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