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