2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 #include "namespace.h"
43 #include "un-namespace.h"
44 #include "block_abi.h"
46 #include "libc_private.h"
49 * The _Block_copy() function is provided by the block runtime.
51 __attribute__((weak)) void*
54 #define ATEXIT_FN_EMPTY 0
55 #define ATEXIT_FN_STD 1
56 #define ATEXIT_FN_CXA 2
58 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
60 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
61 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
62 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x)
65 struct atexit *next; /* next in list */
66 int ind; /* next index in this table */
68 int fn_type; /* ATEXIT_? from above */
70 void (*std_func)(void);
71 void (*cxa_func)(void *);
72 } fn_ptr; /* function pointer */
73 void *fn_arg; /* argument for CXA callback */
74 void *fn_dso; /* shared module handle */
75 } fns[ATEXIT_SIZE]; /* the table itself */
78 static struct atexit *__atexit; /* points to head of LIFO stack */
79 typedef DECLARE_BLOCK(void, atexit_block, void);
81 int atexit_b(atexit_block);
82 int __cxa_atexit(void (*)(void *), void *, void *);
85 * Register the function described by 'fptr' to be called at application
86 * exit or owning shared object unload time. This is a helper function
87 * for atexit and __cxa_atexit.
90 atexit_register(struct atexit_fn *fptr)
92 static struct atexit __atexit0; /* one guaranteed table */
95 _MUTEX_LOCK(&atexit_mutex);
96 if ((p = __atexit) == NULL)
97 __atexit = p = &__atexit0;
98 else while (p->ind >= ATEXIT_SIZE) {
99 struct atexit *old__atexit;
100 old__atexit = __atexit;
101 _MUTEX_UNLOCK(&atexit_mutex);
102 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
104 _MUTEX_LOCK(&atexit_mutex);
105 if (old__atexit != __atexit) {
106 /* Lost race, retry operation */
107 _MUTEX_UNLOCK(&atexit_mutex);
109 _MUTEX_LOCK(&atexit_mutex);
117 p->fns[p->ind++] = *fptr;
118 _MUTEX_UNLOCK(&atexit_mutex);
123 * Register a function to be performed at exit.
126 atexit(void (*func)(void))
131 fn.fn_type = ATEXIT_FN_STD;
132 fn.fn_ptr.std_func = func;
136 error = atexit_register(&fn);
139 __weak_reference(atexit, __libc_atexit);
142 * Register a block to be performed at exit.
145 atexit_b(atexit_block func)
149 if (_Block_copy == 0) {
153 func = _Block_copy(func);
155 // Blocks are not C++ destructors, but they have the same signature (a
156 // single void* parameter), so we can pretend that they are.
157 fn.fn_type = ATEXIT_FN_CXA;
158 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func);
162 error = atexit_register(&fn);
167 * Register a function to be performed at exit or when an shared object
168 * with given dso handle is unloaded dynamically.
171 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
176 fn.fn_type = ATEXIT_FN_CXA;
177 fn.fn_ptr.cxa_func = func;
181 error = atexit_register(&fn);
185 #pragma weak __pthread_cxa_finalize
186 void __pthread_cxa_finalize(const struct dl_phdr_info *);
188 static int global_exit;
191 * Call all handlers registered with __cxa_atexit for the shared
192 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
193 * handlers are called.
196 __cxa_finalize(void *dso)
198 struct dl_phdr_info phdr_info;
204 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
210 _MUTEX_LOCK(&atexit_mutex);
211 for (p = __atexit; p; p = p->next) {
212 for (n = p->ind; --n >= 0;) {
213 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
214 continue; /* already been called */
216 if (dso != NULL && dso != fn.fn_dso) {
218 if (!has_phdr || global_exit ||
219 !__elf_phdr_match_addr(&phdr_info,
224 Mark entry to indicate that this particular handler
225 has already been called.
227 p->fns[n].fn_type = ATEXIT_FN_EMPTY;
228 _MUTEX_UNLOCK(&atexit_mutex);
230 /* Call the function of correct type. */
231 if (fn.fn_type == ATEXIT_FN_CXA)
232 fn.fn_ptr.cxa_func(fn.fn_arg);
233 else if (fn.fn_type == ATEXIT_FN_STD)
234 fn.fn_ptr.std_func();
235 _MUTEX_LOCK(&atexit_mutex);
238 _MUTEX_UNLOCK(&atexit_mutex);
240 _MUTEX_DESTROY(&atexit_mutex);
242 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
243 __pthread_cxa_finalize(&phdr_info);