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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)atexit.c 8.2 (Berkeley) 7/3/94"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 #include "namespace.h" 40 #include <errno.h> 41 #include <link.h> 42 #include <stddef.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 #include <pthread.h> 46 #include "atexit.h" 47 #include "un-namespace.h" 48 #include "block_abi.h" 49 50 #include "libc_private.h" 51 52 /** 53 * The _Block_copy() function is provided by the block runtime. 54 */ 55 __attribute__((weak)) void* 56 _Block_copy(void*); 57 58 #define ATEXIT_FN_EMPTY 0 59 #define ATEXIT_FN_STD 1 60 #define ATEXIT_FN_CXA 2 61 62 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER; 63 64 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x) 65 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x) 66 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x) 67 68 struct atexit { 69 struct atexit *next; /* next in list */ 70 int ind; /* next index in this table */ 71 struct atexit_fn { 72 int fn_type; /* ATEXIT_? from above */ 73 union { 74 void (*std_func)(void); 75 void (*cxa_func)(void *); 76 } fn_ptr; /* function pointer */ 77 void *fn_arg; /* argument for CXA callback */ 78 void *fn_dso; /* shared module handle */ 79 } fns[ATEXIT_SIZE]; /* the table itself */ 80 }; 81 82 static struct atexit *__atexit; /* points to head of LIFO stack */ 83 typedef DECLARE_BLOCK(void, atexit_block, void); 84 85 int atexit_b(atexit_block); 86 int __cxa_atexit(void (*)(void *), void *, void *); 87 88 /* 89 * Register the function described by 'fptr' to be called at application 90 * exit or owning shared object unload time. This is a helper function 91 * for atexit and __cxa_atexit. 92 */ 93 static int 94 atexit_register(struct atexit_fn *fptr) 95 { 96 static struct atexit __atexit0; /* one guaranteed table */ 97 struct atexit *p; 98 99 _MUTEX_LOCK(&atexit_mutex); 100 if ((p = __atexit) == NULL) 101 __atexit = p = &__atexit0; 102 else while (p->ind >= ATEXIT_SIZE) { 103 struct atexit *old__atexit; 104 old__atexit = __atexit; 105 _MUTEX_UNLOCK(&atexit_mutex); 106 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 107 return (-1); 108 _MUTEX_LOCK(&atexit_mutex); 109 if (old__atexit != __atexit) { 110 /* Lost race, retry operation */ 111 _MUTEX_UNLOCK(&atexit_mutex); 112 free(p); 113 _MUTEX_LOCK(&atexit_mutex); 114 p = __atexit; 115 continue; 116 } 117 p->ind = 0; 118 p->next = __atexit; 119 __atexit = p; 120 } 121 p->fns[p->ind++] = *fptr; 122 _MUTEX_UNLOCK(&atexit_mutex); 123 return 0; 124 } 125 126 /* 127 * Register a function to be performed at exit. 128 */ 129 int 130 atexit(void (*func)(void)) 131 { 132 struct atexit_fn fn; 133 int error; 134 135 fn.fn_type = ATEXIT_FN_STD; 136 fn.fn_ptr.std_func = func; 137 fn.fn_arg = NULL; 138 fn.fn_dso = NULL; 139 140 error = atexit_register(&fn); 141 return (error); 142 } 143 __weak_reference(atexit, __libc_atexit); 144 145 /** 146 * Register a block to be performed at exit. 147 */ 148 int 149 atexit_b(atexit_block func) 150 { 151 struct atexit_fn fn; 152 int error; 153 if (_Block_copy == 0) { 154 errno = ENOSYS; 155 return -1; 156 } 157 func = _Block_copy(func); 158 159 // Blocks are not C++ destructors, but they have the same signature (a 160 // single void* parameter), so we can pretend that they are. 161 fn.fn_type = ATEXIT_FN_CXA; 162 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func); 163 fn.fn_arg = func; 164 fn.fn_dso = NULL; 165 166 error = atexit_register(&fn); 167 return (error); 168 } 169 170 /* 171 * Register a function to be performed at exit or when an shared object 172 * with given dso handle is unloaded dynamically. 173 */ 174 int 175 __cxa_atexit(void (*func)(void *), void *arg, void *dso) 176 { 177 struct atexit_fn fn; 178 int error; 179 180 fn.fn_type = ATEXIT_FN_CXA; 181 fn.fn_ptr.cxa_func = func; 182 fn.fn_arg = arg; 183 fn.fn_dso = dso; 184 185 error = atexit_register(&fn); 186 return (error); 187 } 188 189 #pragma weak __pthread_cxa_finalize 190 void __pthread_cxa_finalize(const struct dl_phdr_info *); 191 192 static int global_exit; 193 194 /* 195 * Call all handlers registered with __cxa_atexit for the shared 196 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining 197 * handlers are called. 198 */ 199 void 200 __cxa_finalize(void *dso) 201 { 202 struct dl_phdr_info phdr_info; 203 struct atexit *p; 204 struct atexit_fn fn; 205 int n, has_phdr; 206 207 if (dso != NULL) { 208 has_phdr = _rtld_addr_phdr(dso, &phdr_info); 209 } else { 210 has_phdr = 0; 211 global_exit = 1; 212 } 213 214 _MUTEX_LOCK(&atexit_mutex); 215 for (p = __atexit; p; p = p->next) { 216 for (n = p->ind; --n >= 0;) { 217 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY) 218 continue; /* already been called */ 219 fn = p->fns[n]; 220 if (dso != NULL && dso != fn.fn_dso) { 221 /* wrong DSO ? */ 222 if (!has_phdr || global_exit || 223 !__elf_phdr_match_addr(&phdr_info, 224 fn.fn_ptr.cxa_func)) 225 continue; 226 } 227 /* 228 Mark entry to indicate that this particular handler 229 has already been called. 230 */ 231 p->fns[n].fn_type = ATEXIT_FN_EMPTY; 232 _MUTEX_UNLOCK(&atexit_mutex); 233 234 /* Call the function of correct type. */ 235 if (fn.fn_type == ATEXIT_FN_CXA) 236 fn.fn_ptr.cxa_func(fn.fn_arg); 237 else if (fn.fn_type == ATEXIT_FN_STD) 238 fn.fn_ptr.std_func(); 239 _MUTEX_LOCK(&atexit_mutex); 240 } 241 } 242 _MUTEX_UNLOCK(&atexit_mutex); 243 if (dso == NULL) 244 _MUTEX_DESTROY(&atexit_mutex); 245 246 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL) 247 __pthread_cxa_finalize(&phdr_info); 248 } 249