aboutsummaryrefslogtreecommitdiffstats
path: root/include/asterisk/linkedlists.h
blob: 4c9e27b2823c516083cd7d098b127b3e6850c096 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 * Kevin P. Fleming <kpfleming@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

#ifndef ASTERISK_LINKEDLISTS_H
#define ASTERISK_LINKEDLISTS_H

#include "asterisk/lock.h"

/*!
 * \file linkedlists.h
 * \brief A set of macros to manage forward-linked lists.
 */

/*!
 * \brief Locks a list.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to place an exclusive lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 */
#define AST_LIST_LOCK(head)						\
	ast_mutex_lock(&(head)->lock)

/*!
 * \brief Write locks a list.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to place an exclusive write lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 */
#define AST_RWLIST_WRLOCK(head)                                         \
        ast_rwlock_wrlock(&(head)->lock)

/*!
 * \brief Write locks a list, with timeout.
 * \param head This is a pointer to the list head structure
 * \param ts Pointer to a timespec structure
 *
 * This macro attempts to place an exclusive write lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 *
 * \since 1.6.1
 */
#define	AST_RWLIST_TIMEDWRLOCK(head, ts)	ast_rwlock_timedwrlock(&(head)->lock, ts)

/*!
 * \brief Read locks a list.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to place a read lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 */
#define AST_RWLIST_RDLOCK(head)                                         \
        ast_rwlock_rdlock(&(head)->lock)

/*!
 * \brief Read locks a list, with timeout.
 * \param head This is a pointer to the list head structure
 * \param ts Pointer to a timespec structure
 *
 * This macro attempts to place a read lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 *
 * \since 1.6.1
 */
#define AST_RWLIST_TIMEDRDLOCK(head, ts)                                 \
	ast_rwlock_timedrdlock(&(head)->lock, ts)

/*!
 * \brief Locks a list, without blocking if the list is locked.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to place an exclusive lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 */
#define AST_LIST_TRYLOCK(head)						\
	ast_mutex_trylock(&(head)->lock)

/*!
 * \brief Write locks a list, without blocking if the list is locked.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to place an exclusive write lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 */
#define AST_RWLIST_TRYWRLOCK(head)                                      \
        ast_rwlock_trywrlock(&(head)->lock)

/*!
 * \brief Read locks a list, without blocking if the list is locked.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to place a read lock in the
 * list head structure pointed to by head.
 * \retval 0 on success
 * \retval non-zero on failure
 */
#define AST_RWLIST_TRYRDLOCK(head)                                      \
        ast_rwlock_tryrdlock(&(head)->lock)

/*!
 * \brief Attempts to unlock a list.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to remove an exclusive lock from the
 * list head structure pointed to by head. If the list
 * was not locked by this thread, this macro has no effect.
 */
#define AST_LIST_UNLOCK(head)						\
	ast_mutex_unlock(&(head)->lock)

/*!
 * \brief Attempts to unlock a read/write based list.
 * \param head This is a pointer to the list head structure
 *
 * This macro attempts to remove a read or write lock from the
 * list head structure pointed to by head. If the list
 * was not locked by this thread, this macro has no effect.
 */
#define AST_RWLIST_UNLOCK(head)                                         \
        ast_rwlock_unlock(&(head)->lock)

/*!
 * \brief Defines a structure to be used to hold a list of specified type.
 * \param name This will be the name of the defined structure.
 * \param type This is the type of each list entry.
 *
 * This macro creates a structure definition that can be used
 * to hold a list of the entries of type \a type. It does not actually
 * declare (allocate) a structure; to do that, either follow this
 * macro with the desired name of the instance you wish to declare,
 * or use the specified \a name to declare instances elsewhere.
 *
 * Example usage:
 * \code
 * static AST_LIST_HEAD(entry_list, entry) entries;
 * \endcode
 *
 * This would define \c struct \c entry_list, and declare an instance of it named
 * \a entries, all intended to hold a list of type \c struct \c entry.
 */
#define AST_LIST_HEAD(name, type)					\
struct name {								\
	struct type *first;						\
	struct type *last;						\
	ast_mutex_t lock;						\
}

/*!
 * \brief Defines a structure to be used to hold a read/write list of specified type.
 * \param name This will be the name of the defined structure.
 * \param type This is the type of each list entry.
 *
 * This macro creates a structure definition that can be used
 * to hold a list of the entries of type \a type. It does not actually
 * declare (allocate) a structure; to do that, either follow this
 * macro with the desired name of the instance you wish to declare,
 * or use the specified \a name to declare instances elsewhere.
 *
 * Example usage:
 * \code
 * static AST_RWLIST_HEAD(entry_list, entry) entries;
 * \endcode
 *
 * This would define \c struct \c entry_list, and declare an instance of it named
 * \a entries, all intended to hold a list of type \c struct \c entry.
 */
#define AST_RWLIST_HEAD(name, type)                                     \
struct name {                                                           \
        struct type *first;                                             \
        struct type *last;                                              \
        ast_rwlock_t lock;                                              \
}

/*!
 * \brief Defines a structure to be used to hold a list of specified type (with no lock).
 * \param name This will be the name of the defined structure.
 * \param type This is the type of each list entry.
 *
 * This macro creates a structure definition that can be used
 * to hold a list of the entries of type \a type. It does not actually
 * declare (allocate) a structure; to do that, either follow this
 * macro with the desired name of the instance you wish to declare,
 * or use the specified \a name to declare instances elsewhere.
 *
 * Example usage:
 * \code
 * static AST_LIST_HEAD_NOLOCK(entry_list, entry) entries;
 * \endcode
 *
 * This would define \c struct \c entry_list, and declare an instance of it named
 * \a entries, all intended to hold a list of type \c struct \c entry.
 */
#define AST_LIST_HEAD_NOLOCK(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
}

/*!
 * \brief Defines initial values for a declaration of AST_LIST_HEAD
 */
#define AST_LIST_HEAD_INIT_VALUE	{		\
	.first = NULL,					\
	.last = NULL,					\
	.lock = AST_MUTEX_INIT_VALUE,			\
	}

/*!
 * \brief Defines initial values for a declaration of AST_RWLIST_HEAD
 */
#define AST_RWLIST_HEAD_INIT_VALUE      {               \
        .first = NULL,                                  \
        .last = NULL,                                   \
        .lock = AST_RWLOCK_INIT_VALUE,                  \
        }

/*!
 * \brief Defines initial values for a declaration of AST_LIST_HEAD_NOLOCK
 */
#define AST_LIST_HEAD_NOLOCK_INIT_VALUE	{	\
	.first = NULL,					\
	.last = NULL,					\
	}

/*!
 * \brief Defines a structure to be used to hold a list of specified type, statically initialized.
 * \param name This will be the name of the defined structure.
 * \param type This is the type of each list entry.
 *
 * This macro creates a structure definition that can be used
 * to hold a list of the entries of type \a type, and allocates an instance
 * of it, initialized to be empty.
 *
 * Example usage:
 * \code
 * static AST_LIST_HEAD_STATIC(entry_list, entry);
 * \endcode
 *
 * This would define \c struct \c entry_list, intended to hold a list of
 * type \c struct \c entry.
 */
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS)
#define AST_LIST_HEAD_STATIC(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
	ast_mutex_t lock;						\
} name;									\
static void  __attribute__((constructor)) __init_##name(void)		\
{									\
        AST_LIST_HEAD_INIT(&name);					\
}									\
static void  __attribute__((destructor)) __fini_##name(void)		\
{									\
        AST_LIST_HEAD_DESTROY(&name);					\
}									\
struct __dummy_##name
#else
#define AST_LIST_HEAD_STATIC(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
	ast_mutex_t lock;						\
} name = AST_LIST_HEAD_INIT_VALUE
#endif

/*!
 * \brief Defines a structure to be used to hold a read/write list of specified type, statically initialized.
 * \param name This will be the name of the defined structure.
 * \param type This is the type of each list entry.
 *
 * This macro creates a structure definition that can be used
 * to hold a list of the entries of type \a type, and allocates an instance
 * of it, initialized to be empty.
 *
 * Example usage:
 * \code
 * static AST_RWLIST_HEAD_STATIC(entry_list, entry);
 * \endcode
 *
 * This would define \c struct \c entry_list, intended to hold a list of
 * type \c struct \c entry.
 */
#ifndef HAVE_PTHREAD_RWLOCK_INITIALIZER
#define AST_RWLIST_HEAD_STATIC(name, type)                              \
struct name {                                                           \
        struct type *first;                                             \
        struct type *last;                                              \
        ast_rwlock_t lock;                                              \
} name;                                                                 \
static void  __attribute__((constructor)) __init_##name(void)          \
{                                                                       \
        AST_RWLIST_HEAD_INIT(&name);                                    \
}                                                                       \
static void  __attribute__((destructor)) __fini_##name(void)           \
{                                                                       \
        AST_RWLIST_HEAD_DESTROY(&name);                                 \
}                                                                       \
struct __dummy_##name
#else
#define AST_RWLIST_HEAD_STATIC(name, type)                              \
struct name {                                                           \
        struct type *first;                                             \
        struct type *last;                                              \
        ast_rwlock_t lock;                                              \
} name = AST_RWLIST_HEAD_INIT_VALUE
#endif

/*!
 * \brief Defines a structure to be used to hold a list of specified type, statically initialized.
 *
 * This is the same as AST_LIST_HEAD_STATIC, except without the lock included.
 */
#define AST_LIST_HEAD_NOLOCK_STATIC(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
} name = AST_LIST_HEAD_NOLOCK_INIT_VALUE

/*!
 * \brief Initializes a list head structure with a specified first entry.
 * \param head This is a pointer to the list head structure
 * \param entry pointer to the list entry that will become the head of the list
 *
 * This macro initializes a list head structure by setting the head
 * entry to the supplied value and recreating the embedded lock.
 */
#define AST_LIST_HEAD_SET(head, entry) do {				\
	(head)->first = (entry);					\
	(head)->last = (entry);						\
	ast_mutex_init(&(head)->lock);					\
} while (0)

/*!
 * \brief Initializes an rwlist head structure with a specified first entry.
 * \param head This is a pointer to the list head structure
 * \param entry pointer to the list entry that will become the head of the list
 *
 * This macro initializes a list head structure by setting the head
 * entry to the supplied value and recreating the embedded lock.
 */
#define AST_RWLIST_HEAD_SET(head, entry) do {                           \
        (head)->first = (entry);                                        \
        (head)->last = (entry);                                         \
        ast_rwlock_init(&(head)->lock);                                 \
} while (0)

/*!
 * \brief Initializes a list head structure with a specified first entry.
 * \param head This is a pointer to the list head structure
 * \param entry pointer to the list entry that will become the head of the list
 *
 * This macro initializes a list head structure by setting the head
 * entry to the supplied value.
 */
#define AST_LIST_HEAD_SET_NOLOCK(head, entry) do {			\
	(head)->first = (entry);					\
	(head)->last = (entry);						\
} while (0)

/*!
 * \brief Declare a forward link structure inside a list entry.
 * \param type This is the type of each list entry.
 *
 * This macro declares a structure to be used to link list entries together.
 * It must be used inside the definition of the structure named in
 * \a type, as follows:
 *
 * \code
 * struct list_entry {
      ...
      AST_LIST_ENTRY(list_entry) list;
 * }
 * \endcode
 *
 * The field name \a list here is arbitrary, and can be anything you wish.
 */
#define AST_LIST_ENTRY(type)						\
struct {								\
	struct type *next;						\
}

#define AST_RWLIST_ENTRY AST_LIST_ENTRY

/*!
 * \brief Returns the first entry contained in a list.
 * \param head This is a pointer to the list head structure
 */
#define	AST_LIST_FIRST(head)	((head)->first)

#define AST_RWLIST_FIRST AST_LIST_FIRST

/*!
 * \brief Returns the last entry contained in a list.
 * \param head This is a pointer to the list head structure
 */
#define	AST_LIST_LAST(head)	((head)->last)

#define AST_RWLIST_LAST AST_LIST_LAST

/*!
 * \brief Returns the next entry in the list after the given entry.
 * \param elm This is a pointer to the current entry.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 */
#define AST_LIST_NEXT(elm, field)	((elm)->field.next)

#define AST_RWLIST_NEXT AST_LIST_NEXT

/*!
 * \brief Checks whether the specified list contains any entries.
 * \param head This is a pointer to the list head structure
 *
 * \return zero if the list has entries
 * \return non-zero if not.
 */
#define	AST_LIST_EMPTY(head)	(AST_LIST_FIRST(head) == NULL)

#define AST_RWLIST_EMPTY AST_LIST_EMPTY

/*!
 * \brief Loops over (traverses) the entries in a list.
 * \param head This is a pointer to the list head structure
 * \param var This is the name of the variable that will hold a pointer to the
 * current list entry on each iteration. It must be declared before calling
 * this macro.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * This macro is use to loop over (traverse) the entries in a list. It uses a
 * \a for loop, and supplies the enclosed code with a pointer to each list
 * entry as it loops. It is typically used as follows:
 * \code
 * static AST_LIST_HEAD(entry_list, list_entry) entries;
 * ...
 * struct list_entry {
      ...
      AST_LIST_ENTRY(list_entry) list;
 * }
 * ...
 * struct list_entry *current;
 * ...
 * AST_LIST_TRAVERSE(&entries, current, list) {
     (do something with current here)
 * }
 * \endcode
 * \warning If you modify the forward-link pointer contained in the \a current entry while
 * inside the loop, the behavior will be unpredictable. At a minimum, the following
 * macros will modify the forward-link pointer, and should not be used inside
 * AST_LIST_TRAVERSE() against the entry pointed to by the \a current pointer without
 * careful consideration of their consequences:
 * \li AST_LIST_NEXT() (when used as an lvalue)
 * \li AST_LIST_INSERT_AFTER()
 * \li AST_LIST_INSERT_HEAD()
 * \li AST_LIST_INSERT_TAIL()
 * \li AST_LIST_INSERT_SORTALPHA()
 */
#define AST_LIST_TRAVERSE(head,var,field) 				\
	for((var) = (head)->first; (var); (var) = (var)->field.next)

#define AST_RWLIST_TRAVERSE AST_LIST_TRAVERSE

/*!
 * \brief Loops safely over (traverses) the entries in a list.
 * \param head This is a pointer to the list head structure
 * \param var This is the name of the variable that will hold a pointer to the
 * current list entry on each iteration. It must be declared before calling
 * this macro.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * This macro is used to safely loop over (traverse) the entries in a list. It
 * uses a \a for loop, and supplies the enclosed code with a pointer to each list
 * entry as it loops. It is typically used as follows:
 *
 * \code
 * static AST_LIST_HEAD(entry_list, list_entry) entries;
 * ...
 * struct list_entry {
      ...
      AST_LIST_ENTRY(list_entry) list;
 * }
 * ...
 * struct list_entry *current;
 * ...
 * AST_LIST_TRAVERSE_SAFE_BEGIN(&entries, current, list) {
     (do something with current here)
 * }
 * AST_LIST_TRAVERSE_SAFE_END;
 * \endcode
 *
 * It differs from AST_LIST_TRAVERSE() in that the code inside the loop can modify
 * (or even free, after calling AST_LIST_REMOVE_CURRENT()) the entry pointed to by
 * the \a current pointer without affecting the loop traversal.
 */
#define AST_LIST_TRAVERSE_SAFE_BEGIN(head, var, field) {				\
	typeof((head)) __list_head = head;						\
	typeof(__list_head->first) __list_next;						\
	typeof(__list_head->first) __list_prev = NULL;					\
	typeof(__list_head->first) __new_prev = NULL;					\
	for ((var) = __list_head->first, __new_prev = (var),				\
	      __list_next = (var) ? (var)->field.next : NULL;				\
	     (var);									\
	     __list_prev = __new_prev, (var) = __list_next,				\
	     __new_prev = (var),							\
	     __list_next = (var) ? (var)->field.next : NULL,				\
	     (void) __list_prev								\
	    )

#define AST_RWLIST_TRAVERSE_SAFE_BEGIN AST_LIST_TRAVERSE_SAFE_BEGIN

/*!
 * \brief Removes the \a current entry from a list during a traversal.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * \note This macro can \b only be used inside an AST_LIST_TRAVERSE_SAFE_BEGIN()
 * block; it is used to unlink the current entry from the list without affecting
 * the list traversal (and without having to re-traverse the list to modify the
 * previous entry, if any).
 */
#define AST_LIST_REMOVE_CURRENT(field) do { \
	__new_prev->field.next = NULL;							\
	__new_prev = __list_prev;							\
	if (__list_prev)								\
		__list_prev->field.next = __list_next;					\
	else										\
		__list_head->first = __list_next;					\
	if (!__list_next)								\
		__list_head->last = __list_prev;					\
	} while (0)

#define AST_RWLIST_REMOVE_CURRENT AST_LIST_REMOVE_CURRENT

#define AST_LIST_MOVE_CURRENT(newhead, field) do { \
	typeof ((newhead)->first) __list_cur = __new_prev;				\
	AST_LIST_REMOVE_CURRENT(field);							\
	AST_LIST_INSERT_TAIL((newhead), __list_cur, field);				\
	} while (0)

#define AST_RWLIST_MOVE_CURRENT AST_LIST_MOVE_CURRENT

/*!
 * \brief Inserts a list entry before the current entry during a traversal.
 * \param elm This is a pointer to the entry to be inserted.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * \note This macro can \b only be used inside an AST_LIST_TRAVERSE_SAFE_BEGIN()
 * block.
 */
#define AST_LIST_INSERT_BEFORE_CURRENT(elm, field) do {			\
	if (__list_prev) {						\
		(elm)->field.next = __list_prev->field.next;		\
		__list_prev->field.next = elm;				\
	} else {							\
		(elm)->field.next = __list_head->first;			\
		__list_head->first = (elm);				\
	}								\
	__new_prev = (elm);						\
} while (0)

#define AST_RWLIST_INSERT_BEFORE_CURRENT AST_LIST_INSERT_BEFORE_CURRENT

/*!
 * \brief Closes a safe loop traversal block.
 */
#define AST_LIST_TRAVERSE_SAFE_END  }

#define AST_RWLIST_TRAVERSE_SAFE_END AST_LIST_TRAVERSE_SAFE_END

/*!
 * \brief Initializes a list head structure.
 * \param head This is a pointer to the list head structure
 *
 * This macro initializes a list head structure by setting the head
 * entry to \a NULL (empty list) and recreating the embedded lock.
 */
#define AST_LIST_HEAD_INIT(head) {					\
	(head)->first = NULL;						\
	(head)->last = NULL;						\
	ast_mutex_init(&(head)->lock);					\
}

/*!
 * \brief Initializes an rwlist head structure.
 * \param head This is a pointer to the list head structure
 *
 * This macro initializes a list head structure by setting the head
 * entry to \a NULL (empty list) and recreating the embedded lock.
 */
#define AST_RWLIST_HEAD_INIT(head) {                                    \
        (head)->first = NULL;                                           \
        (head)->last = NULL;                                            \
        ast_rwlock_init(&(head)->lock);                                 \
}

/*!
 * \brief Destroys a list head structure.
 * \param head This is a pointer to the list head structure
 *
 * This macro destroys a list head structure by setting the head
 * entry to \a NULL (empty list) and destroying the embedded lock.
 * It does not free the structure from memory.
 */
#define AST_LIST_HEAD_DESTROY(head) {					\
	(head)->first = NULL;						\
	(head)->last = NULL;						\
	ast_mutex_destroy(&(head)->lock);				\
}

/*!
 * \brief Destroys an rwlist head structure.
 * \param head This is a pointer to the list head structure
 *
 * This macro destroys a list head structure by setting the head
 * entry to \a NULL (empty list) and destroying the embedded lock.
 * It does not free the structure from memory.
 */
#define AST_RWLIST_HEAD_DESTROY(head) {                                 \
        (head)->first = NULL;                                           \
        (head)->last = NULL;                                            \
        ast_rwlock_destroy(&(head)->lock);                              \
}

/*!
 * \brief Initializes a list head structure.
 * \param head This is a pointer to the list head structure
 *
 * This macro initializes a list head structure by setting the head
 * entry to \a NULL (empty list). There is no embedded lock handling
 * with this macro.
 */
#define AST_LIST_HEAD_INIT_NOLOCK(head) {				\
	(head)->first = NULL;						\
	(head)->last = NULL;						\
}

/*!
 * \brief Inserts a list entry after a given entry.
 * \param head This is a pointer to the list head structure
 * \param listelm This is a pointer to the entry after which the new entry should
 * be inserted.
 * \param elm This is a pointer to the entry to be inserted.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 */
#define AST_LIST_INSERT_AFTER(head, listelm, elm, field) do {		\
	(elm)->field.next = (listelm)->field.next;			\
	(listelm)->field.next = (elm);					\
	if ((head)->last == (listelm))					\
		(head)->last = (elm);					\
} while (0)

#define AST_RWLIST_INSERT_AFTER AST_LIST_INSERT_AFTER

/*!
 * \brief Inserts a list entry at the head of a list.
 * \param head This is a pointer to the list head structure
 * \param elm This is a pointer to the entry to be inserted.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 */
#define AST_LIST_INSERT_HEAD(head, elm, field) do {			\
		(elm)->field.next = (head)->first;			\
		(head)->first = (elm);					\
		if (!(head)->last)					\
			(head)->last = (elm);				\
} while (0)

#define AST_RWLIST_INSERT_HEAD AST_LIST_INSERT_HEAD

/*!
 * \brief Appends a list entry to the tail of a list.
 * \param head This is a pointer to the list head structure
 * \param elm This is a pointer to the entry to be appended.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * Note: The link field in the appended entry is \b not modified, so if it is
 * actually the head of a list itself, the entire list will be appended
 * temporarily (until the next AST_LIST_INSERT_TAIL is performed).
 */
#define AST_LIST_INSERT_TAIL(head, elm, field) do {			\
      if (!(head)->first) {						\
		(head)->first = (elm);					\
		(head)->last = (elm);					\
      } else {								\
		(head)->last->field.next = (elm);			\
		(head)->last = (elm);					\
      }									\
} while (0)

#define AST_RWLIST_INSERT_TAIL AST_LIST_INSERT_TAIL

/*!
 * \brief Inserts a list entry into a alphabetically sorted list
 * \param head Pointer to the list head structure
 * \param elm Pointer to the entry to be inserted
 * \param field Name of the list entry field (declared using AST_LIST_ENTRY())
 * \param sortfield Name of the field on which the list is sorted
 * \since 1.6.1
 */
#define AST_LIST_INSERT_SORTALPHA(head, elm, field, sortfield) do { \
	if (!(head)->first) {                                           \
		(head)->first = (elm);                                      \
		(head)->last = (elm);                                       \
	} else {                                                        \
		typeof((head)->first) cur = (head)->first, prev = NULL;     \
		while (cur && strcmp(cur->sortfield, elm->sortfield) < 0) { \
			prev = cur;                                             \
			cur = cur->field.next;                                  \
		}                                                           \
		if (!prev) {                                                \
			AST_LIST_INSERT_HEAD(head, elm, field);                 \
		} else if (!cur) {                                          \
			AST_LIST_INSERT_TAIL(head, elm, field);                 \
		} else {                                                    \
			AST_LIST_INSERT_AFTER(head, prev, elm, field);          \
		}                                                           \
	}                                                               \
} while (0)

#define AST_RWLIST_INSERT_SORTALPHA	AST_LIST_INSERT_SORTALPHA

/*!
 * \brief Appends a whole list to the tail of a list.
 * \param head This is a pointer to the list head structure
 * \param list This is a pointer to the list to be appended.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * Note: The source list (the \a list parameter) will be empty after
 * calling this macro (the list entries are \b moved to the target list).
 */
#define AST_LIST_APPEND_LIST(head, list, field) do {			\
	if (!(list)->first) {						\
		break;							\
	}								\
	if (!(head)->first) {						\
		(head)->first = (list)->first;				\
		(head)->last = (list)->last;				\
	} else {							\
		(head)->last->field.next = (list)->first;		\
		(head)->last = (list)->last;				\
	}								\
	(list)->first = NULL;						\
	(list)->last = NULL;						\
} while (0)

#define AST_RWLIST_APPEND_LIST AST_LIST_APPEND_LIST

/*!
  \brief Inserts a whole list after a specific entry in a list
  \param head This is a pointer to the list head structure
  \param list This is a pointer to the list to be inserted.
  \param elm This is a pointer to the entry after which the new list should
  be inserted.
  \param field This is the name of the field (declared using AST_LIST_ENTRY())
  used to link entries of the lists together.

  Note: The source list (the \a list parameter) will be empty after
  calling this macro (the list entries are \b moved to the target list).
 */
#define AST_LIST_INSERT_LIST_AFTER(head, list, elm, field) do {		\
	(list)->last->field.next = (elm)->field.next;			\
	(elm)->field.next = (list)->first;				\
	if ((head)->last == elm) {					\
		(head)->last = (list)->last;				\
	}								\
	(list)->first = NULL;						\
	(list)->last = NULL;						\
} while(0)

#define AST_RWLIST_INSERT_LIST_AFTER AST_LIST_INSERT_LIST_AFTER

/*!
 * \brief Removes and returns the head entry from a list.
 * \param head This is a pointer to the list head structure
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 *
 * Removes the head entry from the list, and returns a pointer to it.
 * This macro is safe to call on an empty list.
 */
#define AST_LIST_REMOVE_HEAD(head, field) ({				\
		typeof((head)->first) cur = (head)->first;		\
		if (cur) {						\
			(head)->first = cur->field.next;		\
			cur->field.next = NULL;				\
			if ((head)->last == cur)			\
				(head)->last = NULL;			\
		}							\
		cur;							\
	})

#define AST_RWLIST_REMOVE_HEAD AST_LIST_REMOVE_HEAD

/*!
 * \brief Removes a specific entry from a list.
 * \param head This is a pointer to the list head structure
 * \param elm This is a pointer to the entry to be removed.
 * \param field This is the name of the field (declared using AST_LIST_ENTRY())
 * used to link entries of this list together.
 * \warning The removed entry is \b not freed nor modified in any way.
 */
#define AST_LIST_REMOVE(head, elm, field) ({			        \
	__typeof(elm) __res = NULL; \
	__typeof(elm) __tmp = elm; \
	if (!__tmp) { \
		__res = NULL; \
	} else if ((head)->first == (elm)) {					\
		__res = (head)->first;                      \
		(head)->first = (elm)->field.next;			\
		if ((head)->last == (elm))			\
			(head)->last = NULL;			\
	} else {								\
		typeof(elm) curelm = (head)->first;			\
		while (curelm && (curelm->field.next != (elm)))			\
			curelm = curelm->field.next;			\
		if (curelm) { \
			__res = (elm); \
			curelm->field.next = (elm)->field.next;			\
			if ((head)->last == (elm))				\
				(head)->last = curelm;				\
		} \
	}								\
	if (__res) { \
		(__res)->field.next = NULL; \
	} \
	(__res); \
})

#define AST_RWLIST_REMOVE AST_LIST_REMOVE

#endif /* _ASTERISK_LINKEDLISTS_H */