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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 #define ATEXIT_FN_EMPTY 0
48 #define ATEXIT_FN_STD 1
49 #define ATEXIT_FN_CXA 2
51 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
53 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
54 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
55 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x)
58 struct atexit *next; /* next in list */
59 int ind; /* next index in this table */
61 int fn_type; /* ATEXIT_? from above */
63 void (*std_func)(void);
64 void (*cxa_func)(void *);
65 } fn_ptr; /* function pointer */
66 void *fn_arg; /* argument for CXA callback */
67 void *fn_dso; /* shared module handle */
68 } fns[ATEXIT_SIZE]; /* the table itself */
71 static struct atexit *__atexit; /* points to head of LIFO stack */
74 * Register the function described by 'fptr' to be called at application
75 * exit or owning shared object unload time. This is a helper function
76 * for atexit and __cxa_atexit.
79 atexit_register(struct atexit_fn *fptr)
81 static struct atexit __atexit0; /* one guaranteed table */
84 _MUTEX_LOCK(&atexit_mutex);
85 if ((p = __atexit) == NULL)
86 __atexit = p = &__atexit0;
87 else while (p->ind >= ATEXIT_SIZE) {
88 struct atexit *old__atexit;
89 old__atexit = __atexit;
90 _MUTEX_UNLOCK(&atexit_mutex);
91 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
93 _MUTEX_LOCK(&atexit_mutex);
94 if (old__atexit != __atexit) {
95 /* Lost race, retry operation */
96 _MUTEX_UNLOCK(&atexit_mutex);
98 _MUTEX_LOCK(&atexit_mutex);
106 p->fns[p->ind++] = *fptr;
107 _MUTEX_UNLOCK(&atexit_mutex);
112 * Register a function to be performed at exit.
115 atexit(void (*func)(void))
120 fn.fn_type = ATEXIT_FN_STD;
121 fn.fn_ptr.std_func = func;
125 error = atexit_register(&fn);
130 * Register a function to be performed at exit or when an shared object
131 * with given dso handle is unloaded dynamically.
134 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
139 fn.fn_type = ATEXIT_FN_CXA;
140 fn.fn_ptr.cxa_func = func;
144 error = atexit_register(&fn);
148 #pragma weak __pthread_cxa_finalize
149 void __pthread_cxa_finalize(const struct dl_phdr_info *);
152 * Call all handlers registered with __cxa_atexit for the shared
153 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
154 * handlers are called.
157 __cxa_finalize(void *dso)
159 struct dl_phdr_info phdr_info;
165 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
169 _MUTEX_LOCK(&atexit_mutex);
170 for (p = __atexit; p; p = p->next) {
171 for (n = p->ind; --n >= 0;) {
172 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
173 continue; /* already been called */
175 if (dso != NULL && dso != fn.fn_dso) {
177 if (!has_phdr || !__elf_phdr_match_addr(
178 &phdr_info, fn.fn_ptr.cxa_func))
182 Mark entry to indicate that this particular handler
183 has already been called.
185 p->fns[n].fn_type = ATEXIT_FN_EMPTY;
186 _MUTEX_UNLOCK(&atexit_mutex);
188 /* Call the function of correct type. */
189 if (fn.fn_type == ATEXIT_FN_CXA)
190 fn.fn_ptr.cxa_func(fn.fn_arg);
191 else if (fn.fn_type == ATEXIT_FN_STD)
192 fn.fn_ptr.std_func();
193 _MUTEX_LOCK(&atexit_mutex);
196 _MUTEX_UNLOCK(&atexit_mutex);
198 _MUTEX_DESTROY(&atexit_mutex);
200 if (has_phdr && &__pthread_cxa_finalize != NULL)
201 __pthread_cxa_finalize(&phdr_info);