1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)atexit.c 8.2 (Berkeley) 7/3/94 33 * $FreeBSD: head/lib/libc/stdlib/atexit.c 211894 2010-08-27 19:57:17Z kib $ 34 */ 35 36 #include "namespace.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 45 #include "libc_private.h" 46 47 int __cxa_atexit(void (*)(void *), void *, void *); 48 49 #define ATEXIT_FN_EMPTY 0 50 #define ATEXIT_FN_STD 1 51 #define ATEXIT_FN_CXA 2 52 53 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER; 54 55 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x) 56 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x) 57 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x) 58 59 struct atexit { 60 struct atexit *next; /* next in list */ 61 int ind; /* next index in this table */ 62 struct atexit_fn { 63 int fn_type; /* ATEXIT_? from above */ 64 union { 65 void (*std_func)(void); 66 void (*cxa_func)(void *); 67 } fn_ptr; /* function pointer */ 68 void *fn_arg; /* argument for CXA callback */ 69 void *fn_dso; /* shared module handle */ 70 } fns[ATEXIT_SIZE]; /* the table itself */ 71 }; 72 73 static struct atexit *__atexit; /* points to head of LIFO stack */ 74 static int nested_atexit; /* nested atexit() status */ 75 76 #define CXA_DTORS_ITERATIONS 16 /* give up after nested iterations */ 77 78 /* 79 * Register the function described by 'fptr' to be called at application 80 * exit or owning shared object unload time. This is a helper function 81 * for atexit and __cxa_atexit. 82 */ 83 static int 84 atexit_register(struct atexit_fn *fptr) 85 { 86 static struct atexit __atexit0; /* one guaranteed table */ 87 struct atexit *p; 88 89 _MUTEX_LOCK(&atexit_mutex); 90 if ((p = __atexit) == NULL) 91 __atexit = p = &__atexit0; 92 else while (p->ind >= ATEXIT_SIZE) { 93 struct atexit *old__atexit; 94 old__atexit = __atexit; 95 _MUTEX_UNLOCK(&atexit_mutex); 96 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 97 return (-1); 98 _MUTEX_LOCK(&atexit_mutex); 99 if (old__atexit != __atexit) { 100 /* Lost race, retry operation */ 101 _MUTEX_UNLOCK(&atexit_mutex); 102 free(p); 103 _MUTEX_LOCK(&atexit_mutex); 104 p = __atexit; 105 continue; 106 } 107 p->ind = 0; 108 p->next = __atexit; 109 __atexit = p; 110 } 111 p->fns[p->ind++] = *fptr; 112 if (nested_atexit == 1) 113 nested_atexit = 2; 114 _MUTEX_UNLOCK(&atexit_mutex); 115 return 0; 116 } 117 118 /* 119 * Register a function to be performed at exit. 120 */ 121 int 122 atexit(void (*func)(void)) 123 { 124 struct atexit_fn fn; 125 int error; 126 127 fn.fn_type = ATEXIT_FN_STD; 128 fn.fn_ptr.std_func = func; 129 fn.fn_arg = NULL; 130 fn.fn_dso = NULL; 131 132 error = atexit_register(&fn); 133 return (error); 134 } 135 136 /* 137 * Register a function to be performed at exit or when an shared object 138 * with given dso handle is unloaded dynamically. 139 */ 140 int 141 __cxa_atexit(void (*func)(void *), void *arg, void *dso) 142 { 143 struct atexit_fn fn; 144 int error; 145 146 fn.fn_type = ATEXIT_FN_CXA; 147 fn.fn_ptr.cxa_func = func; 148 fn.fn_arg = arg; 149 fn.fn_dso = dso; 150 151 error = atexit_register(&fn); 152 return (error); 153 } 154 155 #pragma weak __pthread_cxa_finalize 156 void __pthread_cxa_finalize(const struct dl_phdr_info *); 157 158 static int global_exit; 159 160 /* 161 * Call all handlers registered with __cxa_atexit for the shared 162 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining 163 * handlers are called. 164 * Attempt to support additional static c++ destructors added from within 165 * destructors in a LIFO manner by relooping. 166 */ 167 void 168 __cxa_finalize(void *dso) 169 { 170 struct dl_phdr_info phdr_info; 171 struct atexit *p; 172 struct atexit_fn fn; 173 int n, ni, has_phdr; 174 175 if (dso != NULL) { 176 has_phdr = _rtld_addr_phdr(dso, &phdr_info); 177 } else { 178 has_phdr = 0; 179 global_exit = 1; 180 } 181 182 _MUTEX_LOCK(&atexit_mutex); 183 ni = CXA_DTORS_ITERATIONS; 184 again: 185 nested_atexit = 1; 186 for (p = __atexit; p; p = p->next) { 187 for (n = p->ind; --n >= 0;) { 188 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY) 189 continue; /* already been called */ 190 fn = p->fns[n]; 191 if (dso != NULL && dso != fn.fn_dso) { 192 /* wrong DSO ? */ 193 if (!has_phdr || global_exit || 194 !__elf_phdr_match_addr(&phdr_info, 195 fn.fn_ptr.cxa_func)) 196 continue; 197 } 198 /* 199 Mark entry to indicate that this particular handler 200 has already been called. 201 */ 202 p->fns[n].fn_type = ATEXIT_FN_EMPTY; 203 _MUTEX_UNLOCK(&atexit_mutex); 204 205 /* Call the function of correct type. */ 206 if (fn.fn_type == ATEXIT_FN_CXA) 207 fn.fn_ptr.cxa_func(fn.fn_arg); 208 else if (fn.fn_type == ATEXIT_FN_STD) 209 fn.fn_ptr.std_func(); 210 _MUTEX_LOCK(&atexit_mutex); 211 212 /* 213 * Reloop if we got more atexit() destructors. 214 */ 215 if (nested_atexit == 2 && ni > 0) { 216 ni--; 217 goto again; 218 } 219 } 220 } 221 _MUTEX_UNLOCK(&atexit_mutex); 222 if (dso == NULL) 223 _MUTEX_DESTROY(&atexit_mutex); 224 225 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL) 226 __pthread_cxa_finalize(&phdr_info); 227 } 228