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
22extern "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
32using namespace fuzzer;
33
34static 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
40namespace fuzzer {
41
42ExternalFunctions::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