mLength > std::numeric_limits<size_t>::max() - mOff)) {
if (mLength == mLimit) {
return false;
}
size_t newLength = (mLength + 1) * 2;
if (newLength < mLength) {
return false;
}
if (newLength > mLimit) {
newLength = mLimit;
}
mPtr = mAlloc.Grow(mPtr, newLength);
mLength = newLength;
return WriteRaw(data, length);
}
std::memcpy(static_cast<char*>(mPtr) + mOff, data, length);
mOff += length;
return true;
}
bool Seek(off_t position) override {
if (position < 0) {
return false;
}
if (static_cast<size_t>(position) > mLength) {
return false;
}
mOff = position;
return true;
}
off_t Tell() const override { return mOff; }
private:
AllocT mAlloc;
void* mPtr;
size_t mLength;
const size_t mLimit;
off_t mOff;
};
class MOZ_STACK_CLASS gfxOTSContext : public ots::OTSContext {
public:
gfxOTSContext() {
using namespace mozilla;
// Whether to apply OTS validation to OpenType Layout tables
mCheckOTLTables = StaticPrefs::gfx_downloadable_fonts_otl_validation();
// Whether to preserve Variation tables in downloaded fonts
mCheckVariationTables =
StaticPrefs::gfx_downloadable_fonts_validate_variation_tables();
// Whether to preserve color bitmap glyphs
mKeepColorBitmaps =
StaticPrefs::gfx_downloadable_fonts_keep_color_bitmaps();
// Whether to preserve SVG glyphs (which can be expensive in Core Text,
// so better to drop them if we're not going to render them anyhow).
mKeepSVG = StaticPrefs::gfx_font_rendering_opentype_svg_enabled();
}
virtual ots::TableAction GetTableAction(uint32_t aTag) override {
// Pass through or validate OTL and Variation tables, depending on prefs.
if ((!mCheckOTLTables && (aTag == TRUETYPE_TAG('G', 'D', 'E', 'F') ||
aTag == TRUETYPE_TAG('G', 'P', 'O', 'S') ||
aTag == TRUETYPE_TAG('G', 'S', 'U', 'B')))) {
return ots::TABLE_ACTION_PASSTHRU;
}
auto isVariationTable = [](uint32_t aTag) -> bool {
return aTag == TRUETYPE_TAG('a', 'v', 'a', 'r') ||
aTag == TRUETYPE_TAG('c', 'v', 'a', 'r') ||
aTag == TRUETYPE_TAG('f', 'v', 'a', 'r') ||
aTag == TRUETYPE_TAG('g', 'v', 'a', 'r') ||
aTag == TRUETYPE_TAG('H', 'V', 'A', 'R') ||
aTag == TRUETYPE_TAG('M', 'V', 'A', 'R') ||
aTag == TRUETYPE_TAG('S', 'T', 'A', 'T') ||
aTag == TRUETYPE_TAG('V', 'V', 'A', 'R');
};
if (!mCheckVariationTables && isVariationTable(aTag)) {
return ots::TABLE_ACTION_PASSTHRU;
}
if (!gfxPlatform::HasVariationFontSupport() && isVariationTable(aTag)) {
return ots::TABLE_ACTION_DROP;
}
// Preserve SVG table if OpenType-SVG rendering is enabled.
if (aTag == TRUETYPE_TAG('S', 'V', 'G', ' ')) {
return mKeepSVG ? ots::TABLE_ACTION_PASSTHRU : ots::TABLE_ACTION_DROP;
}
// Preserve BASE table; harfbuzz will sanitize it before using.
if (aTag == TRUETYPE_TAG('B', 'A', 'S', 'E')) {
return ots::TABLE_ACTION_PASSTHRU;
}
if (mKeepColorBitmaps && (aTag == TRUETYPE_TAG('C', 'B', 'D', 'T') ||
aTag == TRUETYPE_TAG('C', 'B', 'L', 'C'))) {
return ots::TABLE_ACTION_PASSTHRU;
}
return ots::TABLE_ACTION_DEFAULT;
}
static size_t GuessSanitizedFontSize(size_t aLength,
gfxUserFontType aFontType,
bool aStrict = true) {
switch (aFontType) {
case GFX_USERFONT_UNKNOWN:
// If being permissive of unknown types, make a reasonable guess
// at how much room the sanitized font may take, if it passes. Just
// enough extra space to accomodate some growth without excessive
// bloat in case of large fonts. 1.5x is a reasonable compromise
// for growable vectors in general.
return aStrict || !aLength ? 0 : (aLength * 3) / 2;
case GFX_USERFONT_WOFF:
return aLength * 2;
case GFX_USERFONT_WOFF2:
return aLength * 3;
default:
return aLength;
}
}
static size_t GuessSanitizedFontSize(const uint8_t* aData, size_t aLength,
bool aStrict = true) {
gfxUserFontType fontType =
gfxFontUtils::DetermineFontDataType(aData, aLength);
return GuessSanitizedFontSize(aLength, fontType, aStrict);
}
private:
bool mCheckOTLTables;
bool mCheckVariationTables;
bool mKeepColorBitmaps;
bool mKeepSVG;
};
#endif /* GFX_OTS_UTILS_H */
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