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