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1 /* -*- mode: C; c-file-style: "gnu" -*- */
2 /* dbus-threads.h  D-Bus threads handling
3  *
4  * Copyright (C) 2002, 2003, 2006 Red Hat Inc.
5  *
6  * Licensed under the Academic Free License version 2.1
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21  *
22  */
23 #include "dbus-threads.h"
24 #include "dbus-internals.h"
25 #include "dbus-threads-internal.h"
26 #include "dbus-list.h"
27 
28 static DBusThreadFunctions thread_functions =
29 {
30   0,
31   NULL, NULL, NULL, NULL, NULL,
32   NULL, NULL, NULL, NULL, NULL,
33   NULL, NULL, NULL, NULL,
34 
35   NULL, NULL, NULL, NULL
36 };
37 
38 static int thread_init_generation = 0;
39 
40 static DBusList *uninitialized_mutex_list = NULL;
41 static DBusList *uninitialized_condvar_list = NULL;
42 
43 /** This is used for the no-op default mutex pointer, just to be distinct from #NULL */
44 #define _DBUS_DUMMY_MUTEX ((DBusMutex*)0xABCDEF)
45 
46 /** This is used for the no-op default mutex pointer, just to be distinct from #NULL */
47 #define _DBUS_DUMMY_CONDVAR ((DBusCondVar*)0xABCDEF2)
48 
49 /**
50  * @defgroup DBusThreadsInternals Thread functions
51  * @ingroup  DBusInternals
52  * @brief _dbus_mutex_lock(), etc.
53  *
54  * Functions and macros related to threads and thread locks.
55  *
56  * @{
57  */
58 
59 /**
60  * Creates a new mutex using the function supplied to dbus_threads_init(),
61  * or creates a no-op mutex if threads are not initialized.
62  * May return #NULL even if threads are initialized, indicating
63  * out-of-memory.
64  *
65  * @returns new mutex or #NULL
66  */
67 DBusMutex*
_dbus_mutex_new(void)68 _dbus_mutex_new (void)
69 {
70   if (thread_functions.recursive_mutex_new)
71     return (* thread_functions.recursive_mutex_new) ();
72   else if (thread_functions.mutex_new)
73     return (* thread_functions.mutex_new) ();
74   else
75     return _DBUS_DUMMY_MUTEX;
76 }
77 
78 /**
79  * This does the same thing as _dbus_mutex_new.  It however
80  * gives another level of indirection by allocating a pointer
81  * to point to the mutex location.  This allows the threading
82  * module to swap out dummy mutexes for real a real mutex so libraries
83  * can initialize threads even after the D-Bus API has been used.
84  *
85  * @param location_p the location of the new mutex, can return #NULL on OOM
86  */
87 void
_dbus_mutex_new_at_location(DBusMutex ** location_p)88 _dbus_mutex_new_at_location (DBusMutex **location_p)
89 {
90   _dbus_assert (location_p != NULL);
91 
92   *location_p = _dbus_mutex_new();
93 
94   if (thread_init_generation != _dbus_current_generation && *location_p)
95     {
96       if (!_dbus_list_append (&uninitialized_mutex_list, location_p))
97         {
98 	  _dbus_mutex_free (*location_p);
99 	  *location_p = NULL;
100 	}
101     }
102 }
103 
104 /**
105  * Frees a mutex created with dbus_mutex_new(); does
106  * nothing if passed a #NULL pointer.
107  */
108 void
_dbus_mutex_free(DBusMutex * mutex)109 _dbus_mutex_free (DBusMutex *mutex)
110 {
111   if (mutex)
112     {
113       if (mutex && thread_functions.recursive_mutex_free)
114         (* thread_functions.recursive_mutex_free) (mutex);
115       else if (mutex && thread_functions.mutex_free)
116         (* thread_functions.mutex_free) (mutex);
117     }
118 }
119 
120 /**
121  * Frees a mutex and removes it from the
122  * uninitialized_mutex_list;
123  * does nothing if passed a #NULL pointer.
124  */
125 void
_dbus_mutex_free_at_location(DBusMutex ** location_p)126 _dbus_mutex_free_at_location (DBusMutex **location_p)
127 {
128   if (location_p)
129     {
130       if (thread_init_generation != _dbus_current_generation)
131         _dbus_list_remove (&uninitialized_mutex_list, location_p);
132 
133       _dbus_mutex_free (*location_p);
134     }
135 }
136 
137 /**
138  * Locks a mutex. Does nothing if passed a #NULL pointer.
139  * Locks may be recursive if threading implementation initialized
140  * recursive locks.
141  */
142 void
_dbus_mutex_lock(DBusMutex * mutex)143 _dbus_mutex_lock (DBusMutex *mutex)
144 {
145   if (mutex)
146     {
147       if (thread_functions.recursive_mutex_lock)
148         (* thread_functions.recursive_mutex_lock) (mutex);
149       else if (thread_functions.mutex_lock)
150         (* thread_functions.mutex_lock) (mutex);
151     }
152 }
153 
154 /**
155  * Unlocks a mutex. Does nothing if passed a #NULL pointer.
156  *
157  * @returns #TRUE on success
158  */
159 void
_dbus_mutex_unlock(DBusMutex * mutex)160 _dbus_mutex_unlock (DBusMutex *mutex)
161 {
162   if (mutex)
163     {
164       if (thread_functions.recursive_mutex_unlock)
165         (* thread_functions.recursive_mutex_unlock) (mutex);
166       else if (thread_functions.mutex_unlock)
167         (* thread_functions.mutex_unlock) (mutex);
168     }
169 }
170 
171 /**
172  * Creates a new condition variable using the function supplied
173  * to dbus_threads_init(), or creates a no-op condition variable
174  * if threads are not initialized. May return #NULL even if
175  * threads are initialized, indicating out-of-memory.
176  *
177  * @returns new mutex or #NULL
178  */
179 DBusCondVar *
_dbus_condvar_new(void)180 _dbus_condvar_new (void)
181 {
182   if (thread_functions.condvar_new)
183     return (* thread_functions.condvar_new) ();
184   else
185     return _DBUS_DUMMY_CONDVAR;
186 }
187 
188 
189 /**
190  * This does the same thing as _dbus_condvar_new.  It however
191  * gives another level of indirection by allocating a pointer
192  * to point to the condvar location.  This allows the threading
193  * module to swap out dummy condvars for real a real condvar so libraries
194  * can initialize threads even after the D-Bus API has been used.
195  *
196  * @returns the location of a new condvar or #NULL on OOM
197  */
198 
199 void
_dbus_condvar_new_at_location(DBusCondVar ** location_p)200 _dbus_condvar_new_at_location (DBusCondVar **location_p)
201 {
202   *location_p = _dbus_condvar_new();
203 
204   if (thread_init_generation != _dbus_current_generation && *location_p)
205     {
206       if (!_dbus_list_append (&uninitialized_condvar_list, location_p))
207         {
208           _dbus_condvar_free (*location_p);
209           *location_p = NULL;
210         }
211     }
212 }
213 
214 
215 /**
216  * Frees a conditional variable created with dbus_condvar_new(); does
217  * nothing if passed a #NULL pointer.
218  */
219 void
_dbus_condvar_free(DBusCondVar * cond)220 _dbus_condvar_free (DBusCondVar *cond)
221 {
222   if (cond && thread_functions.condvar_free)
223     (* thread_functions.condvar_free) (cond);
224 }
225 
226 /**
227  * Frees a conditional variable and removes it from the
228  * uninitialized_condvar_list;
229  * does nothing if passed a #NULL pointer.
230  */
231 void
_dbus_condvar_free_at_location(DBusCondVar ** location_p)232 _dbus_condvar_free_at_location (DBusCondVar **location_p)
233 {
234   if (location_p)
235     {
236       if (thread_init_generation != _dbus_current_generation)
237         _dbus_list_remove (&uninitialized_condvar_list, location_p);
238 
239       _dbus_condvar_free (*location_p);
240     }
241 }
242 
243 /**
244  * Atomically unlocks the mutex and waits for the conditions
245  * variable to be signalled. Locks the mutex again before
246  * returning.
247  * Does nothing if passed a #NULL pointer.
248  */
249 void
_dbus_condvar_wait(DBusCondVar * cond,DBusMutex * mutex)250 _dbus_condvar_wait (DBusCondVar *cond,
251                     DBusMutex   *mutex)
252 {
253   if (cond && mutex && thread_functions.condvar_wait)
254     (* thread_functions.condvar_wait) (cond, mutex);
255 }
256 
257 /**
258  * Atomically unlocks the mutex and waits for the conditions variable
259  * to be signalled, or for a timeout. Locks the mutex again before
260  * returning.  Does nothing if passed a #NULL pointer.  Return value
261  * is #FALSE if we timed out, #TRUE otherwise.
262  *
263  * @param cond the condition variable
264  * @param mutex the mutex
265  * @param timeout_milliseconds the maximum time to wait
266  * @returns #FALSE if the timeout occurred, #TRUE if not
267  */
268 dbus_bool_t
_dbus_condvar_wait_timeout(DBusCondVar * cond,DBusMutex * mutex,int timeout_milliseconds)269 _dbus_condvar_wait_timeout (DBusCondVar               *cond,
270                             DBusMutex                 *mutex,
271                             int                        timeout_milliseconds)
272 {
273   if (cond && mutex && thread_functions.condvar_wait)
274     return (* thread_functions.condvar_wait_timeout) (cond, mutex, timeout_milliseconds);
275   else
276     return TRUE;
277 }
278 
279 /**
280  * If there are threads waiting on the condition variable, wake
281  * up exactly one.
282  * Does nothing if passed a #NULL pointer.
283  */
284 void
_dbus_condvar_wake_one(DBusCondVar * cond)285 _dbus_condvar_wake_one (DBusCondVar *cond)
286 {
287   if (cond && thread_functions.condvar_wake_one)
288     (* thread_functions.condvar_wake_one) (cond);
289 }
290 
291 /**
292  * If there are threads waiting on the condition variable, wake
293  * up all of them.
294  * Does nothing if passed a #NULL pointer.
295  */
296 void
_dbus_condvar_wake_all(DBusCondVar * cond)297 _dbus_condvar_wake_all (DBusCondVar *cond)
298 {
299   if (cond && thread_functions.condvar_wake_all)
300     (* thread_functions.condvar_wake_all) (cond);
301 }
302 
303 static void
shutdown_global_locks(void * data)304 shutdown_global_locks (void *data)
305 {
306   DBusMutex ***locks = data;
307   int i;
308 
309   i = 0;
310   while (i < _DBUS_N_GLOBAL_LOCKS)
311     {
312       _dbus_mutex_free (*(locks[i]));
313       *(locks[i]) = NULL;
314       ++i;
315     }
316 
317   dbus_free (locks);
318 }
319 
320 static void
shutdown_uninitialized_locks(void * data)321 shutdown_uninitialized_locks (void *data)
322 {
323   _dbus_list_clear (&uninitialized_mutex_list);
324   _dbus_list_clear (&uninitialized_condvar_list);
325 }
326 
327 static dbus_bool_t
init_uninitialized_locks(void)328 init_uninitialized_locks (void)
329 {
330   DBusList *link;
331 
332   _dbus_assert (thread_init_generation != _dbus_current_generation);
333 
334   link = uninitialized_mutex_list;
335   while (link != NULL)
336     {
337       DBusMutex **mp;
338 
339       mp = (DBusMutex **)link->data;
340       _dbus_assert (*mp == _DBUS_DUMMY_MUTEX);
341 
342       *mp = _dbus_mutex_new ();
343       if (*mp == NULL)
344         goto fail_mutex;
345 
346       link = _dbus_list_get_next_link (&uninitialized_mutex_list, link);
347     }
348 
349   link = uninitialized_condvar_list;
350   while (link != NULL)
351     {
352       DBusCondVar **cp;
353 
354       cp = (DBusCondVar **)link->data;
355       _dbus_assert (*cp == _DBUS_DUMMY_CONDVAR);
356 
357       *cp = _dbus_condvar_new ();
358       if (*cp == NULL)
359         goto fail_condvar;
360 
361       link = _dbus_list_get_next_link (&uninitialized_condvar_list, link);
362     }
363 
364   _dbus_list_clear (&uninitialized_mutex_list);
365   _dbus_list_clear (&uninitialized_condvar_list);
366 
367   if (!_dbus_register_shutdown_func (shutdown_uninitialized_locks,
368                                      NULL))
369     goto fail_condvar;
370 
371   return TRUE;
372 
373  fail_condvar:
374   link = uninitialized_condvar_list;
375   while (link != NULL)
376     {
377       DBusCondVar **cp;
378 
379       cp = (DBusCondVar **)link->data;
380 
381       if (*cp != _DBUS_DUMMY_CONDVAR)
382         _dbus_condvar_free (*cp);
383       else
384         break;
385 
386       *cp = _DBUS_DUMMY_CONDVAR;
387 
388       link = _dbus_list_get_next_link (&uninitialized_condvar_list, link);
389     }
390 
391  fail_mutex:
392   link = uninitialized_mutex_list;
393   while (link != NULL)
394     {
395       DBusMutex **mp;
396 
397       mp = (DBusMutex **)link->data;
398 
399       if (*mp != _DBUS_DUMMY_MUTEX)
400         _dbus_mutex_free (*mp);
401       else
402         break;
403 
404       *mp = _DBUS_DUMMY_MUTEX;
405 
406       link = _dbus_list_get_next_link (&uninitialized_mutex_list, link);
407     }
408 
409   return FALSE;
410 }
411 
412 static dbus_bool_t
init_locks(void)413 init_locks (void)
414 {
415   int i;
416   DBusMutex ***dynamic_global_locks;
417 
418   DBusMutex **global_locks[] = {
419 #define LOCK_ADDR(name) (& _dbus_lock_##name)
420     LOCK_ADDR (win_fds),
421     LOCK_ADDR (sid_atom_cache),
422     LOCK_ADDR (list),
423     LOCK_ADDR (connection_slots),
424     LOCK_ADDR (pending_call_slots),
425     LOCK_ADDR (server_slots),
426     LOCK_ADDR (message_slots),
427     LOCK_ADDR (atomic),
428     LOCK_ADDR (bus),
429     LOCK_ADDR (bus_datas),
430     LOCK_ADDR (shutdown_funcs),
431     LOCK_ADDR (system_users),
432     LOCK_ADDR (message_cache),
433     LOCK_ADDR (shared_connections),
434     LOCK_ADDR (machine_uuid)
435 #undef LOCK_ADDR
436   };
437 
438   _dbus_assert (_DBUS_N_ELEMENTS (global_locks) ==
439                 _DBUS_N_GLOBAL_LOCKS);
440 
441   i = 0;
442 
443   dynamic_global_locks = dbus_new (DBusMutex**, _DBUS_N_GLOBAL_LOCKS);
444   if (dynamic_global_locks == NULL)
445     goto failed;
446 
447   while (i < _DBUS_N_ELEMENTS (global_locks))
448     {
449       *global_locks[i] = _dbus_mutex_new ();
450 
451       if (*global_locks[i] == NULL)
452         goto failed;
453 
454       dynamic_global_locks[i] = global_locks[i];
455 
456       ++i;
457     }
458 
459   if (!_dbus_register_shutdown_func (shutdown_global_locks,
460                                      dynamic_global_locks))
461     goto failed;
462 
463   if (!init_uninitialized_locks ())
464     goto failed;
465 
466   return TRUE;
467 
468  failed:
469   dbus_free (dynamic_global_locks);
470 
471   for (i = i - 1; i >= 0; i--)
472     {
473       _dbus_mutex_free (*global_locks[i]);
474       *global_locks[i] = NULL;
475     }
476   return FALSE;
477 }
478 
479 /** @} */ /* end of internals */
480 
481 /**
482  * @defgroup DBusThreads Thread functions
483  * @ingroup  DBus
484  * @brief dbus_threads_init() and dbus_threads_init_default()
485  *
486  * Functions and macros related to threads and thread locks.
487  *
488  * If threads are initialized, the D-Bus library has locks on all
489  * global data structures.  In addition, each #DBusConnection has a
490  * lock, so only one thread at a time can touch the connection.  (See
491  * @ref DBusConnection for more on connection locking.)
492  *
493  * Most other objects, however, do not have locks - they can only be
494  * used from a single thread at a time, unless you lock them yourself.
495  * For example, a #DBusMessage can't be modified from two threads
496  * at once.
497  *
498  * @{
499  */
500 
501 /**
502  *
503  * Initializes threads. If this function is not called, the D-Bus
504  * library will not lock any data structures.  If it is called, D-Bus
505  * will do locking, at some cost in efficiency. Note that this
506  * function must be called BEFORE the second thread is started.
507  *
508  * Almost always, you should use dbus_threads_init_default() instead.
509  * The raw dbus_threads_init() is only useful if you require a
510  * particular thread implementation for some reason.
511  *
512  * A possible reason to use dbus_threads_init() rather than
513  * dbus_threads_init_default() is to insert debugging checks or print
514  * statements.
515  *
516  * dbus_threads_init() may be called more than once.  The first one
517  * wins and subsequent calls are ignored. (Unless you use
518  * dbus_shutdown() to reset libdbus, which will let you re-init
519  * threads.)
520  *
521  * Either recursive or nonrecursive mutex functions must be specified,
522  * but not both. New code should provide only the recursive functions
523  * - specifying the nonrecursive ones is deprecated.
524  *
525  * Because this function effectively sets global state, all code
526  * running in a given application must agree on the thread
527  * implementation. Most code won't care which thread implementation is
528  * used, so there's no problem. However, usually libraries should not
529  * call dbus_threads_init() or dbus_threads_init_default(), instead
530  * leaving this policy choice to applications.
531  *
532  * The exception is for application frameworks (GLib, Qt, etc.)  and
533  * D-Bus bindings based on application frameworks. These frameworks
534  * define a cross-platform thread abstraction and can assume
535  * applications using the framework are OK with using that thread
536  * abstraction.
537  *
538  * However, even these app frameworks may find it easier to simply call
539  * dbus_threads_init_default(), and there's no reason they shouldn't.
540  *
541  * @param functions functions for using threads
542  * @returns #TRUE on success, #FALSE if no memory
543  */
544 dbus_bool_t
dbus_threads_init(const DBusThreadFunctions * functions)545 dbus_threads_init (const DBusThreadFunctions *functions)
546 {
547   dbus_bool_t mutex_set;
548   dbus_bool_t recursive_mutex_set;
549 
550   _dbus_assert (functions != NULL);
551 
552   /* these base functions are required. Future additions to
553    * DBusThreadFunctions may be optional.
554    */
555   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_NEW_MASK);
556   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_FREE_MASK);
557   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_MASK);
558   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_TIMEOUT_MASK);
559   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ONE_MASK);
560   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ALL_MASK);
561   _dbus_assert (functions->condvar_new != NULL);
562   _dbus_assert (functions->condvar_free != NULL);
563   _dbus_assert (functions->condvar_wait != NULL);
564   _dbus_assert (functions->condvar_wait_timeout != NULL);
565   _dbus_assert (functions->condvar_wake_one != NULL);
566   _dbus_assert (functions->condvar_wake_all != NULL);
567 
568   /* Either the mutex function set or recursive mutex set needs
569    * to be available but not both
570    */
571   mutex_set = (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_NEW_MASK) &&
572               (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_FREE_MASK) &&
573               (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_LOCK_MASK) &&
574               (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_UNLOCK_MASK) &&
575                functions->mutex_new &&
576                functions->mutex_free &&
577                functions->mutex_lock &&
578                functions->mutex_unlock;
579 
580   recursive_mutex_set =
581               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_NEW_MASK) &&
582               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK) &&
583               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK) &&
584               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK) &&
585                 functions->recursive_mutex_new &&
586                 functions->recursive_mutex_free &&
587                 functions->recursive_mutex_lock &&
588                 functions->recursive_mutex_unlock;
589 
590   if (!(mutex_set || recursive_mutex_set))
591     _dbus_assert_not_reached ("Either the nonrecusrive or recursive mutex "
592                               "functions sets should be passed into "
593                               "dbus_threads_init. Neither sets were passed.");
594 
595   if (mutex_set && recursive_mutex_set)
596     _dbus_assert_not_reached ("Either the nonrecusrive or recursive mutex "
597                               "functions sets should be passed into "
598                               "dbus_threads_init. Both sets were passed. "
599                               "You most likely just want to set the recursive "
600                               "mutex functions to avoid deadlocks in D-Bus.");
601 
602   /* Check that all bits in the mask actually are valid mask bits.
603    * ensures people won't write code that breaks when we add
604    * new bits.
605    */
606   _dbus_assert ((functions->mask & ~DBUS_THREAD_FUNCTIONS_ALL_MASK) == 0);
607 
608   if (thread_init_generation != _dbus_current_generation)
609     thread_functions.mask = 0; /* allow re-init in new generation */
610 
611   /* Silently allow multiple init
612    * First init wins and D-Bus will always use its threading system
613    */
614   if (thread_functions.mask != 0)
615     return TRUE;
616 
617   thread_functions.mutex_new = functions->mutex_new;
618   thread_functions.mutex_free = functions->mutex_free;
619   thread_functions.mutex_lock = functions->mutex_lock;
620   thread_functions.mutex_unlock = functions->mutex_unlock;
621 
622   thread_functions.condvar_new = functions->condvar_new;
623   thread_functions.condvar_free = functions->condvar_free;
624   thread_functions.condvar_wait = functions->condvar_wait;
625   thread_functions.condvar_wait_timeout = functions->condvar_wait_timeout;
626   thread_functions.condvar_wake_one = functions->condvar_wake_one;
627   thread_functions.condvar_wake_all = functions->condvar_wake_all;
628 
629   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_NEW_MASK)
630     thread_functions.recursive_mutex_new = functions->recursive_mutex_new;
631 
632   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK)
633     thread_functions.recursive_mutex_free = functions->recursive_mutex_free;
634 
635   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK)
636     thread_functions.recursive_mutex_lock = functions->recursive_mutex_lock;
637 
638   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK)
639     thread_functions.recursive_mutex_unlock = functions->recursive_mutex_unlock;
640 
641   thread_functions.mask = functions->mask;
642 
643   if (!init_locks ())
644     return FALSE;
645 
646   thread_init_generation = _dbus_current_generation;
647 
648   return TRUE;
649 }
650 
651 
652 
653 /* Default thread implemenation */
654 
655 /**
656  *
657  * Calls dbus_threads_init() with a default set of
658  * #DBusThreadFunctions appropriate for the platform.
659  *
660  * Most applications should use this rather than dbus_threads_init().
661  *
662  * It's safe to call dbus_threads_init_default() as many times as you
663  * want, but only the first time will have an effect.
664  *
665  * dbus_shutdown() reverses the effects of this function when it
666  * resets all global state in libdbus.
667  *
668  * @returns #TRUE on success, #FALSE if not enough memory
669  */
670 dbus_bool_t
dbus_threads_init_default(void)671 dbus_threads_init_default (void)
672 {
673   return _dbus_threads_init_platform_specific ();
674 }
675 
676 
677 /** @} */
678 
679 #ifdef DBUS_BUILD_TESTS
680 /** Fake mutex used for debugging */
681 typedef struct DBusFakeMutex DBusFakeMutex;
682 /** Fake mutex used for debugging */
683 struct DBusFakeMutex
684 {
685   dbus_bool_t locked; /**< Mutex is "locked" */
686 };
687 
688 static DBusMutex *  dbus_fake_mutex_new            (void);
689 static void         dbus_fake_mutex_free           (DBusMutex   *mutex);
690 static dbus_bool_t  dbus_fake_mutex_lock           (DBusMutex   *mutex);
691 static dbus_bool_t  dbus_fake_mutex_unlock         (DBusMutex   *mutex);
692 static DBusCondVar* dbus_fake_condvar_new          (void);
693 static void         dbus_fake_condvar_free         (DBusCondVar *cond);
694 static void         dbus_fake_condvar_wait         (DBusCondVar *cond,
695                                                     DBusMutex   *mutex);
696 static dbus_bool_t  dbus_fake_condvar_wait_timeout (DBusCondVar *cond,
697                                                     DBusMutex   *mutex,
698                                                     int          timeout_msec);
699 static void         dbus_fake_condvar_wake_one     (DBusCondVar *cond);
700 static void         dbus_fake_condvar_wake_all     (DBusCondVar *cond);
701 
702 
703 static const DBusThreadFunctions fake_functions =
704 {
705   DBUS_THREAD_FUNCTIONS_MUTEX_NEW_MASK |
706   DBUS_THREAD_FUNCTIONS_MUTEX_FREE_MASK |
707   DBUS_THREAD_FUNCTIONS_MUTEX_LOCK_MASK |
708   DBUS_THREAD_FUNCTIONS_MUTEX_UNLOCK_MASK |
709   DBUS_THREAD_FUNCTIONS_CONDVAR_NEW_MASK |
710   DBUS_THREAD_FUNCTIONS_CONDVAR_FREE_MASK |
711   DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_MASK |
712   DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_TIMEOUT_MASK |
713   DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ONE_MASK|
714   DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ALL_MASK,
715   dbus_fake_mutex_new,
716   dbus_fake_mutex_free,
717   dbus_fake_mutex_lock,
718   dbus_fake_mutex_unlock,
719   dbus_fake_condvar_new,
720   dbus_fake_condvar_free,
721   dbus_fake_condvar_wait,
722   dbus_fake_condvar_wait_timeout,
723   dbus_fake_condvar_wake_one,
724   dbus_fake_condvar_wake_all
725 };
726 
727 static DBusMutex *
dbus_fake_mutex_new(void)728 dbus_fake_mutex_new (void)
729 {
730   DBusFakeMutex *mutex;
731 
732   mutex = dbus_new0 (DBusFakeMutex, 1);
733 
734   return (DBusMutex *)mutex;
735 }
736 
737 static void
dbus_fake_mutex_free(DBusMutex * mutex)738 dbus_fake_mutex_free (DBusMutex *mutex)
739 {
740   DBusFakeMutex *fake = (DBusFakeMutex*) mutex;
741 
742   _dbus_assert (!fake->locked);
743 
744   dbus_free (fake);
745 }
746 
747 static dbus_bool_t
dbus_fake_mutex_lock(DBusMutex * mutex)748 dbus_fake_mutex_lock (DBusMutex *mutex)
749 {
750   DBusFakeMutex *fake = (DBusFakeMutex*) mutex;
751 
752   _dbus_assert (!fake->locked);
753 
754   fake->locked = TRUE;
755 
756   return TRUE;
757 }
758 
759 static dbus_bool_t
dbus_fake_mutex_unlock(DBusMutex * mutex)760 dbus_fake_mutex_unlock (DBusMutex *mutex)
761 {
762   DBusFakeMutex *fake = (DBusFakeMutex*) mutex;
763 
764   _dbus_assert (fake->locked);
765 
766   fake->locked = FALSE;
767 
768   return TRUE;
769 }
770 
771 static DBusCondVar*
dbus_fake_condvar_new(void)772 dbus_fake_condvar_new (void)
773 {
774   return (DBusCondVar*) _dbus_strdup ("FakeCondvar");
775 }
776 
777 static void
dbus_fake_condvar_free(DBusCondVar * cond)778 dbus_fake_condvar_free (DBusCondVar *cond)
779 {
780   dbus_free (cond);
781 }
782 
783 static void
dbus_fake_condvar_wait(DBusCondVar * cond,DBusMutex * mutex)784 dbus_fake_condvar_wait (DBusCondVar *cond,
785                         DBusMutex   *mutex)
786 {
787 
788 }
789 
790 static dbus_bool_t
dbus_fake_condvar_wait_timeout(DBusCondVar * cond,DBusMutex * mutex,int timeout_msec)791 dbus_fake_condvar_wait_timeout (DBusCondVar *cond,
792                                 DBusMutex   *mutex,
793                                 int         timeout_msec)
794 {
795   return TRUE;
796 }
797 
798 static void
dbus_fake_condvar_wake_one(DBusCondVar * cond)799 dbus_fake_condvar_wake_one (DBusCondVar *cond)
800 {
801 
802 }
803 
804 static void
dbus_fake_condvar_wake_all(DBusCondVar * cond)805 dbus_fake_condvar_wake_all (DBusCondVar *cond)
806 {
807 
808 }
809 
810 dbus_bool_t
_dbus_threads_init_debug(void)811 _dbus_threads_init_debug (void)
812 {
813   return dbus_threads_init (&fake_functions);
814 }
815 
816 #endif /* DBUS_BUILD_TESTS */
817