atexit.c revision 259288 
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
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)atexit.c	8.2 (Berkeley) 7/3/94";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/10/lib/libc/stdlib/atexit.c 259288 2013-12-13 05:54:30Z kib $");
38
39#include "namespace.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
48#include "libc_private.h"
49
50#define	ATEXIT_FN_EMPTY	0
51#define	ATEXIT_FN_STD	1
52#define	ATEXIT_FN_CXA	2
53
54static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
55
56#define _MUTEX_LOCK(x)		if (__isthreaded) _pthread_mutex_lock(x)
57#define _MUTEX_UNLOCK(x)	if (__isthreaded) _pthread_mutex_unlock(x)
58#define _MUTEX_DESTROY(x)	if (__isthreaded) _pthread_mutex_destroy(x)
59
60struct atexit {
61	struct atexit *next;			/* next in list */
62	int ind;				/* next index in this table */
63	struct atexit_fn {
64		int fn_type;			/* ATEXIT_? from above */
65		union {
66			void (*std_func)(void);
67			void (*cxa_func)(void *);
68		} fn_ptr;			/* function pointer */
69		void *fn_arg;			/* argument for CXA callback */
70		void *fn_dso;			/* shared module handle */
71	} fns[ATEXIT_SIZE];			/* the table itself */
72};
73
74static struct atexit *__atexit;		/* points to head of LIFO stack */
75
76/*
77 * Register the function described by 'fptr' to be called at application
78 * exit or owning shared object unload time. This is a helper function
79 * for atexit and __cxa_atexit.
80 */
81static int
82atexit_register(struct atexit_fn *fptr)
83{
84	static struct atexit __atexit0;	/* one guaranteed table */
85	struct atexit *p;
86
87	_MUTEX_LOCK(&atexit_mutex);
88	if ((p = __atexit) == NULL)
89		__atexit = p = &__atexit0;
90	else while (p->ind >= ATEXIT_SIZE) {
91		struct atexit *old__atexit;
92		old__atexit = __atexit;
93	        _MUTEX_UNLOCK(&atexit_mutex);
94		if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
95			return (-1);
96		_MUTEX_LOCK(&atexit_mutex);
97		if (old__atexit != __atexit) {
98			/* Lost race, retry operation */
99			_MUTEX_UNLOCK(&atexit_mutex);
100			free(p);
101			_MUTEX_LOCK(&atexit_mutex);
102			p = __atexit;
103			continue;
104		}
105		p->ind = 0;
106		p->next = __atexit;
107		__atexit = p;
108	}
109	p->fns[p->ind++] = *fptr;
110	_MUTEX_UNLOCK(&atexit_mutex);
111	return 0;
112}
113
114/*
115 * Register a function to be performed at exit.
116 */
117int
118atexit(void (*func)(void))
119{
120	struct atexit_fn fn;
121	int error;
122
123	fn.fn_type = ATEXIT_FN_STD;
124	fn.fn_ptr.std_func = func;
125	fn.fn_arg = NULL;
126	fn.fn_dso = NULL;
127
128 	error = atexit_register(&fn);
129	return (error);
130}
131
132/*
133 * Register a function to be performed at exit or when an shared object
134 * with given dso handle is unloaded dynamically.
135 */
136int
137__cxa_atexit(void (*func)(void *), void *arg, void *dso)
138{
139	struct atexit_fn fn;
140	int error;
141
142	fn.fn_type = ATEXIT_FN_CXA;
143	fn.fn_ptr.cxa_func = func;
144	fn.fn_arg = arg;
145	fn.fn_dso = dso;
146
147 	error = atexit_register(&fn);
148	return (error);
149}
150
151#pragma weak __pthread_cxa_finalize
152void __pthread_cxa_finalize(const struct dl_phdr_info *);
153
154static int global_exit;
155
156/*
157 * Call all handlers registered with __cxa_atexit for the shared
158 * object owning 'dso'.  Note: if 'dso' is NULL, then all remaining
159 * handlers are called.
160 */
161void
162__cxa_finalize(void *dso)
163{
164	struct dl_phdr_info phdr_info;
165	struct atexit *p;
166	struct atexit_fn fn;
167	int n, has_phdr;
168
169	if (dso != NULL) {
170		has_phdr = _rtld_addr_phdr(dso, &phdr_info);
171	} else {
172		has_phdr = 0;
173		global_exit = 1;
174	}
175
176	_MUTEX_LOCK(&atexit_mutex);
177	for (p = __atexit; p; p = p->next) {
178		for (n = p->ind; --n >= 0;) {
179			if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
180				continue; /* already been called */
181			fn = p->fns[n];
182			if (dso != NULL && dso != fn.fn_dso) {
183				/* wrong DSO ? */
184				if (!has_phdr || global_exit ||
185				    !__elf_phdr_match_addr(&phdr_info,
186				    fn.fn_ptr.cxa_func))
187					continue;
188			}
189			/*
190			  Mark entry to indicate that this particular handler
191			  has already been called.
192			*/
193			p->fns[n].fn_type = ATEXIT_FN_EMPTY;
194		        _MUTEX_UNLOCK(&atexit_mutex);
195
196			/* Call the function of correct type. */
197			if (fn.fn_type == ATEXIT_FN_CXA)
198				fn.fn_ptr.cxa_func(fn.fn_arg);
199			else if (fn.fn_type == ATEXIT_FN_STD)
200				fn.fn_ptr.std_func();
201			_MUTEX_LOCK(&atexit_mutex);
202		}
203	}
204	_MUTEX_UNLOCK(&atexit_mutex);
205	if (dso == NULL)
206		_MUTEX_DESTROY(&atexit_mutex);
207
208	if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
209		__pthread_cxa_finalize(&phdr_info);
210}
211