git.sur5r.net Git - openldap/blob - include/ldap_queue.h

   1 /*
   2  * Copyright 2001-2003 The OpenLDAP Foundation, Redwood City, California, USA
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted only as authorized by the OpenLDAP
   7  * Public License.  A copy of this license is available at
   8  * http://www.OpenLDAP.org/license.html or in file LICENSE in the
   9  * top-level directory of the distribution.
  10  */
  11 /* stolen from FreeBSD for use in OpenLDAP */
  12 /* $OpenLDAP$ */
  13 /*
  14  * Copyright (c) 1991, 1993
  15  *      The Regents of the University of California.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  * 3. All advertising materials mentioning features or use of this software
  26  *    must display the following acknowledgement:
  27  *      This product includes software developed by the University of
  28  *      California, Berkeley and its contributors.
  29  * 4. Neither the name of the University nor the names of its contributors
  30  *    may be used to endorse or promote products derived from this software
  31  *    without specific prior written permission.
  32  *
  33  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  34  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  35  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  36  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  37  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  38  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  39  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  40  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  41  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  42  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  43  * SUCH DAMAGE.
  44  *
  45  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  46  * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.5 2001/09/30 21:12:54 luigi Exp $
  47  */
  48 /* See also: ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change */
  49
  50 #ifndef _LDAP_QUEUE_H_
  51 #define _LDAP_QUEUE_H_
  52
  53 /*
  54  * This file defines five types of data structures: singly-linked lists,
  55  * singly-linked tail queues, lists, tail queues, and circular queues.
  56  *
  57  * A singly-linked list is headed by a single forward pointer. The elements
  58  * are singly linked for minimum space and pointer manipulation overhead at
  59  * the expense of O(n) removal for arbitrary elements. New elements can be
  60  * added to the list after an existing element or at the head of the list.
  61  * Elements being removed from the head of the list should use the explicit
  62  * macro for this purpose for optimum efficiency. A singly-linked list may
  63  * only be traversed in the forward direction.  Singly-linked lists are ideal
  64  * for applications with large datasets and few or no removals or for
  65  * implementing a LIFO queue.
  66  *
  67  * A singly-linked tail queue is headed by a pair of pointers, one to the
  68  * head of the list and the other to the tail of the list. The elements are
  69  * singly linked for minimum space and pointer manipulation overhead at the
  70  * expense of O(n) removal for arbitrary elements. New elements can be added
  71  * to the list after an existing element, at the head of the list, or at the
  72  * end of the list. Elements being removed from the head of the tail queue
  73  * should use the explicit macro for this purpose for optimum efficiency.
  74  * A singly-linked tail queue may only be traversed in the forward direction.
  75  * Singly-linked tail queues are ideal for applications with large datasets
  76  * and few or no removals or for implementing a FIFO queue.
  77  *
  78  * A list is headed by a single forward pointer (or an array of forward
  79  * pointers for a hash table header). The elements are doubly linked
  80  * so that an arbitrary element can be removed without a need to
  81  * traverse the list. New elements can be added to the list before
  82  * or after an existing element or at the head of the list. A list
  83  * may only be traversed in the forward direction.
  84  *
  85  * A tail queue is headed by a pair of pointers, one to the head of the
  86  * list and the other to the tail of the list. The elements are doubly
  87  * linked so that an arbitrary element can be removed without a need to
  88  * traverse the list. New elements can be added to the list before or
  89  * after an existing element, at the head of the list, or at the end of
  90  * the list. A tail queue may be traversed in either direction.
  91  *
  92  * A circle queue is headed by a pair of pointers, one to the head of the
  93  * list and the other to the tail of the list. The elements are doubly
  94  * linked so that an arbitrary element can be removed without a need to
  95  * traverse the list. New elements can be added to the list before or after
  96  * an existing element, at the head of the list, or at the end of the list.
  97  * A circle queue may be traversed in either direction, but has a more
  98  * complex end of list detection.
  99  *
 100  * For details on the use of these macros, see the queue(3) manual page.
 101  * All macros are prefixed with LDAP_.
 102  *
 103  *                      SLIST_  LIST_   STAILQ_ TAILQ_  CIRCLEQ_
 104  * _HEAD                +       +       +       +       +
 105  * _ENTRY               +       +       +       +       +
 106  * _INIT                +       +       +       +       +
 107  * _EMPTY               +       +       +       +       +
 108  * _FIRST               +       +       +       +       +
 109  * _NEXT                +       +       +       +       +
 110  * _PREV                -       -       -       +       +
 111  * _LAST                -       -       +       +       +
 112  * _FOREACH             +       +       +       +       +
 113  * _FOREACH_REVERSE     -       -       -       +       +
 114  * _INSERT_HEAD         +       +       +       +       +
 115  * _INSERT_BEFORE       -       +       -       +       +
 116  * _INSERT_AFTER        +       +       +       +       +
 117  * _INSERT_TAIL         -       -       +       +       +
 118  * _REMOVE_HEAD         +       -       +       -       -
 119  * _REMOVE              +       +       +       +       +
 120  *
 121  */
 122
 123 /*
 124  * Singly-linked List definitions.
 125  */
 126 #define LDAP_SLIST_HEAD(name, type)                                     \
 127 struct name {                                                           \
 128         struct type *slh_first; /* first element */                     \
 129 }
 130
 131 #define LDAP_SLIST_HEAD_INITIALIZER(head)                               \
 132         { NULL }
 133
 134 #define LDAP_SLIST_ENTRY(type)                                          \
 135 struct {                                                                \
 136         struct type *sle_next;  /* next element */                      \
 137 }
 138
 139 #define LDAP_SLIST_ENTRY_INITIALIZER(entry)                             \
 140         { NULL }
 141
 142 /*
 143  * Singly-linked List functions.
 144  */
 145 #define LDAP_SLIST_EMPTY(head)  ((head)->slh_first == NULL)
 146
 147 #define LDAP_SLIST_FIRST(head)  ((head)->slh_first)
 148
 149 #define LDAP_SLIST_FOREACH(var, head, field)                            \
 150         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 151
 152 #define LDAP_SLIST_INIT(head) {                                         \
 153         (head)->slh_first = NULL;                                       \
 154 }
 155
 156 #define LDAP_SLIST_INSERT_AFTER(slistelm, elm, field) do {              \
 157         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 158         (slistelm)->field.sle_next = (elm);                             \
 159 } while (0)
 160
 161 #define LDAP_SLIST_INSERT_HEAD(head, elm, field) do {                   \
 162         (elm)->field.sle_next = (head)->slh_first;                      \
 163         (head)->slh_first = (elm);                                      \
 164 } while (0)
 165
 166 #define LDAP_SLIST_NEXT(elm, field)     ((elm)->field.sle_next)
 167
 168 #define LDAP_SLIST_REMOVE_HEAD(head, field) do {                        \
 169         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 170 } while (0)
 171
 172 #define LDAP_SLIST_REMOVE(head, elm, type, field) do {                  \
 173         if ((head)->slh_first == (elm)) {                               \
 174                 LDAP_SLIST_REMOVE_HEAD((head), field);                  \
 175         }                                                               \
 176         else {                                                          \
 177                 struct type *curelm = (head)->slh_first;                \
 178                 while( curelm->field.sle_next != (elm) )                \
 179                         curelm = curelm->field.sle_next;                \
 180                 curelm->field.sle_next =                                \
 181                     curelm->field.sle_next->field.sle_next;             \
 182         }                                                               \
 183 } while (0)
 184
 185 /*
 186  * Singly-linked Tail queue definitions.
 187  */
 188 #define LDAP_STAILQ_HEAD(name, type)                                    \
 189 struct name {                                                           \
 190         struct type *stqh_first;/* first element */                     \
 191         struct type **stqh_last;/* addr of last next element */         \
 192 }
 193
 194 #define LDAP_STAILQ_HEAD_INITIALIZER(head)                              \
 195         { NULL, &(head).stqh_first }
 196
 197 #define LDAP_STAILQ_ENTRY(type)                                         \
 198 struct {                                                                \
 199         struct type *stqe_next; /* next element */                      \
 200 }
 201
 202 #define LDAP_STAILQ_ENTRY_INITIALIZER(entry)                            \
 203         { NULL }
 204
 205 /*
 206  * Singly-linked Tail queue functions.
 207  */
 208 #define LDAP_STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
 209
 210 #define LDAP_STAILQ_INIT(head) do {                                     \
 211         (head)->stqh_first = NULL;                                      \
 212         (head)->stqh_last = &(head)->stqh_first;                        \
 213 } while (0)
 214
 215 #define LDAP_STAILQ_FIRST(head) ((head)->stqh_first)
 216
 217 #define LDAP_STAILQ_LAST(head, type, field)                             \
 218         (LDAP_STAILQ_EMPTY(head) ?                                      \
 219                 NULL :                                                  \
 220                 ((struct type *)                                        \
 221                 ((char *)((head)->stqh_last) - offsetof(struct type, field))))
 222
 223 #define LDAP_STAILQ_FOREACH(var, head, field)                           \
 224         for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)
 225
 226 #define LDAP_STAILQ_INSERT_HEAD(head, elm, field) do {                  \
 227         if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
 228                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 229         (head)->stqh_first = (elm);                                     \
 230 } while (0)
 231
 232 #define LDAP_STAILQ_INSERT_TAIL(head, elm, field) do {                  \
 233         (elm)->field.stqe_next = NULL;                                  \
 234         *(head)->stqh_last = (elm);                                     \
 235         (head)->stqh_last = &(elm)->field.stqe_next;                    \
 236 } while (0)
 237
 238 #define LDAP_STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {          \
 239         if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
 240                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 241         (tqelm)->field.stqe_next = (elm);                               \
 242 } while (0)
 243
 244 #define LDAP_STAILQ_NEXT(elm, field)    ((elm)->field.stqe_next)
 245
 246 #define LDAP_STAILQ_REMOVE_HEAD(head, field) do {                       \
 247         if (((head)->stqh_first =                                       \
 248              (head)->stqh_first->field.stqe_next) == NULL)              \
 249                 (head)->stqh_last = &(head)->stqh_first;                \
 250 } while (0)
 251
 252 #define LDAP_STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {            \
 253         if (((head)->stqh_first = (elm)->field.stqe_next) == NULL)      \
 254                 (head)->stqh_last = &(head)->stqh_first;                \
 255 } while (0)
 256
 257 #define LDAP_STAILQ_REMOVE(head, elm, type, field) do {                 \
 258         if ((head)->stqh_first == (elm)) {                              \
 259                 LDAP_STAILQ_REMOVE_HEAD(head, field);                   \
 260         }                                                               \
 261         else {                                                          \
 262                 struct type *curelm = (head)->stqh_first;               \
 263                 while( curelm->field.stqe_next != (elm) )               \
 264                         curelm = curelm->field.stqe_next;               \
 265                 if((curelm->field.stqe_next =                           \
 266                     curelm->field.stqe_next->field.stqe_next) == NULL)  \
 267                         (head)->stqh_last = &(curelm)->field.stqe_next; \
 268         }                                                               \
 269 } while (0)
 270
 271 /*
 272  * List definitions.
 273  */
 274 #define LDAP_LIST_HEAD(name, type)                                      \
 275 struct name {                                                           \
 276         struct type *lh_first;  /* first element */                     \
 277 }
 278
 279 #define LDAP_LIST_HEAD_INITIALIZER(head)                                \
 280         { NULL }
 281
 282 #define LDAP_LIST_ENTRY(type)                                           \
 283 struct {                                                                \
 284         struct type *le_next;   /* next element */                      \
 285         struct type **le_prev;  /* address of previous next element */  \
 286 }
 287
 288 #define LDAP_LIST_ENTRY_INITIALIZER(entry)                      \
 289         { NULL, NULL }
 290
 291 /*
 292  * List functions.
 293  */
 294
 295 #define LDAP_LIST_EMPTY(head) ((head)->lh_first == NULL)
 296
 297 #define LDAP_LIST_FIRST(head)   ((head)->lh_first)
 298
 299 #define LDAP_LIST_FOREACH(var, head, field)                             \
 300         for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
 301
 302 #define LDAP_LIST_INIT(head) do {                                       \
 303         (head)->lh_first = NULL;                                        \
 304 } while (0)
 305
 306 #define LDAP_LIST_INSERT_AFTER(listelm, elm, field) do {                \
 307         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 308                 (listelm)->field.le_next->field.le_prev =               \
 309                     &(elm)->field.le_next;                              \
 310         (listelm)->field.le_next = (elm);                               \
 311         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 312 } while (0)
 313
 314 #define LDAP_LIST_INSERT_BEFORE(listelm, elm, field) do {               \
 315         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 316         (elm)->field.le_next = (listelm);                               \
 317         *(listelm)->field.le_prev = (elm);                              \
 318         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 319 } while (0)
 320
 321 #define LDAP_LIST_INSERT_HEAD(head, elm, field) do {                    \
 322         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 323                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 324         (head)->lh_first = (elm);                                       \
 325         (elm)->field.le_prev = &(head)->lh_first;                       \
 326 } while (0)
 327
 328 #define LDAP_LIST_NEXT(elm, field)      ((elm)->field.le_next)
 329
 330 #define LDAP_LIST_REMOVE(elm, field) do {                               \
 331         if ((elm)->field.le_next != NULL)                               \
 332                 (elm)->field.le_next->field.le_prev =                   \
 333                     (elm)->field.le_prev;                               \
 334         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 335 } while (0)
 336
 337 /*
 338  * Tail queue definitions.
 339  */
 340 #define LDAP_TAILQ_HEAD(name, type)                                     \
 341 struct name {                                                           \
 342         struct type *tqh_first; /* first element */                     \
 343         struct type **tqh_last; /* addr of last next element */         \
 344 }
 345
 346 #define LDAP_TAILQ_HEAD_INITIALIZER(head)                               \
 347         { NULL, &(head).tqh_first }
 348
 349 #define LDAP_TAILQ_ENTRY(type)                                          \
 350 struct {                                                                \
 351         struct type *tqe_next;  /* next element */                      \
 352         struct type **tqe_prev; /* address of previous next element */  \
 353 }
 354
 355 #define LDAP_TAILQ_ENTRY_INITIALIZER(entry)                             \
 356         { NULL, NULL }
 357
 358 /*
 359  * Tail queue functions.
 360  */
 361 #define LDAP_TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
 362
 363 #define LDAP_TAILQ_FOREACH(var, head, field)                            \
 364         for (var = LDAP_TAILQ_FIRST(head); var; var = LDAP_TAILQ_NEXT(var, field))
 365
 366 #define LDAP_TAILQ_FOREACH_REVERSE(var, head, type, field)              \
 367         for ((var) = LDAP_TAILQ_LAST((head), type, field);              \
 368              (var);                                                     \
 369              (var) = LDAP_TAILQ_PREV((var), head, type, field))
 370
 371 #define LDAP_TAILQ_FIRST(head) ((head)->tqh_first)
 372
 373 #define LDAP_TAILQ_LAST(head, type, field)                              \
 374         (LDAP_TAILQ_EMPTY(head) ?                                       \
 375                 NULL :                                                  \
 376                 ((struct type *)                                        \
 377                 ((char *)((head)->tqh_last) - offsetof(struct type, field))))
 378
 379 #define LDAP_TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 380
 381 #define LDAP_TAILQ_PREV(elm, head, type, field)                         \
 382         ((struct type *)((elm)->field.tqe_prev) == LDAP_TAILQ_FIRST(head) ? \
 383         NULL :                                                          \
 384         ((struct type *)                                                \
 385         ((char *)((elm)->field.tqe_prev) - offsetof(struct type, field))))
 386
 387 #define LDAP_TAILQ_INIT(head) do {                                      \
 388         (head)->tqh_first = NULL;                                       \
 389         (head)->tqh_last = &(head)->tqh_first;                          \
 390 } while (0)
 391
 392 #define LDAP_TAILQ_INSERT_HEAD(head, elm, field) do {                   \
 393         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 394                 (head)->tqh_first->field.tqe_prev =                     \
 395                     &(elm)->field.tqe_next;                             \
 396         else                                                            \
 397                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 398         (head)->tqh_first = (elm);                                      \
 399         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 400 } while (0)
 401
 402 #define LDAP_TAILQ_INSERT_TAIL(head, elm, field) do {                   \
 403         (elm)->field.tqe_next = NULL;                                   \
 404         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 405         *(head)->tqh_last = (elm);                                      \
 406         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 407 } while (0)
 408
 409 #define LDAP_TAILQ_INSERT_AFTER(head, listelm, elm, field) do {         \
 410         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 411                 (elm)->field.tqe_next->field.tqe_prev =                 \
 412                     &(elm)->field.tqe_next;                             \
 413         else                                                            \
 414                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 415         (listelm)->field.tqe_next = (elm);                              \
 416         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 417 } while (0)
 418
 419 #define LDAP_TAILQ_INSERT_BEFORE(listelm, elm, field) do {              \
 420         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 421         (elm)->field.tqe_next = (listelm);                              \
 422         *(listelm)->field.tqe_prev = (elm);                             \
 423         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 424 } while (0)
 425
 426 #define LDAP_TAILQ_REMOVE(head, elm, field) do {                        \
 427         if (((elm)->field.tqe_next) != NULL)                            \
 428                 (elm)->field.tqe_next->field.tqe_prev =                 \
 429                     (elm)->field.tqe_prev;                              \
 430         else                                                            \
 431                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 432         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 433 } while (0)
 434
 435 /*
 436  * Circular queue definitions.
 437  */
 438 #define LDAP_CIRCLEQ_HEAD(name, type)                                   \
 439 struct name {                                                           \
 440         struct type *cqh_first;         /* first element */             \
 441         struct type *cqh_last;          /* last element */              \
 442 }
 443
 444 #define LDAP_CIRCLEQ_ENTRY(type)                                        \
 445 struct {                                                                \
 446         struct type *cqe_next;          /* next element */              \
 447         struct type *cqe_prev;          /* previous element */          \
 448 }
 449
 450 /*
 451  * Circular queue functions.
 452  */
 453 #define LDAP_CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 454
 455 #define LDAP_CIRCLEQ_FIRST(head) ((head)->cqh_first)
 456
 457 #define LDAP_CIRCLEQ_FOREACH(var, head, field)                          \
 458         for((var) = (head)->cqh_first;                                  \
 459             (var) != (void *)(head);                                    \
 460             (var) = (var)->field.cqe_next)
 461
 462 #define LDAP_CIRCLEQ_FOREACH_REVERSE(var, head, field)                  \
 463         for((var) = (head)->cqh_last;                                   \
 464             (var) != (void *)(head);                                    \
 465             (var) = (var)->field.cqe_prev)
 466
 467 #define LDAP_CIRCLEQ_INIT(head) do {                                    \
 468         (head)->cqh_first = (void *)(head);                             \
 469         (head)->cqh_last = (void *)(head);                              \
 470 } while (0)
 471
 472 #define LDAP_CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {       \
 473         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 474         (elm)->field.cqe_prev = (listelm);                              \
 475         if ((listelm)->field.cqe_next == (void *)(head))                \
 476                 (head)->cqh_last = (elm);                               \
 477         else                                                            \
 478                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 479         (listelm)->field.cqe_next = (elm);                              \
 480 } while (0)
 481
 482 #define LDAP_CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {      \
 483         (elm)->field.cqe_next = (listelm);                              \
 484         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 485         if ((listelm)->field.cqe_prev == (void *)(head))                \
 486                 (head)->cqh_first = (elm);                              \
 487         else                                                            \
 488                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 489         (listelm)->field.cqe_prev = (elm);                              \
 490 } while (0)
 491
 492 #define LDAP_CIRCLEQ_INSERT_HEAD(head, elm, field) do {                 \
 493         (elm)->field.cqe_next = (head)->cqh_first;                      \
 494         (elm)->field.cqe_prev = (void *)(head);                         \
 495         if ((head)->cqh_last == (void *)(head))                         \
 496                 (head)->cqh_last = (elm);                               \
 497         else                                                            \
 498                 (head)->cqh_first->field.cqe_prev = (elm);              \
 499         (head)->cqh_first = (elm);                                      \
 500 } while (0)
 501
 502 #define LDAP_CIRCLEQ_INSERT_TAIL(head, elm, field) do {                 \
 503         (elm)->field.cqe_next = (void *)(head);                         \
 504         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 505         if ((head)->cqh_first == (void *)(head))                        \
 506                 (head)->cqh_first = (elm);                              \
 507         else                                                            \
 508                 (head)->cqh_last->field.cqe_next = (elm);               \
 509         (head)->cqh_last = (elm);                                       \
 510 } while (0)
 511
 512 #define LDAP_CIRCLEQ_LAST(head) ((head)->cqh_last)
 513
 514 #define LDAP_CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 515
 516 #define LDAP_CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 517
 518 #define LDAP_CIRCLEQ_REMOVE(head, elm, field) do {                      \
 519         if ((elm)->field.cqe_next == (void *)(head))                    \
 520                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 521         else                                                            \
 522                 (elm)->field.cqe_next->field.cqe_prev =                 \
 523                     (elm)->field.cqe_prev;                              \
 524         if ((elm)->field.cqe_prev == (void *)(head))                    \
 525                 (head)->cqh_first = (elm)->field.cqe_next;              \
 526         else                                                            \
 527                 (elm)->field.cqe_prev->field.cqe_next =                 \
 528                     (elm)->field.cqe_next;                              \
 529 } while (0)
 530
 531 #endif /* !_LDAP_QUEUE_H_ */