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