path: root/src/core/SkReadBuffer.cpp

/*
 * Copyright 2012 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 "SkErrorInternals.h"
#include "SkImage.h"
#include "SkImageGenerator.h"
#include "SkReadBuffer.h"
#include "SkStream.h"
#include "SkTypeface.h"

static uint32_t default_flags() {
    uint32_t flags = 0;
    flags |= SkReadBuffer::kScalarIsFloat_Flag;
    if (8 == sizeof(void*)) {
        flags |= SkReadBuffer::kPtrIs64Bit_Flag;
    }
    return flags;
}

SkReadBuffer::SkReadBuffer() {
    fFlags = default_flags();
    fVersion = 0;
    fMemoryPtr = nullptr;

    fBitmapStorage = nullptr;
    fTFArray = nullptr;
    fTFCount = 0;

    fFactoryArray = nullptr;
    fFactoryCount = 0;
    fBitmapDecoder = nullptr;
#ifdef DEBUG_NON_DETERMINISTIC_ASSERT
    fDecodedBitmapIndex = -1;
#endif // DEBUG_NON_DETERMINISTIC_ASSERT
}

SkReadBuffer::SkReadBuffer(const void* data, size_t size) {
    fFlags = default_flags();
    fVersion = 0;
    fReader.setMemory(data, size);
    fMemoryPtr = nullptr;

    fBitmapStorage = nullptr;
    fTFArray = nullptr;
    fTFCount = 0;

    fFactoryArray = nullptr;
    fFactoryCount = 0;
    fBitmapDecoder = nullptr;
#ifdef DEBUG_NON_DETERMINISTIC_ASSERT
    fDecodedBitmapIndex = -1;
#endif // DEBUG_NON_DETERMINISTIC_ASSERT
}

SkReadBuffer::SkReadBuffer(SkStream* stream) {
    fFlags = default_flags();
    fVersion = 0;
    const size_t length = stream->getLength();
    fMemoryPtr = sk_malloc_throw(length);
    stream->read(fMemoryPtr, length);
    fReader.setMemory(fMemoryPtr, length);

    fBitmapStorage = nullptr;
    fTFArray = nullptr;
    fTFCount = 0;

    fFactoryArray = nullptr;
    fFactoryCount = 0;
    fBitmapDecoder = nullptr;
#ifdef DEBUG_NON_DETERMINISTIC_ASSERT
    fDecodedBitmapIndex = -1;
#endif // DEBUG_NON_DETERMINISTIC_ASSERT
}

SkReadBuffer::~SkReadBuffer() {
    sk_free(fMemoryPtr);
    SkSafeUnref(fBitmapStorage);
}

bool SkReadBuffer::readBool() {
    return fReader.readBool();
}

SkColor SkReadBuffer::readColor() {
    return fReader.readInt();
}

int32_t SkReadBuffer::readInt() {
    return fReader.readInt();
}

SkScalar SkReadBuffer::readScalar() {
    return fReader.readScalar();
}

uint32_t SkReadBuffer::readUInt() {
    return fReader.readU32();
}

int32_t SkReadBuffer::read32() {
    return fReader.readInt();
}

uint8_t SkReadBuffer::peekByte() {
    SkASSERT(fReader.available() > 0);
    return *((uint8_t*) fReader.peek());
}

void SkReadBuffer::readString(SkString* string) {
    size_t len;
    const char* strContents = fReader.readString(&len);
    string->set(strContents, len);
}

void* SkReadBuffer::readEncodedString(size_t* length, SkPaint::TextEncoding encoding) {
    SkDEBUGCODE(int32_t encodingType = ) fReader.readInt();
    SkASSERT(encodingType == encoding);
    *length =  fReader.readInt();
    void* data = sk_malloc_throw(*length);
    memcpy(data, fReader.skip(SkAlign4(*length)), *length);
    return data;
}

void SkReadBuffer::readPoint(SkPoint* point) {
    point->fX = fReader.readScalar();
    point->fY = fReader.readScalar();
}

void SkReadBuffer::readMatrix(SkMatrix* matrix) {
    fReader.readMatrix(matrix);
}

void SkReadBuffer::readIRect(SkIRect* rect) {
    memcpy(rect, fReader.skip(sizeof(SkIRect)), sizeof(SkIRect));
}

void SkReadBuffer::readRect(SkRect* rect) {
    memcpy(rect, fReader.skip(sizeof(SkRect)), sizeof(SkRect));
}

void SkReadBuffer::readRRect(SkRRect* rrect) {
    fReader.readRRect(rrect);
}

void SkReadBuffer::readRegion(SkRegion* region) {
    fReader.readRegion(region);
}

void SkReadBuffer::readPath(SkPath* path) {
    fReader.readPath(path);
}

bool SkReadBuffer::readArray(void* value, size_t size, size_t elementSize) {
    const size_t count = this->getArrayCount();
    if (count == size) {
        (void)fReader.skip(sizeof(uint32_t)); // Skip array count
        const size_t byteLength = count * elementSize;
        memcpy(value, fReader.skip(SkAlign4(byteLength)), byteLength);
        return true;
    }
    SkASSERT(false);
    fReader.skip(fReader.available());
    return false;
}

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

bool SkReadBuffer::readColorArray(SkColor* colors, size_t size) {
    return readArray(colors, size, sizeof(SkColor));
}

bool SkReadBuffer::readIntArray(int32_t* values, size_t size) {
    return readArray(values, size, sizeof(int32_t));
}

bool SkReadBuffer::readPointArray(SkPoint* points, size_t size) {
    return readArray(points, size, sizeof(SkPoint));
}

bool SkReadBuffer::readScalarArray(SkScalar* values, size_t size) {
    return readArray(values, size, sizeof(SkScalar));
}

uint32_t SkReadBuffer::getArrayCount() {
    return *(uint32_t*)fReader.peek();
}

bool SkReadBuffer::readBitmap(SkBitmap* bitmap) {
    const int width = this->readInt();
    const int height = this->readInt();
    // The writer stored a boolean value to determine whether an SkBitmapHeap was used during
    // writing.
    if (this->readBool()) {
        // An SkBitmapHeap was used for writing. Read the index from the stream and find the
        // corresponding SkBitmap in fBitmapStorage.
        const uint32_t index = this->readUInt();
        this->readUInt(); // bitmap generation ID (see SkWriteBuffer::writeBitmap)
        if (fBitmapStorage) {
            *bitmap = *fBitmapStorage->getBitmap(index);
            fBitmapStorage->releaseRef(index);
            return true;
        } else {
            // The bitmap was stored in a heap, but there is no way to access it. Set an error and
            // fall through to use a place holder bitmap.
            SkErrorInternals::SetError(kParseError_SkError, "SkWriteBuffer::writeBitmap "
                                       "stored the SkBitmap in an SkBitmapHeap, but "
                                       "SkReadBuffer has no SkBitmapHeapReader to "
                                       "retrieve the SkBitmap.");
        }
    } else {
        // The writer stored false, meaning the SkBitmap was not stored in an SkBitmapHeap.
        const size_t length = this->readUInt();
        if (length > 0) {
#ifdef DEBUG_NON_DETERMINISTIC_ASSERT
            fDecodedBitmapIndex++;
#endif // DEBUG_NON_DETERMINISTIC_ASSERT
            // A non-zero size means the SkBitmap was encoded. Read the data and pixel
            // offset.
            const void* data = this->skip(length);
            const int32_t xOffset = this->readInt();
            const int32_t yOffset = this->readInt();
            if (fBitmapDecoder != nullptr && fBitmapDecoder(data, length, bitmap)) {
                if (bitmap->width() == width && bitmap->height() == height) {
#ifdef DEBUG_NON_DETERMINISTIC_ASSERT
                    if (0 != xOffset || 0 != yOffset) {
                        SkDebugf("SkReadBuffer::readBitmap: heights match,"
                                 " but offset is not zero. \nInfo about the bitmap:"
                                 "\n\tIndex: %d\n\tDimensions: [%d %d]\n\tEncoded"
                                 " data size: %d\n\tOffset: (%d, %d)\n",
                                 fDecodedBitmapIndex, width, height, length, xOffset,
                                 yOffset);
                    }
#endif // DEBUG_NON_DETERMINISTIC_ASSERT
                    // If the width and height match, there should be no offset.
                    SkASSERT(0 == xOffset && 0 == yOffset);
                    return true;
                }

                // This case can only be reached if extractSubset was called, so
                // the recorded width and height must be smaller than or equal to
                // the encoded width and height.
                // FIXME (scroggo): This assert assumes that our decoder and the
                // sources encoder agree on the width and height which may not
                // always be the case. Removing until it can be investigated
                // further.
                //SkASSERT(width <= bitmap->width() && height <= bitmap->height());

                SkBitmap subsetBm;
                SkIRect subset = SkIRect::MakeXYWH(xOffset, yOffset, width, height);
                if (bitmap->extractSubset(&subsetBm, subset)) {
                    bitmap->swap(subsetBm);
                    return true;
                }
            }
            // This bitmap was encoded when written, but we are unable to decode, possibly due to
            // not having a decoder.
            SkErrorInternals::SetError(kParseError_SkError,
                                       "Could not decode bitmap. Resulting bitmap will be empty.");
            // Even though we weren't able to decode the pixels, the readbuffer should still be
            // intact, so we return true with an empty bitmap, so we don't force an abort of the
            // larger deserialize.
            bitmap->setInfo(SkImageInfo::MakeUnknown(width, height));
            return true;
        } else if (SkBitmap::ReadRawPixels(this, bitmap)) {
            return true;
        }
    }
    // Could not read the SkBitmap. Use a placeholder bitmap.
    bitmap->setInfo(SkImageInfo::MakeUnknown(width, height));
    return false;
}

namespace {

// This generator intentionally should always fail on all attempts to get its pixels,
// simulating a bad or empty codec stream.
class EmptyImageGenerator final : public SkImageGenerator {
public:
    EmptyImageGenerator(const SkImageInfo& info) : INHERITED(info) { }

private:
    typedef SkImageGenerator INHERITED;
};

} // anonymous namespace

SkImage* SkReadBuffer::readImage() {
    int width = this->read32();
    int height = this->read32();
    if (width <= 0 || height <= 0) {    // SkImage never has a zero dimension
        this->validate(false);
        return nullptr;
    }

    sk_sp<SkData> encoded(this->readByteArrayAsData());
    if (encoded->size() == 0) {
        // The image could not be encoded at serialization time - return an empty placeholder.
        return SkImage::MakeFromGenerator(
            new EmptyImageGenerator(SkImageInfo::MakeN32Premul(width, height))).release();
    }

    int originX = this->read32();
    int originY = this->read32();
    if (originX < 0 || originY < 0) {
        this->validate(false);
        return nullptr;
    }

    const SkIRect subset = SkIRect::MakeXYWH(originX, originY, width, height);
    SkImage* image = SkImage::MakeFromEncoded(std::move(encoded), &subset).release();
    if (image) {
        return image;
    }

    return SkImage::MakeFromGenerator(
            new EmptyImageGenerator(SkImageInfo::MakeN32Premul(width, height))).release();
}

SkTypeface* SkReadBuffer::readTypeface() {

    uint32_t index = fReader.readU32();
    if (0 == index || index > (unsigned)fTFCount) {
        return nullptr;
    } else {
        SkASSERT(fTFArray);
        return fTFArray[index - 1];
    }
}

SkFlattenable* SkReadBuffer::readFlattenable(SkFlattenable::Type ft) {
    //
    // TODO: confirm that ft matches the factory we decide to use
    //

    SkFlattenable::Factory factory = nullptr;

    if (fFactoryCount > 0) {
        int32_t index = fReader.readU32();
        if (0 == index) {
            return nullptr; // writer failed to give us the flattenable
        }
        index -= 1;     // we stored the index-base-1
        if ((unsigned)index >= (unsigned)fFactoryCount) {
            this->validate(false);
            return nullptr;
        }
        factory = fFactoryArray[index];
    } else {
        SkString name;
        if (this->peekByte()) {
            // If the first byte is non-zero, the flattenable is specified by a string.
            this->readString(&name);

            // 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 = fReader.readU32() >> 8;
            if (0 == index) {
                return nullptr; // writer failed to give us the flattenable
            }

            SkString* namePtr = fFlattenableDict.find(index);
            SkASSERT(namePtr);
            name = *namePtr;
        }

        // Check if a custom Factory has been specified for this flattenable.
        if (!(factory = this->getCustomFactory(name))) {
            // If there is no custom Factory, check for a default.
            if (!(factory = SkFlattenable::NameToFactory(name.c_str()))) {
                return nullptr; // writer failed to give us the flattenable
            }
        }
    }

    // if we get here, factory may still be null, but if that is the case, the
    // failure was ours, not the writer.
    sk_sp<SkFlattenable> obj;
    uint32_t sizeRecorded = fReader.readU32();
    if (factory) {
        size_t offset = fReader.offset();
        obj = (*factory)(*this);
        // check that we read the amount we expected
        size_t sizeRead = fReader.offset() - offset;
        if (sizeRecorded != sizeRead) {
            this->validate(false);
            return nullptr;
        }
    } else {
        // we must skip the remaining data
        fReader.skip(sizeRecorded);
    }
    return obj.release();
}

/**
 *  Needs to follow the same pattern as readFlattenable(), but explicitly skip whatever data
 *  has been written.
 */
void SkReadBuffer::skipFlattenable() {
    if (fFactoryCount > 0) {
        if (0 == fReader.readU32()) {
            return;
        }
    } else {
        if (nullptr == this->readFunctionPtr()) {
            return;
        }
    }
    uint32_t sizeRecorded = fReader.readU32();
    fReader.skip(sizeRecorded);
}