compiler-rt/lib/fuzzer/FuzzerExtFunctionsWindows.cpp

   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 #include <stdlib.h>
  18
  19 using namespace fuzzer;
  20
  21 // Intermediate macro to ensure the parameter is expanded before stringified.
  22 #define STRINGIFY_(A) #A
  23 #define STRINGIFY(A) STRINGIFY_(A)
  24
  25 #if LIBFUZZER_MSVC
  26 #define GET_FUNCTION_ADDRESS(fn) &fn
  27 #else
  28 #define GET_FUNCTION_ADDRESS(fn) __builtin_function_start(fn)
  29 #endif // LIBFUZER_MSVC
  30
  31 // Copied from compiler-rt/lib/sanitizer_common/sanitizer_win_defs.h
  32 #if defined(_M_IX86) || defined(__i386__)
  33 #define WIN_SYM_PREFIX "_"
  34 #else
  35 #define WIN_SYM_PREFIX
  36 #endif
  37
  38 // Declare external functions as having alternativenames, so that we can
  39 // determine if they are not defined.
  40 #define EXTERNAL_FUNC(Name, Default)                                           \
  41   __pragma(comment(linker, "/alternatename:" WIN_SYM_PREFIX STRINGIFY(         \
  42                                Name) "=" WIN_SYM_PREFIX STRINGIFY(Default)))
  43
  44 extern "C" {
  45 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN)         \
  46   RETURN_TYPE NAME##Def FUNC_SIG {                          \
  47     Printf("ERROR: Function \"%s\" not defined.\n", #NAME); \
  48     exit(1);                                                \
  49   }                                                         \
  50   EXTERNAL_FUNC(NAME, NAME##Def) RETURN_TYPE NAME FUNC_SIG
  51
  52 #include "FuzzerExtFunctions.def"
  53
  54 #undef EXT_FUNC
  55 }
  56
  57 template <typename T>
  58 static T *GetFnPtr(void *Fun, void *FunDef, const char *FnName,
  59                    bool WarnIfMissing) {
  60   if (Fun == FunDef) {
  61     if (WarnIfMissing)
  62       Printf("WARNING: Failed to find function \"%s\".\n", FnName);
  63     return nullptr;
  64   }
  65   return (T *)Fun;
  66 }
  67
  68 namespace fuzzer {
  69
  70 ExternalFunctions::ExternalFunctions() {
  71 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN)                            \
  72   this->NAME = GetFnPtr<decltype(::NAME)>(GET_FUNCTION_ADDRESS(::NAME),        \
  73                                           GET_FUNCTION_ADDRESS(::NAME##Def),   \
  74                                           #NAME, WARN);
  75
  76 #include "FuzzerExtFunctions.def"
  77
  78 #undef EXT_FUNC
  79 }
  80
  81 }  // namespace fuzzer
  82
  83 #endif // LIBFUZZER_WINDOWS