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 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 static char sccsid[] = "@(#)atexit.c 8.2 (Berkeley) 7/3/94"; 41 #endif /* LIBC_SCCS and not lint */ 42 43 #include <stddef.h> 44 #include <stdlib.h> 45 #include <unistd.h> 46 #include "atexit.h" 47 48 #include "libc_private.h" 49 #include "spinlock.h" 50 51 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 52 53 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock); 54 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock); 55 56 struct atexit *__atexit; /* points to head of LIFO stack */ 57 58 /* 59 * Register a function to be performed at exit. 60 */ 61 int 62 atexit(fn) 63 void (*fn)(); 64 { 65 static struct atexit __atexit0; /* one guaranteed table */ 66 register struct atexit *p; 67 68 THREAD_LOCK(); 69 if ((p = __atexit) == NULL) 70 __atexit = p = &__atexit0; 71 else while (p->ind >= ATEXIT_SIZE) { 72 struct atexit *old__atexit; 73 old__atexit = __atexit; 74 THREAD_UNLOCK(); 75 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 76 return (-1); 77 THREAD_LOCK(); 78 if (old__atexit != __atexit) { 79 /* Lost race, retry operation */ 80 THREAD_UNLOCK(); 81 free(p); 82 THREAD_LOCK(); 83 p = __atexit; 84 continue; 85 } 86 p->ind = 0; 87 p->next = __atexit; 88 __atexit = p; 89 } 90 p->fns[p->ind++] = fn; 91 THREAD_UNLOCK(); 92 return (0); 93 } 94