Adding more validation

src/effects/SkPerlinNoiseShader.cpp

Index: src/effects/SkPerlinNoiseShader.cpp
diff --git a/src/effects/SkPerlinNoiseShader.cpp b/src/effects/SkPerlinNoiseShader.cpp
index f2ce67924e5d4109800cfafc6b490f8868caf950..87c42dc343d93eba243f9fb23b5d05e4a7e7f247 100644
--- a/src/effects/SkPerlinNoiseShader.cpp
+++ b/src/effects/SkPerlinNoiseShader.cpp
@@ -51,6 +51,17 @@ inline SkScalar smoothCurve(SkScalar t) {
     return SkScalarMul(SkScalarSquare(t), SK_Scalar3 - 2 * t);
 }
 
+bool perlin_noise_type_is_valid(SkPerlinNoiseShader::Type type) {
+    switch (type) {
+    case SkPerlinNoiseShader::kFractalNoise_Type:
+    case SkPerlinNoiseShader::kTurbulence_Type:
+        return true;
+    default:
+        break;
+    }
+    return false;
+}
+
 } // end namespace
 
 struct SkPerlinNoiseShader::StitchData {
@@ -301,6 +312,8 @@ SkPerlinNoiseShader::SkPerlinNoiseShader(SkFlattenableReadBuffer& buffer) :
     fTileSize.fHeight = buffer.readInt();
     setTileSize(fTileSize);
     fMatrix.reset();
+    buffer.validate(perlin_noise_type_is_valid(fType) &&
+                    (fNumOctaves >= 0) && (fNumOctaves <= 0xFF));

[Stephen White, 2013/11/22 21:00:17]

Could we express this as decimal 255, unless there's a strong reason for it to
be hex?  Maybe it should be a constant at the top of the file? (Doesn't seem to
be in the spec -- I assume it's a limitation of this implementation.)

Now that I look at it, I see the regular constructor is and'ing the octaves with
0xFF, which seems kinda weird to me. Should probably just be octaves > 255 ? 255
: 0, no?

 }
 
 SkPerlinNoiseShader::~SkPerlinNoiseShader() {