Initial error handling code

src/effects/SkMergeImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMergeImageFilter.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkFlattenableBuffers.h"
+#include "SkValidationUtils.h"
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkMergeImageFilter::initAllocModes() {
     int inputCount = countInputs();
     if (inputCount) {
         size_t size = sizeof(uint8_t) * inputCount;
         if (size <= sizeof(fStorage)) {
             fModes = SkTCast<uint8_t*>(fStorage);
         } else {
@@ skipping 128 matching lines @@
     buffer.writeBool(fModes != NULL);
     if (fModes) {
         buffer.writeByteArray(fModes, countInputs() * sizeof(fModes[0]));
     }
 }
 
 SkMergeImageFilter::SkMergeImageFilter(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
     bool hasModes = buffer.readBool();
     if (hasModes) {
         this->initAllocModes();
-        SkASSERT(buffer.getArrayCount() == countInputs() * sizeof(fModes[0]));
+        int nbInputs = countInputs();
+        SkASSERT(buffer.getArrayCount() == nbInputs * sizeof(fModes[0]));

[Stephen White, 2013/09/09 17:43:00]

Should this also be validated, or is asserting good enough at this point?

         buffer.readByteArray(fModes);
+        for (int i = 0; i < nbInputs; ++i) {
+            buffer.validateData(SkIsValidMode((SkXfermode::Mode)fModes[i]));
+        }
     } else {
         fModes = 0;
     }
 }