gson: add stream parse fuzzer (#6819)

projects/gson/FuzzStreamParser.java

@@ -0,0 +1,33 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////////
+import com.code_intelligence.jazzer.api.FuzzedDataProvider;
+
+import java.io.*;
+import com.google.gson.*;
+
+public class FuzzStreamParser {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
+    try {
+      JsonStreamParser parser = new JsonStreamParser(data.consumeRemainingAsString());
+      JsonElement element;
+      while (parser.hasNext() == true) {
+        // We do not catch NoSuchElementException here as we 
+        // have just checked an element exists.
+        element = parser.next();
+      }
+    } catch (JsonParseException expected) { }
+  }
+}