[libFuzzer] Diff 4 - Split FuzzerUtil implementation for Posix and Windows.

[mpividori]

Summary

Implement utils functions for Windows, using vectored exception handlers as equivalent of POSIX signals. Implementation of timers is incomplete.

[amccarth]

My comments are mostly just things to be aware of. No changes required.

lib/Fuzzer/FuzzerUtil.cpp

233

Implicit conversion from unsigned to signed. Probably not an issue until processors get a lot bigger.

Relying on implicit conversions makes it hard to turn on conversion warnings, which might help detect real bugs in other parts of the code.

lib/Fuzzer/FuzzerUtilPosix.cpp

57

Be aware that this name clashes with the Windows function SetTimer that's in scope here. You're OK, since this is a C++ file and so it'll be name-mangled and thus distinct. If this had been a C source file instead, though, this would be a problem.

lib/Fuzzer/FuzzerUtilWindows.cpp

160

Be aware that this converts from an unsigned to a signed type. This is not a big deal with modern Windows, since it's extremely unlikely you'll ever see a PID approaching 2^31, but it's at least theoretically possible. If some logging somewhere prints this as a signed int, it may not look like the value you'd see in other Window stools.

Raymond Chen mentions seeing PIDs approaching 4 billion, but I suspect that's when they were actually pointers in disguise. http://stackoverflow.com/a/17868515/1386054

187

I'm not sure if libfuzzer has its own coding style guidelines, but I'd probably use nullptr rather than NULL.

[mpividori]

Update Diff.

[zturner]

lib/Fuzzer/FuzzerUtil.cpp

227

I noticed that in the SleepSeconds function, there is a comment that they couldn't use stl because they wanted to avoid coverage of instrumented libc++. You might wait for comments from kcc@ about whether this is relevant here as well. If so, we might need to go back to pure C implementations for each platform.

lib/Fuzzer/FuzzerUtilWindows.cpp

170

This function appears almost entirely the same except _popen vs popen. Perhaps this could be hidden behind a function called OpenProcessPipe and then ExecuteCommandAndReadOutput could be shared.

174–175

This looks wrong to me. fread does not indicate an error by returning a value less than 0, it indicates an error by returning a value different from the requested number of bytes. Then, you check feof and ferr to determine whether it was an error or an end of file. This code doesn't seem to handle the case where there was an error reading the process output.

[mpividori]

lib/Fuzzer/FuzzerUtilWindows.cpp

170

@zturner thanks. Yes, I agree. I will add that modification.

174–175

@zturner, Yes you are right. This code was moved from the previous implementation for Posix. Anyway, I will fix this.

[mpividori]

lib/Fuzzer/FuzzerUtil.cpp

233

@amccarth Ok, I will make an explicit cast.

lib/Fuzzer/FuzzerUtilPosix.cpp

57

@amccarth thanks. Anyway, I remove that function in the diff 7.

lib/Fuzzer/FuzzerUtilWindows.cpp

160

@amccarth Ok. I will add that changes in a new diff.

187

@amccarth it doesn't have own style guidelines... I think we should follow LLVM guidelines. But this requires many changes... If @kcc agrees I can update the code to follow LLVM code guidelines in a new diff.

[mpividori]

@amccarth suggestions were included in the diff: https://reviews.llvm.org/D27281

[kcc]

lib/Fuzzer/FuzzerUtil.h

64

No such ifdefs, please.
Can this be moved to the win-specific file?

[zturner]

lib/Fuzzer/FuzzerUtil.h

64

It is called directly from non platform specific code. The alternative would be to add a function like SearchMemory(), and in Posix file it just calls memmem, and in Win32 it does its own algorithm. Then update callsites to use SearchMemory() instead.

[kcc]

lib/Fuzzer/FuzzerUtil.h

64

Yes, that would be fine.

[mpividori]

lib/Fuzzer/FuzzerUtil.h

64

@kcc @zturner Actually I can remove that #ifdef since it is only a declaration and the type matches the type of the memmem() function in Posix.

[mpividori]

Added changes to include @zturner's suggestion.

[zturner]

lgtm, will wait for kcc to also lgtm before committing.

[mpividori]

lib/Fuzzer/FuzzerUtil.cpp

227

@kcc what do you think about this?

[kcc]

lib/Fuzzer/FuzzerUtil.cpp

217

why this change from >0 to == sizeof(Buff)

In general, please avoid mixing refactoring and functionality changes.

lib/Fuzzer/FuzzerUtil.h

66

This sounds wrong. This declares "fuzzer::memmem", while on Linux we actually use "memmem"

[zturner]

lib/Fuzzer/FuzzerUtil.cpp

217

That change was my suggestion. The code is incorrect as written because fread doesn't use <= 0 to indicate an error, it uses != request_size, then you check ferror. In any case, your point about mixing functionality and refactoring changes is still valid, so it might be worth doing this in a followup as you suggest.

[kcc]

lib/Fuzzer/FuzzerUtil.cpp

217

hmmm. am I reading "man fread" wrong?
On success, fread() and fwrite() return the number of items read or written. This number equals the number of bytes transferred only when size is 1. If an error occurs, or the end of

the file is reached, the return value is a short item count (or zero).

[zturner]

lib/Fuzzer/FuzzerUtil.cpp

217

It's a little bit ambiguous, but it doesn't explicitly state that 0 is for errors and the less specific condition of < request_size is eof. Indeed, the very next line in the man page is "fread() does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred."

So it seems like the modified version is slightly more correct.

[zturner]

lib/Fuzzer/FuzzerUtil.cpp

217

Also, the Microsoft documentation says similarly "fread returns the number of full items actually read, which may be less than count if an error occurs or if the end of the file is encountered before reaching count. Use the feof or ferror function to distinguish a read error from an end-of-file condition." So again, it seems you can't use the return value to distinguish feof and ferr, and it seems theoretically possible that a value greater than 0 but less than the number of bytes requested could still be an error, which would only be determinable through ferror.

[kcc]

lib/Fuzzer/FuzzerUtil.cpp

217

Ok.

[mpividori]

+ Remove memmem() and add SearchMemory() as suggested.
+ Remove changes to fread. I will add that changes in a new diff as suggested.

[zturner]

lib/Fuzzer/FuzzerUtil.cpp

199

Kostya, can you confirm that the call to std::thread::hardware_concurrency() here is ok? The call to sleep earlier has a comment explicitly stating that stl can't be used. Is the same thing going to be true here?

[kcc]

LGTM (I did not read the widows code)
As for every other patch, please ensure check-fuzzer still work on Linux.

lib/Fuzzer/FuzzerUtil.cpp

199

Yep, should be fine.
We should only avoid heavy STL around the calls to the user callback.
This one is happening at init time.

lib/Fuzzer/CMakeLists.txt

add_library(LLVMFuzzerNoMainObjects OBJECT
     FuzzerLoop.cpp
     FuzzerMutate.cpp
     FuzzerSHA1.cpp
     FuzzerTracePC.cpp
     FuzzerTraceState.cpp
     FuzzerUtil.cpp
     FuzzerUtilDarwin.cpp
     FuzzerUtilLinux.cpp
+    FuzzerUtilPosix.cpp
+    FuzzerUtilWindows.cpp
     )
   add_library(LLVMFuzzerNoMain STATIC
     $<TARGET_OBJECTS:LLVMFuzzerNoMainObjects>
     )
   target_link_libraries(LLVMFuzzerNoMain ${PTHREAD_LIB})
   add_library(LLVMFuzzer STATIC
     FuzzerMain.cpp
     $<TARGET_OBJECTS:LLVMFuzzerNoMainObjects>
     )
   target_link_libraries(LLVMFuzzer ${PTHREAD_LIB})
 
   if( LLVM_INCLUDE_TESTS )
     add_subdirectory(test)
   endif()
 endif()

lib/Fuzzer/FuzzerDriver.cpp

 
 #include <algorithm>
 #include <atomic>
 #include <chrono>
 #include <cstring>
 #include <mutex>
 #include <string>
 #include <thread>
-#include <unistd.h>
 
 // This function should be present in the libFuzzer so that the client
 // binary can test for its existence.
 extern "C" __attribute__((used)) void __libfuzzer_is_present() {}
 
 namespace fuzzer {
 
 // Program arguments.
if (Flags.exit_on_src_pos)
     Options.ExitOnSrcPos = Flags.exit_on_src_pos;
   if (Flags.exit_on_item)
     Options.ExitOnItem = Flags.exit_on_item;
 
   unsigned Seed = Flags.seed;
   // Initialize Seed.
   if (Seed == 0)
     Seed = (std::chrono::system_clock::now().time_since_epoch().count() << 10) +
-           getpid();
+           GetPid();
   if (Flags.verbosity)
     Printf("INFO: Seed: %u\n", Seed);
 
   Random Rand(Seed);
   auto *MD = new MutationDispatcher(Rand, Options);
   auto *Corpus = new InputCorpus(Options.OutputCorpus);
   auto *F = new Fuzzer(Callback, *Corpus, *MD, Options);
 

lib/Fuzzer/FuzzerUtil.h

 std::string Base64(const Unit &U);
 
 void PrintPC(const char *SymbolizedFMT, const char *FallbackFMT, uintptr_t PC);
 
 std::string DescribePC(const char *SymbolizedFMT, uintptr_t PC);
 
 int NumberOfCpuCores();
 
+bool ExecuteCommandAndReadOutput(const std::string &Command, std::string *Out);
+
 // Platform specific functions.
 void SetTimer(int Seconds);
 
 void SetSigSegvHandler();
 void SetSigBusHandler();
 void SetSigAbrtHandler();
 void SetSigIllHandler();
 void SetSigFpeHandler();
 void SetSigIntHandler();
 void SetSigTermHandler();
 
 void SleepSeconds(int Seconds);
 
 int GetPid();
 
 size_t GetPeakRSSMb();
 
-bool ExecuteCommandAndReadOutput(const std::string &Command, std::string *Out);
-
 int ExecuteCommand(const std::string &Command);
 
+FILE* OpenProcessPipe(const char *Command, const char *Mode);
+
+const void *memmem(const void *haystack, size_t haystacklen,
+                   const void *needle, size_t needlelen);
+
 }  // namespace fuzzer
 #endif  // LLVM_FUZZER_UTIL_H

lib/Fuzzer/FuzzerUtil.cpp

 //===- FuzzerUtil.cpp - Misc utils ----------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 // Misc utils.
 //===----------------------------------------------------------------------===//
 
 #include "FuzzerUtil.h"
 #include "FuzzerInternal.h"
 #include "FuzzerIO.h"
-#include <sstream>
-#include <iomanip>
-#include <sys/resource.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <sys/syscall.h>
 #include <cassert>
 #include <chrono>
 #include <cstring>
-#include <stdio.h>
+#include <errno.h>
 #include <signal.h>
 #include <sstream>
-#include <unistd.h>
-#include <errno.h>
+#include <stdio.h>
+#include <sys/types.h>
 #include <thread>
 
 namespace fuzzer {
 
 void PrintHexArray(const uint8_t *Data, size_t Size,
                    const char *PrintAfter) {
   for (size_t i = 0; i < Size; i++)
     Printf("0x%x,", (unsigned)Data[i]);
for (size_t i = 0; i < Size; i++)
     PrintASCIIByte(Data[i]);
   Printf("%s", PrintAfter);
 }
 
 void PrintASCII(const Unit &U, const char *PrintAfter) {
   PrintASCII(U.data(), U.size(), PrintAfter);
 }
 
-static void AlarmHandler(int, siginfo_t *, void *) {
-  Fuzzer::StaticAlarmCallback();
-}
-
-static void CrashHandler(int, siginfo_t *, void *) {
-  Fuzzer::StaticCrashSignalCallback();
-}
-
-static void InterruptHandler(int, siginfo_t *, void *) {
-  Fuzzer::StaticInterruptCallback();
-}
-
-static void SetSigaction(int signum,
-                         void (*callback)(int, siginfo_t *, void *)) {
-  struct sigaction sigact;
-  memset(&sigact, 0, sizeof(sigact));
-  sigact.sa_sigaction = callback;
-  if (sigaction(signum, &sigact, 0)) {
-    Printf("libFuzzer: sigaction failed with %d\n", errno);
-    exit(1);
-  }
-}
-
-void SetTimer(int Seconds) {
-  struct itimerval T {{Seconds, 0}, {Seconds, 0}};
-  if (setitimer(ITIMER_REAL, &T, nullptr)) {
-    Printf("libFuzzer: setitimer failed with %d\n", errno);
-    exit(1);
-  }
-  SetSigaction(SIGALRM, AlarmHandler);
-}
-
-void SetSigSegvHandler() { SetSigaction(SIGSEGV, CrashHandler); }
-void SetSigBusHandler() { SetSigaction(SIGBUS, CrashHandler); }
-void SetSigAbrtHandler() { SetSigaction(SIGABRT, CrashHandler); }
-void SetSigIllHandler() { SetSigaction(SIGILL, CrashHandler); }
-void SetSigFpeHandler() { SetSigaction(SIGFPE, CrashHandler); }
-void SetSigIntHandler() { SetSigaction(SIGINT, InterruptHandler); }
-void SetSigTermHandler() { SetSigaction(SIGTERM, InterruptHandler); }
-
-int NumberOfCpuCores() {
-  const char *CmdLine = nullptr;
-  if (LIBFUZZER_LINUX) {
-    CmdLine = "nproc";
-  } else if (LIBFUZZER_APPLE) {
-    CmdLine = "sysctl -n hw.ncpu";
-  } else {
-    assert(0 && "NumberOfCpuCores() is not implemented for your platform");
-  }
-
-  FILE *F = popen(CmdLine, "r");
-  int N = 1;
-  if (!F || fscanf(F, "%d", &N) != 1) {
-    Printf("WARNING: Failed to parse output of command \"%s\" in %s(). "
-           "Assuming CPU count of 1.\n",
-           CmdLine, __func__);
-    N = 1;
-  }
-
-  if (pclose(F)) {
-    Printf("WARNING: Executing command \"%s\" failed in %s(). "
-           "Assuming CPU count of 1.\n",
-           CmdLine, __func__);
-    N = 1;
-  }
-  if (N < 1) {
-    Printf("WARNING: Reported CPU count (%d) from command \"%s\" was invalid "
-           "in %s(). Assuming CPU count of 1.\n",
-           N, CmdLine, __func__);
-    N = 1;
-  }
-  return N;
-}
-
 bool ToASCII(uint8_t *Data, size_t Size) {
   bool Changed = false;
   for (size_t i = 0; i < Size; i++) {
     uint8_t &X = Data[i];
     auto NewX = X;
     NewX &= 127;
     if (!isspace(NewX) && !isprint(NewX))
       NewX = ' ';
if (ParseOneDictionaryEntry(S, &U)) {
       Printf("ParseDictionaryFile: error in line %d\n\t\t%s\n", LineNo,
              S.c_str());
       return false;
     }
   }
   return true;
 }
 
-void SleepSeconds(int Seconds) {
-  sleep(Seconds);  // Use C API to avoid coverage from instrumented libc++.
-}
-
-int GetPid() { return getpid(); }
-
 std::string Base64(const Unit &U) {
   static const char Table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                               "abcdefghijklmnopqrstuvwxyz"
                               "0123456789+/";
   std::string Res;
   size_t i;
   for (i = 0; i + 2 < U.size(); i += 3) {
     uint32_t x = (U[i] << 16) + (U[i + 1] << 8) + U[i + 2];
if (i + 1 == U.size()) {
     Res += Table[(x >> 18) & 63];
     Res += Table[(x >> 12) & 63];
     Res += Table[(x >> 6) & 63];
     Res += "=";
   }
   return Res;
 }
 
-size_t GetPeakRSSMb() {
-  struct rusage usage;
-  if (getrusage(RUSAGE_SELF, &usage))
-    return 0;
-  if (LIBFUZZER_LINUX) {
-    // ru_maxrss is in KiB
-    return usage.ru_maxrss >> 10;
-  } else if (LIBFUZZER_APPLE) {
-    // ru_maxrss is in bytes
-    return usage.ru_maxrss >> 20;
-  }
-  assert(0 && "GetPeakRSSMb() is not implemented for your platform");
-  return 0;
-}
-
 std::string DescribePC(const char *SymbolizedFMT, uintptr_t PC) {
   if (!EF->__sanitizer_symbolize_pc) return "<can not symbolize>";
   char PcDescr[1024];
   EF->__sanitizer_symbolize_pc(reinterpret_cast<void*>(PC),
                                SymbolizedFMT, PcDescr, sizeof(PcDescr));
   PcDescr[sizeof(PcDescr) - 1] = 0;  // Just in case.
   return PcDescr;
 }
 
 void PrintPC(const char *SymbolizedFMT, const char *FallbackFMT, uintptr_t PC) {
   if (EF->__sanitizer_symbolize_pc)
     Printf("%s", DescribePC(SymbolizedFMT, PC).c_str());
   else
     Printf(FallbackFMT, PC);
 }
 
+int NumberOfCpuCores() {
+  unsigned N = std::thread::hardware_concurrency();
+  if (!N) {
+    Printf("WARNING: std::thread::hardware_concurrency not well defined for "
+      "your platform. Assuming CPU count of 1.\n");
+    N = 1;
+  }
+  return N;
+}
+
 bool ExecuteCommandAndReadOutput(const std::string &Command, std::string *Out) {
-  FILE *Pipe = popen(Command.c_str(), "r");
-  if (!Pipe) return false;
+  FILE *Pipe = OpenProcessPipe(Command.c_str(), "r");
+  if (!Pipe) {
+    Printf("OpenProcessPipe failed with %d.\n", errno);
+    exit(1);
+  }
+
   char Buff[1024];
   size_t N;
-  while ((N = fread(Buff, 1, sizeof(Buff), Pipe)) > 0)
-    Out->append(Buff, N);
+  while ((N = fread(Buff, 1, sizeof(Buff), Pipe)) == sizeof(Buff))
+    Out->append(Buff, N);
+  if (ferror(Pipe)) {
+    Printf("Failed to read opened process pipe.\n");
+    exit(1);
+  }
+  // Add last data read.
+
   return true;
 }
 
 }  // namespace fuzzer

lib/Fuzzer/FuzzerUtilPosix.cpp

+//===- FuzzerUtilPosix.cpp - Misc utils for Posix. ------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Misc utils implementation using Posix API.
+//===----------------------------------------------------------------------===//
+
+#include "FuzzerDefs.h"
+#if LIBFUZZER_POSIX
+#include "FuzzerInternal.h"
+#include "FuzzerIO.h"
+#include <cassert>
+#include <chrono>
+#include <cstring>
+#include <errno.h>
+#include <iomanip>
+#include <signal.h>
+#include <sstream>
+#include <stdio.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <thread>
+#include <unistd.h>
+
+namespace fuzzer {
+
+static void AlarmHandler(int, siginfo_t *, void *) {
+  Fuzzer::StaticAlarmCallback();
+}
+
+static void CrashHandler(int, siginfo_t *, void *) {
+  Fuzzer::StaticCrashSignalCallback();
+}
+
+static void InterruptHandler(int, siginfo_t *, void *) {
+  Fuzzer::StaticInterruptCallback();
+}
+
+static void SetSigaction(int signum,
+                         void (*callback)(int, siginfo_t *, void *)) {
+  struct sigaction sigact;
+  memset(&sigact, 0, sizeof(sigact));
+  sigact.sa_sigaction = callback;
+  if (sigaction(signum, &sigact, 0)) {
+    Printf("libFuzzer: sigaction failed with %d\n", errno);
+    exit(1);
+  }
+}
+
+void SetTimer(int Seconds) {
+  struct itimerval T {{Seconds, 0}, {Seconds, 0}};
+  if (setitimer(ITIMER_REAL, &T, nullptr)) {
+    Printf("libFuzzer: setitimer failed with %d\n", errno);
+    exit(1);
+  }
+  SetSigaction(SIGALRM, AlarmHandler);
+}
+
+void SetSigSegvHandler() { SetSigaction(SIGSEGV, CrashHandler); }
+void SetSigBusHandler() { SetSigaction(SIGBUS, CrashHandler); }
+void SetSigAbrtHandler() { SetSigaction(SIGABRT, CrashHandler); }
+void SetSigIllHandler() { SetSigaction(SIGILL, CrashHandler); }
+void SetSigFpeHandler() { SetSigaction(SIGFPE, CrashHandler); }
+void SetSigIntHandler() { SetSigaction(SIGINT, InterruptHandler); }
+void SetSigTermHandler() { SetSigaction(SIGTERM, InterruptHandler); }
+
+void SleepSeconds(int Seconds) {
+  sleep(Seconds);  // Use C API to avoid coverage from instrumented libc++.
+}
+
+int GetPid() { return getpid(); }
+
+size_t GetPeakRSSMb() {
+  struct rusage usage;
+  if (getrusage(RUSAGE_SELF, &usage))
+    return 0;
+  if (LIBFUZZER_LINUX) {
+    // ru_maxrss is in KiB
+    return usage.ru_maxrss >> 10;
+  } else if (LIBFUZZER_APPLE) {
+    // ru_maxrss is in bytes
+    return usage.ru_maxrss >> 20;
+  }
+  assert(0 && "GetPeakRSSMb() is not implemented for your platform");
+  return 0;
+}
+
+FILE* OpenProcessPipe(const char *Command, const char *Mode) {
+  return popen(Command, Mode);
+}
+
+}  // namespace fuzzer
+#endif // LIBFUZZER_POSIX

lib/Fuzzer/FuzzerUtilWindows.cpp

+//===- FuzzerUtilWindows.cpp - Misc utils for Windows. --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Misc utils implementation for Windows.
+//===----------------------------------------------------------------------===//
+
+#include "FuzzerDefs.h"
+#if LIBFUZZER_WINDOWS
+#include "FuzzerInternal.h"
+#include "FuzzerIO.h"
+#include <cassert>
+#include <chrono>
+#include <cstring>
+#include <errno.h>
+#include <iomanip>
+#include <signal.h>
+#include <sstream>
+#include <stdio.h>
+#include <sys/types.h>
+#include <windows.h>
+#include <Psapi.h>
+
+namespace fuzzer {
+
+LONG WINAPI SEGVHandler(PEXCEPTION_POINTERS ExceptionInfo) {
+  switch (ExceptionInfo->ExceptionRecord->ExceptionCode) {
+    case EXCEPTION_ACCESS_VIOLATION:
+    case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
+    case EXCEPTION_STACK_OVERFLOW:
+      Fuzzer::StaticCrashSignalCallback();
+      break;
+  }
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+LONG WINAPI BUSHandler(PEXCEPTION_POINTERS ExceptionInfo) {
+  switch (ExceptionInfo->ExceptionRecord->ExceptionCode) {
+    case EXCEPTION_DATATYPE_MISALIGNMENT:
+    case EXCEPTION_IN_PAGE_ERROR:
+      Fuzzer::StaticCrashSignalCallback();
+      break;
+  }
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+LONG WINAPI ILLHandler(PEXCEPTION_POINTERS ExceptionInfo) {
+  switch (ExceptionInfo->ExceptionRecord->ExceptionCode) {
+    case EXCEPTION_ILLEGAL_INSTRUCTION:
+    case EXCEPTION_PRIV_INSTRUCTION:
+      Fuzzer::StaticCrashSignalCallback();
+      break;
+  }
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+LONG WINAPI FPEHandler(PEXCEPTION_POINTERS ExceptionInfo) {
+  switch (ExceptionInfo->ExceptionRecord->ExceptionCode) {
+    case EXCEPTION_FLT_DENORMAL_OPERAND:
+    case EXCEPTION_FLT_DIVIDE_BY_ZERO:
+    case EXCEPTION_FLT_INEXACT_RESULT:
+    case EXCEPTION_FLT_INVALID_OPERATION:
+    case EXCEPTION_FLT_OVERFLOW:
+    case EXCEPTION_FLT_STACK_CHECK:
+    case EXCEPTION_FLT_UNDERFLOW:
+    case EXCEPTION_INT_DIVIDE_BY_ZERO:
+    case EXCEPTION_INT_OVERFLOW:
+      Fuzzer::StaticCrashSignalCallback();
+      break;
+  }
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+BOOL WINAPI INTHandler(DWORD dwCtrlType) {
+  switch (dwCtrlType) {
+    case CTRL_C_EVENT:
+      Fuzzer::StaticInterruptCallback();
+      return TRUE;
+    default:
+      return FALSE;
+  }
+}
+
+BOOL WINAPI TERMHandler(DWORD dwCtrlType) {
+  switch (dwCtrlType) {
+    case CTRL_BREAK_EVENT:
+      Fuzzer::StaticInterruptCallback();
+      return TRUE;
+    default:
+      return FALSE;
+  }
+}
+
+void SetTimer(int Seconds) {
+  // TODO: Complete this implementation.
+  return;
+}
+
+void SetSigSegvHandler() {
+  if (!AddVectoredExceptionHandler(1, SEGVHandler)) {
+    Printf("libFuzzer: AddVectoredExceptionHandler failed.\n");
+    exit(1);
+  }
+}
+
+void SetSigBusHandler() {
+  if (!AddVectoredExceptionHandler(1, BUSHandler)) {
+    Printf("libFuzzer: AddVectoredExceptionHandler failed.\n");
+    exit(1);
+  }
+}
+
+static void CrashHandler(int) {
+  Fuzzer::StaticCrashSignalCallback();
+}
+
+void SetSigAbrtHandler() { signal(SIGABRT, CrashHandler); }
+
+void SetSigIllHandler() {
+  if (!AddVectoredExceptionHandler(1, ILLHandler)) {
+    Printf("libFuzzer: AddVectoredExceptionHandler failed.\n");
+    exit(1);
+  }
+}
+
+void SetSigFpeHandler() {
+  if (!AddVectoredExceptionHandler(1, FPEHandler)) {
+    Printf("libFuzzer: AddVectoredExceptionHandler failed.\n");
+    exit(1);
+  }
+}
+
+void SetSigIntHandler() {
+  if (!SetConsoleCtrlHandler(INTHandler, TRUE)) {
+    DWORD LastError = GetLastError();
+    Printf("libFuzzer: SetConsoleCtrlHandler failed (Error code: %lu).\n",
+      LastError);
+    exit(1);
+  }
+}
+
+void SetSigTermHandler() {
+  if (!SetConsoleCtrlHandler(TERMHandler, TRUE)) {
+    DWORD LastError = GetLastError();
+    Printf("libFuzzer: SetConsoleCtrlHandler failed (Error code: %lu).\n",
+      LastError);
+    exit(1);
+  }
+}
+
+void SleepSeconds(int Seconds) {
+  Sleep(Seconds * 1000);
+}
+
+int GetPid() { return GetCurrentProcessId(); }
+
+size_t GetPeakRSSMb() {
+  PROCESS_MEMORY_COUNTERS info;
+  if (!GetProcessMemoryInfo(GetCurrentProcess(), &info, sizeof(info)))
+    return 0;
+  return info.PeakWorkingSetSize >> 20;
+}
+
+FILE* OpenProcessPipe(const char *Command, const char *Mode) {
+  return _popen(Command, Mode);
+}
+
+const void *memmem(const void *Data, size_t DataLen, const void *Patt,
+                   size_t PattLen)
+{
+  //TODO: make this implementation more efficient.
+  const char *Cdata = (const char*) Data;
+  const char *Cpatt = (const char*) Patt;
+
+  if (!Data || !Patt || DataLen == 0 || PattLen == 0 || DataLen < PattLen)
+    return NULL;
+
+  if (PattLen == 1)
+    return memchr(Data, *Cpatt, DataLen);
+
+  const char *End = Cdata + DataLen - PattLen;
+
+  for (const char *It = Cdata; It < End; ++It)
+    if (It[0] == Cpatt[0] && memcmp(It, Cpatt, PattLen) == 0)
+      return It;
+
+  return NULL;
+}
+
+int ExecuteCommand(const std::string &Command) {
+  return system(Command.c_str());
+}
+
+} // namespace fuzzer
+#endif // LIBFUZZER_WINDOWS