1*0b57cec5SDimitry Andric //=== FuzzerExtWindows.cpp - Interface to external functions --------------===// 2*0b57cec5SDimitry Andric // 3*0b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*0b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5*0b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*0b57cec5SDimitry Andric // 7*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 8*0b57cec5SDimitry Andric // Implementation of FuzzerExtFunctions for Windows. Uses alternatename when 9*0b57cec5SDimitry Andric // compiled with MSVC. Uses weak aliases when compiled with clang. Unfortunately 10*0b57cec5SDimitry Andric // the method each compiler supports is not supported by the other. 11*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 12*0b57cec5SDimitry Andric #include "FuzzerDefs.h" 13*0b57cec5SDimitry Andric #if LIBFUZZER_WINDOWS 14*0b57cec5SDimitry Andric 15*0b57cec5SDimitry Andric #include "FuzzerExtFunctions.h" 16*0b57cec5SDimitry Andric #include "FuzzerIO.h" 17*0b57cec5SDimitry Andric 18*0b57cec5SDimitry Andric using namespace fuzzer; 19*0b57cec5SDimitry Andric 20*0b57cec5SDimitry Andric // Intermediate macro to ensure the parameter is expanded before stringified. 21*0b57cec5SDimitry Andric #define STRINGIFY_(A) #A 22*0b57cec5SDimitry Andric #define STRINGIFY(A) STRINGIFY_(A) 23*0b57cec5SDimitry Andric 24*0b57cec5SDimitry Andric #if LIBFUZZER_MSVC 25*0b57cec5SDimitry Andric // Copied from compiler-rt/lib/sanitizer_common/sanitizer_win_defs.h 26*0b57cec5SDimitry Andric #if defined(_M_IX86) || defined(__i386__) 27*0b57cec5SDimitry Andric #define WIN_SYM_PREFIX "_" 28*0b57cec5SDimitry Andric #else 29*0b57cec5SDimitry Andric #define WIN_SYM_PREFIX 30*0b57cec5SDimitry Andric #endif 31*0b57cec5SDimitry Andric 32*0b57cec5SDimitry Andric // Declare external functions as having alternativenames, so that we can 33*0b57cec5SDimitry Andric // determine if they are not defined. 34*0b57cec5SDimitry Andric #define EXTERNAL_FUNC(Name, Default) \ 35*0b57cec5SDimitry Andric __pragma(comment(linker, "/alternatename:" WIN_SYM_PREFIX STRINGIFY( \ 36*0b57cec5SDimitry Andric Name) "=" WIN_SYM_PREFIX STRINGIFY(Default))) 37*0b57cec5SDimitry Andric #else 38*0b57cec5SDimitry Andric // Declare external functions as weak to allow them to default to a specified 39*0b57cec5SDimitry Andric // function if not defined explicitly. We must use weak symbols because clang's 40*0b57cec5SDimitry Andric // support for alternatename is not 100%, see 41*0b57cec5SDimitry Andric // https://bugs.llvm.org/show_bug.cgi?id=40218 for more details. 42*0b57cec5SDimitry Andric #define EXTERNAL_FUNC(Name, Default) \ 43*0b57cec5SDimitry Andric __attribute__((weak, alias(STRINGIFY(Default)))) 44*0b57cec5SDimitry Andric #endif // LIBFUZZER_MSVC 45*0b57cec5SDimitry Andric 46*0b57cec5SDimitry Andric extern "C" { 47*0b57cec5SDimitry Andric #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 48*0b57cec5SDimitry Andric RETURN_TYPE NAME##Def FUNC_SIG { \ 49*0b57cec5SDimitry Andric Printf("ERROR: Function \"%s\" not defined.\n", #NAME); \ 50*0b57cec5SDimitry Andric exit(1); \ 51*0b57cec5SDimitry Andric } \ 52*0b57cec5SDimitry Andric EXTERNAL_FUNC(NAME, NAME##Def) RETURN_TYPE NAME FUNC_SIG 53*0b57cec5SDimitry Andric 54*0b57cec5SDimitry Andric #include "FuzzerExtFunctions.def" 55*0b57cec5SDimitry Andric 56*0b57cec5SDimitry Andric #undef EXT_FUNC 57*0b57cec5SDimitry Andric } 58*0b57cec5SDimitry Andric 59*0b57cec5SDimitry Andric template <typename T> 60*0b57cec5SDimitry Andric static T *GetFnPtr(T *Fun, T *FunDef, const char *FnName, bool WarnIfMissing) { 61*0b57cec5SDimitry Andric if (Fun == FunDef) { 62*0b57cec5SDimitry Andric if (WarnIfMissing) 63*0b57cec5SDimitry Andric Printf("WARNING: Failed to find function \"%s\".\n", FnName); 64*0b57cec5SDimitry Andric return nullptr; 65*0b57cec5SDimitry Andric } 66*0b57cec5SDimitry Andric return Fun; 67*0b57cec5SDimitry Andric } 68*0b57cec5SDimitry Andric 69*0b57cec5SDimitry Andric namespace fuzzer { 70*0b57cec5SDimitry Andric 71*0b57cec5SDimitry Andric ExternalFunctions::ExternalFunctions() { 72*0b57cec5SDimitry Andric #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ 73*0b57cec5SDimitry Andric this->NAME = GetFnPtr<decltype(::NAME)>(::NAME, ::NAME##Def, #NAME, WARN); 74*0b57cec5SDimitry Andric 75*0b57cec5SDimitry Andric #include "FuzzerExtFunctions.def" 76*0b57cec5SDimitry Andric 77*0b57cec5SDimitry Andric #undef EXT_FUNC 78*0b57cec5SDimitry Andric } 79*0b57cec5SDimitry Andric 80*0b57cec5SDimitry Andric } // namespace fuzzer 81*0b57cec5SDimitry Andric 82*0b57cec5SDimitry Andric #endif // LIBFUZZER_WINDOWS 83