add libfuzzer custom mutator, minor enhancements and fixes

custom_mutators/libfuzzer/FuzzerDefs.h

@@ -0,0 +1,75 @@
+//===- FuzzerDefs.h - Internal header for the Fuzzer ------------*- C++ -* ===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// Basic definitions.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FUZZER_DEFS_H
+#define LLVM_FUZZER_DEFS_H
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <memory>
+#include <set>
+#include <string>
+#include <vector>
+
+
+namespace fuzzer {
+
+template <class T> T Min(T a, T b) { return a < b ? a : b; }
+template <class T> T Max(T a, T b) { return a > b ? a : b; }
+
+class Random;
+class Dictionary;
+class DictionaryEntry;
+class MutationDispatcher;
+struct FuzzingOptions;
+class InputCorpus;
+struct InputInfo;
+struct ExternalFunctions;
+
+// Global interface to functions that may or may not be available.
+extern ExternalFunctions *EF;
+
+// We are using a custom allocator to give a different symbol name to STL
+// containers in order to avoid ODR violations.
+template<typename T>
+  class fuzzer_allocator: public std::allocator<T> {
+    public:
+      fuzzer_allocator() = default;
+
+      template<class U>
+      fuzzer_allocator(const fuzzer_allocator<U>&) {}
+
+      template<class Other>
+      struct rebind { typedef fuzzer_allocator<Other> other;  };
+  };
+
+template<typename T>
+using Vector = std::vector<T, fuzzer_allocator<T>>;
+
+template<typename T>
+using Set = std::set<T, std::less<T>, fuzzer_allocator<T>>;
+
+typedef Vector<uint8_t> Unit;
+typedef Vector<Unit> UnitVector;
+typedef int (*UserCallback)(const uint8_t *Data, size_t Size);
+
+int FuzzerDriver(int *argc, char ***argv, UserCallback Callback);
+
+uint8_t *ExtraCountersBegin();
+uint8_t *ExtraCountersEnd();
+void ClearExtraCounters();
+
+extern bool RunningUserCallback;
+
+}  // namespace fuzzer
+
+#endif  // LLVM_FUZZER_DEFS_H