Initial error handling code

src/effects/SkDisplacementMapEffect.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDisplacementMapEffect.h"
 #include "SkFlattenableBuffers.h"
 #include "SkUnPreMultiply.h"
@@ skipping 110 matching lines @@
       case SkDisplacementMapEffect::kA_ChannelSelectorType:
         computeDisplacement<SkDisplacementMapEffect::kA_ChannelSelectorType>(
             yChannelSelector, scale, dst, displ, src);
         break;
       case SkDisplacementMapEffect::kUnknown_ChannelSelectorType:
       default:
         SkDEBUGFAIL("Unknown X channel selector");
     }
 }
 
+bool ChannelSelectorTypeIsValid(SkDisplacementMapEffect::ChannelSelectorType channelSelector) {
+    switch (channelSelector) {
+    case SkDisplacementMapEffect::kUnknown_ChannelSelectorType:
+    case SkDisplacementMapEffect::kR_ChannelSelectorType:
+    case SkDisplacementMapEffect::kG_ChannelSelectorType:
+    case SkDisplacementMapEffect::kB_ChannelSelectorType:
+    case SkDisplacementMapEffect::kA_ChannelSelectorType:
+        return true;
+    default:
+        break;
+    }
+    return false;
+}
+
 } // end namespace
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkDisplacementMapEffect::SkDisplacementMapEffect(ChannelSelectorType xChannelSelector,
                                                  ChannelSelectorType yChannelSelector,
                                                  SkScalar scale,
                                                  SkImageFilter* displacement,
                                                  SkImageFilter* color)
   : INHERITED(displacement, color)
   , fXChannelSelector(xChannelSelector)
   , fYChannelSelector(yChannelSelector)
   , fScale(scale)
 {
 }
 
 SkDisplacementMapEffect::~SkDisplacementMapEffect() {
 }
 
 SkDisplacementMapEffect::SkDisplacementMapEffect(SkFlattenableReadBuffer& buffer)
   : INHERITED(buffer)
 {
     fXChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
     fYChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
     fScale            = buffer.readScalar();
+    buffer.validate(ChannelSelectorTypeIsValid(fXChannelSelector) &&
+                    ChannelSelectorTypeIsValid(fYChannelSelector) &&
+                    SkScalarIsFinite(fScale));
 }
 
 void SkDisplacementMapEffect::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeInt((int) fXChannelSelector);
     buffer.writeInt((int) fYChannelSelector);
     buffer.writeScalar(fScale);
 }
 
 bool SkDisplacementMapEffect::onFilterImage(Proxy* proxy,
@@ skipping 328 matching lines @@
                                                         const GrGLCaps&) {
     const GrDisplacementMapEffect& displacementMap =
         drawEffect.castEffect<GrDisplacementMapEffect>();
 
     EffectKey xKey = displacementMap.xChannelSelector();
     EffectKey yKey = displacementMap.yChannelSelector() << SkDisplacementMapEffect::kKeyBits;
 
     return xKey | yKey;
 }
 #endif