[json] using fuzzers from the source repo

Thanks @nlohmann for adding them.

projects/json/Dockerfile

@@ -20,4 +20,4 @@ RUN apt-get install -y binutils gcc
 
 RUN git clone --depth 1 -b develop https://github.com/nlohmann/json.git
 WORKDIR json/
-COPY build.sh parse_fuzzer.* $SRC/
+COPY build.sh *.options $SRC/

projects/json/build.sh

@@ -15,8 +15,9 @@
 #
 ################################################################################
 
-$CXX $CXXFLAGS -std=c++11 -Isrc/ \
-    $SRC/parse_fuzzer.cc -o $OUT/parse_fuzzer \
-    -lFuzzingEngine
-
-cp $SRC/*.options $OUT/
+FUZZER_FILES=$(find -name "fuzzer-parse*.cpp")
+for F in $FUZZER_FILES; do
+    FUZZER=$(basename $F .cpp)
+    $CXX $CXXFLAGS -std=c++11 -Isrc/ $F -o $OUT/$FUZZER -lFuzzingEngine
+    cp $SRC/fuzzer-parse.options $OUT/$FUZZER.options
+done

projects/json/parse_fuzzer.cc

@@ -1,36 +0,0 @@
-// Copyright 2016 Google Inc.
-//
-// 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.
-
-#include <iostream>
-#include <sstream>
-#include <json.hpp>
-
-using json = nlohmann::json;
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  try {
-    std::stringstream s;
-    s << json::parse(data, data + size);
-    try {
-      auto j = json::parse(s.str());
-      std::stringstream s2;
-      s2 << j;
-      assert(s.str() == s2.str());
-      assert(j == json::parse(s.str()));
-    } catch (const std::invalid_argument&) { 
-      assert(0);
-    }
-  } catch (const std::invalid_argument&) { }
-  return 0;
-}