1 /* Copyright (C) 1995,1996 Robert de Bath <rdebath@cix.compulink.co.uk>
2 * This file is part of the Linux-8086 C library and is distributed
3 * under the GNU Library General Public License.
7 * Dec 2000 Manuel Novoa III
9 * Made atexit handling conform to standards... i.e. no args.
10 * Removed on_exit since it did not match gnu libc definition.
11 * Combined atexit and __do_exit into one object file.
13 * Feb 2001 Manuel Novoa III
15 * Reworked file after addition of __uClibc_main.
16 * Changed name of __do_exit to atexit_handler.
17 * Changed name of __cleanup to __uClibc_cleanup.
18 * Moved declaration of __uClibc_cleanup to __uClibc_main
19 * where it is initialized with (possibly weak alias)
22 * Jul 2001 Steve Thayer
24 * Added an on_exit implementation (that now matches gnu libc definition.)
25 * Pulled atexit_handler out of the atexit object since it is now required by
26 * on_exit as well. Renamed it to __exit_handler.
27 * Fixed a problem where exit functions stop getting called if one of
29 * As a side effect of these changes, abort() no longer calls the exit
30 * functions (it now matches the gnu libc definition).
32 * August 2002 Erik Andersen
33 * Added locking so atexit and friends can be thread safe
35 * August 2005 Stephen Warren
36 * Added __cxa_atexit and __cxa_finalize support
47 #include <bits/uClibc_mutex.h>
48 __UCLIBC_MUTEX_EXTERN(__atexit_lock) attribute_hidden;
52 typedef void (*aefuncp)(void); /* atexit function pointer */
53 typedef void (*oefuncp)(int, void *); /* on_exit function pointer */
54 typedef void (*cxaefuncp)(void *); /* __cxa_atexit function pointer */
60 } ef_type; /* exit function types */
62 /* this is in the L_exit object */
63 extern void (*__exit_cleanup)(int) attribute_hidden;
65 /* these are in the L___do_exit object */
66 extern int __exit_slots attribute_hidden;
67 extern int __exit_count attribute_hidden;
68 extern void __exit_handler(int) attribute_hidden;
69 struct exit_function {
71 * 'type' should be of type of the 'enum ef_type' above but since we
72 * need this element in an atomic operation we have to use 'long int'.
74 long int type; /* enum ef_type */
87 #ifdef __UCLIBC_DYNAMIC_ATEXIT__
88 extern struct exit_function *__exit_function_table attribute_hidden;
90 extern struct exit_function __exit_function_table[__UCLIBC_MAX_ATEXIT] attribute_hidden;
92 extern struct exit_function *__new_exitfn(void) attribute_hidden;
94 /* this is in the L___cxa_atexit object */
95 extern int __cxa_atexit(cxaefuncp, void *arg, void *dso_handle);
98 /* remove old_atexit after 0.9.29 */
99 #if defined(L_atexit) || defined(L_old_atexit)
100 extern void *__dso_handle __attribute__ ((__weak__));
103 * register a function to be called at normal program termination
104 * (the registered function takes no arguments)
107 int attribute_hidden atexit(aefuncp func)
109 int old_atexit(aefuncp func);
110 int old_atexit(aefuncp func)
114 * glibc casts aefuncp to cxaefuncp.
115 * This seems dodgy, but I guess calling a function with more
116 * parameters than it needs will work everywhere?
118 return __cxa_atexit((cxaefuncp)func, NULL,
119 &__dso_handle == NULL ? NULL : __dso_handle);
122 weak_alias(old_atexit,atexit)
128 * register a function to be called at normal program termination
129 * the registered function takes two arguments:
130 * status - the exit status that was passed to the exit() function
131 * arg - generic argument
133 int on_exit(oefuncp func, void *arg)
135 struct exit_function *efp;
141 efp = __new_exitfn();
146 efp->funcs.on_exit.func = func;
147 efp->funcs.on_exit.arg = arg;
148 /* assign last for thread safety, since we're now unlocked */
149 efp->type = ef_on_exit;
155 #ifdef L___cxa_atexit
156 libc_hidden_proto(__cxa_atexit)
157 int __cxa_atexit(cxaefuncp func, void *arg, void *dso_handle)
159 struct exit_function *efp;
165 efp = __new_exitfn();
170 efp->funcs.cxa_atexit.func = func;
171 efp->funcs.cxa_atexit.arg = arg;
172 efp->funcs.cxa_atexit.dso_handle = dso_handle;
173 /* assign last for thread safety, since we're now unlocked */
174 efp->type = ef_cxa_atexit;
178 libc_hidden_def(__cxa_atexit)
181 #ifdef L___cxa_finalize
183 * If D is non-NULL, call all functions registered with `__cxa_atexit'
184 * with the same dso handle. Otherwise, if D is NULL, call all of the
185 * registered handlers.
187 void __cxa_finalize(void *dso_handle);
188 void __cxa_finalize(void *dso_handle)
190 struct exit_function *efp;
191 int exit_count_snapshot = __exit_count;
193 /* In reverse order */
194 while (exit_count_snapshot) {
195 efp = &__exit_function_table[--exit_count_snapshot];
198 * We check dso_handle match before we verify the type of the union entry.
199 * However, the atomic_exchange will validate that we were really "allowed"
200 * to read dso_handle...
202 if ((dso_handle == NULL || dso_handle == efp->funcs.cxa_atexit.dso_handle)
203 /* We don't want to run this cleanup more than once. */
204 && !atomic_compare_and_exchange_bool_acq(&efp->type, ef_free, ef_cxa_atexit)
206 /* glibc passes status (0) too, but that's not in the prototype */
207 (*efp->funcs.cxa_atexit.func)(efp->funcs.cxa_atexit.arg);
211 #if 0 /* haven't looked into this yet... */
213 * Remove the registered fork handlers. We do not have to
214 * unregister anything if the program is going to terminate anyway.
216 #ifdef UNREGISTER_ATFORK
218 UNREGISTER_ATFORK(d);
225 #ifdef L___exit_handler
226 int __exit_count = 0; /* Number of registered exit functions */
227 #ifdef __UCLIBC_DYNAMIC_ATEXIT__
228 struct exit_function *__exit_function_table = NULL;
229 int __exit_slots = 0; /* Size of __exit_function_table */
231 struct exit_function __exit_function_table[__UCLIBC_MAX_ATEXIT];
235 * Find and return a new exit_function pointer, for atexit,
236 * onexit and __cxa_atexit to initialize
238 struct exit_function attribute_hidden *__new_exitfn(void)
240 struct exit_function *efp;
242 __UCLIBC_MUTEX_LOCK(__atexit_lock);
245 * Reuse free slots at the end of the list.
246 * This avoids eating memory when dlopen and dlclose modules multiple times.
248 while (__exit_count > 0) {
249 if (__exit_function_table[__exit_count-1].type == ef_free) {
254 #ifdef __UCLIBC_DYNAMIC_ATEXIT__
255 /* If we are out of function table slots, make some more */
256 if (__exit_slots < __exit_count+1) {
257 efp = realloc(__exit_function_table,
258 (__exit_slots+20)*sizeof(struct exit_function));
263 __exit_function_table = efp;
267 if (__exit_count >= __UCLIBC_MAX_ATEXIT) {
274 __exit_cleanup = __exit_handler; /* enable cleanup */
275 efp = &__exit_function_table[__exit_count++];
276 efp->type = ef_in_use;
279 __UCLIBC_MUTEX_UNLOCK(__atexit_lock);
284 * Handle the work of executing the registered exit functions
285 * This is called while we are locked, so no additional locking
288 void __exit_handler(int status)
290 struct exit_function *efp;
292 /* In reverse order */
293 while (__exit_count) {
294 efp = &__exit_function_table[--__exit_count];
297 if (efp->funcs.on_exit.func) {
298 (efp->funcs.on_exit.func)(status, efp->funcs.on_exit.arg);
302 if (efp->funcs.cxa_atexit.func) {
303 /* glibc passes status too, but that's not in the prototype */
304 (efp->funcs.cxa_atexit.func)(efp->funcs.cxa_atexit.arg);
309 #ifdef __UCLIBC_DYNAMIC_ATEXIT__
310 /* Free up memory used by the __exit_function_table structure */
311 free(__exit_function_table);
317 /* Defeat compiler optimization which assumes function addresses are never NULL */
318 static __always_inline int not_null_ptr(const void *p)
322 : "=r" (q) /* output */
323 : "0" (p) /* input */
328 extern void weak_function _stdio_term(void) attribute_hidden;
329 attribute_hidden void (*__exit_cleanup)(int) = 0;
330 __UCLIBC_MUTEX_INIT(__atexit_lock, PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP);
332 extern void __uClibc_fini(void) attribute_hidden;
335 * Normal program termination
339 /* Perform exit-specific cleanup (atexit and on_exit) */
340 __UCLIBC_MUTEX_LOCK(__atexit_lock);
341 if (not_null_ptr(__exit_cleanup)) {
344 __UCLIBC_MUTEX_UNLOCK(__atexit_lock);
348 /* If we are using stdio, try to shut it down. At the very least,
349 * this will attempt to commit all buffered writes. It may also
350 * unbuffer all writable files, or close them outright.
351 * Check the stdio routines for details. */
352 if (not_null_ptr(_stdio_term))
357 libc_hidden_def(exit)