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#include "SkEndian.h"
#include "SkFontHost.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 int count_tables(SkStream* stream, size_t* offsetToDir = NULL) {
SkSharedTTHeader shared;
if (stream->read(&shared, sizeof(shared)) != sizeof(shared)) {
return 0;
}
uint32_t tag = SkEndian_SwapBE32(shared.fCollection.fTag);
if (SkSetFourByteTag('t', 't', 'c', 'f') == tag) {
if (shared.fCollection.fNumOffsets == 0) {
return 0;
}
size_t offset = SkEndian_SwapBE32(shared.fCollection.fOffset0);
stream->rewind();
if (stream->skip(offset) != offset) {
return 0;
}
if (stream->read(&shared, sizeof(shared)) != sizeof(shared)) {
return 0;
}
if (offsetToDir) {
*offsetToDir = offset;
}
} else {
*offsetToDir = 0;
}
return SkEndian_SwapBE16(shared.fSingle.fNumTables);
}
///////////////////////////////////////////////////////////////////////////////
struct SfntHeader {
SfntHeader() : fCount(0), fDir(NULL) {}
~SfntHeader() { sk_free(fDir); }
bool init(SkStream* stream) {
size_t offsetToDir;
fCount = count_tables(stream, &offsetToDir);
if (0 == fCount) {
return false;
}
stream->rewind();
const size_t tableRecordOffset = offsetToDir + sizeof(SkSFNTHeader);
if (stream->skip(tableRecordOffset) != tableRecordOffset) {
return false;
}
size_t size = fCount * sizeof(SkSFNTDirEntry);
fDir = reinterpret_cast<SkSFNTDirEntry*>(sk_malloc_throw(size));
return stream->read(fDir, size) == size;
}
int fCount;
SkSFNTDirEntry* fDir;
};
///////////////////////////////////////////////////////////////////////////////
int SkFontHost::CountTables(SkFontID fontID) {
SkStream* stream = SkFontHost::OpenStream(fontID);
if (NULL == stream) {
return 0;
}
SkAutoUnref au(stream);
return count_tables(stream);
}
int SkFontHost::GetTableTags(SkFontID fontID, SkFontTableTag tags[]) {
SkStream* stream = SkFontHost::OpenStream(fontID);
if (NULL == stream) {
return 0;
}
SkAutoUnref au(stream);
SfntHeader header;
if (!header.init(stream)) {
return 0;
}
for (int i = 0; i < header.fCount; i++) {
tags[i] = SkEndian_SwapBE32(header.fDir[i].fTag);
}
return header.fCount;
}
size_t SkFontHost::GetTableSize(SkFontID fontID, SkFontTableTag tag) {
SkStream* stream = SkFontHost::OpenStream(fontID);
if (NULL == stream) {
return 0;
}
SkAutoUnref au(stream);
SfntHeader header;
if (!header.init(stream)) {
return 0;
}
for (int i = 0; i < header.fCount; i++) {
if (SkEndian_SwapBE32(header.fDir[i].fTag) == tag) {
return SkEndian_SwapBE32(header.fDir[i].fLength);
}
}
return 0;
}
size_t SkFontHost::GetTableData(SkFontID fontID, SkFontTableTag tag,
size_t offset, size_t length, void* data) {
SkStream* stream = SkFontHost::OpenStream(fontID);
if (NULL == stream) {
return 0;
}
SkAutoUnref au(stream);
SfntHeader header;
if (!header.init(stream)) {
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 (offset + length > realLength) {
length = realLength - offset;
}
// skip the stream to the part of the table we want to copy from
stream->rewind();
size_t bytesToSkip = realOffset + offset;
if (stream->skip(bytesToSkip) != bytesToSkip) {
return 0;
}
if (stream->read(data, length) != length) {
return 0;
}
return length;
}
}
return 0;
}
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