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1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
21  *
22  */
23 #include <config.h>
24 #include "dbus-threads.h"
25 #include "dbus-internals.h"
26 #include "dbus-threads-internal.h"
27 #include "dbus-list.h"
28 
29 static DBusThreadFunctions thread_functions =
30 {
31   0,
32   NULL, NULL, NULL, NULL, NULL,
33   NULL, NULL, NULL, NULL, NULL,
34   NULL, NULL, NULL, NULL,
35 
36   NULL, NULL, NULL, NULL
37 };
38 
39 static int thread_init_generation = 0;
40 
41 static DBusList *uninitialized_mutex_list = NULL;
42 static DBusList *uninitialized_condvar_list = NULL;
43 
44 /** This is used for the no-op default mutex pointer, just to be distinct from #NULL */
45 #define _DBUS_DUMMY_MUTEX ((DBusMutex*)0xABCDEF)
46 
47 /** This is used for the no-op default mutex pointer, just to be distinct from #NULL */
48 #define _DBUS_DUMMY_CONDVAR ((DBusCondVar*)0xABCDEF2)
49 
50 /**
51  * @defgroup DBusThreadsInternals Thread functions
52  * @ingroup  DBusInternals
53  * @brief _dbus_mutex_lock(), etc.
54  *
55  * Functions and macros related to threads and thread locks.
56  *
57  * @{
58  */
59 
60 /**
61  * Creates a new mutex using the function supplied to dbus_threads_init(),
62  * or creates a no-op mutex if threads are not initialized.
63  * May return #NULL even if threads are initialized, indicating
64  * out-of-memory.
65  *
66  * @returns new mutex or #NULL
67  */
68 DBusMutex*
_dbus_mutex_new(void)69 _dbus_mutex_new (void)
70 {
71   if (thread_functions.recursive_mutex_new)
72     return (* thread_functions.recursive_mutex_new) ();
73   else if (thread_functions.mutex_new)
74     return (* thread_functions.mutex_new) ();
75   else
76     return _DBUS_DUMMY_MUTEX;
77 }
78 
79 /**
80  * This does the same thing as _dbus_mutex_new.  It however
81  * gives another level of indirection by allocating a pointer
82  * to point to the mutex location.  This allows the threading
83  * module to swap out dummy mutexes for real a real mutex so libraries
84  * can initialize threads even after the D-Bus API has been used.
85  *
86  * @param location_p the location of the new mutex, can return #NULL on OOM
87  */
88 void
_dbus_mutex_new_at_location(DBusMutex ** location_p)89 _dbus_mutex_new_at_location (DBusMutex **location_p)
90 {
91   _dbus_assert (location_p != NULL);
92 
93   *location_p = _dbus_mutex_new();
94 
95   if (thread_init_generation != _dbus_current_generation && *location_p)
96     {
97       if (!_dbus_list_append (&uninitialized_mutex_list, location_p))
98         {
99 	  _dbus_mutex_free (*location_p);
100 	  *location_p = NULL;
101 	}
102     }
103 }
104 
105 /**
106  * Frees a mutex created with dbus_mutex_new(); does
107  * nothing if passed a #NULL pointer.
108  */
109 void
_dbus_mutex_free(DBusMutex * mutex)110 _dbus_mutex_free (DBusMutex *mutex)
111 {
112   if (mutex)
113     {
114       if (mutex && thread_functions.recursive_mutex_free)
115         (* thread_functions.recursive_mutex_free) (mutex);
116       else if (mutex && thread_functions.mutex_free)
117         (* thread_functions.mutex_free) (mutex);
118     }
119 }
120 
121 /**
122  * Frees a mutex and removes it from the
123  * uninitialized_mutex_list;
124  * does nothing if passed a #NULL pointer.
125  */
126 void
_dbus_mutex_free_at_location(DBusMutex ** location_p)127 _dbus_mutex_free_at_location (DBusMutex **location_p)
128 {
129   if (location_p)
130     {
131       if (thread_init_generation != _dbus_current_generation)
132         _dbus_list_remove (&uninitialized_mutex_list, location_p);
133 
134       _dbus_mutex_free (*location_p);
135     }
136 }
137 
138 /**
139  * Locks a mutex. Does nothing if passed a #NULL pointer.
140  * Locks may be recursive if threading implementation initialized
141  * recursive locks.
142  */
143 void
_dbus_mutex_lock(DBusMutex * mutex)144 _dbus_mutex_lock (DBusMutex *mutex)
145 {
146   if (mutex)
147     {
148       if (thread_functions.recursive_mutex_lock)
149         (* thread_functions.recursive_mutex_lock) (mutex);
150       else if (thread_functions.mutex_lock)
151         (* thread_functions.mutex_lock) (mutex);
152     }
153 }
154 
155 /**
156  * Unlocks a mutex. Does nothing if passed a #NULL pointer.
157  *
158  * @returns #TRUE on success
159  */
160 void
_dbus_mutex_unlock(DBusMutex * mutex)161 _dbus_mutex_unlock (DBusMutex *mutex)
162 {
163   if (mutex)
164     {
165       if (thread_functions.recursive_mutex_unlock)
166         (* thread_functions.recursive_mutex_unlock) (mutex);
167       else if (thread_functions.mutex_unlock)
168         (* thread_functions.mutex_unlock) (mutex);
169     }
170 }
171 
172 /**
173  * Creates a new condition variable using the function supplied
174  * to dbus_threads_init(), or creates a no-op condition variable
175  * if threads are not initialized. May return #NULL even if
176  * threads are initialized, indicating out-of-memory.
177  *
178  * @returns new mutex or #NULL
179  */
180 DBusCondVar *
_dbus_condvar_new(void)181 _dbus_condvar_new (void)
182 {
183   if (thread_functions.condvar_new)
184     return (* thread_functions.condvar_new) ();
185   else
186     return _DBUS_DUMMY_CONDVAR;
187 }
188 
189 
190 /**
191  * This does the same thing as _dbus_condvar_new.  It however
192  * gives another level of indirection by allocating a pointer
193  * to point to the condvar location.  This allows the threading
194  * module to swap out dummy condvars for real a real condvar so libraries
195  * can initialize threads even after the D-Bus API has been used.
196  *
197  * @returns the location of a new condvar or #NULL on OOM
198  */
199 
200 void
_dbus_condvar_new_at_location(DBusCondVar ** location_p)201 _dbus_condvar_new_at_location (DBusCondVar **location_p)
202 {
203   *location_p = _dbus_condvar_new();
204 
205   if (thread_init_generation != _dbus_current_generation && *location_p)
206     {
207       if (!_dbus_list_append (&uninitialized_condvar_list, location_p))
208         {
209           _dbus_condvar_free (*location_p);
210           *location_p = NULL;
211         }
212     }
213 }
214 
215 
216 /**
217  * Frees a conditional variable created with dbus_condvar_new(); does
218  * nothing if passed a #NULL pointer.
219  */
220 void
_dbus_condvar_free(DBusCondVar * cond)221 _dbus_condvar_free (DBusCondVar *cond)
222 {
223   if (cond && thread_functions.condvar_free)
224     (* thread_functions.condvar_free) (cond);
225 }
226 
227 /**
228  * Frees a conditional variable and removes it from the
229  * uninitialized_condvar_list;
230  * does nothing if passed a #NULL pointer.
231  */
232 void
_dbus_condvar_free_at_location(DBusCondVar ** location_p)233 _dbus_condvar_free_at_location (DBusCondVar **location_p)
234 {
235   if (location_p)
236     {
237       if (thread_init_generation != _dbus_current_generation)
238         _dbus_list_remove (&uninitialized_condvar_list, location_p);
239 
240       _dbus_condvar_free (*location_p);
241     }
242 }
243 
244 /**
245  * Atomically unlocks the mutex and waits for the conditions
246  * variable to be signalled. Locks the mutex again before
247  * returning.
248  * Does nothing if passed a #NULL pointer.
249  */
250 void
_dbus_condvar_wait(DBusCondVar * cond,DBusMutex * mutex)251 _dbus_condvar_wait (DBusCondVar *cond,
252                     DBusMutex   *mutex)
253 {
254   if (cond && mutex && thread_functions.condvar_wait)
255     (* thread_functions.condvar_wait) (cond, mutex);
256 }
257 
258 /**
259  * Atomically unlocks the mutex and waits for the conditions variable
260  * to be signalled, or for a timeout. Locks the mutex again before
261  * returning.  Does nothing if passed a #NULL pointer.  Return value
262  * is #FALSE if we timed out, #TRUE otherwise.
263  *
264  * @param cond the condition variable
265  * @param mutex the mutex
266  * @param timeout_milliseconds the maximum time to wait
267  * @returns #FALSE if the timeout occurred, #TRUE if not
268  */
269 dbus_bool_t
_dbus_condvar_wait_timeout(DBusCondVar * cond,DBusMutex * mutex,int timeout_milliseconds)270 _dbus_condvar_wait_timeout (DBusCondVar               *cond,
271                             DBusMutex                 *mutex,
272                             int                        timeout_milliseconds)
273 {
274   if (cond && mutex && thread_functions.condvar_wait)
275     return (* thread_functions.condvar_wait_timeout) (cond, mutex, timeout_milliseconds);
276   else
277     return TRUE;
278 }
279 
280 /**
281  * If there are threads waiting on the condition variable, wake
282  * up exactly one.
283  * Does nothing if passed a #NULL pointer.
284  */
285 void
_dbus_condvar_wake_one(DBusCondVar * cond)286 _dbus_condvar_wake_one (DBusCondVar *cond)
287 {
288   if (cond && thread_functions.condvar_wake_one)
289     (* thread_functions.condvar_wake_one) (cond);
290 }
291 
292 /**
293  * If there are threads waiting on the condition variable, wake
294  * up all of them.
295  * Does nothing if passed a #NULL pointer.
296  */
297 void
_dbus_condvar_wake_all(DBusCondVar * cond)298 _dbus_condvar_wake_all (DBusCondVar *cond)
299 {
300   if (cond && thread_functions.condvar_wake_all)
301     (* thread_functions.condvar_wake_all) (cond);
302 }
303 
304 static void
shutdown_global_locks(void * data)305 shutdown_global_locks (void *data)
306 {
307   DBusMutex ***locks = data;
308   int i;
309 
310   i = 0;
311   while (i < _DBUS_N_GLOBAL_LOCKS)
312     {
313       _dbus_mutex_free (*(locks[i]));
314       *(locks[i]) = NULL;
315       ++i;
316     }
317 
318   dbus_free (locks);
319 }
320 
321 static void
shutdown_uninitialized_locks(void * data)322 shutdown_uninitialized_locks (void *data)
323 {
324   _dbus_list_clear (&uninitialized_mutex_list);
325   _dbus_list_clear (&uninitialized_condvar_list);
326 }
327 
328 static dbus_bool_t
init_uninitialized_locks(void)329 init_uninitialized_locks (void)
330 {
331   DBusList *link;
332 
333   _dbus_assert (thread_init_generation != _dbus_current_generation);
334 
335   link = uninitialized_mutex_list;
336   while (link != NULL)
337     {
338       DBusMutex **mp;
339 
340       mp = (DBusMutex **)link->data;
341       _dbus_assert (*mp == _DBUS_DUMMY_MUTEX);
342 
343       *mp = _dbus_mutex_new ();
344       if (*mp == NULL)
345         goto fail_mutex;
346 
347       link = _dbus_list_get_next_link (&uninitialized_mutex_list, link);
348     }
349 
350   link = uninitialized_condvar_list;
351   while (link != NULL)
352     {
353       DBusCondVar **cp;
354 
355       cp = (DBusCondVar **)link->data;
356       _dbus_assert (*cp == _DBUS_DUMMY_CONDVAR);
357 
358       *cp = _dbus_condvar_new ();
359       if (*cp == NULL)
360         goto fail_condvar;
361 
362       link = _dbus_list_get_next_link (&uninitialized_condvar_list, link);
363     }
364 
365   _dbus_list_clear (&uninitialized_mutex_list);
366   _dbus_list_clear (&uninitialized_condvar_list);
367 
368   if (!_dbus_register_shutdown_func (shutdown_uninitialized_locks,
369                                      NULL))
370     goto fail_condvar;
371 
372   return TRUE;
373 
374  fail_condvar:
375   link = uninitialized_condvar_list;
376   while (link != NULL)
377     {
378       DBusCondVar **cp;
379 
380       cp = (DBusCondVar **)link->data;
381 
382       if (*cp != _DBUS_DUMMY_CONDVAR)
383         _dbus_condvar_free (*cp);
384       else
385         break;
386 
387       *cp = _DBUS_DUMMY_CONDVAR;
388 
389       link = _dbus_list_get_next_link (&uninitialized_condvar_list, link);
390     }
391 
392  fail_mutex:
393   link = uninitialized_mutex_list;
394   while (link != NULL)
395     {
396       DBusMutex **mp;
397 
398       mp = (DBusMutex **)link->data;
399 
400       if (*mp != _DBUS_DUMMY_MUTEX)
401         _dbus_mutex_free (*mp);
402       else
403         break;
404 
405       *mp = _DBUS_DUMMY_MUTEX;
406 
407       link = _dbus_list_get_next_link (&uninitialized_mutex_list, link);
408     }
409 
410   return FALSE;
411 }
412 
413 static dbus_bool_t
init_locks(void)414 init_locks (void)
415 {
416   int i;
417   DBusMutex ***dynamic_global_locks;
418 
419   DBusMutex **global_locks[] = {
420 #define LOCK_ADDR(name) (& _dbus_lock_##name)
421     LOCK_ADDR (win_fds),
422     LOCK_ADDR (sid_atom_cache),
423     LOCK_ADDR (list),
424     LOCK_ADDR (connection_slots),
425     LOCK_ADDR (pending_call_slots),
426     LOCK_ADDR (server_slots),
427     LOCK_ADDR (message_slots),
428 #if !DBUS_USE_SYNC
429     LOCK_ADDR (atomic),
430 #endif
431     LOCK_ADDR (bus),
432     LOCK_ADDR (bus_datas),
433     LOCK_ADDR (shutdown_funcs),
434     LOCK_ADDR (system_users),
435     LOCK_ADDR (message_cache),
436     LOCK_ADDR (shared_connections),
437     LOCK_ADDR (machine_uuid)
438 #undef LOCK_ADDR
439   };
440 
441   _dbus_assert (_DBUS_N_ELEMENTS (global_locks) ==
442                 _DBUS_N_GLOBAL_LOCKS);
443 
444   i = 0;
445 
446   dynamic_global_locks = dbus_new (DBusMutex**, _DBUS_N_GLOBAL_LOCKS);
447   if (dynamic_global_locks == NULL)
448     goto failed;
449 
450   while (i < _DBUS_N_ELEMENTS (global_locks))
451     {
452       *global_locks[i] = _dbus_mutex_new ();
453 
454       if (*global_locks[i] == NULL)
455         goto failed;
456 
457       dynamic_global_locks[i] = global_locks[i];
458 
459       ++i;
460     }
461 
462   if (!_dbus_register_shutdown_func (shutdown_global_locks,
463                                      dynamic_global_locks))
464     goto failed;
465 
466   if (!init_uninitialized_locks ())
467     goto failed;
468 
469   return TRUE;
470 
471  failed:
472   dbus_free (dynamic_global_locks);
473 
474   for (i = i - 1; i >= 0; i--)
475     {
476       _dbus_mutex_free (*global_locks[i]);
477       *global_locks[i] = NULL;
478     }
479   return FALSE;
480 }
481 
482 /** @} */ /* end of internals */
483 
484 /**
485  * @defgroup DBusThreads Thread functions
486  * @ingroup  DBus
487  * @brief dbus_threads_init() and dbus_threads_init_default()
488  *
489  * Functions and macros related to threads and thread locks.
490  *
491  * If threads are initialized, the D-Bus library has locks on all
492  * global data structures.  In addition, each #DBusConnection has a
493  * lock, so only one thread at a time can touch the connection.  (See
494  * @ref DBusConnection for more on connection locking.)
495  *
496  * Most other objects, however, do not have locks - they can only be
497  * used from a single thread at a time, unless you lock them yourself.
498  * For example, a #DBusMessage can't be modified from two threads
499  * at once.
500  *
501  * @{
502  */
503 
504 /**
505  *
506  * Initializes threads. If this function is not called, the D-Bus
507  * library will not lock any data structures.  If it is called, D-Bus
508  * will do locking, at some cost in efficiency. Note that this
509  * function must be called BEFORE the second thread is started.
510  *
511  * Almost always, you should use dbus_threads_init_default() instead.
512  * The raw dbus_threads_init() is only useful if you require a
513  * particular thread implementation for some reason.
514  *
515  * A possible reason to use dbus_threads_init() rather than
516  * dbus_threads_init_default() is to insert debugging checks or print
517  * statements.
518  *
519  * dbus_threads_init() may be called more than once.  The first one
520  * wins and subsequent calls are ignored. (Unless you use
521  * dbus_shutdown() to reset libdbus, which will let you re-init
522  * threads.)
523  *
524  * Either recursive or nonrecursive mutex functions must be specified,
525  * but not both. New code should provide only the recursive functions
526  * - specifying the nonrecursive ones is deprecated.
527  *
528  * Because this function effectively sets global state, all code
529  * running in a given application must agree on the thread
530  * implementation. Most code won't care which thread implementation is
531  * used, so there's no problem. However, usually libraries should not
532  * call dbus_threads_init() or dbus_threads_init_default(), instead
533  * leaving this policy choice to applications.
534  *
535  * The exception is for application frameworks (GLib, Qt, etc.)  and
536  * D-Bus bindings based on application frameworks. These frameworks
537  * define a cross-platform thread abstraction and can assume
538  * applications using the framework are OK with using that thread
539  * abstraction.
540  *
541  * However, even these app frameworks may find it easier to simply call
542  * dbus_threads_init_default(), and there's no reason they shouldn't.
543  *
544  * @param functions functions for using threads
545  * @returns #TRUE on success, #FALSE if no memory
546  */
547 dbus_bool_t
dbus_threads_init(const DBusThreadFunctions * functions)548 dbus_threads_init (const DBusThreadFunctions *functions)
549 {
550   dbus_bool_t mutex_set;
551   dbus_bool_t recursive_mutex_set;
552 
553   _dbus_assert (functions != NULL);
554 
555   /* these base functions are required. Future additions to
556    * DBusThreadFunctions may be optional.
557    */
558   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_NEW_MASK);
559   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_FREE_MASK);
560   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_MASK);
561   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_TIMEOUT_MASK);
562   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ONE_MASK);
563   _dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ALL_MASK);
564   _dbus_assert (functions->condvar_new != NULL);
565   _dbus_assert (functions->condvar_free != NULL);
566   _dbus_assert (functions->condvar_wait != NULL);
567   _dbus_assert (functions->condvar_wait_timeout != NULL);
568   _dbus_assert (functions->condvar_wake_one != NULL);
569   _dbus_assert (functions->condvar_wake_all != NULL);
570 
571   /* Either the mutex function set or recursive mutex set needs
572    * to be available but not both
573    */
574   mutex_set = (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_NEW_MASK) &&
575               (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_FREE_MASK) &&
576               (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_LOCK_MASK) &&
577               (functions->mask & DBUS_THREAD_FUNCTIONS_MUTEX_UNLOCK_MASK) &&
578                functions->mutex_new &&
579                functions->mutex_free &&
580                functions->mutex_lock &&
581                functions->mutex_unlock;
582 
583   recursive_mutex_set =
584               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_NEW_MASK) &&
585               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK) &&
586               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK) &&
587               (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK) &&
588                 functions->recursive_mutex_new &&
589                 functions->recursive_mutex_free &&
590                 functions->recursive_mutex_lock &&
591                 functions->recursive_mutex_unlock;
592 
593   if (!(mutex_set || recursive_mutex_set))
594     _dbus_assert_not_reached ("Either the nonrecusrive or recursive mutex "
595                               "functions sets should be passed into "
596                               "dbus_threads_init. Neither sets were passed.");
597 
598   if (mutex_set && recursive_mutex_set)
599     _dbus_assert_not_reached ("Either the nonrecusrive or recursive mutex "
600                               "functions sets should be passed into "
601                               "dbus_threads_init. Both sets were passed. "
602                               "You most likely just want to set the recursive "
603                               "mutex functions to avoid deadlocks in D-Bus.");
604 
605   /* Check that all bits in the mask actually are valid mask bits.
606    * ensures people won't write code that breaks when we add
607    * new bits.
608    */
609   _dbus_assert ((functions->mask & ~DBUS_THREAD_FUNCTIONS_ALL_MASK) == 0);
610 
611   if (thread_init_generation != _dbus_current_generation)
612     thread_functions.mask = 0; /* allow re-init in new generation */
613 
614   /* Silently allow multiple init
615    * First init wins and D-Bus will always use its threading system
616    */
617   if (thread_functions.mask != 0)
618     return TRUE;
619 
620   thread_functions.mutex_new = functions->mutex_new;
621   thread_functions.mutex_free = functions->mutex_free;
622   thread_functions.mutex_lock = functions->mutex_lock;
623   thread_functions.mutex_unlock = functions->mutex_unlock;
624 
625   thread_functions.condvar_new = functions->condvar_new;
626   thread_functions.condvar_free = functions->condvar_free;
627   thread_functions.condvar_wait = functions->condvar_wait;
628   thread_functions.condvar_wait_timeout = functions->condvar_wait_timeout;
629   thread_functions.condvar_wake_one = functions->condvar_wake_one;
630   thread_functions.condvar_wake_all = functions->condvar_wake_all;
631 
632   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_NEW_MASK)
633     thread_functions.recursive_mutex_new = functions->recursive_mutex_new;
634 
635   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK)
636     thread_functions.recursive_mutex_free = functions->recursive_mutex_free;
637 
638   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK)
639     thread_functions.recursive_mutex_lock = functions->recursive_mutex_lock;
640 
641   if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK)
642     thread_functions.recursive_mutex_unlock = functions->recursive_mutex_unlock;
643 
644   thread_functions.mask = functions->mask;
645 
646   if (!init_locks ())
647     return FALSE;
648 
649   thread_init_generation = _dbus_current_generation;
650 
651   return TRUE;
652 }
653 
654 
655 
656 /* Default thread implemenation */
657 
658 /**
659  *
660  * Calls dbus_threads_init() with a default set of
661  * #DBusThreadFunctions appropriate for the platform.
662  *
663  * Most applications should use this rather than dbus_threads_init().
664  *
665  * It's safe to call dbus_threads_init_default() as many times as you
666  * want, but only the first time will have an effect.
667  *
668  * dbus_shutdown() reverses the effects of this function when it
669  * resets all global state in libdbus.
670  *
671  * @returns #TRUE on success, #FALSE if not enough memory
672  */
673 dbus_bool_t
dbus_threads_init_default(void)674 dbus_threads_init_default (void)
675 {
676   return _dbus_threads_init_platform_specific ();
677 }
678 
679 
680 /** @} */
681 
682 #ifdef DBUS_BUILD_TESTS
683 /** Fake mutex used for debugging */
684 typedef struct DBusFakeMutex DBusFakeMutex;
685 /** Fake mutex used for debugging */
686 struct DBusFakeMutex
687 {
688   dbus_bool_t locked; /**< Mutex is "locked" */
689 };
690 
691 static DBusMutex *  dbus_fake_mutex_new            (void);
692 static void         dbus_fake_mutex_free           (DBusMutex   *mutex);
693 static dbus_bool_t  dbus_fake_mutex_lock           (DBusMutex   *mutex);
694 static dbus_bool_t  dbus_fake_mutex_unlock         (DBusMutex   *mutex);
695 static DBusCondVar* dbus_fake_condvar_new          (void);
696 static void         dbus_fake_condvar_free         (DBusCondVar *cond);
697 static void         dbus_fake_condvar_wait         (DBusCondVar *cond,
698                                                     DBusMutex   *mutex);
699 static dbus_bool_t  dbus_fake_condvar_wait_timeout (DBusCondVar *cond,
700                                                     DBusMutex   *mutex,
701                                                     int          timeout_msec);
702 static void         dbus_fake_condvar_wake_one     (DBusCondVar *cond);
703 static void         dbus_fake_condvar_wake_all     (DBusCondVar *cond);
704 
705 
706 static const DBusThreadFunctions fake_functions =
707 {
708   DBUS_THREAD_FUNCTIONS_MUTEX_NEW_MASK |
709   DBUS_THREAD_FUNCTIONS_MUTEX_FREE_MASK |
710   DBUS_THREAD_FUNCTIONS_MUTEX_LOCK_MASK |
711   DBUS_THREAD_FUNCTIONS_MUTEX_UNLOCK_MASK |
712   DBUS_THREAD_FUNCTIONS_CONDVAR_NEW_MASK |
713   DBUS_THREAD_FUNCTIONS_CONDVAR_FREE_MASK |
714   DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_MASK |
715   DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_TIMEOUT_MASK |
716   DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ONE_MASK|
717   DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ALL_MASK,
718   dbus_fake_mutex_new,
719   dbus_fake_mutex_free,
720   dbus_fake_mutex_lock,
721   dbus_fake_mutex_unlock,
722   dbus_fake_condvar_new,
723   dbus_fake_condvar_free,
724   dbus_fake_condvar_wait,
725   dbus_fake_condvar_wait_timeout,
726   dbus_fake_condvar_wake_one,
727   dbus_fake_condvar_wake_all
728 };
729 
730 static DBusMutex *
dbus_fake_mutex_new(void)731 dbus_fake_mutex_new (void)
732 {
733   DBusFakeMutex *mutex;
734 
735   mutex = dbus_new0 (DBusFakeMutex, 1);
736 
737   return (DBusMutex *)mutex;
738 }
739 
740 static void
dbus_fake_mutex_free(DBusMutex * mutex)741 dbus_fake_mutex_free (DBusMutex *mutex)
742 {
743   DBusFakeMutex *fake = (DBusFakeMutex*) mutex;
744 
745   _dbus_assert (!fake->locked);
746 
747   dbus_free (fake);
748 }
749 
750 static dbus_bool_t
dbus_fake_mutex_lock(DBusMutex * mutex)751 dbus_fake_mutex_lock (DBusMutex *mutex)
752 {
753   DBusFakeMutex *fake = (DBusFakeMutex*) mutex;
754 
755   _dbus_assert (!fake->locked);
756 
757   fake->locked = TRUE;
758 
759   return TRUE;
760 }
761 
762 static dbus_bool_t
dbus_fake_mutex_unlock(DBusMutex * mutex)763 dbus_fake_mutex_unlock (DBusMutex *mutex)
764 {
765   DBusFakeMutex *fake = (DBusFakeMutex*) mutex;
766 
767   _dbus_assert (fake->locked);
768 
769   fake->locked = FALSE;
770 
771   return TRUE;
772 }
773 
774 static DBusCondVar*
dbus_fake_condvar_new(void)775 dbus_fake_condvar_new (void)
776 {
777   return (DBusCondVar*) _dbus_strdup ("FakeCondvar");
778 }
779 
780 static void
dbus_fake_condvar_free(DBusCondVar * cond)781 dbus_fake_condvar_free (DBusCondVar *cond)
782 {
783   dbus_free (cond);
784 }
785 
786 static void
dbus_fake_condvar_wait(DBusCondVar * cond,DBusMutex * mutex)787 dbus_fake_condvar_wait (DBusCondVar *cond,
788                         DBusMutex   *mutex)
789 {
790 
791 }
792 
793 static dbus_bool_t
dbus_fake_condvar_wait_timeout(DBusCondVar * cond,DBusMutex * mutex,int timeout_msec)794 dbus_fake_condvar_wait_timeout (DBusCondVar *cond,
795                                 DBusMutex   *mutex,
796                                 int         timeout_msec)
797 {
798   return TRUE;
799 }
800 
801 static void
dbus_fake_condvar_wake_one(DBusCondVar * cond)802 dbus_fake_condvar_wake_one (DBusCondVar *cond)
803 {
804 
805 }
806 
807 static void
dbus_fake_condvar_wake_all(DBusCondVar * cond)808 dbus_fake_condvar_wake_all (DBusCondVar *cond)
809 {
810 
811 }
812 
813 dbus_bool_t
_dbus_threads_init_debug(void)814 _dbus_threads_init_debug (void)
815 {
816 #ifdef DBUS_WIN
817   return _dbus_threads_init_platform_specific();
818 #else
819   return dbus_threads_init (&fake_functions);
820 #endif
821 }
822 
823 #endif /* DBUS_BUILD_TESTS */
824