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 <dlfcn.h> 18 #include <stdint.h> 19 #include <stdio.h> 20 #include <stdlib.h> 21 22 static uintptr_t g_flag = 0; 23 24 static void __attribute__((constructor)) init_flag() { 25 g_flag = reinterpret_cast<uintptr_t>(dlsym(RTLD_DEFAULT, "dlsym")); 26 } 27 28 static const char* is_ctor_called() __attribute__ ((ifunc("is_ctor_called_ifun"))); 29 30 extern "C" const char* foo() __attribute__ ((ifunc ("foo_ifunc"))); 31 32 // Static linker creates GLOBAL/IFUNC symbol and JUMP_SLOT relocation type for plt segment 33 extern "C" const char* is_ctor_called_jump_slot() __attribute__ ((ifunc("is_ctor_called_ifun"))); 34 35 extern "C" const char* is_ctor_called_irelative() { 36 // Call internal ifunc-resolved function with IRELATIVE reloc 37 return is_ctor_called(); 38 } 39 40 extern "C" const char* return_true() { 41 return "true"; 42 } 43 44 extern "C" const char* return_false() { 45 return "false"; 46 } 47 48 extern "C" const char* f1() { 49 return "unset"; 50 } 51 52 extern "C" const char* f2() { 53 return "set"; 54 } 55 56 typedef const char* (*fn_ptr)(); 57 58 extern "C" fn_ptr is_ctor_called_ifun() { 59 return g_flag == 0 ? return_false : return_true; 60 } 61 62 extern "C" fn_ptr foo_ifunc() { 63 char* choice = getenv("IFUNC_CHOICE"); 64 return choice == NULL ? f1 : f2; 65 } 66 67 extern "C" const char* foo_library() { 68 return foo(); 69 } 70
