Initial implementation of a record-level bitcode fuzzer.

include/llvm/Bitcode/NaCl/NaClFuzz.h

+//===- NaClFuzz.h - Fuzz PNaCl bitcode records ------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a basic fuzzer for a list of PNaCl bitcode records.
+//
+// *** WARNING *** The implementation of the fuzzer uses a random
+// number generator.  As a result, this code is not thread safe.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BITCODE_NACL_NACLFUZZ_H
+#define LLVM_BITCODE_NACL_NACLFUZZ_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Bitcode/NaCl/NaClBitcodeMungeUtils.h"
+#include "llvm/Bitcode/NaCl/NaClRandNumGen.h"
+
+#include <random>
+
+namespace naclfuzz {
+
+using namespace llvm;
+
+/// \brief Fuzzes a list of editable bitcode records.
+class RecordFuzzer {
+  RecordFuzzer(const RecordFuzzer&) = delete;
+  void operator=(const RecordFuzzer&) = delete;
+public:
+  typedef NaClMungedBitcode::iterator iterator;
+
+  /// \brief The set of possible fuzzing actions.
+  enum EditAction {
+    /// \brief Inserts a new record into the list of bitcode records.
+    InsertRecord,
+    /// \brief Mutate contents of an existing bitcode record.
+    MutateRecord,
+    /// \brief Removes an existing record from the list of bitcode
+    /// records.
+    RemoveRecord,
+    /// \brief Replaces an existing record with a new bitcode record.
+    ReplaceRecord,
+    /// \brief Swaps two records in the bitcode record list.
+    SwapRecord
+  };
+
+  virtual ~RecordFuzzer();
+
+  /// \brief Generates a random mutation of the bitcode, using the
+  /// provided random number generator. Percentage (a value between 0
+  /// and 1 defined by Count/Base) is used to define the number of
+  /// fuzzing actions applied to the bitcode.  Returns true if fuzzing
+  /// succeeded.
+  ///
+  /// May be called an arbitrary number of times. Results are left in
+  /// the munged bitcode records passed into static method
+  /// createSimpleRecordFuzzer.
+  virtual bool fuzz(unsigned Count, unsigned Base=100) = 0;
+
+  /// \brief Shows how many times each record was edited in the
+  /// corresponding (input) bitcode, over all calls to fuzz.
+  virtual void showRecordDistribution(raw_ostream &Out) const = 0;
+
+  /// \brief Shows how many times each type of edit action was applied
+  /// to the corresponding bitcode, over all calls to fuzz.
+  virtual void showEditDistribution(raw_ostream &Out) const = 0;
+
+  // Creates an instance of a fuzzer for the given bitcode.
+  static RecordFuzzer
+  *createSimpleRecordFuzzer(NaClMungedBitcode &Bitcode,
+                            RandomNumberGenerator &RandGenerator);
+
+  /// Returns printable name for the edit action.
+  static const char *actionName(EditAction Action);
+
+protected:
+  RecordFuzzer(NaClMungedBitcode &Bitcode, RandomNumberGenerator &Generator);
+
+  // Holds the bitcode being munged.
+  NaClMungedBitcode &Bitcode;
+
+  // Hold the random number generator.
+  RandomNumberGenerator &Generator;
+
+  // Erases the last fuzzing result from the munged bitcode records
+  // in Bitcode.
+  virtual void clear();
+};
+
+} // end of namespace naclfuzz
+
+#endif // LLVM_BITCODE_NACL_NACLFUZZ_H