| /* |
| * 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" |
| |
| static bool parse_encoded_origin(const uint8_t* exifData, size_t data_length, uint64_t offset, |
| bool littleEndian, bool is_root, SkEncodedOrigin* orientation) { |
| // 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(exifData + 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. |
| auto data = exifData + offset + 2; |
| |
| const uint16_t kOriginTag = 0x112; |
| const uint16_t kOriginType = 3; |
| const uint16_t kSubIFDOffsetTag = 0x8769; |
| const uint16_t kSubIFDOffsetType = 4; |
| |
| 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 = get_endian_int(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; |
| } |
| } else if (kSubIFDOffsetTag == tag && kSubIFDOffsetType == type && 1 == count && is_root) { |
| uint32_t subifd = get_endian_int(data + 8, littleEndian); |
| if (0 < subifd && subifd < data_length) { |
| if (parse_encoded_origin(exifData, data_length, subifd, littleEndian, false, |
| orientation)) { |
| return true; |
| } |
| } |
| } |
| } |
| |
| return false; |
| } |
| |
| 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; |
| } |
| |
| // 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 = get_endian_int(data + 4, littleEndian); |
| |
| return parse_encoded_origin(data, data_length, offset, littleEndian, true, orientation); |
| } |