1 //===- FuzzerExtFunctionsWeak.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 for Linux. This relies on the linker's support for weak
10 // symbols. We don't use this approach on Apple platforms because it requires
11 // clients of LibFuzzer to pass ``-U _<symbol_name>`` to the linker to allow
12 // weak symbols to be undefined. That is a complication we don't want to expose
13 // to clients right now.
14 //===----------------------------------------------------------------------===//
15 #include "FuzzerInternal.h"
16 #if LIBFUZZER_LINUX
17
18 #include "FuzzerExtFunctions.h"
19
20 extern "C" {
21 // Declare these symbols as weak to allow them to be optionally defined.
22 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
23 __attribute__((weak)) RETURN_TYPE NAME FUNC_SIG
24
25 #include "FuzzerExtFunctions.def"
26
27 #undef EXT_FUNC
28 }
29
30 using namespace fuzzer;
31
CheckFnPtr(void * FnPtr,const char * FnName,bool WarnIfMissing)32 static void CheckFnPtr(void *FnPtr, const char *FnName, bool WarnIfMissing) {
33 if (FnPtr == nullptr && WarnIfMissing) {
34 Printf("WARNING: Failed to find function \"%s\".\n", FnName);
35 }
36 }
37
38 namespace fuzzer {
39
ExternalFunctions()40 ExternalFunctions::ExternalFunctions() {
41 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
42 this->NAME = ::NAME; \
43 CheckFnPtr((void *)::NAME, #NAME, WARN);
44
45 #include "FuzzerExtFunctions.def"
46
47 #undef EXT_FUNC
48 }
49 } // namespace fuzzer
50 #endif // LIBFUZZER_LINUX
51