10b57cec5SDimitry Andric //=== FuzzerExtWindows.cpp - Interface to external functions --------------===// 20b57cec5SDimitry Andric // 30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 60b57cec5SDimitry Andric // 70b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 80b57cec5SDimitry Andric // Implementation of FuzzerExtFunctions for Windows. Uses alternatename when 90b57cec5SDimitry Andric // compiled with MSVC. Uses weak aliases when compiled with clang. Unfortunately 100b57cec5SDimitry Andric // the method each compiler supports is not supported by the other. 110b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 12*5ffd83dbSDimitry Andric #include "FuzzerPlatform.h" 130b57cec5SDimitry Andric #if LIBFUZZER_WINDOWS 140b57cec5SDimitry Andric 150b57cec5SDimitry Andric #include "FuzzerExtFunctions.h" 160b57cec5SDimitry Andric #include "FuzzerIO.h" 170b57cec5SDimitry Andric 180b57cec5SDimitry Andric using namespace fuzzer; 190b57cec5SDimitry Andric 200b57cec5SDimitry Andric // Intermediate macro to ensure the parameter is expanded before stringified. 210b57cec5SDimitry Andric #define STRINGIFY_(A) #A 220b57cec5SDimitry Andric #define STRINGIFY(A) STRINGIFY_(A) 230b57cec5SDimitry Andric 240b57cec5SDimitry Andric #if LIBFUZZER_MSVC 250b57cec5SDimitry Andric // Copied from compiler-rt/lib/sanitizer_common/sanitizer_win_defs.h 260b57cec5SDimitry Andric #if defined(_M_IX86) || defined(__i386__) 270b57cec5SDimitry Andric #define WIN_SYM_PREFIX "_" 280b57cec5SDimitry Andric #else 290b57cec5SDimitry Andric #define WIN_SYM_PREFIX 300b57cec5SDimitry Andric #endif 310b57cec5SDimitry Andric 320b57cec5SDimitry Andric // Declare external functions as having alternativenames, so that we can 330b57cec5SDimitry Andric // determine if they are not defined. 340b57cec5SDimitry Andric #define EXTERNAL_FUNC(Name, Default) \ 350b57cec5SDimitry Andric __pragma(comment(linker, "/alternatename:" WIN_SYM_PREFIX STRINGIFY( \ 360b57cec5SDimitry Andric Name) "=" WIN_SYM_PREFIX STRINGIFY(Default))) 370b57cec5SDimitry Andric #else 380b57cec5SDimitry Andric // Declare external functions as weak to allow them to default to a specified 390b57cec5SDimitry Andric // function if not defined explicitly. We must use weak symbols because clang's 400b57cec5SDimitry Andric // support for alternatename is not 100%, see 410b57cec5SDimitry Andric // https://bugs.llvm.org/show_bug.cgi?id=40218 for more details. 420b57cec5SDimitry Andric #define EXTERNAL_FUNC(Name, Default) \ 430b57cec5SDimitry Andric __attribute__((weak, alias(STRINGIFY(Default)))) 440b57cec5SDimitry Andric #endif // LIBFUZZER_MSVC 450b57cec5SDimitry Andric 460b57cec5SDimitry Andric extern "C" { 470b57cec5SDimitry Andric #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 480b57cec5SDimitry Andric RETURN_TYPE NAME##Def FUNC_SIG { \ 490b57cec5SDimitry Andric Printf("ERROR: Function \"%s\" not defined.\n", #NAME); \ 500b57cec5SDimitry Andric exit(1); \ 510b57cec5SDimitry Andric } \ 520b57cec5SDimitry Andric EXTERNAL_FUNC(NAME, NAME##Def) RETURN_TYPE NAME FUNC_SIG 530b57cec5SDimitry Andric 540b57cec5SDimitry Andric #include "FuzzerExtFunctions.def" 550b57cec5SDimitry Andric 560b57cec5SDimitry Andric #undef EXT_FUNC 570b57cec5SDimitry Andric } 580b57cec5SDimitry Andric 590b57cec5SDimitry Andric template <typename T> 600b57cec5SDimitry Andric static T *GetFnPtr(T *Fun, T *FunDef, const char *FnName, bool WarnIfMissing) { 610b57cec5SDimitry Andric if (Fun == FunDef) { 620b57cec5SDimitry Andric if (WarnIfMissing) 630b57cec5SDimitry Andric Printf("WARNING: Failed to find function \"%s\".\n", FnName); 640b57cec5SDimitry Andric return nullptr; 650b57cec5SDimitry Andric } 660b57cec5SDimitry Andric return Fun; 670b57cec5SDimitry Andric } 680b57cec5SDimitry Andric 690b57cec5SDimitry Andric namespace fuzzer { 700b57cec5SDimitry Andric 710b57cec5SDimitry Andric ExternalFunctions::ExternalFunctions() { 720b57cec5SDimitry Andric #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 730b57cec5SDimitry Andric this->NAME = GetFnPtr<decltype(::NAME)>(::NAME, ::NAME##Def, #NAME, WARN); 740b57cec5SDimitry Andric 750b57cec5SDimitry Andric #include "FuzzerExtFunctions.def" 760b57cec5SDimitry Andric 770b57cec5SDimitry Andric #undef EXT_FUNC 780b57cec5SDimitry Andric } 790b57cec5SDimitry Andric 800b57cec5SDimitry Andric } // namespace fuzzer 810b57cec5SDimitry Andric 820b57cec5SDimitry Andric #endif // LIBFUZZER_WINDOWS 83