The Tor Browser: comparison gfx/skia/trunk/src/core/SkFontStream.cpp

--1:000000000000
+:e4c8cfc025a2
+/*
+* Copyright 2011 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+#include "SkEndian.h"
+#include "SkFontStream.h"
+#include "SkStream.h"
+struct SkSFNTHeader {
+uint32_t    fVersion;
+uint16_t    fNumTables;
+uint16_t    fSearchRange;
+uint16_t    fEntrySelector;
+uint16_t    fRangeShift;
+};
+struct SkTTCFHeader {
+uint32_t    fTag;
+uint32_t    fVersion;
+uint32_t    fNumOffsets;
+uint32_t    fOffset0;   // the first of N (fNumOffsets)
+};
+union SkSharedTTHeader {
+SkSFNTHeader    fSingle;
+SkTTCFHeader    fCollection;
+};
+struct SkSFNTDirEntry {
+uint32_t    fTag;
+uint32_t    fChecksum;
+uint32_t    fOffset;
+uint32_t    fLength;
+};
+static bool read(SkStream* stream, void* buffer, size_t amount) {
+return stream->read(buffer, amount) == amount;
+}
+static bool skip(SkStream* stream, size_t amount) {
+return stream->skip(amount) == amount;
+}
+/** Return the number of tables, or if this is a TTC (collection), return the
+number of tables in the first element of the collection. In either case,
+if offsetToDir is not-null, set it to the offset to the beginning of the
+table headers (SkSFNTDirEntry), relative to the start of the stream.
+On an error, return 0 for number of tables, and ignore offsetToDir
+*/
+static int count_tables(SkStream* stream, int ttcIndex, size_t* offsetToDir) {
+SkASSERT(ttcIndex >= 0);
+SkAutoSMalloc<1024> storage(sizeof(SkSharedTTHeader));
+SkSharedTTHeader* header = (SkSharedTTHeader*)storage.get();
+if (!read(stream, header, sizeof(SkSharedTTHeader))) {
+return 0;
+}
+// by default, SkSFNTHeader is at the start of the stream
+size_t offset = 0;
+// if we're really a collection, the first 4-bytes will be 'ttcf'
+uint32_t tag = SkEndian_SwapBE32(header->fCollection.fTag);
+if (SkSetFourByteTag('t', 't', 'c', 'f') == tag) {
+unsigned count = SkEndian_SwapBE32(header->fCollection.fNumOffsets);
+if ((unsigned)ttcIndex >= count) {
+return 0;
+}
+if (ttcIndex > 0) { // need to read more of the shared header
+stream->rewind();
+size_t amount = sizeof(SkSharedTTHeader) + ttcIndex * sizeof(uint32_t);
+header = (SkSharedTTHeader*)storage.reset(amount);
+if (!read(stream, header, amount)) {
+return 0;
+}
+}
+// this is the offset to the local SkSFNTHeader
+offset = SkEndian_SwapBE32((&header->fCollection.fOffset0)[ttcIndex]);
+stream->rewind();
+if (!skip(stream, offset)) {
+return 0;
+}
+if (!read(stream, header, sizeof(SkSFNTHeader))) {
+return 0;
+}
+}
+if (offsetToDir) {
+// add the size of the header, so we will point to the DirEntries
+*offsetToDir = offset + sizeof(SkSFNTHeader);
+}
+return SkEndian_SwapBE16(header->fSingle.fNumTables);
+}
+///////////////////////////////////////////////////////////////////////////////
+struct SfntHeader {
+SfntHeader() : fCount(0), fDir(NULL) {}
+~SfntHeader() { sk_free(fDir); }
+/** If it returns true, then fCount and fDir are properly initialized.
+Note: fDir will point to the raw array of SkSFNTDirEntry values,
+meaning they will still be in the file's native endianness (BE).
+fDir will be automatically freed when this object is destroyed
+*/
+bool init(SkStream* stream, int ttcIndex) {
+stream->rewind();
+size_t offsetToDir;
+fCount = count_tables(stream, ttcIndex, &offsetToDir);
+if (0 == fCount) {
+return false;
+}
+stream->rewind();
+if (!skip(stream, offsetToDir)) {
+return false;
+}
+size_t size = fCount * sizeof(SkSFNTDirEntry);
+fDir = reinterpret_cast<SkSFNTDirEntry*>(sk_malloc_throw(size));
+return read(stream, fDir, size);
+}
+int             fCount;
+SkSFNTDirEntry* fDir;
+};
+///////////////////////////////////////////////////////////////////////////////
+int SkFontStream::CountTTCEntries(SkStream* stream) {
+stream->rewind();
+SkSharedTTHeader shared;
+if (!read(stream, &shared, sizeof(shared))) {
+return 0;
+}
+// if we're really a collection, the first 4-bytes will be 'ttcf'
+uint32_t tag = SkEndian_SwapBE32(shared.fCollection.fTag);
+if (SkSetFourByteTag('t', 't', 'c', 'f') == tag) {
+return SkEndian_SwapBE32(shared.fCollection.fNumOffsets);
+} else {
+return 1;   // normal 'sfnt' has 1 dir entry
+}
+}
+int SkFontStream::GetTableTags(SkStream* stream, int ttcIndex,
+SkFontTableTag tags[]) {
+SfntHeader  header;
+if (!header.init(stream, ttcIndex)) {
+return 0;
+}
+if (tags) {
+for (int i = 0; i < header.fCount; i++) {
+tags[i] = SkEndian_SwapBE32(header.fDir[i].fTag);
+}
+}
+return header.fCount;
+}
+size_t SkFontStream::GetTableData(SkStream* stream, int ttcIndex,
+SkFontTableTag tag,
+size_t offset, size_t length, void* data) {
+SfntHeader  header;
+if (!header.init(stream, ttcIndex)) {
+return 0;
+}
+for (int i = 0; i < header.fCount; i++) {
+if (SkEndian_SwapBE32(header.fDir[i].fTag) == tag) {
+size_t realOffset = SkEndian_SwapBE32(header.fDir[i].fOffset);
+size_t realLength = SkEndian_SwapBE32(header.fDir[i].fLength);
+// now sanity check the caller's offset/length
+if (offset >= realLength) {
+return 0;
+}
+// if the caller is trusting the length from the file, then a
+// hostile file might choose a value which would overflow offset +
+// length.
+if (offset + length < offset) {
+return 0;
+}
+if (length > realLength - offset) {
+length = realLength - offset;
+}
+if (data) {
+// skip the stream to the part of the table we want to copy from
+stream->rewind();
+size_t bytesToSkip = realOffset + offset;
+if (!skip(stream, bytesToSkip)) {
+return 0;
+}
+if (!read(stream, data, length)) {
+return 0;
+}
+}
+return length;
+}
+}
+return 0;
+}

The Tor Browser / file comparison

comparison: gfx/skia/trunk/src/core/SkFontStream.cpp

gfx/skia/trunk/src/core/SkFontStream.cpp