2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
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7 * This code is derived from software contributed to Berkeley by
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22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)atexit.c 8.2 (Berkeley) 7/3/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include "namespace.h"
49 #include "un-namespace.h"
50 #include "block_abi.h"
52 #include "libc_private.h"
55 * The _Block_copy() function is provided by the block runtime.
57 __attribute__((weak)) void*
60 #define ATEXIT_FN_EMPTY 0
61 #define ATEXIT_FN_STD 1
62 #define ATEXIT_FN_CXA 2
64 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
66 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
67 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
68 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x)
71 struct atexit *next; /* next in list */
72 int ind; /* next index in this table */
74 int fn_type; /* ATEXIT_? from above */
76 void (*std_func)(void);
77 void (*cxa_func)(void *);
78 } fn_ptr; /* function pointer */
79 void *fn_arg; /* argument for CXA callback */
80 void *fn_dso; /* shared module handle */
81 } fns[ATEXIT_SIZE]; /* the table itself */
84 static struct atexit *__atexit; /* points to head of LIFO stack */
85 typedef DECLARE_BLOCK(void, atexit_block, void);
87 int atexit_b(atexit_block);
88 int __cxa_atexit(void (*)(void *), void *, void *);
91 * Register the function described by 'fptr' to be called at application
92 * exit or owning shared object unload time. This is a helper function
93 * for atexit and __cxa_atexit.
96 atexit_register(struct atexit_fn *fptr)
98 static struct atexit __atexit0; /* one guaranteed table */
101 _MUTEX_LOCK(&atexit_mutex);
102 if ((p = __atexit) == NULL)
103 __atexit = p = &__atexit0;
104 else while (p->ind >= ATEXIT_SIZE) {
105 struct atexit *old__atexit;
106 old__atexit = __atexit;
107 _MUTEX_UNLOCK(&atexit_mutex);
108 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
110 _MUTEX_LOCK(&atexit_mutex);
111 if (old__atexit != __atexit) {
112 /* Lost race, retry operation */
113 _MUTEX_UNLOCK(&atexit_mutex);
115 _MUTEX_LOCK(&atexit_mutex);
123 p->fns[p->ind++] = *fptr;
124 _MUTEX_UNLOCK(&atexit_mutex);
129 * Register a function to be performed at exit.
132 atexit(void (*func)(void))
137 fn.fn_type = ATEXIT_FN_STD;
138 fn.fn_ptr.std_func = func;
142 error = atexit_register(&fn);
147 * Register a block to be performed at exit.
150 atexit_b(atexit_block func)
154 if (_Block_copy == 0) {
158 func = _Block_copy(func);
160 // Blocks are not C++ destructors, but they have the same signature (a
161 // single void* parameter), so we can pretend that they are.
162 fn.fn_type = ATEXIT_FN_CXA;
163 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func);
167 error = atexit_register(&fn);
172 * Register a function to be performed at exit or when an shared object
173 * with given dso handle is unloaded dynamically.
176 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
181 fn.fn_type = ATEXIT_FN_CXA;
182 fn.fn_ptr.cxa_func = func;
186 error = atexit_register(&fn);
190 #pragma weak __pthread_cxa_finalize
191 void __pthread_cxa_finalize(const struct dl_phdr_info *);
193 static int global_exit;
196 * Call all handlers registered with __cxa_atexit for the shared
197 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
198 * handlers are called.
201 __cxa_finalize(void *dso)
203 struct dl_phdr_info phdr_info;
209 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
215 _MUTEX_LOCK(&atexit_mutex);
216 for (p = __atexit; p; p = p->next) {
217 for (n = p->ind; --n >= 0;) {
218 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
219 continue; /* already been called */
221 if (dso != NULL && dso != fn.fn_dso) {
223 if (!has_phdr || global_exit ||
224 !__elf_phdr_match_addr(&phdr_info,
229 Mark entry to indicate that this particular handler
230 has already been called.
232 p->fns[n].fn_type = ATEXIT_FN_EMPTY;
233 _MUTEX_UNLOCK(&atexit_mutex);
235 /* Call the function of correct type. */
236 if (fn.fn_type == ATEXIT_FN_CXA)
237 fn.fn_ptr.cxa_func(fn.fn_arg);
238 else if (fn.fn_type == ATEXIT_FN_STD)
239 fn.fn_ptr.std_func();
240 _MUTEX_LOCK(&atexit_mutex);
243 _MUTEX_UNLOCK(&atexit_mutex);
245 _MUTEX_DESTROY(&atexit_mutex);
247 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
248 __pthread_cxa_finalize(&phdr_info);