1//===- FuzzerExtFunctionsWeak.cpp - Interface to external functions -------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// Implementation for Linux. This relies on the linker's support for weak 10// symbols. We don't use this approach on Apple platforms because it requires 11// clients of LibFuzzer to pass ``-U _<symbol_name>`` to the linker to allow 12// weak symbols to be undefined. That is a complication we don't want to expose 13// to clients right now. 14//===----------------------------------------------------------------------===// 15#include "FuzzerDefs.h" 16#if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FUCHSIA || \ 17 LIBFUZZER_FREEBSD || LIBFUZZER_OPENBSD 18 19#include "FuzzerExtFunctions.h" 20#include "FuzzerIO.h" 21 22extern "C" { 23// Declare these symbols as weak to allow them to be optionally defined. 24#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 25 __attribute__((weak, visibility("default"))) RETURN_TYPE NAME FUNC_SIG 26 27#include "FuzzerExtFunctions.def" 28 29#undef EXT_FUNC 30} 31 32using namespace fuzzer; 33 34static void CheckFnPtr(void *FnPtr, const char *FnName, bool WarnIfMissing) { 35 if (FnPtr == nullptr && WarnIfMissing) { 36 Printf("WARNING: Failed to find function \"%s\".\n", FnName); 37 } 38} 39 40namespace fuzzer { 41 42ExternalFunctions::ExternalFunctions() { 43#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 44 this->NAME = ::NAME; \ 45 CheckFnPtr(reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(::NAME)), \ 46 #NAME, WARN); 47 48#include "FuzzerExtFunctions.def" 49 50#undef EXT_FUNC 51} 52 53} // namespace fuzzer 54 55#endif 56