[libFuzzer] simplify FuzzerInterface.h

llvm-svn: 269448

llvm/lib/Fuzzer/CMakeLists.txt

@@ -4,7 +4,6 @@ set(CMAKE_CXX_FLAGS_RELEASE "${LIBFUZZER_FLAGS_BASE} -O2 -fno-sanitize=all -fno-
 if( LLVM_USE_SANITIZE_COVERAGE )
   add_library(LLVMFuzzerNoMainObjects OBJECT
     FuzzerCrossOver.cpp
-    FuzzerInterface.cpp
     FuzzerTraceState.cpp
     FuzzerDriver.cpp
     FuzzerIO.cpp

llvm/lib/Fuzzer/FuzzerInterface.cpp

@@ -1,20 +0,0 @@
-//===- FuzzerInterface.cpp - Mutate a test input --------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-// Parts of public interface for libFuzzer.
-//===----------------------------------------------------------------------===//
-
-
-#include "FuzzerInterface.h"
-#include "FuzzerInternal.h"
-#include <random>
-
-namespace fuzzer {
-
-
-}  // namespace fuzzer.

llvm/lib/Fuzzer/FuzzerInterface.h

@@ -6,75 +6,53 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-// Define the interface between the Fuzzer and the library being tested.
+// Define the interface between libFuzzer and the library being tested.
 //===----------------------------------------------------------------------===//
 
-// WARNING: keep the interface free of STL or any other header-based C++ lib,
-// to avoid bad interactions between the code used in the fuzzer and
-// the code used in the target function.
+// NOTE: the libFuzzer interface is thin and in the majority of cases
+// you should not include this file into your target. In 95% of cases
+// all you need is to define the following function in your file:
+// extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
+
+// WARNING: keep the interface in C.
 
 #ifndef LLVM_FUZZER_INTERFACE_H
 #define LLVM_FUZZER_INTERFACE_H
 
-#include <cstddef>
-#include <cstdint>
+#include <stddef.h>
+#include <stdint.h>
 
-// Plain C interface. Should be sufficient for most uses.
+#ifdef __cplusplus
 extern "C" {
-// The target function, mandatory.
+#endif  // __cplusplus
+
+// Mandatory user-provided target function.
+// Executes the code under test with [Data, Data+Size) as the input.
+// libFuzzer will invoke this function *many* times with different inputs.
 // Must return 0.
 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
-// The initialization function, optional.
+
+// Optional user-provided initialization function.
+// If provided, this function will be called by libFuzzer once at startup.
+// It may read and modify argc/argv.
+// Must return 0.
 int LLVMFuzzerInitialize(int *argc, char ***argv);
-// Custom mutator, optional.
-// Mutates raw data in [Data, Data+Size] inplace.
+
+// Optional user-provided custom mutator.
+// Mutates raw data in [Data, Data+Size) inplace.
 // Returns the new size, which is not greater than MaxSize.
 // Given the same Seed produces the same mutation.
 size_t LLVMFuzzerCustomMutator(uint8_t *Data, size_t Size, size_t MaxSize,
                                unsigned int Seed);
 
-}  // extern "C"
-
-namespace fuzzer {
-
-/// Returns an int 0. Values other than zero are reserved for future.
-typedef int (*UserCallback)(const uint8_t *Data, size_t Size);
-/** Simple C-like interface with a single user-supplied callback.
-
-Usage:
-
-#\code
-#include "FuzzerInterface.h"
-
-int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
-  DoStuffWithData(Data, Size);
-  return 0;
-}
-
-// Optional.
-// Define this only if you need to read/modify argc/argv at startup
-// and you are using libFuzzer's main().
-// Must return 0.
-int LLVMFuzzerInitialize(int *argc, char ***argv) {
-  ReadAndMaybeModify(argc, argv);
-  return 0;
-}
-
-// Implement your own main() or use the one from FuzzerMain.cpp.
-// *NOT* recommended for most cases.
-int main(int argc, char **argv) {
-  InitializeMeIfNeeded();
-  return fuzzer::FuzzerDriver(argc, argv, LLVMFuzzerTestOneInput);
-}
-#\endcode
-*/
-int FuzzerDriver(int argc, char **argv, UserCallback Callback);
-
-// Mutates raw data in [Data, Data+Size] inplace.
+// Experimental, may go away in future.
+// libFuzzer-provided function to be used inside LLVMFuzzerTestOneInput.
+// Mutates raw data in [Data, Data+Size) inplace.
 // Returns the new size, which is not greater than MaxSize.
-// Can be used inside the user-supplied LLVMFuzzerTestOneInput.
-size_t Mutate(uint8_t *Data, size_t Size, size_t MaxSize);
+size_t LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize);
 
-}  // namespace fuzzer
+#ifdef __cplusplus
+}  // extern "C"
+#endif  // __cplusplus
 
 #endif  // LLVM_FUZZER_INTERFACE_H

llvm/lib/Fuzzer/FuzzerInternal.h

@@ -28,6 +28,10 @@
 #include "FuzzerTracePC.h"
 
 namespace fuzzer {
+
+typedef int (*UserCallback)(const uint8_t *Data, size_t Size);
+int FuzzerDriver(int argc, char **argv, UserCallback Callback);
+
 using namespace std::chrono;
 typedef std::vector<uint8_t> Unit;
 typedef std::vector<Unit> UnitVector;

llvm/lib/Fuzzer/FuzzerLoop.cpp

@@ -76,11 +76,6 @@ static void MissingWeakApiFunction(const char *FnName) {
 // Only one Fuzzer per process.
 static Fuzzer *F;
 
-size_t Mutate(uint8_t *Data, size_t Size, size_t MaxSize) {
-  assert(F);
-  return F->GetMD().Mutate(Data, Size, MaxSize);
-}
-
 struct CoverageController {
   static void Reset() {
     CHECK_WEAK_API_FUNCTION(__sanitizer_reset_coverage);
@@ -767,3 +762,11 @@ void Fuzzer::UpdateCorpusDistribution() {
 }
 
 } // namespace fuzzer
+
+extern "C" {
+
+size_t LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize) {
+  assert(fuzzer::F);
+  return fuzzer::F->GetMD().Mutate(Data, Size, MaxSize);
+}
+}  // extern "C"

llvm/lib/Fuzzer/test/CustomMutatorTest.cpp

@@ -34,5 +34,5 @@ extern "C" size_t LLVMFuzzerCustomMutator(uint8_t *Data, size_t Size,
     std::cerr << "In LLVMFuzzerCustomMutator\n";
     Printed = true;
   }
-  return fuzzer::Mutate(Data, Size, MaxSize);
+  return LLVMFuzzerMutate(Data, Size, MaxSize);
 }