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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 */
76 * Register the function described by 'fptr' to be called at application
77 * exit or owning shared object unload time. This is a helper function
78 * for atexit and __cxa_atexit.
81 atexit_register(struct atexit_fn *fptr)
83 static struct atexit __atexit0; /* one guaranteed table */
86 _MUTEX_LOCK(&atexit_mutex);
87 if ((p = __atexit) == NULL)
88 __atexit = p = &__atexit0;
89 else while (p->ind >= ATEXIT_SIZE) {
90 struct atexit *old__atexit;
91 old__atexit = __atexit;
92 _MUTEX_UNLOCK(&atexit_mutex);
93 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
95 _MUTEX_LOCK(&atexit_mutex);
96 if (old__atexit != __atexit) {
97 /* Lost race, retry operation */
98 _MUTEX_UNLOCK(&atexit_mutex);
100 _MUTEX_LOCK(&atexit_mutex);
108 p->fns[p->ind++] = *fptr;
109 _MUTEX_UNLOCK(&atexit_mutex);
114 * Register a function to be performed at exit.
117 atexit(void (*func)(void))
122 fn.fn_type = ATEXIT_FN_STD;
123 fn.fn_ptr.std_func = func;
127 error = atexit_register(&fn);
132 * Register a function to be performed at exit or when an shared object
133 * with given dso handle is unloaded dynamically.
136 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
141 fn.fn_type = ATEXIT_FN_CXA;
142 fn.fn_ptr.cxa_func = func;
146 error = atexit_register(&fn);
150 #pragma weak __pthread_cxa_finalize
151 void __pthread_cxa_finalize(const struct dl_phdr_info *);
153 static int global_exit;
156 * Call all handlers registered with __cxa_atexit for the shared
157 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
158 * handlers are called.
161 __cxa_finalize(void *dso)
163 struct dl_phdr_info phdr_info;
169 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
175 _MUTEX_LOCK(&atexit_mutex);
176 for (p = __atexit; p; p = p->next) {
177 for (n = p->ind; --n >= 0;) {
178 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
179 continue; /* already been called */
181 if (dso != NULL && dso != fn.fn_dso) {
183 if (!has_phdr || global_exit ||
184 !__elf_phdr_match_addr(&phdr_info,
189 Mark entry to indicate that this particular handler
190 has already been called.
192 p->fns[n].fn_type = ATEXIT_FN_EMPTY;
193 _MUTEX_UNLOCK(&atexit_mutex);
195 /* Call the function of correct type. */
196 if (fn.fn_type == ATEXIT_FN_CXA)
197 fn.fn_ptr.cxa_func(fn.fn_arg);
198 else if (fn.fn_type == ATEXIT_FN_STD)
199 fn.fn_ptr.std_func();
200 _MUTEX_LOCK(&atexit_mutex);
203 _MUTEX_UNLOCK(&atexit_mutex);
205 _MUTEX_DESTROY(&atexit_mutex);
207 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
208 __pthread_cxa_finalize(&phdr_info);