--- a/lib/Fuzzer/FuzzerMain.cpp	Wed Feb 18 14:56:07 2015 +0900
+++ b/lib/Fuzzer/FuzzerMain.cpp	Tue Oct 13 17:48:58 2015 +0900
@@ -9,185 +9,12 @@
 // main() and flags.
 //===----------------------------------------------------------------------===//
 
+#include "FuzzerInterface.h"
 #include "FuzzerInternal.h"
 
-#include <cstring>
-#include <unistd.h>
-#include <iostream>
-#include <thread>
-#include <atomic>
-#include <mutex>
-
-// Program arguments.
-struct FlagDescription {
-  const char *Name;
-  const char *Description;
-  int   Default;
-  int   *Flag;
-};
-
-struct {
-#define FUZZER_FLAG(Type, Name, Default, Description) Type Name;
-#include "FuzzerFlags.def"
-#undef FUZZER_FLAG
-} Flags;
-
-static FlagDescription FlagDescriptions [] {
-#define FUZZER_FLAG(Type, Name, Default, Description) {#Name, Description, Default, &Flags.Name},
-#include "FuzzerFlags.def"
-#undef FUZZER_FLAG
-};
-
-static const size_t kNumFlags =
-    sizeof(FlagDescriptions) / sizeof(FlagDescriptions[0]);
-
-static std::vector<std::string> inputs;
-static const char *ProgName;
-
-static void PrintHelp() {
-  std::cerr << "Usage: " << ProgName
-            << " [-flag1=val1 [-flag2=val2 ...] ] [dir1 [dir2 ...] ]\n";
-  std::cerr << "\nFlags: (strictly in form -flag=value)\n";
-  size_t MaxFlagLen = 0;
-  for (size_t F = 0; F < kNumFlags; F++)
-    MaxFlagLen = std::max(strlen(FlagDescriptions[F].Name), MaxFlagLen);
-
-  for (size_t F = 0; F < kNumFlags; F++) {
-    const auto &D = FlagDescriptions[F];
-    std::cerr << "  " << D.Name;
-    for (size_t i = 0, n = MaxFlagLen - strlen(D.Name); i < n; i++)
-      std::cerr << " ";
-    std::cerr << "\t";
-    std::cerr << D.Default << "\t" << D.Description << "\n";
-  }
-}
-
-static const char *FlagValue(const char *Param, const char *Name) {
-  size_t Len = strlen(Name);
-  if (Param[0] == '-' && strstr(Param + 1, Name) == Param + 1 &&
-      Param[Len + 1] == '=')
-      return &Param[Len + 2];
-  return nullptr;
-}
-
-static bool ParseOneFlag(const char *Param) {
-  if (Param[0] != '-') return false;
-  for (size_t F = 0; F < kNumFlags; F++) {
-    const char *Name = FlagDescriptions[F].Name;
-    const char *Str = FlagValue(Param, Name);
-    if (Str)  {
-      int Val = std::stol(Str);
-      *FlagDescriptions[F].Flag = Val;
-      if (Flags.verbosity >= 2)
-        std::cerr << "Flag: " << Name << " " << Val << "\n";
-      return true;
-    }
-  }
-  PrintHelp();
-  exit(1);
-}
-
-// We don't use any library to minimize dependencies.
-static void ParseFlags(int argc, char **argv) {
-  for (size_t F = 0; F < kNumFlags; F++)
-    *FlagDescriptions[F].Flag = FlagDescriptions[F].Default;
-  for (int A = 1; A < argc; A++) {
-    if (ParseOneFlag(argv[A])) continue;
-    inputs.push_back(argv[A]);
-  }
-}
-
-static void WorkerThread(const std::string &Cmd, std::atomic<int> *Counter,
-                        int NumJobs, std::atomic<bool> *HasErrors) {
-  static std::mutex CerrMutex;
-  while (true) {
-    int C = (*Counter)++;
-    if (C >= NumJobs) break;
-    std::string Log = "fuzz-" + std::to_string(C) + ".log";
-    std::string ToRun = Cmd + " > " + Log + " 2>&1\n";
-    if (Flags.verbosity)
-      std::cerr << ToRun;
-    int ExitCode = system(ToRun.c_str());
-    if (ExitCode != 0)
-      *HasErrors = true;
-    std::lock_guard<std::mutex> Lock(CerrMutex);
-    std::cerr << "================== Job " << C
-              << " exited with exit code " << ExitCode
-              << " =================\n";
-    fuzzer::CopyFileToErr(Log);
-  }
-}
-
-static int RunInMultipleProcesses(int argc, char **argv, int NumWorkers,
-                                  int NumJobs) {
-  std::atomic<int> Counter(0);
-  std::atomic<bool> HasErrors(false);
-  std::string Cmd;
-  for (int i = 0; i < argc; i++) {
-    if (FlagValue(argv[i], "jobs") || FlagValue(argv[i], "workers")) continue;
-    Cmd += argv[i];
-    Cmd += " ";
-  }
-  std::vector<std::thread> V;
-  for (int i = 0; i < NumWorkers; i++)
-    V.push_back(std::thread(WorkerThread, Cmd, &Counter, NumJobs, &HasErrors));
-  for (auto &T : V)
-    T.join();
-  return HasErrors ? 1 : 0;
-}
+// This function should be defined by the user.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
 
 int main(int argc, char **argv) {
-  using namespace fuzzer;
-
-  ProgName = argv[0];
-  ParseFlags(argc, argv);
-  if (Flags.help) {
-    PrintHelp();
-    return 0;
-  }
-
-  if (Flags.workers > 0 && Flags.jobs > 0)
-    return RunInMultipleProcesses(argc, argv, Flags.workers, Flags.jobs);
-
-  Fuzzer::FuzzingOptions Options;
-  Options.Verbosity = Flags.verbosity;
-  Options.MaxLen = Flags.max_len;
-  Options.DoCrossOver = Flags.cross_over;
-  Options.MutateDepth = Flags.mutate_depth;
-  Options.ExitOnFirst = Flags.exit_on_first;
-  Options.UseFullCoverageSet = Flags.use_full_coverage_set;
-  Options.PreferSmallDuringInitialShuffle =
-      Flags.prefer_small_during_initial_shuffle;
-  if (Flags.runs >= 0)
-    Options.MaxNumberOfRuns = Flags.runs;
-  if (!inputs.empty())
-    Options.OutputCorpus = inputs[0];
-  Fuzzer F(Options);
-
-  unsigned seed = Flags.seed;
-  // Initialize seed.
-  if (seed == 0)
-    seed = time(0) * 10000 + getpid();
-  if (Flags.verbosity)
-    std::cerr << "Seed: " << seed << "\n";
-  srand(seed);
-
-  // Timer
-  if (Flags.timeout > 0)
-    SetTimer(Flags.timeout);
-
-  for (auto &inp : inputs)
-    F.ReadDir(inp);
-
-  if (F.CorpusSize() == 0)
-    F.AddToCorpus(Unit());  // Can't fuzz empty corpus, so add an empty input.
-  F.ShuffleAndMinimize();
-  if (Flags.save_minimized_corpus)
-    F.SaveCorpus();
-  F.Loop(Flags.iterations < 0 ? INT_MAX : Flags.iterations);
-  if (Flags.verbosity)
-    std::cerr << "Done " << F.getTotalNumberOfRuns()
-              << " runs in " << F.secondsSinceProcessStartUp()
-              << " seconds\n";
-  return 0;
+  return fuzzer::FuzzerDriver(argc, argv, LLVMFuzzerTestOneInput);
 }