compiler-rt/lib/fuzzer/FuzzerDriver.cpp

   1 //===- FuzzerDriver.cpp - FuzzerDriver function and flags -----------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 // FuzzerDriver and flag parsing.
   9 //===----------------------------------------------------------------------===//
  10
  11 #include "FuzzerCommand.h"
  12 #include "FuzzerCorpus.h"
  13 #include "FuzzerFork.h"
  14 #include "FuzzerIO.h"
  15 #include "FuzzerInterface.h"
  16 #include "FuzzerInternal.h"
  17 #include "FuzzerMerge.h"
  18 #include "FuzzerMutate.h"
  19 #include "FuzzerPlatform.h"
  20 #include "FuzzerRandom.h"
  21 #include "FuzzerTracePC.h"
  22 #include <algorithm>
  23 #include <atomic>
  24 #include <chrono>
  25 #include <cstdlib>
  26 #include <cstring>
  27 #include <mutex>
  28 #include <string>
  29 #include <thread>
  30 #include <fstream>
  31
  32 // This function should be present in the libFuzzer so that the client
  33 // binary can test for its existence.
  34 #if LIBFUZZER_MSVC
  35 extern "C" void __libfuzzer_is_present() {}
  36 #if defined(_M_IX86) || defined(__i386__)
  37 #pragma comment(linker, "/include:___libfuzzer_is_present")
  38 #else
  39 #pragma comment(linker, "/include:__libfuzzer_is_present")
  40 #endif
  41 #else
  42 extern "C" __attribute__((used)) void __libfuzzer_is_present() {}
  43 #endif  // LIBFUZZER_MSVC
  44
  45 namespace fuzzer {
  46
  47 // Program arguments.
  48 struct FlagDescription {
  49   const char *Name;
  50   const char *Description;
  51   int   Default;
  52   int   *IntFlag;
  53   const char **StrFlag;
  54   unsigned int *UIntFlag;
  55 };
  56
  57 struct {
  58 #define FUZZER_DEPRECATED_FLAG(Name)
  59 #define FUZZER_FLAG_INT(Name, Default, Description) int Name;
  60 #define FUZZER_FLAG_UNSIGNED(Name, Default, Description) unsigned int Name;
  61 #define FUZZER_FLAG_STRING(Name, Description) const char *Name;
  62 #include "FuzzerFlags.def"
  63 #undef FUZZER_DEPRECATED_FLAG
  64 #undef FUZZER_FLAG_INT
  65 #undef FUZZER_FLAG_UNSIGNED
  66 #undef FUZZER_FLAG_STRING
  67 } Flags;
  68
  69 static const FlagDescription FlagDescriptions [] {
  70 #define FUZZER_DEPRECATED_FLAG(Name)                                           \
  71   {#Name, "Deprecated; don't use", 0, nullptr, nullptr, nullptr},
  72 #define FUZZER_FLAG_INT(Name, Default, Description)                            \
  73   {#Name, Description, Default, &Flags.Name, nullptr, nullptr},
  74 #define FUZZER_FLAG_UNSIGNED(Name, Default, Description)                       \
  75   {#Name,   Description, static_cast<int>(Default),                            \
  76    nullptr, nullptr, &Flags.Name},
  77 #define FUZZER_FLAG_STRING(Name, Description)                                  \
  78   {#Name, Description, 0, nullptr, &Flags.Name, nullptr},
  79 #include "FuzzerFlags.def"
  80 #undef FUZZER_DEPRECATED_FLAG
  81 #undef FUZZER_FLAG_INT
  82 #undef FUZZER_FLAG_UNSIGNED
  83 #undef FUZZER_FLAG_STRING
  84 };
  85
  86 static const size_t kNumFlags =
  87     sizeof(FlagDescriptions) / sizeof(FlagDescriptions[0]);
  88
  89 static std::vector<std::string> *Inputs;
  90 static std::string *ProgName;
  91
  92 static void PrintHelp() {
  93   Printf("Usage:\n");
  94   auto Prog = ProgName->c_str();
  95   Printf("\nTo run fuzzing pass 0 or more directories.\n");
  96   Printf("%s [-flag1=val1 [-flag2=val2 ...] ] [dir1 [dir2 ...] ]\n", Prog);
  97
  98   Printf("\nTo run individual tests without fuzzing pass 1 or more files:\n");
  99   Printf("%s [-flag1=val1 [-flag2=val2 ...] ] file1 [file2 ...]\n", Prog);
 100
 101   Printf("\nFlags: (strictly in form -flag=value)\n");
 102   size_t MaxFlagLen = 0;
 103   for (size_t F = 0; F < kNumFlags; F++)
 104     MaxFlagLen = std::max(strlen(FlagDescriptions[F].Name), MaxFlagLen);
 105
 106   for (size_t F = 0; F < kNumFlags; F++) {
 107     const auto &D = FlagDescriptions[F];
 108     if (strstr(D.Description, "internal flag") == D.Description) continue;
 109     Printf(" %s", D.Name);
 110     for (size_t i = 0, n = MaxFlagLen - strlen(D.Name); i < n; i++)
 111       Printf(" ");
 112     Printf("\t");
 113     Printf("%d\t%s\n", D.Default, D.Description);
 114   }
 115   Printf("\nFlags starting with '--' will be ignored and "
 116             "will be passed verbatim to subprocesses.\n");
 117 }
 118
 119 static const char *FlagValue(const char *Param, const char *Name) {
 120   size_t Len = strlen(Name);
 121   if (Param[0] == '-' && strstr(Param + 1, Name) == Param + 1 &&
 122       Param[Len + 1] == '=')
 123       return &Param[Len + 2];
 124   return nullptr;
 125 }
 126
 127 // Avoid calling stol as it triggers a bug in clang/glibc build.
 128 static long MyStol(const char *Str) {
 129   long Res = 0;
 130   long Sign = 1;
 131   if (*Str == '-') {
 132     Str++;
 133     Sign = -1;
 134   }
 135   for (size_t i = 0; Str[i]; i++) {
 136     char Ch = Str[i];
 137     if (Ch < '0' || Ch > '9')
 138       return Res;
 139     Res = Res * 10 + (Ch - '0');
 140   }
 141   return Res * Sign;
 142 }
 143
 144 static bool ParseOneFlag(const char *Param) {
 145   if (Param[0] != '-') return false;
 146   if (Param[1] == '-') {
 147     static bool PrintedWarning = false;
 148     if (!PrintedWarning) {
 149       PrintedWarning = true;
 150       Printf("INFO: libFuzzer ignores flags that start with '--'\n");
 151     }
 152     for (size_t F = 0; F < kNumFlags; F++)
 153       if (FlagValue(Param + 1, FlagDescriptions[F].Name))
 154         Printf("WARNING: did you mean '%s' (single dash)?\n", Param + 1);
 155     return true;
 156   }
 157   for (size_t F = 0; F < kNumFlags; F++) {
 158     const char *Name = FlagDescriptions[F].Name;
 159     const char *Str = FlagValue(Param, Name);
 160     if (Str)  {
 161       if (FlagDescriptions[F].IntFlag) {
 162         auto Val = MyStol(Str);
 163         *FlagDescriptions[F].IntFlag = static_cast<int>(Val);
 164         if (Flags.verbosity >= 2)
 165           Printf("Flag: %s %d\n", Name, Val);
 166         return true;
 167       } else if (FlagDescriptions[F].UIntFlag) {
 168         auto Val = std::stoul(Str);
 169         *FlagDescriptions[F].UIntFlag = static_cast<unsigned int>(Val);
 170         if (Flags.verbosity >= 2)
 171           Printf("Flag: %s %u\n", Name, Val);
 172         return true;
 173       } else if (FlagDescriptions[F].StrFlag) {
 174         *FlagDescriptions[F].StrFlag = Str;
 175         if (Flags.verbosity >= 2)
 176           Printf("Flag: %s %s\n", Name, Str);
 177         return true;
 178       } else {  // Deprecated flag.
 179         Printf("Flag: %s: deprecated, don't use\n", Name);
 180         return true;
 181       }
 182     }
 183   }
 184   Printf("\n\nWARNING: unrecognized flag '%s'; "
 185          "use -help=1 to list all flags\n\n", Param);
 186   return true;
 187 }
 188
 189 // We don't use any library to minimize dependencies.
 190 static void ParseFlags(const std::vector<std::string> &Args,
 191                        const ExternalFunctions *EF) {
 192   for (size_t F = 0; F < kNumFlags; F++) {
 193     if (FlagDescriptions[F].IntFlag)
 194       *FlagDescriptions[F].IntFlag = FlagDescriptions[F].Default;
 195     if (FlagDescriptions[F].UIntFlag)
 196       *FlagDescriptions[F].UIntFlag =
 197           static_cast<unsigned int>(FlagDescriptions[F].Default);
 198     if (FlagDescriptions[F].StrFlag)
 199       *FlagDescriptions[F].StrFlag = nullptr;
 200   }
 201
 202   // Disable len_control by default, if LLVMFuzzerCustomMutator is used.
 203   if (EF->LLVMFuzzerCustomMutator) {
 204     Flags.len_control = 0;
 205     Printf("INFO: found LLVMFuzzerCustomMutator (%p). "
 206            "Disabling -len_control by default.\n", EF->LLVMFuzzerCustomMutator);
 207   }
 208
 209   Inputs = new std::vector<std::string>;
 210   for (size_t A = 1; A < Args.size(); A++) {
 211     if (ParseOneFlag(Args[A].c_str())) {
 212       if (Flags.ignore_remaining_args)
 213         break;
 214       continue;
 215     }
 216     Inputs->push_back(Args[A]);
 217   }
 218 }
 219
 220 static std::mutex Mu;
 221
 222 static void PulseThread() {
 223   while (true) {
 224     SleepSeconds(600);
 225     std::lock_guard<std::mutex> Lock(Mu);
 226     Printf("pulse...\n");
 227   }
 228 }
 229
 230 static void WorkerThread(const Command &BaseCmd, std::atomic<unsigned> *Counter,
 231                          unsigned NumJobs, std::atomic<bool> *HasErrors) {
 232   while (true) {
 233     unsigned C = (*Counter)++;
 234     if (C >= NumJobs) break;
 235     std::string Log = "fuzz-" + std::to_string(C) + ".log";
 236     Command Cmd(BaseCmd);
 237     Cmd.setOutputFile(Log);
 238     Cmd.combineOutAndErr();
 239     if (Flags.verbosity) {
 240       std::string CommandLine = Cmd.toString();
 241       Printf("%s\n", CommandLine.c_str());
 242     }
 243     int ExitCode = ExecuteCommand(Cmd);
 244     if (ExitCode != 0)
 245       *HasErrors = true;
 246     std::lock_guard<std::mutex> Lock(Mu);
 247     Printf("================== Job %u exited with exit code %d ============\n",
 248            C, ExitCode);
 249     fuzzer::CopyFileToErr(Log);
 250   }
 251 }
 252
 253 static void ValidateDirectoryExists(const std::string &Path,
 254                                     bool CreateDirectory) {
 255   if (Path.empty()) {
 256     Printf("ERROR: Provided directory path is an empty string\n");
 257     exit(1);
 258   }
 259
 260   if (IsDirectory(Path))
 261     return;
 262
 263   if (CreateDirectory) {
 264     if (!MkDirRecursive(Path)) {
 265       Printf("ERROR: Failed to create directory \"%s\"\n", Path.c_str());
 266       exit(1);
 267     }
 268     return;
 269   }
 270
 271   Printf("ERROR: The required directory \"%s\" does not exist\n", Path.c_str());
 272   exit(1);
 273 }
 274
 275 std::string CloneArgsWithoutX(const std::vector<std::string> &Args,
 276                               const char *X1, const char *X2) {
 277   std::string Cmd;
 278   for (auto &S : Args) {
 279     if (FlagValue(S.c_str(), X1) || FlagValue(S.c_str(), X2))
 280       continue;
 281     Cmd += S + " ";
 282   }
 283   return Cmd;
 284 }
 285
 286 static int RunInMultipleProcesses(const std::vector<std::string> &Args,
 287                                   unsigned NumWorkers, unsigned NumJobs) {
 288   std::atomic<unsigned> Counter(0);
 289   std::atomic<bool> HasErrors(false);
 290   Command Cmd(Args);
 291   Cmd.removeFlag("jobs");
 292   Cmd.removeFlag("workers");
 293   std::vector<std::thread> V;
 294   std::thread Pulse(PulseThread);
 295   Pulse.detach();
 296   V.resize(NumWorkers);
 297   for (unsigned i = 0; i < NumWorkers; i++) {
 298     V[i] = std::thread(WorkerThread, std::ref(Cmd), &Counter, NumJobs,
 299                             &HasErrors);
 300     SetThreadName(V[i], "FuzzerWorker");
 301   }
 302   for (auto &T : V)
 303     T.join();
 304   return HasErrors ? 1 : 0;
 305 }
 306
 307 static void RssThread(Fuzzer *F, size_t RssLimitMb) {
 308   while (true) {
 309     SleepSeconds(1);
 310     size_t Peak = GetPeakRSSMb();
 311     if (Peak > RssLimitMb)
 312       F->RssLimitCallback();
 313   }
 314 }
 315
 316 static void StartRssThread(Fuzzer *F, size_t RssLimitMb) {
 317   if (!RssLimitMb)
 318     return;
 319   std::thread T(RssThread, F, RssLimitMb);
 320   T.detach();
 321 }
 322
 323 int RunOneTest(Fuzzer *F, const char *InputFilePath, size_t MaxLen) {
 324   Unit U = FileToVector(InputFilePath);
 325   if (MaxLen && MaxLen < U.size())
 326     U.resize(MaxLen);
 327   F->ExecuteCallback(U.data(), U.size());
 328   if (Flags.print_full_coverage) {
 329     // Leak detection is not needed when collecting full coverage data.
 330     F->TPCUpdateObservedPCs();
 331   } else {
 332     F->TryDetectingAMemoryLeak(U.data(), U.size(), true);
 333   }
 334   return 0;
 335 }
 336
 337 static bool AllInputsAreFiles() {
 338   if (Inputs->empty()) return false;
 339   for (auto &Path : *Inputs)
 340     if (!IsFile(Path))
 341       return false;
 342   return true;
 343 }
 344
 345 static std::string GetDedupTokenFromCmdOutput(const std::string &S) {
 346   auto Beg = S.find("DEDUP_TOKEN:");
 347   if (Beg == std::string::npos)
 348     return "";
 349   auto End = S.find('\n', Beg);
 350   if (End == std::string::npos)
 351     return "";
 352   return S.substr(Beg, End - Beg);
 353 }
 354
 355 int CleanseCrashInput(const std::vector<std::string> &Args,
 356                       const FuzzingOptions &Options) {
 357   if (Inputs->size() != 1 || !Flags.exact_artifact_path) {
 358     Printf("ERROR: -cleanse_crash should be given one input file and"
 359           " -exact_artifact_path\n");
 360     exit(1);
 361   }
 362   std::string InputFilePath = Inputs->at(0);
 363   std::string OutputFilePath = Flags.exact_artifact_path;
 364   Command Cmd(Args);
 365   Cmd.removeFlag("cleanse_crash");
 366
 367   assert(Cmd.hasArgument(InputFilePath));
 368   Cmd.removeArgument(InputFilePath);
 369
 370   auto TmpFilePath = TempPath("CleanseCrashInput", ".repro");
 371   Cmd.addArgument(TmpFilePath);
 372   Cmd.setOutputFile(getDevNull());
 373   Cmd.combineOutAndErr();
 374
 375   std::string CurrentFilePath = InputFilePath;
 376   auto U = FileToVector(CurrentFilePath);
 377   size_t Size = U.size();
 378
 379   const std::vector<uint8_t> ReplacementBytes = {' ', 0xff};
 380   for (int NumAttempts = 0; NumAttempts < 5; NumAttempts++) {
 381     bool Changed = false;
 382     for (size_t Idx = 0; Idx < Size; Idx++) {
 383       Printf("CLEANSE[%d]: Trying to replace byte %zd of %zd\n", NumAttempts,
 384              Idx, Size);
 385       uint8_t OriginalByte = U[Idx];
 386       if (ReplacementBytes.end() != std::find(ReplacementBytes.begin(),
 387                                               ReplacementBytes.end(),
 388                                               OriginalByte))
 389         continue;
 390       for (auto NewByte : ReplacementBytes) {
 391         U[Idx] = NewByte;
 392         WriteToFile(U, TmpFilePath);
 393         auto ExitCode = ExecuteCommand(Cmd);
 394         RemoveFile(TmpFilePath);
 395         if (!ExitCode) {
 396           U[Idx] = OriginalByte;
 397         } else {
 398           Changed = true;
 399           Printf("CLEANSE: Replaced byte %zd with 0x%x\n", Idx, NewByte);
 400           WriteToFile(U, OutputFilePath);
 401           break;
 402         }
 403       }
 404     }
 405     if (!Changed) break;
 406   }
 407   return 0;
 408 }
 409
 410 int MinimizeCrashInput(const std::vector<std::string> &Args,
 411                        const FuzzingOptions &Options) {
 412   if (Inputs->size() != 1) {
 413     Printf("ERROR: -minimize_crash should be given one input file\n");
 414     exit(1);
 415   }
 416   std::string InputFilePath = Inputs->at(0);
 417   Command BaseCmd(Args);
 418   BaseCmd.removeFlag("minimize_crash");
 419   BaseCmd.removeFlag("exact_artifact_path");
 420   assert(BaseCmd.hasArgument(InputFilePath));
 421   BaseCmd.removeArgument(InputFilePath);
 422   if (Flags.runs <= 0 && Flags.max_total_time == 0) {
 423     Printf("INFO: you need to specify -runs=N or "
 424            "-max_total_time=N with -minimize_crash=1\n"
 425            "INFO: defaulting to -max_total_time=600\n");
 426     BaseCmd.addFlag("max_total_time", "600");
 427   }
 428
 429   BaseCmd.combineOutAndErr();
 430
 431   std::string CurrentFilePath = InputFilePath;
 432   while (true) {
 433     Unit U = FileToVector(CurrentFilePath);
 434     Printf("CRASH_MIN: minimizing crash input: '%s' (%zd bytes)\n",
 435            CurrentFilePath.c_str(), U.size());
 436
 437     Command Cmd(BaseCmd);
 438     Cmd.addArgument(CurrentFilePath);
 439
 440     Printf("CRASH_MIN: executing: %s\n", Cmd.toString().c_str());
 441     std::string CmdOutput;
 442     bool Success = ExecuteCommand(Cmd, &CmdOutput);
 443     if (Success) {
 444       Printf("ERROR: the input %s did not crash\n", CurrentFilePath.c_str());
 445       exit(1);
 446     }
 447     Printf("CRASH_MIN: '%s' (%zd bytes) caused a crash. Will try to minimize "
 448            "it further\n",
 449            CurrentFilePath.c_str(), U.size());
 450     auto DedupToken1 = GetDedupTokenFromCmdOutput(CmdOutput);
 451     if (!DedupToken1.empty())
 452       Printf("CRASH_MIN: DedupToken1: %s\n", DedupToken1.c_str());
 453
 454     std::string ArtifactPath =
 455         Flags.exact_artifact_path
 456             ? Flags.exact_artifact_path
 457             : Options.ArtifactPrefix + "minimized-from-" + Hash(U);
 458     Cmd.addFlag("minimize_crash_internal_step", "1");
 459     Cmd.addFlag("exact_artifact_path", ArtifactPath);
 460     Printf("CRASH_MIN: executing: %s\n", Cmd.toString().c_str());
 461     CmdOutput.clear();
 462     Success = ExecuteCommand(Cmd, &CmdOutput);
 463     Printf("%s", CmdOutput.c_str());
 464     if (Success) {
 465       if (Flags.exact_artifact_path) {
 466         CurrentFilePath = Flags.exact_artifact_path;
 467         WriteToFile(U, CurrentFilePath);
 468       }
 469       Printf("CRASH_MIN: failed to minimize beyond %s (%zu bytes), exiting\n",
 470              CurrentFilePath.c_str(), U.size());
 471       break;
 472     }
 473     auto DedupToken2 = GetDedupTokenFromCmdOutput(CmdOutput);
 474     if (!DedupToken2.empty())
 475       Printf("CRASH_MIN: DedupToken2: %s\n", DedupToken2.c_str());
 476
 477     if (DedupToken1 != DedupToken2) {
 478       if (Flags.exact_artifact_path) {
 479         CurrentFilePath = Flags.exact_artifact_path;
 480         WriteToFile(U, CurrentFilePath);
 481       }
 482       Printf("CRASH_MIN: mismatch in dedup tokens"
 483              " (looks like a different bug). Won't minimize further\n");
 484       break;
 485     }
 486
 487     CurrentFilePath = ArtifactPath;
 488     Printf("*********************************\n");
 489   }
 490   return 0;
 491 }
 492
 493 int MinimizeCrashInputInternalStep(Fuzzer *F, InputCorpus *Corpus) {
 494   assert(Inputs->size() == 1);
 495   std::string InputFilePath = Inputs->at(0);
 496   Unit U = FileToVector(InputFilePath);
 497   Printf("INFO: Starting MinimizeCrashInputInternalStep: %zd\n", U.size());
 498   if (U.size() < 2) {
 499     Printf("INFO: The input is small enough, exiting\n");
 500     exit(0);
 501   }
 502   F->SetMaxInputLen(U.size());
 503   F->SetMaxMutationLen(U.size() - 1);
 504   F->MinimizeCrashLoop(U);
 505   Printf("INFO: Done MinimizeCrashInputInternalStep, no crashes found\n");
 506   exit(0);
 507 }
 508
 509 void Merge(Fuzzer *F, FuzzingOptions &Options,
 510            const std::vector<std::string> &Args,
 511            const std::vector<std::string> &Corpora, const char *CFPathOrNull) {
 512   if (Corpora.size() < 2) {
 513     Printf("INFO: Merge requires two or more corpus dirs\n");
 514     exit(0);
 515   }
 516
 517   std::vector<SizedFile> OldCorpus, NewCorpus;
 518   GetSizedFilesFromDir(Corpora[0], &OldCorpus);
 519   for (size_t i = 1; i < Corpora.size(); i++)
 520     GetSizedFilesFromDir(Corpora[i], &NewCorpus);
 521   std::sort(OldCorpus.begin(), OldCorpus.end());
 522   std::sort(NewCorpus.begin(), NewCorpus.end());
 523
 524   std::string CFPath = CFPathOrNull ? CFPathOrNull : TempPath("Merge", ".txt");
 525   std::vector<std::string> NewFiles;
 526   std::set<uint32_t> NewFeatures, NewCov;
 527   CrashResistantMerge(Args, OldCorpus, NewCorpus, &NewFiles, {}, &NewFeatures,
 528                       {}, &NewCov, CFPath, true, Flags.set_cover_merge);
 529   for (auto &Path : NewFiles)
 530     F->WriteToOutputCorpus(FileToVector(Path, Options.MaxLen));
 531   // We are done, delete the control file if it was a temporary one.
 532   if (!Flags.merge_control_file)
 533     RemoveFile(CFPath);
 534
 535   exit(0);
 536 }
 537
 538 int AnalyzeDictionary(Fuzzer *F, const std::vector<Unit> &Dict,
 539                       UnitVector &Corpus) {
 540   Printf("Started dictionary minimization (up to %zu tests)\n",
 541          Dict.size() * Corpus.size() * 2);
 542
 543   // Scores and usage count for each dictionary unit.
 544   std::vector<int> Scores(Dict.size());
 545   std::vector<int> Usages(Dict.size());
 546
 547   std::vector<size_t> InitialFeatures;
 548   std::vector<size_t> ModifiedFeatures;
 549   for (auto &C : Corpus) {
 550     // Get coverage for the testcase without modifications.
 551     F->ExecuteCallback(C.data(), C.size());
 552     InitialFeatures.clear();
 553     TPC.CollectFeatures([&](size_t Feature) {
 554       InitialFeatures.push_back(Feature);
 555     });
 556
 557     for (size_t i = 0; i < Dict.size(); ++i) {
 558       std::vector<uint8_t> Data = C;
 559       auto StartPos = std::search(Data.begin(), Data.end(),
 560                                   Dict[i].begin(), Dict[i].end());
 561       // Skip dictionary unit, if the testcase does not contain it.
 562       if (StartPos == Data.end())
 563         continue;
 564
 565       ++Usages[i];
 566       while (StartPos != Data.end()) {
 567         // Replace all occurrences of dictionary unit in the testcase.
 568         auto EndPos = StartPos + Dict[i].size();
 569         for (auto It = StartPos; It != EndPos; ++It)
 570           *It ^= 0xFF;
 571
 572         StartPos = std::search(EndPos, Data.end(),
 573                                Dict[i].begin(), Dict[i].end());
 574       }
 575
 576       // Get coverage for testcase with masked occurrences of dictionary unit.
 577       F->ExecuteCallback(Data.data(), Data.size());
 578       ModifiedFeatures.clear();
 579       TPC.CollectFeatures([&](size_t Feature) {
 580         ModifiedFeatures.push_back(Feature);
 581       });
 582
 583       if (InitialFeatures == ModifiedFeatures)
 584         --Scores[i];
 585       else
 586         Scores[i] += 2;
 587     }
 588   }
 589
 590   Printf("###### Useless dictionary elements. ######\n");
 591   for (size_t i = 0; i < Dict.size(); ++i) {
 592     // Dictionary units with positive score are treated as useful ones.
 593     if (Scores[i] > 0)
 594        continue;
 595
 596     Printf("\"");
 597     PrintASCII(Dict[i].data(), Dict[i].size(), "\"");
 598     Printf(" # Score: %d, Used: %d\n", Scores[i], Usages[i]);
 599   }
 600   Printf("###### End of useless dictionary elements. ######\n");
 601   return 0;
 602 }
 603
 604 std::vector<std::string> ParseSeedInuts(const char *seed_inputs) {
 605   // Parse -seed_inputs=file1,file2,... or -seed_inputs=@seed_inputs_file
 606   std::vector<std::string> Files;
 607   if (!seed_inputs) return Files;
 608   std::string SeedInputs;
 609   if (Flags.seed_inputs[0] == '@')
 610     SeedInputs = FileToString(Flags.seed_inputs + 1); // File contains list.
 611   else
 612     SeedInputs = Flags.seed_inputs; // seed_inputs contains the list.
 613   if (SeedInputs.empty()) {
 614     Printf("seed_inputs is empty or @file does not exist.\n");
 615     exit(1);
 616   }
 617   // Parse SeedInputs.
 618   size_t comma_pos = 0;
 619   while ((comma_pos = SeedInputs.find_last_of(',')) != std::string::npos) {
 620     Files.push_back(SeedInputs.substr(comma_pos + 1));
 621     SeedInputs = SeedInputs.substr(0, comma_pos);
 622   }
 623   Files.push_back(SeedInputs);
 624   return Files;
 625 }
 626
 627 static std::vector<SizedFile>
 628 ReadCorpora(const std::vector<std::string> &CorpusDirs,
 629             const std::vector<std::string> &ExtraSeedFiles) {
 630   std::vector<SizedFile> SizedFiles;
 631   size_t LastNumFiles = 0;
 632   for (auto &Dir : CorpusDirs) {
 633     GetSizedFilesFromDir(Dir, &SizedFiles);
 634     Printf("INFO: % 8zd files found in %s\n", SizedFiles.size() - LastNumFiles,
 635            Dir.c_str());
 636     LastNumFiles = SizedFiles.size();
 637   }
 638   for (auto &File : ExtraSeedFiles)
 639     if (auto Size = FileSize(File))
 640       SizedFiles.push_back({File, Size});
 641   return SizedFiles;
 642 }
 643
 644 int FuzzerDriver(int *argc, char ***argv, UserCallback Callback) {
 645   using namespace fuzzer;
 646   assert(argc && argv && "Argument pointers cannot be nullptr");
 647   std::string Argv0((*argv)[0]);
 648   EF = new ExternalFunctions();
 649   if (EF->LLVMFuzzerInitialize)
 650     EF->LLVMFuzzerInitialize(argc, argv);
 651   if (EF->__msan_scoped_disable_interceptor_checks)
 652     EF->__msan_scoped_disable_interceptor_checks();
 653   const std::vector<std::string> Args(*argv, *argv + *argc);
 654   assert(!Args.empty());
 655   ProgName = new std::string(Args[0]);
 656   if (Argv0 != *ProgName) {
 657     Printf("ERROR: argv[0] has been modified in LLVMFuzzerInitialize\n");
 658     exit(1);
 659   }
 660   ParseFlags(Args, EF);
 661   if (Flags.help) {
 662     PrintHelp();
 663     return 0;
 664   }
 665
 666   if (Flags.close_fd_mask & 2)
 667     DupAndCloseStderr();
 668   if (Flags.close_fd_mask & 1)
 669     CloseStdout();
 670
 671   if (Flags.jobs > 0 && Flags.workers == 0) {
 672     Flags.workers = std::min(NumberOfCpuCores() / 2, Flags.jobs);
 673     if (Flags.workers > 1)
 674       Printf("Running %u workers\n", Flags.workers);
 675   }
 676
 677   if (Flags.workers > 0 && Flags.jobs > 0)
 678     return RunInMultipleProcesses(Args, Flags.workers, Flags.jobs);
 679
 680   FuzzingOptions Options;
 681   Options.Verbosity = Flags.verbosity;
 682   Options.MaxLen = Flags.max_len;
 683   Options.LenControl = Flags.len_control;
 684   Options.KeepSeed = Flags.keep_seed;
 685   Options.UnitTimeoutSec = Flags.timeout;
 686   Options.ErrorExitCode = Flags.error_exitcode;
 687   Options.TimeoutExitCode = Flags.timeout_exitcode;
 688   Options.IgnoreTimeouts = Flags.ignore_timeouts;
 689   Options.IgnoreOOMs = Flags.ignore_ooms;
 690   Options.IgnoreCrashes = Flags.ignore_crashes;
 691   Options.MaxTotalTimeSec = Flags.max_total_time;
 692   Options.DoCrossOver = Flags.cross_over;
 693   Options.CrossOverUniformDist = Flags.cross_over_uniform_dist;
 694   Options.MutateDepth = Flags.mutate_depth;
 695   Options.ReduceDepth = Flags.reduce_depth;
 696   Options.UseCounters = Flags.use_counters;
 697   Options.UseMemmem = Flags.use_memmem;
 698   Options.UseCmp = Flags.use_cmp;
 699   Options.UseValueProfile = Flags.use_value_profile;
 700   Options.Shrink = Flags.shrink;
 701   Options.ReduceInputs = Flags.reduce_inputs;
 702   Options.ShuffleAtStartUp = Flags.shuffle;
 703   Options.PreferSmall = Flags.prefer_small;
 704   Options.ReloadIntervalSec = Flags.reload;
 705   Options.OnlyASCII = Flags.only_ascii;
 706   Options.DetectLeaks = Flags.detect_leaks;
 707   Options.PurgeAllocatorIntervalSec = Flags.purge_allocator_interval;
 708   Options.TraceMalloc = Flags.trace_malloc;
 709   Options.RssLimitMb = Flags.rss_limit_mb;
 710   Options.MallocLimitMb = Flags.malloc_limit_mb;
 711   if (!Options.MallocLimitMb)
 712     Options.MallocLimitMb = Options.RssLimitMb;
 713   if (Flags.runs >= 0)
 714     Options.MaxNumberOfRuns = Flags.runs;
 715   if (!Inputs->empty() && !Flags.minimize_crash_internal_step) {
 716     // Ensure output corpus assumed to be the first arbitrary argument input
 717     // is not a path to an existing file.
 718     std::string OutputCorpusDir = (*Inputs)[0];
 719     if (!IsFile(OutputCorpusDir)) {
 720       Options.OutputCorpus = OutputCorpusDir;
 721       ValidateDirectoryExists(Options.OutputCorpus, Flags.create_missing_dirs);
 722     }
 723   }
 724   Options.ReportSlowUnits = Flags.report_slow_units;
 725   if (Flags.artifact_prefix) {
 726     Options.ArtifactPrefix = Flags.artifact_prefix;
 727
 728     // Since the prefix could be a full path to a file name prefix, assume
 729     // that if the path ends with the platform's separator that a directory
 730     // is desired
 731     std::string ArtifactPathDir = Options.ArtifactPrefix;
 732     if (!IsSeparator(ArtifactPathDir[ArtifactPathDir.length() - 1])) {
 733       ArtifactPathDir = DirName(ArtifactPathDir);
 734     }
 735     ValidateDirectoryExists(ArtifactPathDir, Flags.create_missing_dirs);
 736   }
 737   if (Flags.exact_artifact_path) {
 738     Options.ExactArtifactPath = Flags.exact_artifact_path;
 739     ValidateDirectoryExists(DirName(Options.ExactArtifactPath),
 740                             Flags.create_missing_dirs);
 741   }
 742   std::vector<Unit> Dictionary;
 743   if (Flags.dict)
 744     if (!ParseDictionaryFile(FileToString(Flags.dict), &Dictionary))
 745       return 1;
 746   if (Flags.verbosity > 0 && !Dictionary.empty())
 747     Printf("Dictionary: %zd entries\n", Dictionary.size());
 748   bool RunIndividualFiles = AllInputsAreFiles();
 749   Options.SaveArtifacts =
 750       !RunIndividualFiles || Flags.minimize_crash_internal_step;
 751   Options.PrintNewCovPcs = Flags.print_pcs;
 752   Options.PrintNewCovFuncs = Flags.print_funcs;
 753   Options.PrintFinalStats = Flags.print_final_stats;
 754   Options.PrintCorpusStats = Flags.print_corpus_stats;
 755   Options.PrintCoverage = Flags.print_coverage;
 756   Options.PrintFullCoverage = Flags.print_full_coverage;
 757   if (Flags.exit_on_src_pos)
 758     Options.ExitOnSrcPos = Flags.exit_on_src_pos;
 759   if (Flags.exit_on_item)
 760     Options.ExitOnItem = Flags.exit_on_item;
 761   if (Flags.focus_function)
 762     Options.FocusFunction = Flags.focus_function;
 763   if (Flags.data_flow_trace)
 764     Options.DataFlowTrace = Flags.data_flow_trace;
 765   if (Flags.features_dir) {
 766     Options.FeaturesDir = Flags.features_dir;
 767     ValidateDirectoryExists(Options.FeaturesDir, Flags.create_missing_dirs);
 768   }
 769   if (Flags.mutation_graph_file)
 770     Options.MutationGraphFile = Flags.mutation_graph_file;
 771   if (Flags.collect_data_flow)
 772     Options.CollectDataFlow = Flags.collect_data_flow;
 773   if (Flags.stop_file)
 774     Options.StopFile = Flags.stop_file;
 775   Options.Entropic = Flags.entropic;
 776   Options.EntropicFeatureFrequencyThreshold =
 777       (size_t)Flags.entropic_feature_frequency_threshold;
 778   Options.EntropicNumberOfRarestFeatures =
 779       (size_t)Flags.entropic_number_of_rarest_features;
 780   Options.EntropicScalePerExecTime = Flags.entropic_scale_per_exec_time;
 781   if (!Options.FocusFunction.empty())
 782     Options.Entropic = false; // FocusFunction overrides entropic scheduling.
 783   if (Options.Entropic)
 784     Printf("INFO: Running with entropic power schedule (0x%zX, %zu).\n",
 785            Options.EntropicFeatureFrequencyThreshold,
 786            Options.EntropicNumberOfRarestFeatures);
 787   struct EntropicOptions Entropic;
 788   Entropic.Enabled = Options.Entropic;
 789   Entropic.FeatureFrequencyThreshold =
 790       Options.EntropicFeatureFrequencyThreshold;
 791   Entropic.NumberOfRarestFeatures = Options.EntropicNumberOfRarestFeatures;
 792   Entropic.ScalePerExecTime = Options.EntropicScalePerExecTime;
 793
 794   unsigned Seed = Flags.seed;
 795   // Initialize Seed.
 796   if (Seed == 0)
 797     Seed = static_cast<unsigned>(
 798         std::chrono::system_clock::now().time_since_epoch().count() + GetPid());
 799   if (Flags.verbosity)
 800     Printf("INFO: Seed: %u\n", Seed);
 801
 802   if (Flags.collect_data_flow && Flags.data_flow_trace && !Flags.fork &&
 803       !(Flags.merge || Flags.set_cover_merge)) {
 804     if (RunIndividualFiles)
 805       return CollectDataFlow(Flags.collect_data_flow, Flags.data_flow_trace,
 806                         ReadCorpora({}, *Inputs));
 807     else
 808       return CollectDataFlow(Flags.collect_data_flow, Flags.data_flow_trace,
 809                         ReadCorpora(*Inputs, {}));
 810   }
 811
 812   Random Rand(Seed);
 813   auto *MD = new MutationDispatcher(Rand, Options);
 814   auto *Corpus = new InputCorpus(Options.OutputCorpus, Entropic);
 815   auto *F = new Fuzzer(Callback, *Corpus, *MD, Options);
 816
 817   for (auto &U: Dictionary)
 818     if (U.size() <= Word::GetMaxSize())
 819       MD->AddWordToManualDictionary(Word(U.data(), U.size()));
 820
 821       // Threads are only supported by Chrome. Don't use them with emscripten
 822       // for now.
 823 #if !LIBFUZZER_EMSCRIPTEN
 824   StartRssThread(F, Flags.rss_limit_mb);
 825 #endif // LIBFUZZER_EMSCRIPTEN
 826
 827   Options.HandleAbrt = Flags.handle_abrt;
 828   Options.HandleAlrm = !Flags.minimize_crash;
 829   Options.HandleBus = Flags.handle_bus;
 830   Options.HandleFpe = Flags.handle_fpe;
 831   Options.HandleIll = Flags.handle_ill;
 832   Options.HandleInt = Flags.handle_int;
 833   Options.HandleSegv = Flags.handle_segv;
 834   Options.HandleTerm = Flags.handle_term;
 835   Options.HandleXfsz = Flags.handle_xfsz;
 836   Options.HandleUsr1 = Flags.handle_usr1;
 837   Options.HandleUsr2 = Flags.handle_usr2;
 838   Options.HandleWinExcept = Flags.handle_winexcept;
 839
 840   SetSignalHandler(Options);
 841
 842   std::atexit(Fuzzer::StaticExitCallback);
 843
 844   if (Flags.minimize_crash)
 845     return MinimizeCrashInput(Args, Options);
 846
 847   if (Flags.minimize_crash_internal_step)
 848     return MinimizeCrashInputInternalStep(F, Corpus);
 849
 850   if (Flags.cleanse_crash)
 851     return CleanseCrashInput(Args, Options);
 852
 853   if (RunIndividualFiles) {
 854     Options.SaveArtifacts = false;
 855     int Runs = std::max(1, Flags.runs);
 856     Printf("%s: Running %zd inputs %d time(s) each.\n", ProgName->c_str(),
 857            Inputs->size(), Runs);
 858     for (auto &Path : *Inputs) {
 859       auto StartTime = system_clock::now();
 860       Printf("Running: %s\n", Path.c_str());
 861       for (int Iter = 0; Iter < Runs; Iter++)
 862         RunOneTest(F, Path.c_str(), Options.MaxLen);
 863       auto StopTime = system_clock::now();
 864       auto MS = duration_cast<milliseconds>(StopTime - StartTime).count();
 865       Printf("Executed %s in %ld ms\n", Path.c_str(), (long)MS);
 866     }
 867     Printf("***\n"
 868            "*** NOTE: fuzzing was not performed, you have only\n"
 869            "***       executed the target code on a fixed set of inputs.\n"
 870            "***\n");
 871     F->PrintFinalStats();
 872     exit(0);
 873   }
 874
 875   Options.ForkCorpusGroups = Flags.fork_corpus_groups;
 876   if (Flags.fork)
 877     FuzzWithFork(F->GetMD().GetRand(), Options, Args, *Inputs, Flags.fork);
 878
 879   if (Flags.merge || Flags.set_cover_merge)
 880     Merge(F, Options, Args, *Inputs, Flags.merge_control_file);
 881
 882   if (Flags.merge_inner) {
 883     const size_t kDefaultMaxMergeLen = 1 << 20;
 884     if (Options.MaxLen == 0)
 885       F->SetMaxInputLen(kDefaultMaxMergeLen);
 886     assert(Flags.merge_control_file);
 887     F->CrashResistantMergeInternalStep(Flags.merge_control_file,
 888                                        !strncmp(Flags.merge_inner, "2", 1));
 889     exit(0);
 890   }
 891
 892   if (Flags.analyze_dict) {
 893     size_t MaxLen = INT_MAX;  // Large max length.
 894     UnitVector InitialCorpus;
 895     for (auto &Inp : *Inputs) {
 896       Printf("Loading corpus dir: %s\n", Inp.c_str());
 897       ReadDirToVectorOfUnits(Inp.c_str(), &InitialCorpus, nullptr,
 898                              MaxLen, /*ExitOnError=*/false);
 899     }
 900
 901     if (Dictionary.empty() || Inputs->empty()) {
 902       Printf("ERROR: can't analyze dict without dict and corpus provided\n");
 903       return 1;
 904     }
 905     if (AnalyzeDictionary(F, Dictionary, InitialCorpus)) {
 906       Printf("Dictionary analysis failed\n");
 907       exit(1);
 908     }
 909     Printf("Dictionary analysis succeeded\n");
 910     exit(0);
 911   }
 912
 913   auto CorporaFiles = ReadCorpora(*Inputs, ParseSeedInuts(Flags.seed_inputs));
 914   F->Loop(CorporaFiles);
 915
 916   if (Flags.verbosity)
 917     Printf("Done %zd runs in %zd second(s)\n", F->getTotalNumberOfRuns(),
 918            F->secondsSinceProcessStartUp());
 919   F->PrintFinalStats();
 920
 921   exit(0);  // Don't let F destroy itself.
 922 }
 923
 924 extern "C" ATTRIBUTE_INTERFACE int
 925 LLVMFuzzerRunDriver(int *argc, char ***argv,
 926                     int (*UserCb)(const uint8_t *Data, size_t Size)) {
 927   return FuzzerDriver(argc, argv, UserCb);
 928 }
 929
 930 // Storage for global ExternalFunctions object.
 931 ExternalFunctions *EF = nullptr;
 932
 933 }  // namespace fuzzer