C++ CheckedInt32类代码示例

// Returns true if an image of aWidth x aHeight is allowed and legal.
static bool
AllowedImageSize(int32_t aWidth, int32_t aHeight)
{
  // reject over-wide or over-tall images
  const int32_t k64KLimit = 0x0000FFFF;
  if (MOZ_UNLIKELY(aWidth > k64KLimit || aHeight > k64KLimit )) {
    NS_WARNING("image too big");
    return false;
  }

  // protect against invalid sizes
  if (MOZ_UNLIKELY(aHeight <= 0 || aWidth <= 0)) {
    return false;
  }

  // check to make sure we don't overflow a 32-bit
  CheckedInt32 requiredBytes = CheckedInt32(aWidth) * CheckedInt32(aHeight) * 4;
  if (MOZ_UNLIKELY(!requiredBytes.isValid())) {
    NS_WARNING("width or height too large");
    return false;
  }
#if defined(XP_MACOSX)
  // CoreGraphics is limited to images < 32K in *height*, so clamp all surfaces
  // on the Mac to that height
  if (MOZ_UNLIKELY(aHeight > SHRT_MAX)) {
    NS_WARNING("image too big");
    return false;
  }
#endif
  return true;
}

void
ImageBitmap::SetPictureRect(const IntRect& aRect, ErrorResult& aRv)
{
  gfx::IntRect rect = aRect;

  // fix up negative dimensions
  if (rect.width < 0) {
    CheckedInt32 checkedX = CheckedInt32(rect.x) + rect.width;

    if (!checkedX.isValid()) {
      aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
      return;
    }

    rect.x = checkedX.value();
    rect.width = -(rect.width);
  }

  if (rect.height < 0) {
    CheckedInt32 checkedY = CheckedInt32(rect.y) + rect.height;

    if (!checkedY.isValid()) {
      aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
      return;
    }

    rect.y = checkedY.value();
    rect.height = -(rect.height);
  }

  mPictureRect = rect;
}

void
gfxXlibSurface::TakePixmap()
{
    NS_ASSERTION(!mPixmapTaken, "I already own the Pixmap!");
    mPixmapTaken = true;

    // The bit depth returned from Cairo is technically int, but this is
    // the last place we'd be worried about that scenario.
    unsigned int bitDepth = cairo_xlib_surface_get_depth(CairoSurface());
    MOZ_ASSERT((bitDepth % 8) == 0, "Memory used not recorded correctly");    

    // Divide by 8 because surface_get_depth gives us the number of *bits* per
    // pixel.
    gfxIntSize size = GetSize();
    CheckedInt32 totalBytes = CheckedInt32(size.width) * CheckedInt32(size.height) * (bitDepth/8);

    // Don't do anything in the "else" case.  We could add INT32_MAX, but that
    // would overflow the memory used counter.  It would also mean we tried for
    // a 2G image.  For now, we'll just assert,
    MOZ_ASSERT(totalBytes.isValid(),"Did not expect to exceed 2Gb image");
    if (totalBytes.isValid()) {
        RecordMemoryUsed(totalBytes.value());
    }
}

size_t
BufferSizeFromStrideAndHeight(int32_t aStride,
                              int32_t aHeight,
                              int32_t aExtraBytes)
{
  if (MOZ_UNLIKELY(aHeight <= 0)) {
    return 0;
  }

  // We limit the length returned to values that can be represented by int32_t
  // because we don't want to allocate buffers any bigger than that. This
  // allows for a buffer size of over 2 GiB which is already rediculously
  // large and will make the process janky. (Note the choice of the signed type
  // is deliberate because we specifically don't want the returned value to
  // overflow if someone stores the buffer length in an int32_t variable.)

  CheckedInt32 requiredBytes =
    CheckedInt32(aStride) * CheckedInt32(aHeight) + CheckedInt32(aExtraBytes);
  if (MOZ_UNLIKELY(!requiredBytes.isValid())) {
    gfxWarning() << "Buffer size too big; returning zero";
    return 0;
  }
  return requiredBytes.value();
}

/* static */
nsresult
ImageEncoder::ExtractDataInternal(const nsAString& aType,
                                  const nsAString& aOptions,
                                  uint8_t* aImageBuffer,
                                  int32_t aFormat,
                                  const nsIntSize aSize,
                                  layers::Image* aImage,
                                  nsICanvasRenderingContextInternal* aContext,
                                  layers::AsyncCanvasRenderer* aRenderer,
                                  nsIInputStream** aStream,
                                  imgIEncoder* aEncoder)
{
  if (aSize.IsEmpty()) {
    return NS_ERROR_INVALID_ARG;
  }

  nsCOMPtr<nsIInputStream> imgStream;

  // get image bytes
  nsresult rv;
  if (aImageBuffer) {
    rv = ImageEncoder::GetInputStream(
      aSize.width,
      aSize.height,
      aImageBuffer,
      aFormat,
      aEncoder,
      nsPromiseFlatString(aOptions).get(),
      getter_AddRefs(imgStream));
  } else if (aContext) {
    NS_ConvertUTF16toUTF8 encoderType(aType);
    rv = aContext->GetInputStream(encoderType.get(),
                                  nsPromiseFlatString(aOptions).get(),
                                  getter_AddRefs(imgStream));
  } else if (aRenderer) {
    NS_ConvertUTF16toUTF8 encoderType(aType);
    rv = aRenderer->GetInputStream(encoderType.get(),
                                   nsPromiseFlatString(aOptions).get(),
                                   getter_AddRefs(imgStream));
  } else if (aImage) {
    // It is safe to convert PlanarYCbCr format from YUV to RGB off-main-thread.
    // Other image formats could have problem to convert format off-main-thread.
    // So here it uses a help function GetBRGADataSourceSurfaceSync() to convert
    // format on main thread.
    if (aImage->GetFormat() == ImageFormat::PLANAR_YCBCR) {
      nsTArray<uint8_t> data;
      layers::PlanarYCbCrImage* ycbcrImage = static_cast<layers::PlanarYCbCrImage*> (aImage);
      gfxImageFormat format = SurfaceFormat::A8R8G8B8_UINT32;
      uint32_t stride = GetAlignedStride<16>(aSize.width * 4);
      size_t length = BufferSizeFromStrideAndHeight(stride, aSize.height);
      data.SetCapacity(length);

      ConvertYCbCrToRGB(*ycbcrImage->GetData(),
                        format,
                        aSize,
                        data.Elements(),
                        stride);

      rv = aEncoder->InitFromData(data.Elements(),
                                  aSize.width * aSize.height * 4,
                                  aSize.width,
                                  aSize.height,
                                  aSize.width * 4,
                                  imgIEncoder::INPUT_FORMAT_HOSTARGB,
                                  aOptions);
    } else {
      RefPtr<gfx::DataSourceSurface> dataSurface;
      RefPtr<layers::Image> image(aImage);
      dataSurface = GetBRGADataSourceSurfaceSync(image.forget());

      DataSourceSurface::MappedSurface map;
      if (!dataSurface->Map(gfx::DataSourceSurface::MapType::READ, &map)) {
        return NS_ERROR_INVALID_ARG;
      }
      rv = aEncoder->InitFromData(map.mData,
                                  aSize.width * aSize.height * 4,
                                  aSize.width,
                                  aSize.height,
                                  aSize.width * 4,
                                  imgIEncoder::INPUT_FORMAT_HOSTARGB,
                                  aOptions);
      dataSurface->Unmap();
    }

    if (NS_SUCCEEDED(rv)) {
      imgStream = do_QueryInterface(aEncoder);
    }
  } else {
    CheckedInt32 requiredBytes = CheckedInt32(aSize.width) * CheckedInt32(aSize.height) * 4;
    if (MOZ_UNLIKELY(!requiredBytes.isValid())) {
      return NS_ERROR_INVALID_ARG;
    }


    // no context, so we have to encode an empty image
    // note that if we didn't have a current context, the spec says we're
    // supposed to just return transparent black pixels of the canvas
    // dimensions.
    RefPtr<DataSourceSurface> emptyCanvas =
//.........这里部分代码省略.........