1*3cab2bb3Spatrick //===- FuzzerExtFunctionsDlsym.cpp - Interface to external functions ------===// 2*3cab2bb3Spatrick // 3*3cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*3cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information. 5*3cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*3cab2bb3Spatrick // 7*3cab2bb3Spatrick //===----------------------------------------------------------------------===// 8*3cab2bb3Spatrick // Implementation for operating systems that support dlsym(). We only use it on 9*3cab2bb3Spatrick // Apple platforms for now. We don't use this approach on Linux because it 10*3cab2bb3Spatrick // requires that clients of LibFuzzer pass ``--export-dynamic`` to the linker. 11*3cab2bb3Spatrick // That is a complication we don't wish to expose to clients right now. 12*3cab2bb3Spatrick //===----------------------------------------------------------------------===// 13*3cab2bb3Spatrick #include "FuzzerDefs.h" 14*3cab2bb3Spatrick #if LIBFUZZER_APPLE 15*3cab2bb3Spatrick 16*3cab2bb3Spatrick #include "FuzzerExtFunctions.h" 17*3cab2bb3Spatrick #include "FuzzerIO.h" 18*3cab2bb3Spatrick #include <dlfcn.h> 19*3cab2bb3Spatrick 20*3cab2bb3Spatrick using namespace fuzzer; 21*3cab2bb3Spatrick 22*3cab2bb3Spatrick template <typename T> 23*3cab2bb3Spatrick static T GetFnPtr(const char *FnName, bool WarnIfMissing) { 24*3cab2bb3Spatrick dlerror(); // Clear any previous errors. 25*3cab2bb3Spatrick void *Fn = dlsym(RTLD_DEFAULT, FnName); 26*3cab2bb3Spatrick if (Fn == nullptr) { 27*3cab2bb3Spatrick if (WarnIfMissing) { 28*3cab2bb3Spatrick const char *ErrorMsg = dlerror(); 29*3cab2bb3Spatrick Printf("WARNING: Failed to find function \"%s\".", FnName); 30*3cab2bb3Spatrick if (ErrorMsg) 31*3cab2bb3Spatrick Printf(" Reason %s.", ErrorMsg); 32*3cab2bb3Spatrick Printf("\n"); 33*3cab2bb3Spatrick } 34*3cab2bb3Spatrick } 35*3cab2bb3Spatrick return reinterpret_cast<T>(Fn); 36*3cab2bb3Spatrick } 37*3cab2bb3Spatrick 38*3cab2bb3Spatrick namespace fuzzer { 39*3cab2bb3Spatrick 40*3cab2bb3Spatrick ExternalFunctions::ExternalFunctions() { 41*3cab2bb3Spatrick #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 42*3cab2bb3Spatrick this->NAME = GetFnPtr<decltype(ExternalFunctions::NAME)>(#NAME, WARN) 43*3cab2bb3Spatrick 44*3cab2bb3Spatrick #include "FuzzerExtFunctions.def" 45*3cab2bb3Spatrick 46*3cab2bb3Spatrick #undef EXT_FUNC 47*3cab2bb3Spatrick } 48*3cab2bb3Spatrick 49*3cab2bb3Spatrick } // namespace fuzzer 50*3cab2bb3Spatrick 51*3cab2bb3Spatrick #endif // LIBFUZZER_APPLE 52