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9 * modification, are permitted provided that the following conditions
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32 * @(#)atexit.c 8.2 (Berkeley) 7/3/94
33 * $FreeBSD: head/lib/libc/stdlib/atexit.c 211894 2010-08-27 19:57:17Z kib $
36 #include "namespace.h"
43 #include "un-namespace.h"
45 #include "libc_private.h"
47 int __cxa_atexit(void (*)(void *), void *, void *);
49 #define ATEXIT_FN_EMPTY 0
50 #define ATEXIT_FN_STD 1
51 #define ATEXIT_FN_CXA 2
53 static pthread_mutex_t atexit_mutex
= PTHREAD_MUTEX_INITIALIZER
;
55 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
56 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
57 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x)
60 struct atexit
*next
; /* next in list */
61 int ind
; /* next index in this table */
63 int fn_type
; /* ATEXIT_? from above */
65 void (*std_func
)(void);
66 void (*cxa_func
)(void *);
67 } fn_ptr
; /* function pointer */
68 void *fn_arg
; /* argument for CXA callback */
69 void *fn_dso
; /* shared module handle */
70 } fns
[ATEXIT_SIZE
]; /* the table itself */
73 static struct atexit
*__atexit
; /* points to head of LIFO stack */
74 static int nested_atexit
; /* nested atexit() status */
76 #define CXA_DTORS_ITERATIONS 16 /* give up after nested iterations */
79 * Register the function described by 'fptr' to be called at application
80 * exit or owning shared object unload time. This is a helper function
81 * for atexit and __cxa_atexit.
84 atexit_register(struct atexit_fn
*fptr
)
86 static struct atexit __atexit0
; /* one guaranteed table */
89 _MUTEX_LOCK(&atexit_mutex
);
90 if ((p
= __atexit
) == NULL
)
91 __atexit
= p
= &__atexit0
;
92 else while (p
->ind
>= ATEXIT_SIZE
) {
93 struct atexit
*old__atexit
;
94 old__atexit
= __atexit
;
95 _MUTEX_UNLOCK(&atexit_mutex
);
96 if ((p
= (struct atexit
*)malloc(sizeof(*p
))) == NULL
)
98 _MUTEX_LOCK(&atexit_mutex
);
99 if (old__atexit
!= __atexit
) {
100 /* Lost race, retry operation */
101 _MUTEX_UNLOCK(&atexit_mutex
);
103 _MUTEX_LOCK(&atexit_mutex
);
111 p
->fns
[p
->ind
++] = *fptr
;
112 if (nested_atexit
== 1)
114 _MUTEX_UNLOCK(&atexit_mutex
);
119 * Register a function to be performed at exit.
122 atexit(void (*func
)(void))
127 fn
.fn_type
= ATEXIT_FN_STD
;
128 fn
.fn_ptr
.std_func
= func
;
132 error
= atexit_register(&fn
);
137 * Register a function to be performed at exit or when an shared object
138 * with given dso handle is unloaded dynamically.
141 __cxa_atexit(void (*func
)(void *), void *arg
, void *dso
)
146 fn
.fn_type
= ATEXIT_FN_CXA
;
147 fn
.fn_ptr
.cxa_func
= func
;
151 error
= atexit_register(&fn
);
155 #pragma weak __pthread_cxa_finalize
156 void __pthread_cxa_finalize(const struct dl_phdr_info
*);
158 static int global_exit
;
161 * Call all handlers registered with __cxa_atexit for the shared
162 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
163 * handlers are called.
164 * Attempt to support additional static c++ destructors added from within
165 * destructors in a LIFO manner by relooping.
168 __cxa_finalize(void *dso
)
170 struct dl_phdr_info phdr_info
;
176 has_phdr
= _rtld_addr_phdr(dso
, &phdr_info
);
182 _MUTEX_LOCK(&atexit_mutex
);
183 ni
= CXA_DTORS_ITERATIONS
;
186 for (p
= __atexit
; p
; p
= p
->next
) {
187 for (n
= p
->ind
; --n
>= 0;) {
188 if (p
->fns
[n
].fn_type
== ATEXIT_FN_EMPTY
)
189 continue; /* already been called */
191 if (dso
!= NULL
&& dso
!= fn
.fn_dso
) {
193 if (!has_phdr
|| global_exit
||
194 !__elf_phdr_match_addr(&phdr_info
,
199 Mark entry to indicate that this particular handler
200 has already been called.
202 p
->fns
[n
].fn_type
= ATEXIT_FN_EMPTY
;
203 _MUTEX_UNLOCK(&atexit_mutex
);
205 /* Call the function of correct type. */
206 if (fn
.fn_type
== ATEXIT_FN_CXA
)
207 fn
.fn_ptr
.cxa_func(fn
.fn_arg
);
208 else if (fn
.fn_type
== ATEXIT_FN_STD
)
209 fn
.fn_ptr
.std_func();
210 _MUTEX_LOCK(&atexit_mutex
);
213 * Reloop if we got more atexit() destructors.
215 if (nested_atexit
== 2 && ni
> 0) {
221 _MUTEX_UNLOCK(&atexit_mutex
);
223 _MUTEX_DESTROY(&atexit_mutex
);
225 if (has_phdr
&& !global_exit
&& &__pthread_cxa_finalize
!= NULL
)
226 __pthread_cxa_finalize(&phdr_info
);