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 * 4. 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: src/lib/libc/stdlib/atexit.c,v 1.8 2007/01/09 00:28:09 imp Exp $");
38
39#include "namespace.h"
40#include <errno.h>
41#include <stddef.h>
42#include <stdlib.h>
43#include <unistd.h>
44#include <assert.h>
45#include <pthread.h>
46#if defined(__DYNAMIC__) || defined (__BLOCKS__)
47#include <dlfcn.h>
48#endif /* defined(__DYNAMIC__) */
49#include "atexit.h"
50#include "un-namespace.h"
51
52#ifdef __BLOCKS__
53#include <Block.h>
54#include <Block_private.h>
55#endif /* __BLOCKS__ */
56#include "libc_private.h"
57#include <os/alloc_once_private.h>
58
59#include <TargetConditionals.h>
60
61#define	ATEXIT_FN_EMPTY	0
62#define	ATEXIT_FN_STD	1
63#define	ATEXIT_FN_CXA	2
64#ifdef __BLOCKS__
65#define	ATEXIT_FN_BLK	3
66#endif /* __BLOCKS__ */
67
68static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
69
70#define _MUTEX_LOCK(x)		if (__isthreaded) _pthread_mutex_lock(x)
71#define _MUTEX_UNLOCK(x)	if (__isthreaded) _pthread_mutex_unlock(x)
72
73struct atexit {
74	struct atexit *next;			/* next in list */
75	int ind;				/* next index in this table */
76	struct atexit_fn {
77		int fn_type;			/* ATEXIT_? from above */
78		union {
79			void (*std_func)(void);
80			void (*cxa_func)(void *);
81#ifdef __BLOCKS__
82			void (^block)(void);
83#endif /* __BLOCKS__ */
84		} fn_ptr;			/* function pointer */
85		void *fn_arg;			/* argument for CXA callback */
86		void *fn_dso;			/* shared module handle */
87	} fns[ATEXIT_SIZE];			/* the table itself */
88};
89
90static struct atexit *__atexit;		/* points to head of LIFO stack */
91static int __atexit_new_registration;
92
93__attribute__ ((visibility ("hidden")))
94void
95__atexit_init(void)
96{
97	__atexit = os_alloc_once(OS_ALLOC_ONCE_KEY_LIBSYSTEM_C,
98			sizeof(struct atexit), NULL);
99}
100
101/*
102 * Register the function described by 'fptr' to be called at application
103 * exit or owning shared object unload time. This is a helper function
104 * for atexit and __cxa_atexit.
105 */
106static int
107atexit_register(struct atexit_fn *fptr)
108{
109	struct atexit *p = __atexit;
110	assert(p);
111	_MUTEX_LOCK(&atexit_mutex);
112	while (p->ind >= ATEXIT_SIZE) {
113		struct atexit *old__atexit;
114		old__atexit = __atexit;
115	        _MUTEX_UNLOCK(&atexit_mutex);
116		if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
117			return (-1);
118		_MUTEX_LOCK(&atexit_mutex);
119		if (old__atexit != __atexit) {
120			/* Lost race, retry operation */
121			_MUTEX_UNLOCK(&atexit_mutex);
122			free(p);
123			_MUTEX_LOCK(&atexit_mutex);
124			p = __atexit;
125			continue;
126		}
127		p->ind = 0;
128		p->next = __atexit;
129		__atexit = p;
130	}
131	p->fns[p->ind++] = *fptr;
132	__atexit_new_registration = 1;
133	_MUTEX_UNLOCK(&atexit_mutex);
134	return 0;
135}
136
137/*
138 * Register a function to be performed at exit.
139 */
140int
141atexit(void (*func)(void))
142{
143	struct atexit_fn fn;
144	int error;
145
146	fn.fn_type = ATEXIT_FN_STD;
147	fn.fn_ptr.std_func = func;
148	fn.fn_arg = NULL;
149	fn.fn_dso = NULL;
150
151#if defined(__DYNAMIC__) && !TARGET_OS_IPHONE
152	// <rdar://problem/14596032&15173956>
153	struct dl_info info;
154	if (dladdr(func, &info)) {
155		fn.fn_dso = info.dli_fbase;
156	}
157#endif
158
159 	error = atexit_register(&fn);
160	return (error);
161}
162
163#ifdef __BLOCKS__
164int
165atexit_b(void (^block)(void))
166{
167	struct atexit_fn fn;
168	int error;
169
170	fn.fn_type = ATEXIT_FN_BLK;
171	fn.fn_ptr.block = Block_copy(block);
172	fn.fn_arg = NULL;
173	fn.fn_dso = NULL;
174
175 	error = atexit_register(&fn);
176	return (error);
177}
178#endif /* __BLOCKS__ */
179
180/*
181 * Register a function to be performed at exit or when an shared object
182 * with given dso handle is unloaded dynamically.
183 */
184int
185__cxa_atexit(void (*func)(void *), void *arg, void *dso)
186{
187	struct atexit_fn fn;
188	int error;
189
190	fn.fn_type = ATEXIT_FN_CXA;
191	fn.fn_ptr.cxa_func = func;;
192	fn.fn_arg = arg;
193	fn.fn_dso = dso;
194
195 	error = atexit_register(&fn);
196	return (error);
197}
198
199static bool
200__cxa_in_range(const struct __cxa_range_t ranges[],
201			   unsigned int count,
202			   const void* fn)
203{
204	uintptr_t addr = (uintptr_t)fn;
205
206	unsigned int i;
207	for (i = 0; i < count; ++i) {
208		const struct __cxa_range_t *r = &ranges[i];
209		if (addr < (uintptr_t)r->addr) {
210			continue;
211		}
212		if (addr < ((uintptr_t)r->addr + r->length)) {
213			return true;
214		}
215	}
216	return false;
217}
218
219/*
220 * Call handlers registered via __cxa_atexit/atexit that are in a
221 * a range specified.
222 * Note: rangeCount==0, means call all handlers.
223 */
224void
225__cxa_finalize_ranges(const struct __cxa_range_t ranges[], unsigned int count)
226{
227	struct atexit *p;
228	struct atexit_fn *fn;
229	int n;
230	_MUTEX_LOCK(&atexit_mutex);
231
232restart:
233	for (p = __atexit; p; p = p->next) {
234		for (n = p->ind; --n >= 0;) {
235			fn = &p->fns[n];
236
237			if (fn->fn_type == ATEXIT_FN_EMPTY) {
238				continue; // already been called
239			}
240
241			// Verify that the entry is within the range being unloaded.
242			if (count > 0) {
243				if (fn->fn_type == ATEXIT_FN_CXA) {
244					// for __cxa_atexit(), call if *dso* is in range be unloaded
245					if (!__cxa_in_range(ranges, count, fn->fn_dso)) {
246						continue; // not being unloaded yet
247					}
248				} else if (fn->fn_type == ATEXIT_FN_STD) {
249					// for atexit, call if *function* is in range be unloaded
250					if (!__cxa_in_range(ranges, count,  fn->fn_ptr.std_func)) {
251						continue; // not being unloaded yet
252					}
253#ifdef __BLOCKS__
254				} else if (fn->fn_type == ATEXIT_FN_BLK) {
255					// for atexit_b, call if block code is in range be unloaded
256					void *a = ((struct Block_layout *)fn->fn_ptr.block)->invoke;
257					if (!__cxa_in_range(ranges, count, a)) {
258						continue; // not being unloaded yet
259					}
260#endif // __BLOCKS__
261				}
262			}
263
264			// Clear the entry to indicate that this handler has been called.
265			int fn_type = fn->fn_type;
266			fn->fn_type = ATEXIT_FN_EMPTY;
267
268			// Detect recursive registrations.
269			__atexit_new_registration = 0;
270			_MUTEX_UNLOCK(&atexit_mutex);
271
272			// Call the handler.
273			if (fn_type == ATEXIT_FN_CXA) {
274				fn->fn_ptr.cxa_func(fn->fn_arg);
275			} else if (fn_type == ATEXIT_FN_STD) {
276				fn->fn_ptr.std_func();
277#ifdef __BLOCKS__
278			} else if (fn_type == ATEXIT_FN_BLK) {
279				fn->fn_ptr.block();
280#endif // __BLOCKS__
281			}
282
283			// Call any recursively registered handlers.
284			_MUTEX_LOCK(&atexit_mutex);
285			if (__atexit_new_registration) {
286			    goto restart;
287			}
288		}
289	}
290	_MUTEX_UNLOCK(&atexit_mutex);
291}
292
293
294/*
295 * Call all handlers registered with __cxa_atexit for the shared
296 * object owning 'dso'.  Note: if 'dso' is NULL, then all remaining
297 * handlers are called.
298 */
299void
300__cxa_finalize(const void *dso)
301{
302	if (dso != NULL) {
303		// Note: this should not happen as only dyld should be calling
304		// this and dyld has switched to call __cxa_finalize_ranges directly.
305		struct __cxa_range_t range;
306		range.addr = dso;
307		range.length = 1;
308		__cxa_finalize_ranges(&range, 1);
309	} else {
310		__cxa_finalize_ranges(NULL, 0);
311	}
312}
313
314#if !TARGET_IPHONE_SIMULATOR && (__i386__ || __x86_64__)
315/*
316 * Support for thread_local in C++, using existing _tlv_atexit() in libdyld
317 */
318
319void _tlv_atexit(void(*f)(void*), void* arg); /* in libdyld */
320
321void
322__cxa_thread_atexit(void(*f)(void*), void* arg)
323{
324    _tlv_atexit(f, arg);
325}
326#endif
327