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 || LIBFUZZER_NETBSD || LIBFUZZER_FUCHSIA || \
17 LIBFUZZER_FREEBSD || LIBFUZZER_OPENBSD
18
19 #include "FuzzerExtFunctions.h"
20 #include "FuzzerIO.h"
21
22 extern "C" {
23 // Declare these symbols as weak to allow them to be optionally defined.
24 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
25 __attribute__((weak, visibility("default"))) RETURN_TYPE NAME FUNC_SIG
26
27 #include "FuzzerExtFunctions.def"
28
29 #undef EXT_FUNC
30 }
31
32 using namespace fuzzer;
33
CheckFnPtr(void * FnPtr,const char * FnName,bool WarnIfMissing)34 static void CheckFnPtr(void *FnPtr, const char *FnName, bool WarnIfMissing) {
35 if (FnPtr == nullptr && WarnIfMissing) {
36 Printf("WARNING: Failed to find function \"%s\".\n", FnName);
37 }
38 }
39
40 namespace fuzzer {
41
ExternalFunctions()42 ExternalFunctions::ExternalFunctions() {
43 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
44 this->NAME = ::NAME; \
45 CheckFnPtr(reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(::NAME)), \
46 #NAME, WARN);
47
48 #include "FuzzerExtFunctions.def"
49
50 #undef EXT_FUNC
51 }
52
53 } // namespace fuzzer
54
55 #endif
56