contrib/compiler-rt/lib/fuzzer/FuzzerExtFunctionsWeakAlias.cpp

   1 //===- FuzzerExtFunctionsWeakAlias.cpp - Interface to external functions --===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 // Implementation using weak aliases. Works for Windows.
  10 //===----------------------------------------------------------------------===//
  11 #include "FuzzerDefs.h"
  12 #if LIBFUZZER_WINDOWS
  13
  14 #include "FuzzerExtFunctions.h"
  15 #include "FuzzerIO.h"
  16
  17 using namespace fuzzer;
  18
  19 extern "C" {
  20 // Declare these symbols as weak to allow them to be optionally defined.
  21 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN)                            \
  22   RETURN_TYPE NAME##Def FUNC_SIG {                                             \
  23     Printf("ERROR: Function \"%s\" not defined.\n", #NAME);                    \
  24     exit(1);                                                                   \
  25   }                                                                            \
  26   RETURN_TYPE NAME FUNC_SIG __attribute__((weak, alias(#NAME "Def")));
  27
  28 #include "FuzzerExtFunctions.def"
  29
  30 #undef EXT_FUNC
  31 }
  32
  33 template <typename T>
  34 static T *GetFnPtr(T *Fun, T *FunDef, const char *FnName, bool WarnIfMissing) {
  35   if (Fun == FunDef) {
  36     if (WarnIfMissing)
  37       Printf("WARNING: Failed to find function \"%s\".\n", FnName);
  38     return nullptr;
  39   }
  40   return Fun;
  41 }
  42
  43 namespace fuzzer {
  44
  45 ExternalFunctions::ExternalFunctions() {
  46 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN)                            \
  47   this->NAME = GetFnPtr<decltype(::NAME)>(::NAME, ::NAME##Def, #NAME, WARN);
  48
  49 #include "FuzzerExtFunctions.def"
  50
  51 #undef EXT_FUNC
  52 }
  53
  54 } // namespace fuzzer
  55
  56 #endif // LIBFUZZER_WINDOWS