1*0b57cec5SDimitry Andric //===- FuzzerExtFunctionsDlsym.cpp - Interface to external functions ------===//
2*0b57cec5SDimitry Andric //
3*0b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*0b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5*0b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*0b57cec5SDimitry Andric //
7*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
8*0b57cec5SDimitry Andric // Implementation for operating systems that support dlsym(). We only use it on
9*0b57cec5SDimitry Andric // Apple platforms for now. We don't use this approach on Linux because it
10*0b57cec5SDimitry Andric // requires that clients of LibFuzzer pass ``--export-dynamic`` to the linker.
11*0b57cec5SDimitry Andric // That is a complication we don't wish to expose to clients right now.
12*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
13*0b57cec5SDimitry Andric #include "FuzzerPlatform.h"
14*0b57cec5SDimitry Andric #if LIBFUZZER_APPLE
15*0b57cec5SDimitry Andric
16*0b57cec5SDimitry Andric #include "FuzzerExtFunctions.h"
17*0b57cec5SDimitry Andric #include "FuzzerIO.h"
18*0b57cec5SDimitry Andric #include <dlfcn.h>
19*0b57cec5SDimitry Andric
20*0b57cec5SDimitry Andric using namespace fuzzer;
21*0b57cec5SDimitry Andric
22*0b57cec5SDimitry Andric template <typename T>
GetFnPtr(const char * FnName,bool WarnIfMissing)23*0b57cec5SDimitry Andric static T GetFnPtr(const char *FnName, bool WarnIfMissing) {
24*0b57cec5SDimitry Andric dlerror(); // Clear any previous errors.
25*0b57cec5SDimitry Andric void *Fn = dlsym(RTLD_DEFAULT, FnName);
26*0b57cec5SDimitry Andric if (Fn == nullptr) {
27*0b57cec5SDimitry Andric if (WarnIfMissing) {
28*0b57cec5SDimitry Andric const char *ErrorMsg = dlerror();
29*0b57cec5SDimitry Andric Printf("WARNING: Failed to find function \"%s\".", FnName);
30*0b57cec5SDimitry Andric if (ErrorMsg)
31*0b57cec5SDimitry Andric Printf(" Reason %s.", ErrorMsg);
32*0b57cec5SDimitry Andric Printf("\n");
33*0b57cec5SDimitry Andric }
34*0b57cec5SDimitry Andric }
35*0b57cec5SDimitry Andric return reinterpret_cast<T>(Fn);
36*0b57cec5SDimitry Andric }
37*0b57cec5SDimitry Andric
38*0b57cec5SDimitry Andric namespace fuzzer {
39*0b57cec5SDimitry Andric
ExternalFunctions()40*0b57cec5SDimitry Andric ExternalFunctions::ExternalFunctions() {
41*0b57cec5SDimitry Andric #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
42*0b57cec5SDimitry Andric this->NAME = GetFnPtr<decltype(ExternalFunctions::NAME)>(#NAME, WARN)
43*0b57cec5SDimitry Andric
44*0b57cec5SDimitry Andric #include "FuzzerExtFunctions.def"
45*0b57cec5SDimitry Andric
46*0b57cec5SDimitry Andric #undef EXT_FUNC
47*0b57cec5SDimitry Andric }
48*0b57cec5SDimitry Andric
49*0b57cec5SDimitry Andric } // namespace fuzzer
50*0b57cec5SDimitry Andric
51*0b57cec5SDimitry Andric #endif // LIBFUZZER_APPLE
52