Initial error handling code

src/core/SkBitmap.cpp

Index: src/core/SkBitmap.cpp
diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index 05f5208a69bfd62fba985d9f2e54e59d4853bb0d..046e20ab62b416f45f347efbbc14de833bcecccd 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -19,6 +19,7 @@
 #include "SkThread.h"
 #include "SkUnPreMultiply.h"
 #include "SkUtils.h"
+#include "SkValidationUtils.h"
 #include "SkPackBits.h"
 #include <new>
 
@@ -268,7 +269,7 @@ void SkBitmap::getBounds(SkIRect* bounds) const {
 ///////////////////////////////////////////////////////////////////////////////
 
 static bool validate_alphaType(SkBitmap::Config config, SkAlphaType alphaType,
-                               SkAlphaType* canonical) {
+                               SkAlphaType* canonical = NULL) {
     switch (config) {
         case SkBitmap::kNo_Config:
             alphaType = kIgnore_SkAlphaType;
@@ -1604,10 +1605,12 @@ void SkBitmap::unflatten(SkFlattenableReadBuffer& buffer) {
     int width = buffer.readInt();
     int height = buffer.readInt();
     int rowBytes = buffer.readInt();
-    int config = buffer.readInt();
-    int alphaType = buffer.readInt();
+    Config config = (Config)buffer.readInt();
+    SkAlphaType alphaType = (SkAlphaType)buffer.readInt();
+    buffer.validate((width >= 0) && (height >= 0) && (rowBytes >= 0) &&
+                    SkIsValidConfig(config) && validate_alphaType(config, alphaType));
 
-    this->setConfig((Config)config, width, height, rowBytes, (SkAlphaType)alphaType);
+    this->setConfig(config, width, height, rowBytes, alphaType);
 
     int reftype = buffer.readInt();
     switch (reftype) {
@@ -1620,6 +1623,7 @@ void SkBitmap::unflatten(SkFlattenableReadBuffer& buffer) {
         case SERIALIZE_PIXELTYPE_NONE:
             break;
         default:
+            buffer.validate(false);
             SkDEBUGFAIL("unrecognized pixeltype in serialized data");
             sk_throw();
     }