blob: 1fa11ef7bdf396bfcf8732d47d706291213d7e89 [file] [log] [blame]
/*
* Copyright 2018 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "include/core/SkTypes.h"
#include "src/codec/SkCodecPriv.h"
bool SkParseEncodedOrigin(const uint8_t* data, size_t data_length, SkEncodedOrigin* orientation) {
SkASSERT(orientation);
bool littleEndian;
// We need eight bytes to read the endian marker and the offset, below.
if (data_length < 8 || !is_valid_endian_marker(data, &littleEndian)) {
return false;
}
auto getEndianInt = [](const uint8_t* data, bool littleEndian) -> uint32_t {
if (littleEndian) {
return (data[3] << 24) | (data[2] << 16) | (data[1] << 8) | (data[0]);
}
return (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | (data[3]);
};
// Get the offset from the start of the marker.
// Though this only reads four bytes, use a larger int in case it overflows.
uint64_t offset = getEndianInt(data + 4, littleEndian);
// Require that the marker is at least large enough to contain the number of entries.
if (data_length < offset + 2) {
return false;
}
uint32_t numEntries = get_endian_short(data + offset, littleEndian);
// Tag (2 bytes), Datatype (2 bytes), Number of elements (4 bytes), Data (4 bytes)
const uint32_t kEntrySize = 12;
const auto max = SkTo<uint32_t>((data_length - offset - 2) / kEntrySize);
numEntries = std::min(numEntries, max);
// Advance the data to the start of the entries.
data += offset + 2;
const uint16_t kOriginTag = 0x112;
const uint16_t kOriginType = 3;
for (uint32_t i = 0; i < numEntries; i++, data += kEntrySize) {
uint16_t tag = get_endian_short(data, littleEndian);
uint16_t type = get_endian_short(data + 2, littleEndian);
uint32_t count = getEndianInt(data + 4, littleEndian);
if (kOriginTag == tag && kOriginType == type && 1 == count) {
uint16_t val = get_endian_short(data + 8, littleEndian);
if (0 < val && val <= kLast_SkEncodedOrigin) {
*orientation = (SkEncodedOrigin) val;
return true;
}
}
}
return false;
}