| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <dlfcn.h> |
| #include <stdint.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| |
| static uintptr_t g_flag = 0; |
| |
| static void __attribute__((constructor)) init_flag() { |
| g_flag = reinterpret_cast<uintptr_t>(dlsym(RTLD_DEFAULT, "dlsym")); |
| } |
| |
| static const char* is_ctor_called() __attribute__ ((ifunc("is_ctor_called_ifun"))); |
| |
| extern "C" const char* foo() __attribute__ ((ifunc ("foo_ifunc"))); |
| |
| // Static linker creates GLOBAL/IFUNC symbol and JUMP_SLOT relocation type for plt segment |
| extern "C" const char* is_ctor_called_jump_slot() __attribute__ ((ifunc("is_ctor_called_ifun"))); |
| |
| extern "C" const char* is_ctor_called_irelative() { |
| // Call internal ifunc-resolved function with IRELATIVE reloc |
| return is_ctor_called(); |
| } |
| |
| extern "C" const char* var_true = "true"; |
| extern "C" const char* var_false = "false"; |
| |
| extern "C" const char* v1 = "unset"; |
| extern "C" const char* v2 = "set"; |
| |
| extern "C" void* is_ctor_called_ifun() { |
| return g_flag == 0 ? &var_false : &var_true; |
| } |
| |
| extern "C" void* foo_ifunc() { |
| char* choice = getenv("IFUNC_CHOICE"); |
| return choice == NULL ? &v1 : &v2; |
| } |