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tenfourfox/image/decoders/nsICODecoder.cpp

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/* vim:set tw=80 expandtab softtabstop=2 ts=2 sw=2: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* This is a Cross-Platform ICO Decoder, which should work everywhere, including
* Big-Endian machines like the PowerPC. */
#include <stdlib.h>
#include "mozilla/Endian.h"
#include "mozilla/Move.h"
#include "nsICODecoder.h"
#include "RasterImage.h"
using namespace mozilla::gfx;
namespace mozilla {
namespace image {
// Constants.
static const uint32_t ICOHEADERSIZE = 6;
static const uint32_t BITMAPINFOSIZE = bmp::InfoHeaderLength::WIN_ICO;
// ----------------------------------------
// Actual Data Processing
// ----------------------------------------
// Obtains the number of colors from the bits per pixel
uint16_t
nsICODecoder::GetNumColors()
{
uint16_t numColors = 0;
if (mBPP <= 8) {
switch (mBPP) {
case 1:
numColors = 2;
break;
case 4:
numColors = 16;
break;
case 8:
numColors = 256;
break;
default:
numColors = (uint16_t)-1;
}
}
return numColors;
}
nsICODecoder::nsICODecoder(RasterImage* aImage)
: Decoder(aImage)
, mLexer(Transition::To(ICOState::HEADER, ICOHEADERSIZE))
, mBiggestResourceColorDepth(0)
, mBestResourceDelta(INT_MIN)
, mBestResourceColorDepth(0)
, mNumIcons(0)
, mCurrIcon(0)
, mBPP(0)
, mMaskRowSize(0)
, mCurrMaskLine(0)
, mIsCursor(false)
, mHasMaskAlpha(false)
{ }
void
nsICODecoder::FinishInternal()
{
// We shouldn't be called in error cases
MOZ_ASSERT(!HasError(), "Shouldn't call FinishInternal after error!");
GetFinalStateFromContainedDecoder();
}
void
nsICODecoder::FinishWithErrorInternal()
{
GetFinalStateFromContainedDecoder();
}
void
nsICODecoder::GetFinalStateFromContainedDecoder()
{
if (!mContainedDecoder) {
return;
}
// Finish the internally used decoder.
mContainedDecoder->CompleteDecode();
mDecodeDone = mContainedDecoder->GetDecodeDone();
mDataError = mDataError || mContainedDecoder->HasDataError();
mFailCode = NS_SUCCEEDED(mFailCode) ? mContainedDecoder->GetDecoderError()
: mFailCode;
mDecodeAborted = mContainedDecoder->WasAborted();
mProgress |= mContainedDecoder->TakeProgress();
mInvalidRect.UnionRect(mInvalidRect, mContainedDecoder->TakeInvalidRect());
mCurrentFrame = mContainedDecoder->GetCurrentFrameRef();
MOZ_ASSERT(HasError() || !mCurrentFrame || mCurrentFrame->IsImageComplete());
}
bool
nsICODecoder::CheckAndFixBitmapSize(int8_t* aBIH)
{
// Get the width from the BMP file information header. This is
// (unintuitively) a signed integer; see the documentation at:
//
// https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx
//
// However, we reject negative widths since they aren't meaningful.
const int32_t width = LittleEndian::readInt32(aBIH + 4);
if (width <= 0 || width > 256) {
return false;
}
// Verify that the BMP width matches the width we got from the ICO directory
// entry. If not, decoding fails, because if we were to allow it to continue
// the intrinsic size of the image wouldn't match the size of the decoded
// surface.
if (width != int32_t(GetRealWidth())) {
return false;
}
// Get the height from the BMP file information header. This is also signed,
// but in this case negative values are meaningful; see below.
int32_t height = LittleEndian::readInt32(aBIH + 8);
if (height == 0) {
return false;
}
// BMPs can be stored inverted by having a negative height.
// XXX(seth): Should we really be writing the absolute value into the BIH
// below? Seems like this could be problematic for inverted BMPs.
height = abs(height);
// The height field is double the actual height of the image to account for
// the AND mask. This is true even if the AND mask is not present.
height /= 2;
if (height > 256) {
return false;
}
// Verify that the BMP height matches the height we got from the ICO directory
// entry. If not, again, decoding fails.
if (height != int32_t(GetRealHeight())) {
return false;
}
// Fix the BMP height in the BIH so that the BMP decoder, which does not know
// about the AND mask that may follow the actual bitmap, can work properly.
LittleEndian::writeInt32(aBIH + 8, GetRealHeight());
return true;
}
LexerTransition<ICOState>
nsICODecoder::ReadHeader(const char* aData)
{
// If the third byte is 1, this is an icon. If 2, a cursor.
if ((aData[2] != 1) && (aData[2] != 2)) {
return Transition::TerminateFailure();
}
mIsCursor = (aData[2] == 2);
// The fifth and sixth bytes specify the number of resources in the file.
mNumIcons = LittleEndian::readUint16(aData + 4);
if (mNumIcons == 0) {
return Transition::TerminateSuccess(); // Nothing to do.
}
// Downscale-during-decode can end up decoding different resources in the ICO
// file depending on the target size. Since the resources are not necessarily
// scaled versions of the same image, some may be transparent and some may not
// be. We could be precise about transparency if we decoded the metadata of
// every resource, but for now we don't and it's safest to assume that
// transparency could be present.
PostHasTransparency();
return Transition::To(ICOState::DIR_ENTRY, ICODIRENTRYSIZE);
}
size_t
nsICODecoder::FirstResourceOffset() const
{
MOZ_ASSERT(mNumIcons > 0,
"Calling FirstResourceOffset before processing header");
// The first resource starts right after the directory, which starts right
// after the ICO header.
return ICOHEADERSIZE + mNumIcons * ICODIRENTRYSIZE;
}
LexerTransition<ICOState>
nsICODecoder::ReadDirEntry(const char* aData)
{
mCurrIcon++;
// Read the directory entry.
IconDirEntry e;
e.mWidth = aData[0];
e.mHeight = aData[1];
e.mColorCount = aData[2];
e.mReserved = aData[3];
e.mPlanes = LittleEndian::readUint16(aData + 4);
e.mBitCount = LittleEndian::readUint16(aData + 6);
e.mBytesInRes = LittleEndian::readUint32(aData + 8);
e.mImageOffset = LittleEndian::readUint32(aData + 12);
// Determine if this is the biggest resource we've seen so far. We always use
// the biggest resource for the intrinsic size, and if we're not downscaling,
// we select it as the best resource as well.
IntSize entrySize(GetRealWidth(e), GetRealHeight(e));
if (e.mBitCount >= mBiggestResourceColorDepth &&
entrySize.width * entrySize.height >=
mBiggestResourceSize.width * mBiggestResourceSize.height) {
mBiggestResourceSize = entrySize;
mBiggestResourceColorDepth = e.mBitCount;
mBiggestResourceHotSpot = IntSize(e.mXHotspot, e.mYHotspot);
if (!mDownscaler) {
mDirEntry = e;
}
}
if (mDownscaler) {
// Calculate the delta between this resource's size and the desired size, so
// we can see if it is better than our current-best option. In the case of
// several equally-good resources, we use the last one. "Better" in this
// case is determined by |delta|, a measure of the difference in size
// between the entry we've found and the downscaler's target size. We will
// choose the smallest resource that is >= the target size (i.e. we assume
// it's better to downscale a larger icon than to upscale a smaller one).
IntSize desiredSize = mDownscaler->TargetSize();
int32_t delta = std::min(entrySize.width - desiredSize.width,
entrySize.height - desiredSize.height);
if (e.mBitCount >= mBestResourceColorDepth &&
((mBestResourceDelta < 0 && delta >= mBestResourceDelta) ||
(delta >= 0 && delta <= mBestResourceDelta))) {
mBestResourceDelta = delta;
mBestResourceColorDepth = e.mBitCount;
mDirEntry = e;
}
}
if (mCurrIcon == mNumIcons) {
// Ensure the resource we selected has an offset past the ICO headers.
if (mDirEntry.mImageOffset < FirstResourceOffset()) {
return Transition::TerminateFailure();
}
// If this is a cursor, set the hotspot. We use the hotspot from the biggest
// resource since we also use that resource for the intrinsic size.
if (mIsCursor) {
mImageMetadata.SetHotspot(mBiggestResourceHotSpot.width,
mBiggestResourceHotSpot.height);
}
// We always report the biggest resource's size as the intrinsic size; this
// is necessary for downscale-during-decode to work since we won't even
// attempt to *upscale* while decoding.
PostSize(mBiggestResourceSize.width, mBiggestResourceSize.height);
if (IsMetadataDecode()) {
return Transition::TerminateSuccess();
}
// If the resource we selected matches the downscaler's target size
// perfectly, we don't need to do any downscaling.
if (mDownscaler && GetRealSize() == mDownscaler->TargetSize()) {
mDownscaler.reset();
}
size_t offsetToResource = mDirEntry.mImageOffset - FirstResourceOffset();
return Transition::ToUnbuffered(ICOState::FOUND_RESOURCE,
ICOState::SKIP_TO_RESOURCE,
offsetToResource);
}
return Transition::To(ICOState::DIR_ENTRY, ICODIRENTRYSIZE);
}
LexerTransition<ICOState>
nsICODecoder::SniffResource(const char* aData)
{
// We use the first PNGSIGNATURESIZE bytes to determine whether this resource
// is a PNG or a BMP.
bool isPNG = !memcmp(aData, nsPNGDecoder::pngSignatureBytes,
PNGSIGNATURESIZE);
if (isPNG) {
// Create a PNG decoder which will do the rest of the work for us.
mContainedDecoder = new nsPNGDecoder(mImage);
mContainedDecoder->SetMetadataDecode(IsMetadataDecode());
mContainedDecoder->SetDecoderFlags(GetDecoderFlags());
mContainedDecoder->SetSurfaceFlags(GetSurfaceFlags());
if (mDownscaler) {
mContainedDecoder->SetTargetSize(mDownscaler->TargetSize());
}
mContainedDecoder->Init();
if (!WriteToContainedDecoder(aData, PNGSIGNATURESIZE)) {
return Transition::TerminateFailure();
}
if (mDirEntry.mBytesInRes <= PNGSIGNATURESIZE) {
return Transition::TerminateFailure();
}
// Read in the rest of the PNG unbuffered.
size_t toRead = mDirEntry.mBytesInRes - PNGSIGNATURESIZE;
return Transition::ToUnbuffered(ICOState::FINISHED_RESOURCE,
ICOState::READ_PNG,
toRead);
} else {
// Make sure we have a sane size for the bitmap information header.
int32_t bihSize = LittleEndian::readUint32(aData);
if (bihSize != static_cast<int32_t>(BITMAPINFOSIZE)) {
return Transition::TerminateFailure();
}
// Buffer the first part of the bitmap information header.
memcpy(mBIHraw, aData, PNGSIGNATURESIZE);
// Read in the rest of the bitmap information header.
return Transition::To(ICOState::READ_BIH,
BITMAPINFOSIZE - PNGSIGNATURESIZE);
}
}
LexerTransition<ICOState>
nsICODecoder::ReadPNG(const char* aData, uint32_t aLen)
{
if (!WriteToContainedDecoder(aData, aLen)) {
return Transition::TerminateFailure();
}
// Raymond Chen says that 32bpp only are valid PNG ICOs
// http://blogs.msdn.com/b/oldnewthing/archive/2010/10/22/10079192.aspx
if (!static_cast<nsPNGDecoder*>(mContainedDecoder.get())->IsValidICO()) {
return Transition::TerminateFailure();
}
return Transition::ContinueUnbuffered(ICOState::READ_PNG);
}
LexerTransition<ICOState>
nsICODecoder::ReadBIH(const char* aData)
{
// Buffer the rest of the bitmap information header.
memcpy(mBIHraw + PNGSIGNATURESIZE, aData, BITMAPINFOSIZE - PNGSIGNATURESIZE);
// Extract the BPP from the BIH header; it should be trusted over the one
// we have from the ICO header which is usually set to 0.
mBPP = LittleEndian::readUint16(mBIHraw + 14);
// The ICO format when containing a BMP does not include the 14 byte
// bitmap file header. So we create the BMP decoder via the constructor that
// tells it to skip this, and pass in the required data (dataOffset) that
// would have been present in the header.
uint32_t dataOffset = bmp::FILE_HEADER_LENGTH + BITMAPINFOSIZE;
if (mDirEntry.mBitCount <= 8) {
// The color table is present only if BPP is <= 8.
uint16_t numColors = GetNumColors();
if (numColors == (uint16_t)-1) {
return Transition::TerminateFailure();
}
dataOffset += 4 * numColors;
}
// Create a BMP decoder which will do most of the work for us; the exception
// is the AND mask, which isn't present in standalone BMPs.
RefPtr<nsBMPDecoder> bmpDecoder = new nsBMPDecoder(mImage, dataOffset);
mContainedDecoder = bmpDecoder;
mContainedDecoder->SetMetadataDecode(IsMetadataDecode());
mContainedDecoder->SetDecoderFlags(GetDecoderFlags());
mContainedDecoder->SetSurfaceFlags(GetSurfaceFlags());
if (mDownscaler) {
mContainedDecoder->SetTargetSize(mDownscaler->TargetSize());
}
mContainedDecoder->Init();
// Verify that the BIH width and height values match the ICO directory entry,
// and fix the BIH height value to compensate for the fact that the underlying
// BMP decoder doesn't know about AND masks.
if (!CheckAndFixBitmapSize(reinterpret_cast<int8_t*>(mBIHraw))) {
return Transition::TerminateFailure();
}
// Write out the BMP's bitmap info header.
if (!WriteToContainedDecoder(mBIHraw, sizeof(mBIHraw))) {
return Transition::TerminateFailure();
}
// Check to make sure we have valid color settings.
uint16_t numColors = GetNumColors();
if (numColors == uint16_t(-1)) {
return Transition::TerminateFailure();
}
// Do we have an AND mask on this BMP? If so, we need to read it after we read
// the BMP data itself.
uint32_t bmpDataLength = bmpDecoder->GetCompressedImageSize() + 4 * numColors;
bool hasANDMask = (BITMAPINFOSIZE + bmpDataLength) < mDirEntry.mBytesInRes;
ICOState afterBMPState = hasANDMask ? ICOState::PREPARE_FOR_MASK
: ICOState::FINISHED_RESOURCE;
// Read in the rest of the BMP unbuffered.
return Transition::ToUnbuffered(afterBMPState,
ICOState::READ_BMP,
bmpDataLength);
}
LexerTransition<ICOState>
nsICODecoder::ReadBMP(const char* aData, uint32_t aLen)
{
if (!WriteToContainedDecoder(aData, aLen)) {
return Transition::TerminateFailure();
}
return Transition::ContinueUnbuffered(ICOState::READ_BMP);
}
LexerTransition<ICOState>
nsICODecoder::PrepareForMask()
{
RefPtr<nsBMPDecoder> bmpDecoder =
static_cast<nsBMPDecoder*>(mContainedDecoder.get());
uint16_t numColors = GetNumColors();
MOZ_ASSERT(numColors != uint16_t(-1));
// Determine the length of the AND mask.
uint32_t bmpLengthWithHeader =
BITMAPINFOSIZE + bmpDecoder->GetCompressedImageSize() + 4 * numColors;
MOZ_ASSERT(bmpLengthWithHeader < mDirEntry.mBytesInRes);
uint32_t maskLength = mDirEntry.mBytesInRes - bmpLengthWithHeader;
// If the BMP provides its own transparency, we ignore the AND mask. We can
// also obviously ignore it if the image has zero width or zero height.
if (bmpDecoder->HasTransparency() ||
GetRealWidth() == 0 || GetRealHeight() == 0) {
return Transition::ToUnbuffered(ICOState::FINISHED_RESOURCE,
ICOState::SKIP_MASK,
maskLength);
}
// Compute the row size for the mask.
mMaskRowSize = ((GetRealWidth() + 31) / 32) * 4; // + 31 to round up
// If the expected size of the AND mask is larger than its actual size, then
// we must have a truncated (and therefore corrupt) AND mask.
uint32_t expectedLength = mMaskRowSize * GetRealHeight();
if (maskLength < expectedLength) {
return Transition::TerminateFailure();
}
// If we're downscaling, the mask is the wrong size for the surface we've
// produced, so we need to downscale the mask into a temporary buffer and then
// combine the mask's alpha values with the color values from the image.
if (mDownscaler) {
MOZ_ASSERT(bmpDecoder->GetImageDataLength() ==
mDownscaler->TargetSize().width *
mDownscaler->TargetSize().height *
sizeof(uint32_t));
mMaskBuffer = MakeUnique<uint8_t[]>(bmpDecoder->GetImageDataLength());
nsresult rv = mDownscaler->BeginFrame(GetRealSize(), Nothing(),
mMaskBuffer.get(),
/* aHasAlpha = */ true,
/* aFlipVertically = */ true);
if (NS_FAILED(rv)) {
return Transition::TerminateFailure();
}
}
mCurrMaskLine = GetRealHeight();
return Transition::To(ICOState::READ_MASK_ROW, mMaskRowSize);
}
LexerTransition<ICOState>
nsICODecoder::ReadMaskRow(const char* aData)
{
mCurrMaskLine--;
uint8_t sawTransparency = 0;
// Get the mask row we're reading.
const uint8_t* mask = reinterpret_cast<const uint8_t*>(aData);
const uint8_t* maskRowEnd = mask + mMaskRowSize;
// Get the corresponding row of the mask buffer (if we're downscaling) or the
// decoded image data (if we're not).
uint32_t* decoded = nullptr;
if (mDownscaler) {
// Initialize the row to all white and fully opaque.
memset(mDownscaler->RowBuffer(), 0xFF, GetRealWidth() * sizeof(uint32_t));
decoded = reinterpret_cast<uint32_t*>(mDownscaler->RowBuffer());
} else {
RefPtr<nsBMPDecoder> bmpDecoder =
static_cast<nsBMPDecoder*>(mContainedDecoder.get());
uint32_t* imageData = bmpDecoder->GetImageData();
if (!imageData) {
return Transition::TerminateFailure();
}
decoded = imageData + mCurrMaskLine * GetRealWidth();
}
MOZ_ASSERT(decoded);
uint32_t* decodedRowEnd = decoded + GetRealWidth();
// Iterate simultaneously through the AND mask and the image data.
while (mask < maskRowEnd) {
uint8_t idx = *mask++;
sawTransparency |= idx;
for (uint8_t bit = 0x80; bit && decoded < decodedRowEnd; bit >>= 1) {
// Clear pixel completely for transparency.
if (idx & bit) {
*decoded = 0;
}
decoded++;
}
}
if (mDownscaler) {
mDownscaler->CommitRow();
}
// If any bits are set in sawTransparency, then we know at least one pixel was
// transparent.
if (sawTransparency) {
mHasMaskAlpha = true;
}
if (mCurrMaskLine == 0) {
return Transition::To(ICOState::FINISH_MASK, 0);
}
return Transition::To(ICOState::READ_MASK_ROW, mMaskRowSize);
}
LexerTransition<ICOState>
nsICODecoder::FinishMask()
{
// If we're downscaling, we now have the appropriate alpha values in
// mMaskBuffer. We just need to transfer them to the image.
if (mDownscaler) {
// Retrieve the image data.
RefPtr<nsBMPDecoder> bmpDecoder =
static_cast<nsBMPDecoder*>(mContainedDecoder.get());
uint8_t* imageData = reinterpret_cast<uint8_t*>(bmpDecoder->GetImageData());
if (!imageData) {
return Transition::TerminateFailure();
}
// Iterate through the alpha values, copying from mask to image.
MOZ_ASSERT(mMaskBuffer);
MOZ_ASSERT(bmpDecoder->GetImageDataLength() > 0);
for (size_t i = 3 ; i < bmpDecoder->GetImageDataLength() ; i += 4) {
imageData[i] = mMaskBuffer[i];
}
}
// If the mask contained any transparent pixels, record that fact.
if (mHasMaskAlpha) {
PostHasTransparency();
RefPtr<nsBMPDecoder> bmpDecoder =
static_cast<nsBMPDecoder*>(mContainedDecoder.get());
bmpDecoder->SetHasTransparency();
}
return Transition::To(ICOState::FINISHED_RESOURCE, 0);
}
LexerTransition<ICOState>
nsICODecoder::FinishResource()
{
// Make sure the actual size of the resource matches the size in the directory
// entry. If not, we consider the image corrupt.
if (mContainedDecoder->HasSize() &&
mContainedDecoder->GetSize() != GetRealSize()) {
return Transition::TerminateFailure();
}
return Transition::TerminateSuccess();
}
void
nsICODecoder::WriteInternal(const char* aBuffer, uint32_t aCount)
{
MOZ_ASSERT(!HasError(), "Shouldn't call WriteInternal after error!");
MOZ_ASSERT(aBuffer);
MOZ_ASSERT(aCount > 0);
Maybe<TerminalState> terminalState =
mLexer.Lex(aBuffer, aCount,
[=](ICOState aState, const char* aData, size_t aLength) {
switch (aState) {
case ICOState::HEADER:
return ReadHeader(aData);
case ICOState::DIR_ENTRY:
return ReadDirEntry(aData);
case ICOState::SKIP_TO_RESOURCE:
return Transition::ContinueUnbuffered(ICOState::SKIP_TO_RESOURCE);
case ICOState::FOUND_RESOURCE:
return Transition::To(ICOState::SNIFF_RESOURCE, PNGSIGNATURESIZE);
case ICOState::SNIFF_RESOURCE:
return SniffResource(aData);
case ICOState::READ_PNG:
return ReadPNG(aData, aLength);
case ICOState::READ_BIH:
return ReadBIH(aData);
case ICOState::READ_BMP:
return ReadBMP(aData, aLength);
case ICOState::PREPARE_FOR_MASK:
return PrepareForMask();
case ICOState::READ_MASK_ROW:
return ReadMaskRow(aData);
case ICOState::FINISH_MASK:
return FinishMask();
case ICOState::SKIP_MASK:
return Transition::ContinueUnbuffered(ICOState::SKIP_MASK);
case ICOState::FINISHED_RESOURCE:
return FinishResource();
default:
MOZ_CRASH("Unknown ICOState");
}
});
if (terminalState == Some(TerminalState::FAILURE)) {
PostDataError();
}
}
bool
nsICODecoder::WriteToContainedDecoder(const char* aBuffer, uint32_t aCount)
{
mContainedDecoder->Write(aBuffer, aCount);
mProgress |= mContainedDecoder->TakeProgress();
mInvalidRect.UnionRect(mInvalidRect, mContainedDecoder->TakeInvalidRect());
if (mContainedDecoder->HasDataError()) {
PostDataError();
}
if (mContainedDecoder->HasDecoderError()) {
PostDecoderError(mContainedDecoder->GetDecoderError());
}
return !HasError();
}
} // namespace image
} // namespace mozilla
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