1 /*
2  * Copyright (C) 2014 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 <stdio.h>
18 #include <stdlib.h>
19 
20 static int g_flag = 0;
21 
init_flag()22 static void __attribute__((constructor)) init_flag() {
23   g_flag = 1;
24 }
25 
26 static const char* is_ctor_called() __attribute__ ((ifunc("is_ctor_called_ifun")));
27 
28 const char* foo() __attribute__ ((ifunc ("foo_ifunc")));
29 
30 // Static linker creates GLOBAL/IFUNC symbol and JUMP_SLOT relocation type for plt segment
31 const char* is_ctor_called_jump_slot() __attribute__ ((ifunc("is_ctor_called_ifun")));
32 
is_ctor_called_irelative()33 const char* is_ctor_called_irelative() {
34   // Call internal ifunc-resolved function with IRELATIVE reloc
35   return is_ctor_called();
36 }
37 
return_true()38 const char* return_true() {
39   return "true";
40 }
41 
return_false()42 const char* return_false() {
43   return "false";
44 }
45 
f1()46 const char* f1() {
47   return "unset";
48 }
49 
f2()50 const char* f2() {
51   return "set";
52 }
53 
is_ctor_called_ifun()54 void* is_ctor_called_ifun() {
55   return g_flag == 0 ? return_false : return_true;
56 }
57 
foo_ifunc()58 void* foo_ifunc() {
59    char* choice = getenv("IFUNC_CHOICE");
60    return choice == NULL ? f1 : f2;
61 }
62 
foo_library()63 const char* foo_library() {
64    return foo();
65 }
66