Handle zero-length encoded images gracefully during deserialization

src/core/SkWriteBuffer.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 "SkWriteBuffer.h"
 #include "SkBitmap.h"
@@ skipping 205 matching lines @@
 
     this->writeUInt(0); // signal raw pixels
     SkBitmap::WriteRawPixels(this, bitmap);
 }
 
 void SkWriteBuffer::writeImage(const SkImage* image) {
     this->writeInt(image->width());
     this->writeInt(image->height());
 
     SkAutoTUnref<SkData> encoded(image->encode(this->getPixelSerializer()));
-    if (encoded) {
+    if (encoded && encoded->size() > 0) {
         write_encoded_bitmap(this, encoded, SkIPoint::Make(0, 0));
         return;
     }
 
     this->writeUInt(0); // signal no pixels (in place of the size of the encoded data)
 }
 
 void SkWriteBuffer::writeTypeface(SkTypeface* obj) {
     if (nullptr == obj || nullptr == fTFSet) {
         fWriter.write32(0);
@@ skipping 97 matching lines @@
     // make room for the size of the flattened object
     (void)fWriter.reserve(sizeof(uint32_t));
     // record the current size, so we can subtract after the object writes.
     size_t offset = fWriter.bytesWritten();
     // now flatten the object
     flattenable->flatten(*this);
     size_t objSize = fWriter.bytesWritten() - offset;
     // record the obj's size
     fWriter.overwriteTAt(offset - sizeof(uint32_t), SkToU32(objSize));
 }