1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <dlfcn.h>
18#include <stdint.h>
19#include <stdio.h>
20#include <stdlib.h>
21
22static uintptr_t g_flag = 0;
23
24static void __attribute__((constructor)) init_flag() {
25  g_flag = reinterpret_cast<uintptr_t>(dlsym(RTLD_DEFAULT, "dlsym"));
26}
27
28static const char* is_ctor_called() __attribute__ ((ifunc("is_ctor_called_ifun")));
29
30extern "C" const char* foo() __attribute__ ((ifunc ("foo_ifunc")));
31
32// Static linker creates GLOBAL/IFUNC symbol and JUMP_SLOT relocation type for plt segment
33extern "C" const char* is_ctor_called_jump_slot() __attribute__ ((ifunc("is_ctor_called_ifun")));
34
35extern "C" const char* is_ctor_called_irelative() {
36  // Call internal ifunc-resolved function with IRELATIVE reloc
37  return is_ctor_called();
38}
39
40extern "C" const char* var_true = "true";
41extern "C" const char* var_false = "false";
42
43extern "C" const char* v1 = "unset";
44extern "C" const char* v2 = "set";
45
46extern "C" void* is_ctor_called_ifun() {
47  return g_flag == 0 ? &var_false : &var_true;
48}
49
50extern "C" void* foo_ifunc() {
51   char* choice = getenv("IFUNC_CHOICE");
52   return choice == NULL ? &v1 : &v2;
53}
54