src/core/SkValidatingReadBuffer.cpp - skia - Git at Google

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "SkBitmap.h"
 #include "SkValidatingReadBuffer.h"
 #include "SkStream.h"
 #include "SkTypeface.h"

 SkValidatingReadBuffer::SkValidatingReadBuffer(const void* data, size_t size) :
     fError(false) {
     this->setMemory(data, size);
     this->setFlags(SkReadBuffer::kValidation_Flag);
 }

 SkValidatingReadBuffer::~SkValidatingReadBuffer() {
 }

 bool SkValidatingReadBuffer::validate(bool isValid) {
     if (!fError && !isValid) {
         // When an error is found, send the read cursor to the end of the stream
         fReader.skip(fReader.available());
         fError = true;
     }
     return !fError;
 }

 bool SkValidatingReadBuffer::isValid() const {
     return !fError;
 }

 void SkValidatingReadBuffer::setMemory(const void* data, size_t size) {
     this->validate(IsPtrAlign4(data) && (SkAlign4(size) == size));
     if (!fError) {
         fReader.setMemory(data, size);
     }
 }

 const void* SkValidatingReadBuffer::skip(size_t size) {
     size_t inc = SkAlign4(size);
     this->validate(inc >= size);
     const void* addr = fReader.peek();
     this->validate(IsPtrAlign4(addr) && fReader.isAvailable(inc));
     if (fError) {
         return nullptr;
     }

     fReader.skip(size);
     return addr;
 }

 // All the methods in this file funnel down into either readInt(), readScalar() or skip(),
 // followed by a memcpy. So we've got all our validation in readInt(), readScalar() and skip();
 // if they fail they'll return a zero value or skip nothing, respectively, and set fError to
 // true, which the caller should check to see if an error occurred during the read operation.

 bool SkValidatingReadBuffer::readBool() {
     uint32_t value = this->readInt();
     // Boolean value should be either 0 or 1
     this->validate(!(value & ~1));
     return value != 0;
 }

 SkColor SkValidatingReadBuffer::readColor() {
     return this->readInt();
 }

 int32_t SkValidatingReadBuffer::readInt() {
     const size_t inc = sizeof(int32_t);
     this->validate(IsPtrAlign4(fReader.peek()) && fReader.isAvailable(inc));
     return fError ? 0 : fReader.readInt();
 }

 SkScalar SkValidatingReadBuffer::readScalar() {
     const size_t inc = sizeof(SkScalar);
     this->validate(IsPtrAlign4(fReader.peek()) && fReader.isAvailable(inc));
     return fError ? 0 : fReader.readScalar();
 }

 uint32_t SkValidatingReadBuffer::readUInt() {
     return this->readInt();
 }

 int32_t SkValidatingReadBuffer::read32() {
     return this->readInt();
 }

 uint8_t SkValidatingReadBuffer::peekByte() {
     if (fReader.available() <= 0) {
         fError = true;
         return 0;
     }
     return *((uint8_t*) fReader.peek());
 }

 void SkValidatingReadBuffer::readString(SkString* string) {
     const size_t len = this->readUInt();
     const void* ptr = fReader.peek();
     const char* cptr = (const char*)ptr;

     // skip over the string + '\0' and then pad to a multiple of 4
     const size_t alignedSize = SkAlign4(len + 1);
     this->skip(alignedSize);
     if (!fError) {
         this->validate(cptr[len] == '\0');
     }
     if (!fError) {
         string->set(cptr, len);
     }
 }

 void SkValidatingReadBuffer::readColor4f(SkColor4f* color) {
     const void* ptr = this->skip(sizeof(SkColor4f));
     if (!fError) {
         memcpy(color, ptr, sizeof(SkColor4f));
     } else {
         *color = SkColor4f::FromColor(SK_ColorBLACK);
     }
 }

 void SkValidatingReadBuffer::readPoint(SkPoint* point) {
     point->fX = this->readScalar();
     point->fY = this->readScalar();
 }

 void SkValidatingReadBuffer::readPoint3(SkPoint3* point) {
     point->fX = this->readScalar();
     point->fY = this->readScalar();
     point->fZ = this->readScalar();
 }

 void SkValidatingReadBuffer::readMatrix(SkMatrix* matrix) {
     size_t size = 0;
     if (!fError) {
         size = matrix->readFromMemory(fReader.peek(), fReader.available());
         this->validate((SkAlign4(size) == size) && (0 != size));
     }
     if (!fError) {
         (void)this->skip(size);
     }
 }

 void SkValidatingReadBuffer::readIRect(SkIRect* rect) {
     const void* ptr = this->skip(sizeof(SkIRect));
     if (!fError) {
         memcpy(rect, ptr, sizeof(SkIRect));
     } else {
         rect->setEmpty();
     }
 }

 void SkValidatingReadBuffer::readRect(SkRect* rect) {
     const void* ptr = this->skip(sizeof(SkRect));
     if (!fError) {
         memcpy(rect, ptr, sizeof(SkRect));
     } else {
         rect->setEmpty();
     }
 }

 void SkValidatingReadBuffer::readRRect(SkRRect* rrect) {
     const void* ptr = this->skip(sizeof(SkRRect));
     if (!fError) {
         memcpy(rrect, ptr, sizeof(SkRRect));
         this->validate(rrect->isValid());
     }

     if (fError) {
         rrect->setEmpty();
     }
 }

 void SkValidatingReadBuffer::readRegion(SkRegion* region) {
     size_t size = 0;
     if (!fError) {
         size = region->readFromMemory(fReader.peek(), fReader.available());
         this->validate((SkAlign4(size) == size) && (0 != size));
     }
     if (!fError) {
         (void)this->skip(size);
     }
 }

 void SkValidatingReadBuffer::readPath(SkPath* path) {
     size_t size = 0;
     if (!fError) {
         size = path->readFromMemory(fReader.peek(), fReader.available());
         this->validate((SkAlign4(size) == size) && (0 != size));
     }
     if (!fError) {
         (void)this->skip(size);
     }
 }

 bool SkValidatingReadBuffer::readArray(void* value, size_t size, size_t elementSize) {
     const uint32_t count = this->getArrayCount();
     this->validate(size == count);
     (void)this->skip(sizeof(uint32_t)); // Skip array count
     const uint64_t byteLength64 = sk_64_mul(count, elementSize);
     const size_t byteLength = count * elementSize;
     this->validate(byteLength == byteLength64);
     const void* ptr = this->skip(SkAlign4(byteLength));
     if (!fError) {
         memcpy(value, ptr, byteLength);
         return true;
     }
     return false;
 }

 bool SkValidatingReadBuffer::readByteArray(void* value, size_t size) {
     return this->readArray(static_cast<unsigned char*>(value), size, sizeof(unsigned char));
 }

 bool SkValidatingReadBuffer::readColorArray(SkColor* colors, size_t size) {
     return this->readArray(colors, size, sizeof(SkColor));
 }

 bool SkValidatingReadBuffer::readColor4fArray(SkColor4f* colors, size_t size) {
     return this->readArray(colors, size, sizeof(SkColor4f));
 }

 bool SkValidatingReadBuffer::readIntArray(int32_t* values, size_t size) {
     return this->readArray(values, size, sizeof(int32_t));
 }

 bool SkValidatingReadBuffer::readPointArray(SkPoint* points, size_t size) {
     return this->readArray(points, size, sizeof(SkPoint));
 }

 bool SkValidatingReadBuffer::readScalarArray(SkScalar* values, size_t size) {
     return this->readArray(values, size, sizeof(SkScalar));
 }

 uint32_t SkValidatingReadBuffer::getArrayCount() {
     const size_t inc = sizeof(uint32_t);
     fError = fError || !IsPtrAlign4(fReader.peek()) || !fReader.isAvailable(inc);
     return fError ? 0 : *(uint32_t*)fReader.peek();
 }

 bool SkValidatingReadBuffer::validateAvailable(size_t size) {
     return this->validate((size <= SK_MaxU32) && fReader.isAvailable(static_cast<uint32_t>(size)));
 }

 SkFlattenable* SkValidatingReadBuffer::readFlattenable(SkFlattenable::Type type) {
     // The validating read buffer always uses strings and string-indices for unflattening.
     SkASSERT(0 == this->factoryCount());

     uint8_t firstByte = this->peekByte();
     if (fError) {
         return nullptr;
     }

     SkString name;
     if (firstByte) {
         // If the first byte is non-zero, the flattenable is specified by a string.
         this->readString(&name);
         if (fError) {
             return nullptr;
         }

         // Add the string to the dictionary.
         fFlattenableDict.set(fFlattenableDict.count() + 1, name);
     } else {
         // Read the index.  We are guaranteed that the first byte
         // is zeroed, so we must shift down a byte.
         uint32_t index = this->readUInt() >> 8;
         if (0 == index) {
             return nullptr; // writer failed to give us the flattenable
         }

         SkString* namePtr = fFlattenableDict.find(index);
         if (!namePtr) {
             return nullptr;
         }
         name = *namePtr;
     }

     // Is this the type we wanted ?
     const char* cname = name.c_str();
     SkFlattenable::Type baseType;
     if (!SkFlattenable::NameToType(cname, &baseType) || (baseType != type)) {
         return nullptr;
     }

     // Get the factory for this flattenable.
     SkFlattenable::Factory factory = this->getCustomFactory(name);
     if (!factory) {
         factory = SkFlattenable::NameToFactory(cname);
         if (!factory) {
             return nullptr; // writer failed to give us the flattenable
         }
     }

     // If we get here, the factory is non-null.
     sk_sp<SkFlattenable> obj;
     uint32_t sizeRecorded = this->readUInt();
     size_t offset = fReader.offset();
     obj = (*factory)(*this);
     // check that we read the amount we expected
     size_t sizeRead = fReader.offset() - offset;
     this->validate(sizeRecorded == sizeRead);
     if (fError) {
         obj = nullptr;
     }
     return obj.release();
 }
	/*
	* Copyright 2013 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "SkBitmap.h"
	#include "SkValidatingReadBuffer.h"
	#include "SkStream.h"
	#include "SkTypeface.h"

	SkValidatingReadBuffer::SkValidatingReadBuffer(const void* data, size_t size) :
	fError(false) {
	this->setMemory(data, size);
	this->setFlags(SkReadBuffer::kValidation_Flag);
	}

	SkValidatingReadBuffer::~SkValidatingReadBuffer() {
	}

	bool SkValidatingReadBuffer::validate(bool isValid) {
	if (!fError && !isValid) {
	// When an error is found, send the read cursor to the end of the stream
	fReader.skip(fReader.available());
	fError = true;
	}
	return !fError;
	}

	bool SkValidatingReadBuffer::isValid() const {
	return !fError;
	}

	void SkValidatingReadBuffer::setMemory(const void* data, size_t size) {
	this->validate(IsPtrAlign4(data) && (SkAlign4(size) == size));
	if (!fError) {
	fReader.setMemory(data, size);
	}
	}

	const void* SkValidatingReadBuffer::skip(size_t size) {
	size_t inc = SkAlign4(size);
	this->validate(inc >= size);
	const void* addr = fReader.peek();
	this->validate(IsPtrAlign4(addr) && fReader.isAvailable(inc));
	if (fError) {
	return nullptr;
	}

	fReader.skip(size);
	return addr;
	}

	// All the methods in this file funnel down into either readInt(), readScalar() or skip(),
	// followed by a memcpy. So we've got all our validation in readInt(), readScalar() and skip();
	// if they fail they'll return a zero value or skip nothing, respectively, and set fError to
	// true, which the caller should check to see if an error occurred during the read operation.

	bool SkValidatingReadBuffer::readBool() {
	uint32_t value = this->readInt();
	// Boolean value should be either 0 or 1
	this->validate(!(value & ~1));
	return value != 0;
	}

	SkColor SkValidatingReadBuffer::readColor() {
	return this->readInt();
	}

	int32_t SkValidatingReadBuffer::readInt() {
	const size_t inc = sizeof(int32_t);
	this->validate(IsPtrAlign4(fReader.peek()) && fReader.isAvailable(inc));
	return fError ? 0 : fReader.readInt();
	}

	SkScalar SkValidatingReadBuffer::readScalar() {
	const size_t inc = sizeof(SkScalar);
	this->validate(IsPtrAlign4(fReader.peek()) && fReader.isAvailable(inc));
	return fError ? 0 : fReader.readScalar();
	}

	uint32_t SkValidatingReadBuffer::readUInt() {
	return this->readInt();
	}

	int32_t SkValidatingReadBuffer::read32() {
	return this->readInt();
	}

	uint8_t SkValidatingReadBuffer::peekByte() {
	if (fReader.available() <= 0) {
	fError = true;
	return 0;
	}
	return ((uint8_t) fReader.peek());
	}

	void SkValidatingReadBuffer::readString(SkString* string) {
	const size_t len = this->readUInt();
	const void* ptr = fReader.peek();
	const char* cptr = (const char*)ptr;

	// skip over the string + '\0' and then pad to a multiple of 4
	const size_t alignedSize = SkAlign4(len + 1);
	this->skip(alignedSize);
	if (!fError) {
	this->validate(cptr[len] == '\0');
	}
	if (!fError) {
	string->set(cptr, len);
	}
	}

	void SkValidatingReadBuffer::readColor4f(SkColor4f* color) {
	const void* ptr = this->skip(sizeof(SkColor4f));
	if (!fError) {
	memcpy(color, ptr, sizeof(SkColor4f));
	} else {
	*color = SkColor4f::FromColor(SK_ColorBLACK);
	}
	}

	void SkValidatingReadBuffer::readPoint(SkPoint* point) {
	point->fX = this->readScalar();
	point->fY = this->readScalar();
	}

	void SkValidatingReadBuffer::readPoint3(SkPoint3* point) {
	point->fX = this->readScalar();
	point->fY = this->readScalar();
	point->fZ = this->readScalar();
	}

	void SkValidatingReadBuffer::readMatrix(SkMatrix* matrix) {
	size_t size = 0;
	if (!fError) {
	size = matrix->readFromMemory(fReader.peek(), fReader.available());
	this->validate((SkAlign4(size) == size) && (0 != size));
	}
	if (!fError) {
	(void)this->skip(size);
	}
	}

	void SkValidatingReadBuffer::readIRect(SkIRect* rect) {
	const void* ptr = this->skip(sizeof(SkIRect));
	if (!fError) {
	memcpy(rect, ptr, sizeof(SkIRect));
	} else {
	rect->setEmpty();
	}
	}

	void SkValidatingReadBuffer::readRect(SkRect* rect) {
	const void* ptr = this->skip(sizeof(SkRect));
	if (!fError) {
	memcpy(rect, ptr, sizeof(SkRect));
	} else {
	rect->setEmpty();
	}
	}

	void SkValidatingReadBuffer::readRRect(SkRRect* rrect) {
	const void* ptr = this->skip(sizeof(SkRRect));
	if (!fError) {
	memcpy(rrect, ptr, sizeof(SkRRect));
	this->validate(rrect->isValid());
	}

	if (fError) {
	rrect->setEmpty();
	}
	}

	void SkValidatingReadBuffer::readRegion(SkRegion* region) {
	size_t size = 0;
	if (!fError) {
	size = region->readFromMemory(fReader.peek(), fReader.available());
	this->validate((SkAlign4(size) == size) && (0 != size));
	}
	if (!fError) {
	(void)this->skip(size);
	}
	}

	void SkValidatingReadBuffer::readPath(SkPath* path) {
	size_t size = 0;
	if (!fError) {
	size = path->readFromMemory(fReader.peek(), fReader.available());
	this->validate((SkAlign4(size) == size) && (0 != size));
	}
	if (!fError) {
	(void)this->skip(size);
	}
	}

	bool SkValidatingReadBuffer::readArray(void* value, size_t size, size_t elementSize) {
	const uint32_t count = this->getArrayCount();
	this->validate(size == count);
	(void)this->skip(sizeof(uint32_t)); // Skip array count
	const uint64_t byteLength64 = sk_64_mul(count, elementSize);
	const size_t byteLength = count * elementSize;
	this->validate(byteLength == byteLength64);
	const void* ptr = this->skip(SkAlign4(byteLength));
	if (!fError) {
	memcpy(value, ptr, byteLength);
	return true;
	}
	return false;
	}

	bool SkValidatingReadBuffer::readByteArray(void* value, size_t size) {
	return this->readArray(static_cast<unsigned char*>(value), size, sizeof(unsigned char));
	}

	bool SkValidatingReadBuffer::readColorArray(SkColor* colors, size_t size) {
	return this->readArray(colors, size, sizeof(SkColor));
	}

	bool SkValidatingReadBuffer::readColor4fArray(SkColor4f* colors, size_t size) {
	return this->readArray(colors, size, sizeof(SkColor4f));
	}

	bool SkValidatingReadBuffer::readIntArray(int32_t* values, size_t size) {
	return this->readArray(values, size, sizeof(int32_t));
	}

	bool SkValidatingReadBuffer::readPointArray(SkPoint* points, size_t size) {
	return this->readArray(points, size, sizeof(SkPoint));
	}

	bool SkValidatingReadBuffer::readScalarArray(SkScalar* values, size_t size) {
	return this->readArray(values, size, sizeof(SkScalar));
	}

	uint32_t SkValidatingReadBuffer::getArrayCount() {
	const size_t inc = sizeof(uint32_t);
	fError = fError \|\| !IsPtrAlign4(fReader.peek()) \|\| !fReader.isAvailable(inc);
	return fError ? 0 : (uint32_t)fReader.peek();
	}

	bool SkValidatingReadBuffer::validateAvailable(size_t size) {
	return this->validate((size <= SK_MaxU32) && fReader.isAvailable(static_cast<uint32_t>(size)));
	}

	SkFlattenable* SkValidatingReadBuffer::readFlattenable(SkFlattenable::Type type) {
	// The validating read buffer always uses strings and string-indices for unflattening.
	SkASSERT(0 == this->factoryCount());

	uint8_t firstByte = this->peekByte();
	if (fError) {
	return nullptr;
	}

	SkString name;
	if (firstByte) {
	// If the first byte is non-zero, the flattenable is specified by a string.
	this->readString(&name);
	if (fError) {
	return nullptr;
	}

	// Add the string to the dictionary.
	fFlattenableDict.set(fFlattenableDict.count() + 1, name);
	} else {
	// Read the index. We are guaranteed that the first byte
	// is zeroed, so we must shift down a byte.
	uint32_t index = this->readUInt() >> 8;
	if (0 == index) {
	return nullptr; // writer failed to give us the flattenable
	}

	SkString* namePtr = fFlattenableDict.find(index);
	if (!namePtr) {
	return nullptr;
	}
	name = *namePtr;
	}

	// Is this the type we wanted ?
	const char* cname = name.c_str();
	SkFlattenable::Type baseType;
	if (!SkFlattenable::NameToType(cname, &baseType) \|\| (baseType != type)) {
	return nullptr;
	}

	// Get the factory for this flattenable.
	SkFlattenable::Factory factory = this->getCustomFactory(name);
	if (!factory) {
	factory = SkFlattenable::NameToFactory(cname);
	if (!factory) {
	return nullptr; // writer failed to give us the flattenable
	}
	}

	// If we get here, the factory is non-null.
	sk_sp<SkFlattenable> obj;
	uint32_t sizeRecorded = this->readUInt();
	size_t offset = fReader.offset();
	obj = (factory)(this);
	// check that we read the amount we expected
	size_t sizeRead = fReader.offset() - offset;
	this->validate(sizeRecorded == sizeRead);
	if (fError) {
	obj = nullptr;
	}
	return obj.release();
	}