1//===- FuzzerExtFunctionsDlsym.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 for operating systems that support dlsym(). We only use it on
9// Apple platforms for now. We don't use this approach on Linux because it
10// requires that clients of LibFuzzer pass ``--export-dynamic`` to the linker.
11// That is a complication we don't wish to expose to clients right now.
12//===----------------------------------------------------------------------===//
13#include "FuzzerPlatform.h"
14#if LIBFUZZER_APPLE
15
16#include "FuzzerExtFunctions.h"
17#include "FuzzerIO.h"
18#include <dlfcn.h>
19
20using namespace fuzzer;
21
22template <typename T>
23static T GetFnPtr(const char *FnName, bool WarnIfMissing) {
24 dlerror(); // Clear any previous errors.
25 void *Fn = dlsym(RTLD_DEFAULT, FnName);
26 if (Fn == nullptr) {
27 if (WarnIfMissing) {
28 const char *ErrorMsg = dlerror();
29 Printf("WARNING: Failed to find function \"%s\".", FnName);
30 if (ErrorMsg)
31 Printf(" Reason %s.", ErrorMsg);
32 Printf("\n");
33 }
34 }
35 return reinterpret_cast<T>(Fn);
36}
37
38namespace fuzzer {
39
40ExternalFunctions::ExternalFunctions() {
41#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
42 this->NAME = GetFnPtr<decltype(ExternalFunctions::NAME)>(#NAME, WARN)
43
44#include "FuzzerExtFunctions.def"
45
46#undef EXT_FUNC
47}
48
49} // namespace fuzzer
50
51#endif // LIBFUZZER_APPLE
52