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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $FreeBSD: src/lib/libc/stdlib/atexit.c,v 1.3.6.1 2002/03/10 20:28:40 tegge Exp $ 37 * $DragonFly: src/lib/libc/stdlib/atexit.c,v 1.6 2004/06/15 13:43:20 joerg Exp $ 38 * 39 * @(#)atexit.c 8.2 (Berkeley) 7/3/94 40 */ 41 42 #include <stddef.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 #include "atexit.h" 46 47 #include "libc_private.h" 48 #include "spinlock.h" 49 50 #define ATEXIT_FN_EMPTY 0 51 #define ATEXIT_FN_STD 1 52 #define ATEXIT_FN_CXA 2 53 54 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 55 56 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock); 57 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock); 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 75 /* 76 * Register the function described by 'fptr' to be called at application 77 * exit or owning shared object unload time. This is a helper function 78 * for atexit and __cxa_atexit. 79 */ 80 static int 81 atexit_register(struct atexit_fn *fptr) 82 { 83 static struct atexit __atexit0; /* one guaranteed table */ 84 struct atexit *p; 85 86 THREAD_LOCK(); 87 if ((p = __atexit) == NULL) 88 __atexit = p = &__atexit0; 89 else while (p->ind >= ATEXIT_SIZE) { 90 struct atexit *old__atexit; 91 old__atexit = __atexit; 92 THREAD_UNLOCK(); 93 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 94 return (-1); 95 THREAD_LOCK(); 96 if (old__atexit != __atexit) { 97 /* Lost race, retry operation */ 98 THREAD_UNLOCK(); 99 free(p); 100 THREAD_LOCK(); 101 p = __atexit; 102 continue; 103 } 104 p->ind = 0; 105 p->next = __atexit; 106 __atexit = p; 107 } 108 p->fns[p->ind++] = *fptr; 109 THREAD_UNLOCK(); 110 return (0); 111 } 112 113 /* 114 * Register a function to be performed at exit. 115 */ 116 int 117 atexit(void (*func)(void)) 118 { 119 struct atexit_fn fn; 120 int error; 121 122 fn.fn_type = ATEXIT_FN_STD; 123 fn.fn_ptr.std_func = func;; 124 fn.fn_arg = NULL; 125 fn.fn_dso = NULL; 126 127 error = atexit_register(&fn); 128 return (error); 129 } 130 131 /* 132 * Register a function to be performed at exit or when an shared object 133 * with given dso handle is unloaded dynamically. 134 */ 135 int 136 __cxa_atexit(void (*func)(void *), void *arg, void *dso) 137 { 138 struct atexit_fn fn; 139 int error; 140 141 fn.fn_type = ATEXIT_FN_CXA; 142 fn.fn_ptr.cxa_func = func;; 143 fn.fn_arg = arg; 144 fn.fn_dso = dso; 145 146 error = atexit_register(&fn); 147 return (error); 148 } 149 150 /* 151 * Call all handlers registered with __cxa_atexit for the shared 152 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining 153 * handlers are called. 154 */ 155 void 156 __cxa_finalize(void *dso) 157 { 158 struct atexit *p; 159 struct atexit_fn fn; 160 int n; 161 162 THREAD_LOCK(); 163 for (p = __atexit; p; p = p->next) { 164 for (n = p->ind; --n >= 0;) { 165 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY) 166 continue; /* already been called */ 167 if (dso != NULL && dso != p->fns[n].fn_dso) 168 continue; /* wrong DSO */ 169 fn = p->fns[n]; 170 /* 171 Mark entry to indicate that this particular handler 172 has already been called. 173 */ 174 p->fns[n].fn_type = ATEXIT_FN_EMPTY; 175 THREAD_UNLOCK(); 176 177 /* Call the function of correct type. */ 178 if (fn.fn_type == ATEXIT_FN_CXA) 179 fn.fn_ptr.cxa_func(fn.fn_arg); 180 else if (fn.fn_type == ATEXIT_FN_STD) 181 fn.fn_ptr.std_func(); 182 THREAD_LOCK(); 183 } 184 } 185 THREAD_UNLOCK(); 186 } 187