static FPDFEMB_RESULT file_readblock(FPDFEMB_FILE_ACCESS* file, void* dst,
unsigned int offset, unsigned int size) {
SkStream* stream = (SkStream*)file->user;
// SkDebugf("---- readblock %p %p %d %d\n", stream, dst, offset, size);
if (!stream->rewind()) {
SkDebugf("---- rewind failed\n");
return FPDFERR_ERROR;
}
if (stream->skip(offset) != offset) {
SkDebugf("---- skip failed\n");
return FPDFERR_ERROR;
}
if (stream->read(dst, size) != size) {
SkDebugf("---- read failed\n");
return FPDFERR_ERROR;
}
return FPDFERR_SUCCESS;
}
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;
}