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 "FuzzerDefs.h"
16 #if LIBFUZZER_LINUX
17
18 #include "FuzzerExtFunctions.h"
19 #include "FuzzerIO.h"
20
21 extern "C" {
22 // Declare these symbols as weak to allow them to be optionally defined.
23 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
24 __attribute__((weak)) RETURN_TYPE NAME FUNC_SIG
25
26 #include "FuzzerExtFunctions.def"
27
28 #undef EXT_FUNC
29 }
30
31 using namespace fuzzer;
32
CheckFnPtr(void * FnPtr,const char * FnName,bool WarnIfMissing)33 static void CheckFnPtr(void *FnPtr, const char *FnName, bool WarnIfMissing) {
34 if (FnPtr == nullptr && WarnIfMissing) {
35 Printf("WARNING: Failed to find function \"%s\".\n", FnName);
36 }
37 }
38
39 namespace fuzzer {
40
ExternalFunctions()41 ExternalFunctions::ExternalFunctions() {
42 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
43 this->NAME = ::NAME; \
44 CheckFnPtr((void *)::NAME, #NAME, WARN);
45
46 #include "FuzzerExtFunctions.def"
47
48 #undef EXT_FUNC
49 }
50
51 } // namespace fuzzer
52
53 #endif // LIBFUZZER_LINUX
54