fix misc asserts and checks found by fuzzer

include/core/SkPathEffect.h

 
 /*
  * Copyright 2006 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.
  */
 
 
 #ifndef SkPathEffect_DEFINED
@@ skipping 165 matching lines @@
     This subclass of SkPathEffect composes its two arguments, to create
     a compound pathEffect.
 */
 class SkComposePathEffect : public SkPairPathEffect {
 public:
     /** Construct a pathEffect whose effect is to apply first the inner pathEffect
         and the the outer pathEffect (e.g. outer(inner(path)))
         The reference counts for outer and inner are both incremented in the constructor,
         and decremented in the destructor.
     */
-    static SkComposePathEffect* Create(SkPathEffect* outer, SkPathEffect* inner) {
+    static SkPathEffect* Create(SkPathEffect* outer, SkPathEffect* inner) {
+        if (!outer) {
+            return SkSafeRef(inner);
+        }
+        if (!inner) {
+            return SkSafeRef(outer);
+        }
         return new SkComposePathEffect(outer, inner);
     }
 
     virtual bool filterPath(SkPath* dst, const SkPath& src,
                             SkStrokeRec*, const SkRect*) const override;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkComposePathEffect)
 
 #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
@@ skipping 16 matching lines @@
     This subclass of SkPathEffect applies two pathEffects, one after the other.
     Its filterPath() returns true if either of the effects succeeded.
 */
 class SkSumPathEffect : public SkPairPathEffect {
 public:
     /** Construct a pathEffect whose effect is to apply two effects, in sequence.
         (e.g. first(path) + second(path))
         The reference counts for first and second are both incremented in the constructor,
         and decremented in the destructor.
     */
-    static SkSumPathEffect* Create(SkPathEffect* first, SkPathEffect* second) {
+    static SkPathEffect* Create(SkPathEffect* first, SkPathEffect* second) {
+        if (!first) {
+            return SkSafeRef(second);
+        }
+        if (!second) {
+            return SkSafeRef(first);
+        }
         return new SkSumPathEffect(first, second);
     }
 
     virtual bool filterPath(SkPath* dst, const SkPath& src,
                             SkStrokeRec*, const SkRect*) const override;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSumPathEffect)
 
 #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
     bool exposedInAndroidJavaAPI() const override { return true; }
 #endif
 
 protected:
     SkSumPathEffect(SkPathEffect* first, SkPathEffect* second) : INHERITED(first, second) {}
 
 private:
     // illegal
     SkSumPathEffect(const SkSumPathEffect&);
     SkSumPathEffect& operator=(const SkSumPathEffect&);
 
     typedef SkPairPathEffect INHERITED;
 };
 
 #endif