src/codec/SkTiffUtility.cpp - skia - Git at Google

 /*
  * Copyright 2023 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "src/codec/SkTiffUtility.h"

 #include "include/core/SkData.h"
 #include "src/codec/SkCodecPriv.h"

 #include <cstddef>
 #include <utility>

 constexpr size_t kSizeEntry = 12;
 constexpr size_t kSizeShort = 2;
 constexpr size_t kSizeLong = 4;

 bool SkTiffImageFileDirectory::IsValidType(uint16_t type) { return type >= 1 && type <= 12; }

 size_t SkTiffImageFileDirectory::BytesForType(uint16_t type) {
     switch (type) {
         case kTypeUnsignedByte:
             return 1;
         case kTypeAsciiString:
             return 1;
         case kTypeUnsignedShort:
             return kSizeShort;
         case kTypeUnsignedLong:
             return kSizeLong;
         case kTypeUnsignedRational:
             return 8;
         case kTypeSignedByte:
             return 1;
         case kTypeUndefined:
             return 1;
         case kTypeSignedShort:
             return kSizeShort;
         case kTypeSignedLong:
             return kSizeLong;
         case kTypeSignedRational:
             return 8;
         case kTypeSingleFloat:
             return 4;
         case kTypeDoubleFloat:
             return 8;
     }
     return 0;
 }

 // Helper function for computing the address of an entry.
 static const uint8_t* get_entry_address(const SkData* data,
                                         uint32_t ifdOffset,
                                         uint16_t entryIndex) {
     return data->bytes() +           // Base address
            ifdOffset +               // IFD offset
            kSizeShort +              // IFD number of entries
            kSizeEntry * entryIndex;  // Entries
 }

 // Return true if the IFD starting at |ifdOffset| contains valid number of entries (that doesn't
 // overrun |data|).
 static bool validate_ifd(const SkData* data,
                          bool littleEndian,
                          uint32_t ifdOffset,
                          uint16_t* outNumEntries,
                          uint32_t* outNextIfdOffset) {
     const uint8_t* dataCurrent = data->bytes();
     size_t dataSize = data->size();

     // Seek to the IFD offset.
     if (dataSize < ifdOffset) {
         SkCodecPrintf("IFD offset is too large.\n");
         return false;
     }
     dataCurrent += ifdOffset;
     dataSize -= ifdOffset;

     // Read the number of entries.
     if (dataSize < kSizeShort) {
         SkCodecPrintf("Insufficient space to store number of entries.\n");
         return false;
     }
     uint16_t numEntries = get_endian_short(dataCurrent, littleEndian);
     dataCurrent += kSizeShort;
     dataSize -= kSizeShort;

     // Check that there is enough space for all entries.
     if (dataSize < kSizeEntry * numEntries) {
         SkCodecPrintf("Insufficient space (%u) to store all %u entries.\n",
                       static_cast<uint32_t>(data->size()),
                       numEntries);
         return false;
     }

     // Save the number of entries.
     *outNumEntries = numEntries;

     // Seek past the entries.
     dataCurrent += kSizeEntry * numEntries;
     dataSize -= kSizeEntry * numEntries;

     // Read the next IFD offset.
     if (dataSize < kSizeLong) {
         SkCodecPrintf("Insufficient space to store next IFD offset.\n");
         return false;
     }

     // Save the next IFD offset.
     *outNextIfdOffset = get_endian_int(dataCurrent, littleEndian);
     return true;
 }

 bool SkTiffImageFileDirectory::ParseHeader(const SkData* data,
                                            bool* outLittleEndian,
                                            uint32_t* outIfdOffset) {
     // Read the endianness (4 bytes) and IFD offset (4 bytes).
     if (data->size() < 8) {
         SkCodecPrintf("Tiff header must be at least 8 bytes.\n");
         return false;
     }
     if (!is_valid_endian_marker(data->bytes(), outLittleEndian)) {
         SkCodecPrintf("Tiff header had invalid endian marker 0x%x,0x%x,0x%x,0x%x.\n",
                       data->bytes()[0],
                       data->bytes()[1],
                       data->bytes()[2],
                       data->bytes()[3]);
         return false;
     }
     *outIfdOffset = get_endian_int(data->bytes() + 4, *outLittleEndian);
     return true;
 }

 std::unique_ptr<SkTiffImageFileDirectory> SkTiffImageFileDirectory::MakeFromOffset(
         sk_sp<SkData> data, bool littleEndian, uint32_t ifdOffset) {
     uint16_t numEntries = 0;
     uint32_t nextOffset = 0;
     if (!validate_ifd(data.get(), littleEndian, ifdOffset, &numEntries, &nextOffset)) {
         SkCodecPrintf("Failed to validate IFD.\n");
         return nullptr;
     }
     return std::unique_ptr<SkTiffImageFileDirectory>(new SkTiffImageFileDirectory(
             std::move(data), littleEndian, ifdOffset, numEntries, nextOffset));
 }

 SkTiffImageFileDirectory::SkTiffImageFileDirectory(sk_sp<SkData> data,
                                                    bool littleEndian,
                                                    uint32_t offset,
                                                    uint16_t numEntries,
                                                    uint32_t nextIfdOffset)
         : fData(std::move(data))
         , fLittleEndian(littleEndian)
         , fOffset(offset)
         , fNumEntries(numEntries)
         , fNextIfdOffset(nextIfdOffset) {}

 uint16_t SkTiffImageFileDirectory::getEntryTag(uint16_t entryIndex) const {
     const uint8_t* entry = get_entry_address(fData.get(), fOffset, entryIndex);
     return get_endian_short(entry, fLittleEndian);
 }

 bool SkTiffImageFileDirectory::getEntryRawData(uint16_t entryIndex,
                                                uint16_t* outTag,
                                                uint16_t* outType,
                                                uint32_t* outCount,
                                                const uint8_t** outData,
                                                size_t* outDataSize) const {
     const uint8_t* entry = get_entry_address(fData.get(), fOffset, entryIndex);

     // Read the tag
     const uint16_t tag = get_endian_short(entry, fLittleEndian);
     entry += kSizeShort;

     // Read the type.
     const uint16_t type = get_endian_short(entry, fLittleEndian);
     entry += kSizeShort;
     if (!IsValidType(type)) {
         return false;
     }

     // Read the count.
     const uint32_t count = get_endian_int(entry, fLittleEndian);
     entry += kSizeLong;

     // If the entry fits in the remaining 4 bytes, use that.
     const size_t entryDataBytes = BytesForType(type) * count;
     const uint8_t* entryData = nullptr;
     if (entryDataBytes <= kSizeLong) {
         entryData = entry;
     } else {
         // Otherwise, the next 4 bytes specify an offset where the data can be found.
         const uint32_t entryDataOffset = get_endian_int(entry, fLittleEndian);
         if (fData->size() < entryDataOffset || fData->size() - entryDataOffset < entryDataBytes) {
             return false;
         }
         entryData = fData->bytes() + entryDataOffset;
     }

     if (outTag) *outTag = tag;
     if (outType) *outType = type;
     if (outCount) *outCount = count;
     if (outData) *outData = entryData;
     if (outDataSize) *outDataSize = entryDataBytes;
     return true;
 }

 sk_sp<SkData> SkTiffImageFileDirectory::getEntryUndefinedData(uint16_t entryIndex) const {
     uint16_t type = 0;
     uint32_t count = 0;
     const uint8_t* data = nullptr;
     size_t size = 0;
     if (!getEntryRawData(entryIndex, nullptr, &type, &count, &data, &size)) {
         return nullptr;
     }
     if (type != kTypeUndefined) {
         return nullptr;
     }
     return SkData::MakeSubset(fData.get(), data - fData->bytes(), size);
 }

 bool SkTiffImageFileDirectory::getEntryValuesGeneric(uint16_t entryIndex,
                                                      uint16_t type,
                                                      uint32_t count,
                                                      void* values) const {
     uint16_t entryType = 0;
     uint32_t entryCount = 0;
     const uint8_t* entryData = nullptr;
     if (!getEntryRawData(entryIndex, nullptr, &entryType, &entryCount, &entryData, nullptr)) {
         return false;
     }
     if (type != entryType) {
         return false;
     }
     if (count != entryCount) {
         return false;
     }
     for (uint32_t i = 0; i < count; ++i) {
         const uint8_t* data = entryData + i * BytesForType(kTypeUnsignedLong);
         switch (type) {
             case kTypeUnsignedShort:
                 reinterpret_cast<uint16_t*>(values)[i] = get_endian_short(data, fLittleEndian);
                 break;
             case kTypeUnsignedLong:
                 reinterpret_cast<uint32_t*>(values)[i] = get_endian_int(data, fLittleEndian);
                 break;
             case kTypeSignedRational: {
                 uint32_t numerator = get_endian_int(data, fLittleEndian);
                 uint32_t denominator = get_endian_int(data + kSizeLong, fLittleEndian);
                 if (denominator == 0) {
                     // The TIFF specification does not indicate a behavior when the denominator is
                     // zero.  The behavior of returning zero for a denominator of zero is a
                     // preservation of the behavior introduced in https://crrev.com/767874.
                     reinterpret_cast<float*>(values)[i] = 0;
                 } else {
                     reinterpret_cast<float*>(values)[i] =
                             numerator / static_cast<float>(denominator);
                 }
                 break;
             }
             case kTypeUnsignedRational: {
                 uint32_t numerator = get_endian_int(data, fLittleEndian);
                 uint32_t denominator = get_endian_int(data + kSizeLong, fLittleEndian);
                 if (denominator == 0) {
                     // See comments in kTypeSignedRational.
                     reinterpret_cast<float*>(values)[i] = 0.f;
                 } else {
                     reinterpret_cast<float*>(values)[i] =
                             numerator / static_cast<float>(denominator);
                 }
                 break;
             }
             default:
                 SkCodecPrintf("Unsupported type %u\n", type);
                 return false;
                 break;
         }
     }
     return true;
 }
	/*
	* Copyright 2023 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "src/codec/SkTiffUtility.h"

	#include "include/core/SkData.h"
	#include "src/codec/SkCodecPriv.h"

	#include <cstddef>
	#include <utility>

	constexpr size_t kSizeEntry = 12;
	constexpr size_t kSizeShort = 2;
	constexpr size_t kSizeLong = 4;

	bool SkTiffImageFileDirectory::IsValidType(uint16_t type) { return type >= 1 && type <= 12; }

	size_t SkTiffImageFileDirectory::BytesForType(uint16_t type) {
	switch (type) {
	case kTypeUnsignedByte:
	return 1;
	case kTypeAsciiString:
	return 1;
	case kTypeUnsignedShort:
	return kSizeShort;
	case kTypeUnsignedLong:
	return kSizeLong;
	case kTypeUnsignedRational:
	return 8;
	case kTypeSignedByte:
	return 1;
	case kTypeUndefined:
	return 1;
	case kTypeSignedShort:
	return kSizeShort;
	case kTypeSignedLong:
	return kSizeLong;
	case kTypeSignedRational:
	return 8;
	case kTypeSingleFloat:
	return 4;
	case kTypeDoubleFloat:
	return 8;
	}
	return 0;
	}

	// Helper function for computing the address of an entry.
	static const uint8_t* get_entry_address(const SkData* data,
	uint32_t ifdOffset,
	uint16_t entryIndex) {
	return data->bytes() + // Base address
	ifdOffset + // IFD offset
	kSizeShort + // IFD number of entries
	kSizeEntry * entryIndex; // Entries
	}

	// Return true if the IFD starting at \|ifdOffset\| contains valid number of entries (that doesn't
	// overrun \|data\|).
	static bool validate_ifd(const SkData* data,
	bool littleEndian,
	uint32_t ifdOffset,
	uint16_t* outNumEntries,
	uint32_t* outNextIfdOffset) {
	const uint8_t* dataCurrent = data->bytes();
	size_t dataSize = data->size();

	// Seek to the IFD offset.
	if (dataSize < ifdOffset) {
	SkCodecPrintf("IFD offset is too large.\n");
	return false;
	}
	dataCurrent += ifdOffset;
	dataSize -= ifdOffset;

	// Read the number of entries.
	if (dataSize < kSizeShort) {
	SkCodecPrintf("Insufficient space to store number of entries.\n");
	return false;
	}
	uint16_t numEntries = get_endian_short(dataCurrent, littleEndian);
	dataCurrent += kSizeShort;
	dataSize -= kSizeShort;

	// Check that there is enough space for all entries.
	if (dataSize < kSizeEntry * numEntries) {
	SkCodecPrintf("Insufficient space (%u) to store all %u entries.\n",
	static_cast<uint32_t>(data->size()),
	numEntries);
	return false;
	}

	// Save the number of entries.
	*outNumEntries = numEntries;

	// Seek past the entries.
	dataCurrent += kSizeEntry * numEntries;
	dataSize -= kSizeEntry * numEntries;

	// Read the next IFD offset.
	if (dataSize < kSizeLong) {
	SkCodecPrintf("Insufficient space to store next IFD offset.\n");
	return false;
	}

	// Save the next IFD offset.
	*outNextIfdOffset = get_endian_int(dataCurrent, littleEndian);
	return true;
	}

	bool SkTiffImageFileDirectory::ParseHeader(const SkData* data,
	bool* outLittleEndian,
	uint32_t* outIfdOffset) {
	// Read the endianness (4 bytes) and IFD offset (4 bytes).
	if (data->size() < 8) {
	SkCodecPrintf("Tiff header must be at least 8 bytes.\n");
	return false;
	}
	if (!is_valid_endian_marker(data->bytes(), outLittleEndian)) {
	SkCodecPrintf("Tiff header had invalid endian marker 0x%x,0x%x,0x%x,0x%x.\n",
	data->bytes()[0],
	data->bytes()[1],
	data->bytes()[2],
	data->bytes()[3]);
	return false;
	}
	outIfdOffset = get_endian_int(data->bytes() + 4, outLittleEndian);
	return true;
	}

	std::unique_ptr<SkTiffImageFileDirectory> SkTiffImageFileDirectory::MakeFromOffset(
	sk_sp<SkData> data, bool littleEndian, uint32_t ifdOffset) {
	uint16_t numEntries = 0;
	uint32_t nextOffset = 0;
	if (!validate_ifd(data.get(), littleEndian, ifdOffset, &numEntries, &nextOffset)) {
	SkCodecPrintf("Failed to validate IFD.\n");
	return nullptr;
	}
	return std::unique_ptr<SkTiffImageFileDirectory>(new SkTiffImageFileDirectory(
	std::move(data), littleEndian, ifdOffset, numEntries, nextOffset));
	}

	SkTiffImageFileDirectory::SkTiffImageFileDirectory(sk_sp<SkData> data,
	bool littleEndian,
	uint32_t offset,
	uint16_t numEntries,
	uint32_t nextIfdOffset)
	: fData(std::move(data))
	, fLittleEndian(littleEndian)
	, fOffset(offset)
	, fNumEntries(numEntries)
	, fNextIfdOffset(nextIfdOffset) {}

	uint16_t SkTiffImageFileDirectory::getEntryTag(uint16_t entryIndex) const {
	const uint8_t* entry = get_entry_address(fData.get(), fOffset, entryIndex);
	return get_endian_short(entry, fLittleEndian);
	}

	bool SkTiffImageFileDirectory::getEntryRawData(uint16_t entryIndex,
	uint16_t* outTag,
	uint16_t* outType,
	uint32_t* outCount,
	const uint8_t** outData,
	size_t* outDataSize) const {
	const uint8_t* entry = get_entry_address(fData.get(), fOffset, entryIndex);

	// Read the tag
	const uint16_t tag = get_endian_short(entry, fLittleEndian);
	entry += kSizeShort;

	// Read the type.
	const uint16_t type = get_endian_short(entry, fLittleEndian);
	entry += kSizeShort;
	if (!IsValidType(type)) {
	return false;
	}

	// Read the count.
	const uint32_t count = get_endian_int(entry, fLittleEndian);
	entry += kSizeLong;

	// If the entry fits in the remaining 4 bytes, use that.
	const size_t entryDataBytes = BytesForType(type) * count;
	const uint8_t* entryData = nullptr;
	if (entryDataBytes <= kSizeLong) {
	entryData = entry;
	} else {
	// Otherwise, the next 4 bytes specify an offset where the data can be found.
	const uint32_t entryDataOffset = get_endian_int(entry, fLittleEndian);
	if (fData->size() < entryDataOffset \|\| fData->size() - entryDataOffset < entryDataBytes) {
	return false;
	}
	entryData = fData->bytes() + entryDataOffset;
	}

	if (outTag) *outTag = tag;
	if (outType) *outType = type;
	if (outCount) *outCount = count;
	if (outData) *outData = entryData;
	if (outDataSize) *outDataSize = entryDataBytes;
	return true;
	}

	sk_sp<SkData> SkTiffImageFileDirectory::getEntryUndefinedData(uint16_t entryIndex) const {
	uint16_t type = 0;
	uint32_t count = 0;
	const uint8_t* data = nullptr;
	size_t size = 0;
	if (!getEntryRawData(entryIndex, nullptr, &type, &count, &data, &size)) {
	return nullptr;
	}
	if (type != kTypeUndefined) {
	return nullptr;
	}
	return SkData::MakeSubset(fData.get(), data - fData->bytes(), size);
	}

	bool SkTiffImageFileDirectory::getEntryValuesGeneric(uint16_t entryIndex,
	uint16_t type,
	uint32_t count,
	void* values) const {
	uint16_t entryType = 0;
	uint32_t entryCount = 0;
	const uint8_t* entryData = nullptr;
	if (!getEntryRawData(entryIndex, nullptr, &entryType, &entryCount, &entryData, nullptr)) {
	return false;
	}
	if (type != entryType) {
	return false;
	}
	if (count != entryCount) {
	return false;
	}
	for (uint32_t i = 0; i < count; ++i) {
	const uint8_t* data = entryData + i * BytesForType(kTypeUnsignedLong);
	switch (type) {
	case kTypeUnsignedShort:
	reinterpret_cast<uint16_t*>(values)[i] = get_endian_short(data, fLittleEndian);
	break;
	case kTypeUnsignedLong:
	reinterpret_cast<uint32_t*>(values)[i] = get_endian_int(data, fLittleEndian);
	break;
	case kTypeSignedRational: {
	uint32_t numerator = get_endian_int(data, fLittleEndian);
	uint32_t denominator = get_endian_int(data + kSizeLong, fLittleEndian);
	if (denominator == 0) {
	// The TIFF specification does not indicate a behavior when the denominator is
	// zero. The behavior of returning zero for a denominator of zero is a
	// preservation of the behavior introduced in https://crrev.com/767874.
	reinterpret_cast<float*>(values)[i] = 0;
	} else {
	reinterpret_cast<float*>(values)[i] =
	numerator / static_cast<float>(denominator);
	}
	break;
	}
	case kTypeUnsignedRational: {
	uint32_t numerator = get_endian_int(data, fLittleEndian);
	uint32_t denominator = get_endian_int(data + kSizeLong, fLittleEndian);
	if (denominator == 0) {
	// See comments in kTypeSignedRational.
	reinterpret_cast<float*>(values)[i] = 0.f;
	} else {
	reinterpret_cast<float*>(values)[i] =
	numerator / static_cast<float>(denominator);
	}
	break;
	}
	default:
	SkCodecPrintf("Unsupported type %u\n", type);
	return false;
	break;
	}
	}
	return true;
	}