Fix ImageData constructor infelicity.

Source/core/html/ImageData.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 66 matching lines @@
     dataSize *= width;
     dataSize *= height;
     if (dataSize.hasOverflowed()) {
         exceptionState.throwDOMException(IndexSizeError, "The requested image size exceeds the supported range.");
         return nullptr;
     }
 
     return adoptRefWillBeNoop(new ImageData(IntSize(width, height)));
 }
 
+bool ImageData::validateConstructorArguments(DOMUint8ClampedArray* data, unsigned width, unsigned& lengthInPixels, ExceptionState& exceptionState)
+{
+    if (!width) {
+        exceptionState.throwDOMException(IndexSizeError, "The source width is zero or not a number.");
+        return false;
+    }
+    ASSERT(data);
+    unsigned length = data->length();
+    if (!length) {
+        exceptionState.throwDOMException(IndexSizeError, "The input data has a zero byte length.");
+        return false;
+    }
+    if (length % 4) {
+        exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not a multiple of 4.");
+        return false;
+    }
+    length /= 4;
+    if (length % width) {
+        exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not a multiple of (4 * width).");
+        return false;
+    }
+    lengthInPixels = length;
+    return true;
+}
+
+PassRefPtrWillBeRawPtr<ImageData> ImageData::create(DOMUint8ClampedArray* data, unsigned width, ExceptionState& exceptionState)
+{
+    if (!RuntimeEnabledFeatures::imageDataConstructorEnabled()) {
+        exceptionState.throwTypeError("Illegal constructor");
+        return nullptr;
+    }
+    unsigned lengthInPixels = 0;
+    if (!validateConstructorArguments(data, width, lengthInPixels, exceptionState)) {
+        ASSERT(exceptionState.hadException());
+        return nullptr;
+    }
+    ASSERT(lengthInPixels && width);
+    unsigned height = lengthInPixels / width;
+    return adoptRefWillBeNoop(new ImageData(IntSize(width, height), data));
+}
+
 PassRefPtrWillBeRawPtr<ImageData> ImageData::create(DOMUint8ClampedArray* data, unsigned width, unsigned height, ExceptionState& exceptionState)
 {
     if (!RuntimeEnabledFeatures::imageDataConstructorEnabled()) {
         exceptionState.throwTypeError("Illegal constructor");
         return nullptr;
     }
-    if (!data) {
-        exceptionState.throwTypeError("Expected a Uint8ClampedArray as first argument.");
+    unsigned lengthInPixels = 0;
+    if (!validateConstructorArguments(data, width, lengthInPixels, exceptionState)) {
+        ASSERT(exceptionState.hadException());
         return nullptr;
     }
-    if (!width) {
-        exceptionState.throwDOMException(IndexSizeError, "The source width is zero or not a number.");
-        return nullptr;
-    }
-
-    unsigned length = data->length();
-    if (!length) {
-        exceptionState.throwDOMException(IndexSizeError, "The input data has a zero byte length.");
-        return nullptr;
-    }
-    if (length % 4) {
-        exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not a multiple of 4.");
-        return nullptr;
-    }
-    length /= 4;
-    if (length % width) {
-        exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not a multiple of (4 * width).");
-        return nullptr;
-    }
-    if (!height) {
-        height = length / width;
-    } else if (height != length / width) {
+    ASSERT(lengthInPixels && width);
+    if (height != lengthInPixels / width) {
         exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not equal to (4 * width * height).");
         return nullptr;
     }
-
     return adoptRefWillBeNoop(new ImageData(IntSize(width, height), data));
 }
 
 v8::Handle<v8::Object> ImageData::associateWithWrapper(v8::Isolate* isolate, const WrapperTypeInfo* wrapperType, v8::Handle<v8::Object> wrapper)
 {
     ScriptWrappable::associateWithWrapper(isolate, wrapperType, wrapper);
 
     if (!wrapper.IsEmpty()) {
         // Create a V8 Uint8ClampedArray object.
         v8::Handle<v8::Value> pixelArray = toV8(m_data.get(), wrapper, isolate);
@@ skipping 13 matching lines @@
 }
 
 ImageData::ImageData(const IntSize& size, PassRefPtr<DOMUint8ClampedArray> byteArray)
     : m_size(size)
     , m_data(byteArray)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(static_cast<unsigned>(size.width() * size.height() * 4) <= m_data->length());
 }
 
 } // namespace blink