diff -r 000000000000 -r 6474c204b198 image/decoders/nsIconDecoder.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/image/decoders/nsIconDecoder.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,126 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 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/. */
+
+#include "nsIconDecoder.h"
+#include "nsIInputStream.h"
+#include "RasterImage.h"
+#include "nspr.h"
+#include "nsRect.h"
+
+#include "nsError.h"
+#include <algorithm>
+
+namespace mozilla {
+namespace image {
+
+nsIconDecoder::nsIconDecoder(RasterImage &aImage)
+ : Decoder(aImage),
+   mWidth(-1),
+   mHeight(-1),
+   mPixBytesRead(0),
+   mState(iconStateStart)
+{
+  // Nothing to do
+}
+
+nsIconDecoder::~nsIconDecoder()
+{ }
+
+void
+nsIconDecoder::WriteInternal(const char *aBuffer, uint32_t aCount, DecodeStrategy)
+{
+  NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");
+
+  // We put this here to avoid errors about crossing initialization with case
+  // jumps on linux.
+  uint32_t bytesToRead = 0;
+
+  // Loop until the input data is gone
+  while (aCount > 0) {
+    switch (mState) {
+      case iconStateStart:
+
+        // Grab the width
+        mWidth = (uint8_t)*aBuffer;
+
+        // Book Keeping
+        aBuffer++;
+        aCount--;
+        mState = iconStateHaveHeight;
+        break;
+
+      case iconStateHaveHeight:
+
+        // Grab the Height
+        mHeight = (uint8_t)*aBuffer;
+
+        // Post our size to the superclass
+        PostSize(mWidth, mHeight);
+        if (HasError()) {
+          // Setting the size led to an error.
+          mState = iconStateFinished;
+          return;
+        }
+
+        // If We're doing a size decode, we're done
+        if (IsSizeDecode()) {
+          mState = iconStateFinished;
+          break;
+        }
+
+        if (!mImageData) {
+          PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
+          return;
+        }
+
+        // Book Keeping
+        aBuffer++;
+        aCount--;
+        mState = iconStateReadPixels;
+        break;
+
+      case iconStateReadPixels:
+      {
+
+        // How many bytes are we reading?
+        bytesToRead = std::min(aCount, mImageDataLength - mPixBytesRead);
+
+        // Copy the bytes
+        memcpy(mImageData + mPixBytesRead, aBuffer, bytesToRead);
+
+        // Performance isn't critical here, so our update rectangle is
+        // always the full icon
+        nsIntRect r(0, 0, mWidth, mHeight);
+
+        // Invalidate
+        PostInvalidation(r);
+
+        // Book Keeping
+        aBuffer += bytesToRead;
+        aCount -= bytesToRead;
+        mPixBytesRead += bytesToRead;
+
+        // If we've got all the pixel bytes, we're finished
+        if (mPixBytesRead == mImageDataLength) {
+          PostFrameStop();
+          PostDecodeDone();
+          mState = iconStateFinished;
+        }
+        break;
+      }
+
+      case iconStateFinished:
+
+        // Consume all excess data silently
+        aCount = 0;
+
+        break;
+    }
+  }
+}
+
+} // namespace image
+} // namespace mozilla