fix null-pointer deref in SkComposeShader::toString()

src/core/SkComposeShader.cpp

 
 /*
  * 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.
  */
 
 
 #include "SkComposeShader.h"
@@ skipping 180 matching lines @@
             x += n;
             count -= n;
         } while (count > 0);
     }
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkComposeShader::toString(SkString* str) const {
     str->append("SkComposeShader: (");
 
     str->append("ShaderA: ");

[robertphillips, 2015/06/16 17:46:13]

might as well add guards for fShaderA & fShaderB while we're at it.

     fShaderA->toString(str);
     str->append(" ShaderB: ");
     fShaderB->toString(str);
-    str->append(" Xfermode: ");
-    fMode->toString(str);
+    if (fMode) {
+        str->append(" Xfermode: ");
+        fMode->toString(str);
+    }
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif