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 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <errno.h> 43 #include <link.h> 44 #include <stddef.h> 45 #include <stdlib.h> 46 #include <unistd.h> 47 #include <pthread.h> 48 #include "atexit.h" 49 #include "un-namespace.h" 50 #include "block_abi.h" 51 52 #include "libc_private.h" 53 54 /** 55 * The _Block_copy() function is provided by the block runtime. 56 */ 57 __attribute__((weak)) void* 58 _Block_copy(void*); 59 60 #define ATEXIT_FN_EMPTY 0 61 #define ATEXIT_FN_STD 1 62 #define ATEXIT_FN_CXA 2 63 64 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER; 65 66 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x) 67 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x) 68 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x) 69 70 struct atexit { 71 struct atexit *next; /* next in list */ 72 int ind; /* next index in this table */ 73 struct atexit_fn { 74 int fn_type; /* ATEXIT_? from above */ 75 union { 76 void (*std_func)(void); 77 void (*cxa_func)(void *); 78 } fn_ptr; /* function pointer */ 79 void *fn_arg; /* argument for CXA callback */ 80 void *fn_dso; /* shared module handle */ 81 } fns[ATEXIT_SIZE]; /* the table itself */ 82 }; 83 84 static struct atexit *__atexit; /* points to head of LIFO stack */ 85 typedef DECLARE_BLOCK(void, atexit_block, void); 86 87 int atexit_b(atexit_block); 88 int __cxa_atexit(void (*)(void *), void *, void *); 89 90 /* 91 * Register the function described by 'fptr' to be called at application 92 * exit or owning shared object unload time. This is a helper function 93 * for atexit and __cxa_atexit. 94 */ 95 static int 96 atexit_register(struct atexit_fn *fptr) 97 { 98 static struct atexit __atexit0; /* one guaranteed table */ 99 struct atexit *p; 100 101 _MUTEX_LOCK(&atexit_mutex); 102 if ((p = __atexit) == NULL) 103 __atexit = p = &__atexit0; 104 else while (p->ind >= ATEXIT_SIZE) { 105 struct atexit *old__atexit; 106 old__atexit = __atexit; 107 _MUTEX_UNLOCK(&atexit_mutex); 108 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 109 return (-1); 110 _MUTEX_LOCK(&atexit_mutex); 111 if (old__atexit != __atexit) { 112 /* Lost race, retry operation */ 113 _MUTEX_UNLOCK(&atexit_mutex); 114 free(p); 115 _MUTEX_LOCK(&atexit_mutex); 116 p = __atexit; 117 continue; 118 } 119 p->ind = 0; 120 p->next = __atexit; 121 __atexit = p; 122 } 123 p->fns[p->ind++] = *fptr; 124 _MUTEX_UNLOCK(&atexit_mutex); 125 return 0; 126 } 127 128 /* 129 * Register a function to be performed at exit. 130 */ 131 int 132 atexit(void (*func)(void)) 133 { 134 struct atexit_fn fn; 135 int error; 136 137 fn.fn_type = ATEXIT_FN_STD; 138 fn.fn_ptr.std_func = func; 139 fn.fn_arg = NULL; 140 fn.fn_dso = NULL; 141 142 error = atexit_register(&fn); 143 return (error); 144 } 145 146 /** 147 * Register a block to be performed at exit. 148 */ 149 int 150 atexit_b(atexit_block func) 151 { 152 struct atexit_fn fn; 153 int error; 154 if (_Block_copy == 0) { 155 errno = ENOSYS; 156 return -1; 157 } 158 func = _Block_copy(func); 159 160 // Blocks are not C++ destructors, but they have the same signature (a 161 // single void* parameter), so we can pretend that they are. 162 fn.fn_type = ATEXIT_FN_CXA; 163 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func); 164 fn.fn_arg = func; 165 fn.fn_dso = NULL; 166 167 error = atexit_register(&fn); 168 return (error); 169 } 170 171 /* 172 * Register a function to be performed at exit or when an shared object 173 * with given dso handle is unloaded dynamically. 174 */ 175 int 176 __cxa_atexit(void (*func)(void *), void *arg, void *dso) 177 { 178 struct atexit_fn fn; 179 int error; 180 181 fn.fn_type = ATEXIT_FN_CXA; 182 fn.fn_ptr.cxa_func = func; 183 fn.fn_arg = arg; 184 fn.fn_dso = dso; 185 186 error = atexit_register(&fn); 187 return (error); 188 } 189 190 #pragma weak __pthread_cxa_finalize 191 void __pthread_cxa_finalize(const struct dl_phdr_info *); 192 193 static int global_exit; 194 195 /* 196 * Call all handlers registered with __cxa_atexit for the shared 197 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining 198 * handlers are called. 199 */ 200 void 201 __cxa_finalize(void *dso) 202 { 203 struct dl_phdr_info phdr_info; 204 struct atexit *p; 205 struct atexit_fn fn; 206 int n, has_phdr; 207 208 if (dso != NULL) { 209 has_phdr = _rtld_addr_phdr(dso, &phdr_info); 210 } else { 211 has_phdr = 0; 212 global_exit = 1; 213 } 214 215 _MUTEX_LOCK(&atexit_mutex); 216 for (p = __atexit; p; p = p->next) { 217 for (n = p->ind; --n >= 0;) { 218 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY) 219 continue; /* already been called */ 220 fn = p->fns[n]; 221 if (dso != NULL && dso != fn.fn_dso) { 222 /* wrong DSO ? */ 223 if (!has_phdr || global_exit || 224 !__elf_phdr_match_addr(&phdr_info, 225 fn.fn_ptr.cxa_func)) 226 continue; 227 } 228 /* 229 Mark entry to indicate that this particular handler 230 has already been called. 231 */ 232 p->fns[n].fn_type = ATEXIT_FN_EMPTY; 233 _MUTEX_UNLOCK(&atexit_mutex); 234 235 /* Call the function of correct type. */ 236 if (fn.fn_type == ATEXIT_FN_CXA) 237 fn.fn_ptr.cxa_func(fn.fn_arg); 238 else if (fn.fn_type == ATEXIT_FN_STD) 239 fn.fn_ptr.std_func(); 240 _MUTEX_LOCK(&atexit_mutex); 241 } 242 } 243 _MUTEX_UNLOCK(&atexit_mutex); 244 if (dso == NULL) 245 _MUTEX_DESTROY(&atexit_mutex); 246 247 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL) 248 __pthread_cxa_finalize(&phdr_info); 249 } 250