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 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         int Val = MyStol(Str);
163         *FlagDescriptions[F].IntFlag = Val;
164         if (Flags.verbosity >= 2)
165           Printf("Flag: %s %d\n", Name, Val);
166         return true;
167       } else if (FlagDescriptions[F].UIntFlag) {
168         unsigned int Val = std::stoul(Str);
169         *FlagDescriptions[F].UIntFlag = 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 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 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 std::string CloneArgsWithoutX(const Vector<std::string> &Args,
254                               const char *X1, const char *X2) {
255   std::string Cmd;
256   for (auto &S : Args) {
257     if (FlagValue(S.c_str(), X1) || FlagValue(S.c_str(), X2))
258       continue;
259     Cmd += S + " ";
260   }
261   return Cmd;
262 }
263 
264 static int RunInMultipleProcesses(const Vector<std::string> &Args,
265                                   unsigned NumWorkers, unsigned NumJobs) {
266   std::atomic<unsigned> Counter(0);
267   std::atomic<bool> HasErrors(false);
268   Command Cmd(Args);
269   Cmd.removeFlag("jobs");
270   Cmd.removeFlag("workers");
271   Vector<std::thread> V;
272   std::thread Pulse(PulseThread);
273   Pulse.detach();
274   for (unsigned i = 0; i < NumWorkers; i++)
275     V.push_back(std::thread(WorkerThread, std::ref(Cmd), &Counter, NumJobs, &HasErrors));
276   for (auto &T : V)
277     T.join();
278   return HasErrors ? 1 : 0;
279 }
280 
281 static void RssThread(Fuzzer *F, size_t RssLimitMb) {
282   while (true) {
283     SleepSeconds(1);
284     size_t Peak = GetPeakRSSMb();
285     if (Peak > RssLimitMb)
286       F->RssLimitCallback();
287   }
288 }
289 
290 static void StartRssThread(Fuzzer *F, size_t RssLimitMb) {
291   if (!RssLimitMb)
292     return;
293   std::thread T(RssThread, F, RssLimitMb);
294   T.detach();
295 }
296 
297 int RunOneTest(Fuzzer *F, const char *InputFilePath, size_t MaxLen) {
298   Unit U = FileToVector(InputFilePath);
299   if (MaxLen && MaxLen < U.size())
300     U.resize(MaxLen);
301   F->ExecuteCallback(U.data(), U.size());
302   F->TryDetectingAMemoryLeak(U.data(), U.size(), true);
303   return 0;
304 }
305 
306 static bool AllInputsAreFiles() {
307   if (Inputs->empty()) return false;
308   for (auto &Path : *Inputs)
309     if (!IsFile(Path))
310       return false;
311   return true;
312 }
313 
314 static std::string GetDedupTokenFromCmdOutput(const std::string &S) {
315   auto Beg = S.find("DEDUP_TOKEN:");
316   if (Beg == std::string::npos)
317     return "";
318   auto End = S.find('\n', Beg);
319   if (End == std::string::npos)
320     return "";
321   return S.substr(Beg, End - Beg);
322 }
323 
324 int CleanseCrashInput(const Vector<std::string> &Args,
325                        const FuzzingOptions &Options) {
326   if (Inputs->size() != 1 || !Flags.exact_artifact_path) {
327     Printf("ERROR: -cleanse_crash should be given one input file and"
328           " -exact_artifact_path\n");
329     exit(1);
330   }
331   std::string InputFilePath = Inputs->at(0);
332   std::string OutputFilePath = Flags.exact_artifact_path;
333   Command Cmd(Args);
334   Cmd.removeFlag("cleanse_crash");
335 
336   assert(Cmd.hasArgument(InputFilePath));
337   Cmd.removeArgument(InputFilePath);
338 
339   auto TmpFilePath = TempPath("CleanseCrashInput", ".repro");
340   Cmd.addArgument(TmpFilePath);
341   Cmd.setOutputFile(getDevNull());
342   Cmd.combineOutAndErr();
343 
344   std::string CurrentFilePath = InputFilePath;
345   auto U = FileToVector(CurrentFilePath);
346   size_t Size = U.size();
347 
348   const Vector<uint8_t> ReplacementBytes = {' ', 0xff};
349   for (int NumAttempts = 0; NumAttempts < 5; NumAttempts++) {
350     bool Changed = false;
351     for (size_t Idx = 0; Idx < Size; Idx++) {
352       Printf("CLEANSE[%d]: Trying to replace byte %zd of %zd\n", NumAttempts,
353              Idx, Size);
354       uint8_t OriginalByte = U[Idx];
355       if (ReplacementBytes.end() != std::find(ReplacementBytes.begin(),
356                                               ReplacementBytes.end(),
357                                               OriginalByte))
358         continue;
359       for (auto NewByte : ReplacementBytes) {
360         U[Idx] = NewByte;
361         WriteToFile(U, TmpFilePath);
362         auto ExitCode = ExecuteCommand(Cmd);
363         RemoveFile(TmpFilePath);
364         if (!ExitCode) {
365           U[Idx] = OriginalByte;
366         } else {
367           Changed = true;
368           Printf("CLEANSE: Replaced byte %zd with 0x%x\n", Idx, NewByte);
369           WriteToFile(U, OutputFilePath);
370           break;
371         }
372       }
373     }
374     if (!Changed) break;
375   }
376   return 0;
377 }
378 
379 int MinimizeCrashInput(const Vector<std::string> &Args,
380                        const FuzzingOptions &Options) {
381   if (Inputs->size() != 1) {
382     Printf("ERROR: -minimize_crash should be given one input file\n");
383     exit(1);
384   }
385   std::string InputFilePath = Inputs->at(0);
386   Command BaseCmd(Args);
387   BaseCmd.removeFlag("minimize_crash");
388   BaseCmd.removeFlag("exact_artifact_path");
389   assert(BaseCmd.hasArgument(InputFilePath));
390   BaseCmd.removeArgument(InputFilePath);
391   if (Flags.runs <= 0 && Flags.max_total_time == 0) {
392     Printf("INFO: you need to specify -runs=N or "
393            "-max_total_time=N with -minimize_crash=1\n"
394            "INFO: defaulting to -max_total_time=600\n");
395     BaseCmd.addFlag("max_total_time", "600");
396   }
397 
398   BaseCmd.combineOutAndErr();
399 
400   std::string CurrentFilePath = InputFilePath;
401   while (true) {
402     Unit U = FileToVector(CurrentFilePath);
403     Printf("CRASH_MIN: minimizing crash input: '%s' (%zd bytes)\n",
404            CurrentFilePath.c_str(), U.size());
405 
406     Command Cmd(BaseCmd);
407     Cmd.addArgument(CurrentFilePath);
408 
409     Printf("CRASH_MIN: executing: %s\n", Cmd.toString().c_str());
410     std::string CmdOutput;
411     bool Success = ExecuteCommand(Cmd, &CmdOutput);
412     if (Success) {
413       Printf("ERROR: the input %s did not crash\n", CurrentFilePath.c_str());
414       exit(1);
415     }
416     Printf("CRASH_MIN: '%s' (%zd bytes) caused a crash. Will try to minimize "
417            "it further\n",
418            CurrentFilePath.c_str(), U.size());
419     auto DedupToken1 = GetDedupTokenFromCmdOutput(CmdOutput);
420     if (!DedupToken1.empty())
421       Printf("CRASH_MIN: DedupToken1: %s\n", DedupToken1.c_str());
422 
423     std::string ArtifactPath =
424         Flags.exact_artifact_path
425             ? Flags.exact_artifact_path
426             : Options.ArtifactPrefix + "minimized-from-" + Hash(U);
427     Cmd.addFlag("minimize_crash_internal_step", "1");
428     Cmd.addFlag("exact_artifact_path", ArtifactPath);
429     Printf("CRASH_MIN: executing: %s\n", Cmd.toString().c_str());
430     CmdOutput.clear();
431     Success = ExecuteCommand(Cmd, &CmdOutput);
432     Printf("%s", CmdOutput.c_str());
433     if (Success) {
434       if (Flags.exact_artifact_path) {
435         CurrentFilePath = Flags.exact_artifact_path;
436         WriteToFile(U, CurrentFilePath);
437       }
438       Printf("CRASH_MIN: failed to minimize beyond %s (%d bytes), exiting\n",
439              CurrentFilePath.c_str(), U.size());
440       break;
441     }
442     auto DedupToken2 = GetDedupTokenFromCmdOutput(CmdOutput);
443     if (!DedupToken2.empty())
444       Printf("CRASH_MIN: DedupToken2: %s\n", DedupToken2.c_str());
445 
446     if (DedupToken1 != DedupToken2) {
447       if (Flags.exact_artifact_path) {
448         CurrentFilePath = Flags.exact_artifact_path;
449         WriteToFile(U, CurrentFilePath);
450       }
451       Printf("CRASH_MIN: mismatch in dedup tokens"
452              " (looks like a different bug). Won't minimize further\n");
453       break;
454     }
455 
456     CurrentFilePath = ArtifactPath;
457     Printf("*********************************\n");
458   }
459   return 0;
460 }
461 
462 int MinimizeCrashInputInternalStep(Fuzzer *F, InputCorpus *Corpus) {
463   assert(Inputs->size() == 1);
464   std::string InputFilePath = Inputs->at(0);
465   Unit U = FileToVector(InputFilePath);
466   Printf("INFO: Starting MinimizeCrashInputInternalStep: %zd\n", U.size());
467   if (U.size() < 2) {
468     Printf("INFO: The input is small enough, exiting\n");
469     exit(0);
470   }
471   F->SetMaxInputLen(U.size());
472   F->SetMaxMutationLen(U.size() - 1);
473   F->MinimizeCrashLoop(U);
474   Printf("INFO: Done MinimizeCrashInputInternalStep, no crashes found\n");
475   exit(0);
476   return 0;
477 }
478 
479 void Merge(Fuzzer *F, FuzzingOptions &Options, const Vector<std::string> &Args,
480            const Vector<std::string> &Corpora, const char *CFPathOrNull) {
481   if (Corpora.size() < 2) {
482     Printf("INFO: Merge requires two or more corpus dirs\n");
483     exit(0);
484   }
485 
486   Vector<SizedFile> OldCorpus, NewCorpus;
487   GetSizedFilesFromDir(Corpora[0], &OldCorpus);
488   for (size_t i = 1; i < Corpora.size(); i++)
489     GetSizedFilesFromDir(Corpora[i], &NewCorpus);
490   std::sort(OldCorpus.begin(), OldCorpus.end());
491   std::sort(NewCorpus.begin(), NewCorpus.end());
492 
493   std::string CFPath = CFPathOrNull ? CFPathOrNull : TempPath("Merge", ".txt");
494   Vector<std::string> NewFiles;
495   Set<uint32_t> NewFeatures, NewCov;
496   CrashResistantMerge(Args, OldCorpus, NewCorpus, &NewFiles, {}, &NewFeatures,
497                       {}, &NewCov, CFPath, true);
498   for (auto &Path : NewFiles)
499     F->WriteToOutputCorpus(FileToVector(Path, Options.MaxLen));
500   // We are done, delete the control file if it was a temporary one.
501   if (!Flags.merge_control_file)
502     RemoveFile(CFPath);
503 
504   exit(0);
505 }
506 
507 int AnalyzeDictionary(Fuzzer *F, const Vector<Unit>& Dict,
508                       UnitVector& Corpus) {
509   Printf("Started dictionary minimization (up to %d tests)\n",
510          Dict.size() * Corpus.size() * 2);
511 
512   // Scores and usage count for each dictionary unit.
513   Vector<int> Scores(Dict.size());
514   Vector<int> Usages(Dict.size());
515 
516   Vector<size_t> InitialFeatures;
517   Vector<size_t> ModifiedFeatures;
518   for (auto &C : Corpus) {
519     // Get coverage for the testcase without modifications.
520     F->ExecuteCallback(C.data(), C.size());
521     InitialFeatures.clear();
522     TPC.CollectFeatures([&](size_t Feature) {
523       InitialFeatures.push_back(Feature);
524     });
525 
526     for (size_t i = 0; i < Dict.size(); ++i) {
527       Vector<uint8_t> Data = C;
528       auto StartPos = std::search(Data.begin(), Data.end(),
529                                   Dict[i].begin(), Dict[i].end());
530       // Skip dictionary unit, if the testcase does not contain it.
531       if (StartPos == Data.end())
532         continue;
533 
534       ++Usages[i];
535       while (StartPos != Data.end()) {
536         // Replace all occurrences of dictionary unit in the testcase.
537         auto EndPos = StartPos + Dict[i].size();
538         for (auto It = StartPos; It != EndPos; ++It)
539           *It ^= 0xFF;
540 
541         StartPos = std::search(EndPos, Data.end(),
542                                Dict[i].begin(), Dict[i].end());
543       }
544 
545       // Get coverage for testcase with masked occurrences of dictionary unit.
546       F->ExecuteCallback(Data.data(), Data.size());
547       ModifiedFeatures.clear();
548       TPC.CollectFeatures([&](size_t Feature) {
549         ModifiedFeatures.push_back(Feature);
550       });
551 
552       if (InitialFeatures == ModifiedFeatures)
553         --Scores[i];
554       else
555         Scores[i] += 2;
556     }
557   }
558 
559   Printf("###### Useless dictionary elements. ######\n");
560   for (size_t i = 0; i < Dict.size(); ++i) {
561     // Dictionary units with positive score are treated as useful ones.
562     if (Scores[i] > 0)
563        continue;
564 
565     Printf("\"");
566     PrintASCII(Dict[i].data(), Dict[i].size(), "\"");
567     Printf(" # Score: %d, Used: %d\n", Scores[i], Usages[i]);
568   }
569   Printf("###### End of useless dictionary elements. ######\n");
570   return 0;
571 }
572 
573 Vector<std::string> ParseSeedInuts(const char *seed_inputs) {
574   // Parse -seed_inputs=file1,file2,... or -seed_inputs=@seed_inputs_file
575   Vector<std::string> Files;
576   if (!seed_inputs) return Files;
577   std::string SeedInputs;
578   if (Flags.seed_inputs[0] == '@')
579     SeedInputs = FileToString(Flags.seed_inputs + 1); // File contains list.
580   else
581     SeedInputs = Flags.seed_inputs; // seed_inputs contains the list.
582   if (SeedInputs.empty()) {
583     Printf("seed_inputs is empty or @file does not exist.\n");
584     exit(1);
585   }
586   // Parse SeedInputs.
587   size_t comma_pos = 0;
588   while ((comma_pos = SeedInputs.find_last_of(',')) != std::string::npos) {
589     Files.push_back(SeedInputs.substr(comma_pos + 1));
590     SeedInputs = SeedInputs.substr(0, comma_pos);
591   }
592   Files.push_back(SeedInputs);
593   return Files;
594 }
595 
596 static Vector<SizedFile> ReadCorpora(const Vector<std::string> &CorpusDirs,
597     const Vector<std::string> &ExtraSeedFiles) {
598   Vector<SizedFile> SizedFiles;
599   size_t LastNumFiles = 0;
600   for (auto &Dir : CorpusDirs) {
601     GetSizedFilesFromDir(Dir, &SizedFiles);
602     Printf("INFO: % 8zd files found in %s\n", SizedFiles.size() - LastNumFiles,
603            Dir.c_str());
604     LastNumFiles = SizedFiles.size();
605   }
606   for (auto &File : ExtraSeedFiles)
607     if (auto Size = FileSize(File))
608       SizedFiles.push_back({File, Size});
609   return SizedFiles;
610 }
611 
612 int FuzzerDriver(int *argc, char ***argv, UserCallback Callback) {
613   using namespace fuzzer;
614   assert(argc && argv && "Argument pointers cannot be nullptr");
615   std::string Argv0((*argv)[0]);
616   EF = new ExternalFunctions();
617   if (EF->LLVMFuzzerInitialize)
618     EF->LLVMFuzzerInitialize(argc, argv);
619   if (EF->__msan_scoped_disable_interceptor_checks)
620     EF->__msan_scoped_disable_interceptor_checks();
621   const Vector<std::string> Args(*argv, *argv + *argc);
622   assert(!Args.empty());
623   ProgName = new std::string(Args[0]);
624   if (Argv0 != *ProgName) {
625     Printf("ERROR: argv[0] has been modified in LLVMFuzzerInitialize\n");
626     exit(1);
627   }
628   ParseFlags(Args, EF);
629   if (Flags.help) {
630     PrintHelp();
631     return 0;
632   }
633 
634   if (Flags.close_fd_mask & 2)
635     DupAndCloseStderr();
636   if (Flags.close_fd_mask & 1)
637     CloseStdout();
638 
639   if (Flags.jobs > 0 && Flags.workers == 0) {
640     Flags.workers = std::min(NumberOfCpuCores() / 2, Flags.jobs);
641     if (Flags.workers > 1)
642       Printf("Running %u workers\n", Flags.workers);
643   }
644 
645   if (Flags.workers > 0 && Flags.jobs > 0)
646     return RunInMultipleProcesses(Args, Flags.workers, Flags.jobs);
647 
648   FuzzingOptions Options;
649   Options.Verbosity = Flags.verbosity;
650   Options.MaxLen = Flags.max_len;
651   Options.LenControl = Flags.len_control;
652   Options.UnitTimeoutSec = Flags.timeout;
653   Options.ErrorExitCode = Flags.error_exitcode;
654   Options.TimeoutExitCode = Flags.timeout_exitcode;
655   Options.IgnoreTimeouts = Flags.ignore_timeouts;
656   Options.IgnoreOOMs = Flags.ignore_ooms;
657   Options.IgnoreCrashes = Flags.ignore_crashes;
658   Options.MaxTotalTimeSec = Flags.max_total_time;
659   Options.DoCrossOver = Flags.cross_over;
660   Options.MutateDepth = Flags.mutate_depth;
661   Options.ReduceDepth = Flags.reduce_depth;
662   Options.UseCounters = Flags.use_counters;
663   Options.UseMemmem = Flags.use_memmem;
664   Options.UseCmp = Flags.use_cmp;
665   Options.UseValueProfile = Flags.use_value_profile;
666   Options.Shrink = Flags.shrink;
667   Options.ReduceInputs = Flags.reduce_inputs;
668   Options.ShuffleAtStartUp = Flags.shuffle;
669   Options.PreferSmall = Flags.prefer_small;
670   Options.ReloadIntervalSec = Flags.reload;
671   Options.OnlyASCII = Flags.only_ascii;
672   Options.DetectLeaks = Flags.detect_leaks;
673   Options.PurgeAllocatorIntervalSec = Flags.purge_allocator_interval;
674   Options.TraceMalloc = Flags.trace_malloc;
675   Options.RssLimitMb = Flags.rss_limit_mb;
676   Options.MallocLimitMb = Flags.malloc_limit_mb;
677   if (!Options.MallocLimitMb)
678     Options.MallocLimitMb = Options.RssLimitMb;
679   if (Flags.runs >= 0)
680     Options.MaxNumberOfRuns = Flags.runs;
681   if (!Inputs->empty() && !Flags.minimize_crash_internal_step)
682     Options.OutputCorpus = (*Inputs)[0];
683   Options.ReportSlowUnits = Flags.report_slow_units;
684   if (Flags.artifact_prefix)
685     Options.ArtifactPrefix = Flags.artifact_prefix;
686   if (Flags.exact_artifact_path)
687     Options.ExactArtifactPath = Flags.exact_artifact_path;
688   Vector<Unit> Dictionary;
689   if (Flags.dict)
690     if (!ParseDictionaryFile(FileToString(Flags.dict), &Dictionary))
691       return 1;
692   if (Flags.verbosity > 0 && !Dictionary.empty())
693     Printf("Dictionary: %zd entries\n", Dictionary.size());
694   bool RunIndividualFiles = AllInputsAreFiles();
695   Options.SaveArtifacts =
696       !RunIndividualFiles || Flags.minimize_crash_internal_step;
697   Options.PrintNewCovPcs = Flags.print_pcs;
698   Options.PrintNewCovFuncs = Flags.print_funcs;
699   Options.PrintFinalStats = Flags.print_final_stats;
700   Options.PrintCorpusStats = Flags.print_corpus_stats;
701   Options.PrintCoverage = Flags.print_coverage;
702   if (Flags.exit_on_src_pos)
703     Options.ExitOnSrcPos = Flags.exit_on_src_pos;
704   if (Flags.exit_on_item)
705     Options.ExitOnItem = Flags.exit_on_item;
706   if (Flags.focus_function)
707     Options.FocusFunction = Flags.focus_function;
708   if (Flags.data_flow_trace)
709     Options.DataFlowTrace = Flags.data_flow_trace;
710   if (Flags.features_dir)
711     Options.FeaturesDir = Flags.features_dir;
712   if (Flags.collect_data_flow)
713     Options.CollectDataFlow = Flags.collect_data_flow;
714   if (Flags.stop_file)
715     Options.StopFile = Flags.stop_file;
716   Options.Entropic = Flags.entropic;
717   Options.EntropicFeatureFrequencyThreshold =
718       (size_t)Flags.entropic_feature_frequency_threshold;
719   Options.EntropicNumberOfRarestFeatures =
720       (size_t)Flags.entropic_number_of_rarest_features;
721   if (Options.Entropic) {
722     if (!Options.FocusFunction.empty()) {
723       Printf("ERROR: The parameters `--entropic` and `--focus_function` cannot "
724              "be used together.\n");
725       exit(1);
726     }
727     Printf("INFO: Running with entropic power schedule (0x%X, %d).\n",
728            Options.EntropicFeatureFrequencyThreshold,
729            Options.EntropicNumberOfRarestFeatures);
730   }
731   struct EntropicOptions Entropic;
732   Entropic.Enabled = Options.Entropic;
733   Entropic.FeatureFrequencyThreshold =
734       Options.EntropicFeatureFrequencyThreshold;
735   Entropic.NumberOfRarestFeatures = Options.EntropicNumberOfRarestFeatures;
736 
737   unsigned Seed = Flags.seed;
738   // Initialize Seed.
739   if (Seed == 0)
740     Seed =
741         std::chrono::system_clock::now().time_since_epoch().count() + GetPid();
742   if (Flags.verbosity)
743     Printf("INFO: Seed: %u\n", Seed);
744 
745   if (Flags.collect_data_flow && !Flags.fork && !Flags.merge) {
746     if (RunIndividualFiles)
747       return CollectDataFlow(Flags.collect_data_flow, Flags.data_flow_trace,
748                         ReadCorpora({}, *Inputs));
749     else
750       return CollectDataFlow(Flags.collect_data_flow, Flags.data_flow_trace,
751                         ReadCorpora(*Inputs, {}));
752   }
753 
754   Random Rand(Seed);
755   auto *MD = new MutationDispatcher(Rand, Options);
756   auto *Corpus = new InputCorpus(Options.OutputCorpus, Entropic);
757   auto *F = new Fuzzer(Callback, *Corpus, *MD, Options);
758 
759   for (auto &U: Dictionary)
760     if (U.size() <= Word::GetMaxSize())
761       MD->AddWordToManualDictionary(Word(U.data(), U.size()));
762 
763       // Threads are only supported by Chrome. Don't use them with emscripten
764       // for now.
765 #if !LIBFUZZER_EMSCRIPTEN
766   StartRssThread(F, Flags.rss_limit_mb);
767 #endif // LIBFUZZER_EMSCRIPTEN
768 
769   Options.HandleAbrt = Flags.handle_abrt;
770   Options.HandleAlrm = !Flags.minimize_crash;
771   Options.HandleBus = Flags.handle_bus;
772   Options.HandleFpe = Flags.handle_fpe;
773   Options.HandleIll = Flags.handle_ill;
774   Options.HandleInt = Flags.handle_int;
775   Options.HandleSegv = Flags.handle_segv;
776   Options.HandleTerm = Flags.handle_term;
777   Options.HandleXfsz = Flags.handle_xfsz;
778   Options.HandleUsr1 = Flags.handle_usr1;
779   Options.HandleUsr2 = Flags.handle_usr2;
780   SetSignalHandler(Options);
781 
782   std::atexit(Fuzzer::StaticExitCallback);
783 
784   if (Flags.minimize_crash)
785     return MinimizeCrashInput(Args, Options);
786 
787   if (Flags.minimize_crash_internal_step)
788     return MinimizeCrashInputInternalStep(F, Corpus);
789 
790   if (Flags.cleanse_crash)
791     return CleanseCrashInput(Args, Options);
792 
793   if (RunIndividualFiles) {
794     Options.SaveArtifacts = false;
795     int Runs = std::max(1, Flags.runs);
796     Printf("%s: Running %zd inputs %d time(s) each.\n", ProgName->c_str(),
797            Inputs->size(), Runs);
798     for (auto &Path : *Inputs) {
799       auto StartTime = system_clock::now();
800       Printf("Running: %s\n", Path.c_str());
801       for (int Iter = 0; Iter < Runs; Iter++)
802         RunOneTest(F, Path.c_str(), Options.MaxLen);
803       auto StopTime = system_clock::now();
804       auto MS = duration_cast<milliseconds>(StopTime - StartTime).count();
805       Printf("Executed %s in %zd ms\n", Path.c_str(), (long)MS);
806     }
807     Printf("***\n"
808            "*** NOTE: fuzzing was not performed, you have only\n"
809            "***       executed the target code on a fixed set of inputs.\n"
810            "***\n");
811     F->PrintFinalStats();
812     exit(0);
813   }
814 
815   if (Flags.fork)
816     FuzzWithFork(F->GetMD().GetRand(), Options, Args, *Inputs, Flags.fork);
817 
818   if (Flags.merge)
819     Merge(F, Options, Args, *Inputs, Flags.merge_control_file);
820 
821   if (Flags.merge_inner) {
822     const size_t kDefaultMaxMergeLen = 1 << 20;
823     if (Options.MaxLen == 0)
824       F->SetMaxInputLen(kDefaultMaxMergeLen);
825     assert(Flags.merge_control_file);
826     F->CrashResistantMergeInternalStep(Flags.merge_control_file);
827     exit(0);
828   }
829 
830   if (Flags.analyze_dict) {
831     size_t MaxLen = INT_MAX;  // Large max length.
832     UnitVector InitialCorpus;
833     for (auto &Inp : *Inputs) {
834       Printf("Loading corpus dir: %s\n", Inp.c_str());
835       ReadDirToVectorOfUnits(Inp.c_str(), &InitialCorpus, nullptr,
836                              MaxLen, /*ExitOnError=*/false);
837     }
838 
839     if (Dictionary.empty() || Inputs->empty()) {
840       Printf("ERROR: can't analyze dict without dict and corpus provided\n");
841       return 1;
842     }
843     if (AnalyzeDictionary(F, Dictionary, InitialCorpus)) {
844       Printf("Dictionary analysis failed\n");
845       exit(1);
846     }
847     Printf("Dictionary analysis succeeded\n");
848     exit(0);
849   }
850 
851   auto CorporaFiles = ReadCorpora(*Inputs, ParseSeedInuts(Flags.seed_inputs));
852   F->Loop(CorporaFiles);
853 
854   if (Flags.verbosity)
855     Printf("Done %zd runs in %zd second(s)\n", F->getTotalNumberOfRuns(),
856            F->secondsSinceProcessStartUp());
857   F->PrintFinalStats();
858 
859   exit(0);  // Don't let F destroy itself.
860 }
861 
862 extern "C" ATTRIBUTE_INTERFACE int
863 LLVMFuzzerRunDriver(int *argc, char ***argv,
864                     int (*UserCb)(const uint8_t *Data, size_t Size)) {
865   return FuzzerDriver(argc, argv, UserCb);
866 }
867 
868 // Storage for global ExternalFunctions object.
869 ExternalFunctions *EF = nullptr;
870 
871 }  // namespace fuzzer
872