1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include "namespace.h" 36 #include <errno.h> 37 #include <link.h> 38 #include <stddef.h> 39 #include <stdlib.h> 40 #include <unistd.h> 41 #include <pthread.h> 42 #include "atexit.h" 43 #include "un-namespace.h" 44 #include "block_abi.h" 45 46 #include "libc_private.h" 47 48 /** 49 * The _Block_copy() function is provided by the block runtime. 50 */ 51 __attribute__((weak)) void* 52 _Block_copy(void*); 53 54 #define ATEXIT_FN_EMPTY 0 55 #define ATEXIT_FN_STD 1 56 #define ATEXIT_FN_CXA 2 57 58 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER; 59 60 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x) 61 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x) 62 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x) 63 64 struct atexit { 65 struct atexit *next; /* next in list */ 66 int ind; /* next index in this table */ 67 struct atexit_fn { 68 int fn_type; /* ATEXIT_? from above */ 69 union { 70 void (*std_func)(void); 71 void (*cxa_func)(void *); 72 } fn_ptr; /* function pointer */ 73 void *fn_arg; /* argument for CXA callback */ 74 void *fn_dso; /* shared module handle */ 75 } fns[ATEXIT_SIZE]; /* the table itself */ 76 }; 77 78 static struct atexit *__atexit; /* points to head of LIFO stack */ 79 typedef DECLARE_BLOCK(void, atexit_block, void); 80 81 int atexit_b(atexit_block); 82 int __cxa_atexit(void (*)(void *), void *, void *); 83 84 /* 85 * Register the function described by 'fptr' to be called at application 86 * exit or owning shared object unload time. This is a helper function 87 * for atexit and __cxa_atexit. 88 */ 89 static int 90 atexit_register(struct atexit_fn *fptr) 91 { 92 static struct atexit __atexit0; /* one guaranteed table */ 93 struct atexit *p; 94 95 _MUTEX_LOCK(&atexit_mutex); 96 if ((p = __atexit) == NULL) 97 __atexit = p = &__atexit0; 98 else while (p->ind >= ATEXIT_SIZE) { 99 struct atexit *old__atexit; 100 old__atexit = __atexit; 101 _MUTEX_UNLOCK(&atexit_mutex); 102 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 103 return (-1); 104 _MUTEX_LOCK(&atexit_mutex); 105 if (old__atexit != __atexit) { 106 /* Lost race, retry operation */ 107 _MUTEX_UNLOCK(&atexit_mutex); 108 free(p); 109 _MUTEX_LOCK(&atexit_mutex); 110 p = __atexit; 111 continue; 112 } 113 p->ind = 0; 114 p->next = __atexit; 115 __atexit = p; 116 } 117 p->fns[p->ind++] = *fptr; 118 _MUTEX_UNLOCK(&atexit_mutex); 119 return 0; 120 } 121 122 /* 123 * Register a function to be performed at exit. 124 */ 125 int 126 atexit(void (*func)(void)) 127 { 128 struct atexit_fn fn; 129 int error; 130 131 fn.fn_type = ATEXIT_FN_STD; 132 fn.fn_ptr.std_func = func; 133 fn.fn_arg = NULL; 134 fn.fn_dso = NULL; 135 136 error = atexit_register(&fn); 137 return (error); 138 } 139 __weak_reference(atexit, __libc_atexit); 140 141 /** 142 * Register a block to be performed at exit. 143 */ 144 int 145 atexit_b(atexit_block func) 146 { 147 struct atexit_fn fn; 148 int error; 149 if (_Block_copy == 0) { 150 errno = ENOSYS; 151 return -1; 152 } 153 func = _Block_copy(func); 154 155 // Blocks are not C++ destructors, but they have the same signature (a 156 // single void* parameter), so we can pretend that they are. 157 fn.fn_type = ATEXIT_FN_CXA; 158 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func); 159 fn.fn_arg = func; 160 fn.fn_dso = NULL; 161 162 error = atexit_register(&fn); 163 return (error); 164 } 165 166 /* 167 * Register a function to be performed at exit or when an shared object 168 * with given dso handle is unloaded dynamically. 169 */ 170 int 171 __cxa_atexit(void (*func)(void *), void *arg, void *dso) 172 { 173 struct atexit_fn fn; 174 int error; 175 176 fn.fn_type = ATEXIT_FN_CXA; 177 fn.fn_ptr.cxa_func = func; 178 fn.fn_arg = arg; 179 fn.fn_dso = dso; 180 181 error = atexit_register(&fn); 182 return (error); 183 } 184 185 #pragma weak __pthread_cxa_finalize 186 void __pthread_cxa_finalize(const struct dl_phdr_info *); 187 188 static int global_exit; 189 190 /* 191 * Call all handlers registered with __cxa_atexit for the shared 192 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining 193 * handlers are called. 194 */ 195 void 196 __cxa_finalize(void *dso) 197 { 198 struct dl_phdr_info phdr_info; 199 struct atexit *p; 200 struct atexit_fn fn; 201 int n, has_phdr; 202 203 if (dso != NULL) { 204 has_phdr = _rtld_addr_phdr(dso, &phdr_info); 205 } else { 206 has_phdr = 0; 207 global_exit = 1; 208 } 209 210 _MUTEX_LOCK(&atexit_mutex); 211 for (p = __atexit; p; p = p->next) { 212 for (n = p->ind; --n >= 0;) { 213 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY) 214 continue; /* already been called */ 215 fn = p->fns[n]; 216 if (dso != NULL && dso != fn.fn_dso) { 217 /* wrong DSO ? */ 218 if (!has_phdr || global_exit || 219 !__elf_phdr_match_addr(&phdr_info, 220 fn.fn_ptr.cxa_func)) 221 continue; 222 } 223 /* 224 Mark entry to indicate that this particular handler 225 has already been called. 226 */ 227 p->fns[n].fn_type = ATEXIT_FN_EMPTY; 228 _MUTEX_UNLOCK(&atexit_mutex); 229 230 /* Call the function of correct type. */ 231 if (fn.fn_type == ATEXIT_FN_CXA) 232 fn.fn_ptr.cxa_func(fn.fn_arg); 233 else if (fn.fn_type == ATEXIT_FN_STD) 234 fn.fn_ptr.std_func(); 235 _MUTEX_LOCK(&atexit_mutex); 236 } 237 } 238 _MUTEX_UNLOCK(&atexit_mutex); 239 if (dso == NULL) 240 _MUTEX_DESTROY(&atexit_mutex); 241 242 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL) 243 __pthread_cxa_finalize(&phdr_info); 244 } 245