crypto/openssh/openbsd-compat/sys-queue.h

   1 /*      $OpenBSD: queue.h,v 1.45 2018/07/12 14:22:54 sashan Exp $       */
   2 /*      $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $       */
   3
   4 /*
   5  * Copyright (c) 1991, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  33  */
  34
  35 /* OPENBSD ORIGINAL: sys/sys/queue.h */
  36
  37 #ifndef _FAKE_QUEUE_H_
  38 #define _FAKE_QUEUE_H_
  39
  40 /*
  41  * Require for OS/X and other platforms that have old/broken/incomplete
  42  * <sys/queue.h>.
  43  */
  44 #undef CIRCLEQ_EMPTY
  45 #undef CIRCLEQ_END
  46 #undef CIRCLEQ_ENTRY
  47 #undef CIRCLEQ_FIRST
  48 #undef CIRCLEQ_FOREACH
  49 #undef CIRCLEQ_FOREACH_REVERSE
  50 #undef CIRCLEQ_HEAD
  51 #undef CIRCLEQ_HEAD_INITIALIZER
  52 #undef CIRCLEQ_INIT
  53 #undef CIRCLEQ_INSERT_AFTER
  54 #undef CIRCLEQ_INSERT_BEFORE
  55 #undef CIRCLEQ_INSERT_HEAD
  56 #undef CIRCLEQ_INSERT_TAIL
  57 #undef CIRCLEQ_LAST
  58 #undef CIRCLEQ_NEXT
  59 #undef CIRCLEQ_PREV
  60 #undef CIRCLEQ_REMOVE
  61 #undef CIRCLEQ_REPLACE
  62 #undef LIST_EMPTY
  63 #undef LIST_END
  64 #undef LIST_ENTRY
  65 #undef LIST_FIRST
  66 #undef LIST_FOREACH
  67 #undef LIST_FOREACH_SAFE
  68 #undef LIST_HEAD
  69 #undef LIST_HEAD_INITIALIZER
  70 #undef LIST_INIT
  71 #undef LIST_INSERT_AFTER
  72 #undef LIST_INSERT_BEFORE
  73 #undef LIST_INSERT_HEAD
  74 #undef LIST_NEXT
  75 #undef LIST_REMOVE
  76 #undef LIST_REPLACE
  77 #undef SIMPLEQ_CONCAT
  78 #undef SIMPLEQ_EMPTY
  79 #undef SIMPLEQ_END
  80 #undef SIMPLEQ_ENTRY
  81 #undef SIMPLEQ_FIRST
  82 #undef SIMPLEQ_FOREACH
  83 #undef SIMPLEQ_FOREACH_SAFE
  84 #undef SIMPLEQ_HEAD
  85 #undef SIMPLEQ_HEAD_INITIALIZER
  86 #undef SIMPLEQ_INIT
  87 #undef SIMPLEQ_INSERT_AFTER
  88 #undef SIMPLEQ_INSERT_HEAD
  89 #undef SIMPLEQ_INSERT_TAIL
  90 #undef SIMPLEQ_NEXT
  91 #undef SIMPLEQ_REMOVE_AFTER
  92 #undef SIMPLEQ_REMOVE_HEAD
  93 #undef SLIST_EMPTY
  94 #undef SLIST_END
  95 #undef SLIST_ENTRY
  96 #undef SLIST_FIRST
  97 #undef SLIST_FOREACH
  98 #undef SLIST_FOREACH_PREVPTR
  99 #undef SLIST_FOREACH_SAFE
 100 #undef SLIST_HEAD
 101 #undef SLIST_HEAD_INITIALIZER
 102 #undef SLIST_INIT
 103 #undef SLIST_INSERT_AFTER
 104 #undef SLIST_INSERT_HEAD
 105 #undef SLIST_NEXT
 106 #undef SLIST_REMOVE
 107 #undef SLIST_REMOVE_AFTER
 108 #undef SLIST_REMOVE_HEAD
 109 #undef SLIST_REMOVE_NEXT
 110 #undef TAILQ_CONCAT
 111 #undef TAILQ_EMPTY
 112 #undef TAILQ_END
 113 #undef TAILQ_ENTRY
 114 #undef TAILQ_FIRST
 115 #undef TAILQ_FOREACH
 116 #undef TAILQ_FOREACH_REVERSE
 117 #undef TAILQ_FOREACH_REVERSE_SAFE
 118 #undef TAILQ_FOREACH_SAFE
 119 #undef TAILQ_HEAD
 120 #undef TAILQ_HEAD_INITIALIZER
 121 #undef TAILQ_INIT
 122 #undef TAILQ_INSERT_AFTER
 123 #undef TAILQ_INSERT_BEFORE
 124 #undef TAILQ_INSERT_HEAD
 125 #undef TAILQ_INSERT_TAIL
 126 #undef TAILQ_LAST
 127 #undef TAILQ_NEXT
 128 #undef TAILQ_PREV
 129 #undef TAILQ_REMOVE
 130 #undef TAILQ_REPLACE
 131
 132 /*
 133  * This file defines five types of data structures: singly-linked lists,
 134  * lists, simple queues, tail queues and XOR simple queues.
 135  *
 136  *
 137  * A singly-linked list is headed by a single forward pointer. The elements
 138  * are singly linked for minimum space and pointer manipulation overhead at
 139  * the expense of O(n) removal for arbitrary elements. New elements can be
 140  * added to the list after an existing element or at the head of the list.
 141  * Elements being removed from the head of the list should use the explicit
 142  * macro for this purpose for optimum efficiency. A singly-linked list may
 143  * only be traversed in the forward direction.  Singly-linked lists are ideal
 144  * for applications with large datasets and few or no removals or for
 145  * implementing a LIFO queue.
 146  *
 147  * A list is headed by a single forward pointer (or an array of forward
 148  * pointers for a hash table header). The elements are doubly linked
 149  * so that an arbitrary element can be removed without a need to
 150  * traverse the list. New elements can be added to the list before
 151  * or after an existing element or at the head of the list. A list
 152  * may only be traversed in the forward direction.
 153  *
 154  * A simple queue is headed by a pair of pointers, one to the head of the
 155  * list and the other to the tail of the list. The elements are singly
 156  * linked to save space, so elements can only be removed from the
 157  * head of the list. New elements can be added to the list before or after
 158  * an existing element, at the head of the list, or at the end of the
 159  * list. A simple queue may only be traversed in the forward direction.
 160  *
 161  * A tail queue is headed by a pair of pointers, one to the head of the
 162  * list and the other to the tail of the list. The elements are doubly
 163  * linked so that an arbitrary element can be removed without a need to
 164  * traverse the list. New elements can be added to the list before or
 165  * after an existing element, at the head of the list, or at the end of
 166  * the list. A tail queue may be traversed in either direction.
 167  *
 168  * An XOR simple queue is used in the same way as a regular simple queue.
 169  * The difference is that the head structure also includes a "cookie" that
 170  * is XOR'd with the queue pointer (first, last or next) to generate the
 171  * real pointer value.
 172  *
 173  * For details on the use of these macros, see the queue(3) manual page.
 174  */
 175
 176 #if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
 177 #define _Q_INVALID ((void *)-1)
 178 #define _Q_INVALIDATE(a) (a) = _Q_INVALID
 179 #else
 180 #define _Q_INVALIDATE(a)
 181 #endif
 182
 183 /*
 184  * Singly-linked List definitions.
 185  */
 186 #define SLIST_HEAD(name, type)                                          \
 187 struct name {                                                           \
 188         struct type *slh_first; /* first element */                     \
 189 }
 190
 191 #define SLIST_HEAD_INITIALIZER(head)                                    \
 192         { NULL }
 193
 194 #define SLIST_ENTRY(type)                                               \
 195 struct {                                                                \
 196         struct type *sle_next;  /* next element */                      \
 197 }
 198
 199 /*
 200  * Singly-linked List access methods.
 201  */
 202 #define SLIST_FIRST(head)       ((head)->slh_first)
 203 #define SLIST_END(head)         NULL
 204 #define SLIST_EMPTY(head)       (SLIST_FIRST(head) == SLIST_END(head))
 205 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 206
 207 #define SLIST_FOREACH(var, head, field)                                 \
 208         for((var) = SLIST_FIRST(head);                                  \
 209             (var) != SLIST_END(head);                                   \
 210             (var) = SLIST_NEXT(var, field))
 211
 212 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 213         for ((var) = SLIST_FIRST(head);                         \
 214             (var) && ((tvar) = SLIST_NEXT(var, field), 1);              \
 215             (var) = (tvar))
 216
 217 /*
 218  * Singly-linked List functions.
 219  */
 220 #define SLIST_INIT(head) {                                              \
 221         SLIST_FIRST(head) = SLIST_END(head);                            \
 222 }
 223
 224 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 225         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 226         (slistelm)->field.sle_next = (elm);                             \
 227 } while (0)
 228
 229 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 230         (elm)->field.sle_next = (head)->slh_first;                      \
 231         (head)->slh_first = (elm);                                      \
 232 } while (0)
 233
 234 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 235         (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;  \
 236 } while (0)
 237
 238 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 239         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 240 } while (0)
 241
 242 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 243         if ((head)->slh_first == (elm)) {                               \
 244                 SLIST_REMOVE_HEAD((head), field);                       \
 245         } else {                                                        \
 246                 struct type *curelm = (head)->slh_first;                \
 247                                                                         \
 248                 while (curelm->field.sle_next != (elm))                 \
 249                         curelm = curelm->field.sle_next;                \
 250                 curelm->field.sle_next =                                \
 251                     curelm->field.sle_next->field.sle_next;             \
 252         }                                                               \
 253         _Q_INVALIDATE((elm)->field.sle_next);                           \
 254 } while (0)
 255
 256 /*
 257  * List definitions.
 258  */
 259 #define LIST_HEAD(name, type)                                           \
 260 struct name {                                                           \
 261         struct type *lh_first;  /* first element */                     \
 262 }
 263
 264 #define LIST_HEAD_INITIALIZER(head)                                     \
 265         { NULL }
 266
 267 #define LIST_ENTRY(type)                                                \
 268 struct {                                                                \
 269         struct type *le_next;   /* next element */                      \
 270         struct type **le_prev;  /* address of previous next element */  \
 271 }
 272
 273 /*
 274  * List access methods.
 275  */
 276 #define LIST_FIRST(head)                ((head)->lh_first)
 277 #define LIST_END(head)                  NULL
 278 #define LIST_EMPTY(head)                (LIST_FIRST(head) == LIST_END(head))
 279 #define LIST_NEXT(elm, field)           ((elm)->field.le_next)
 280
 281 #define LIST_FOREACH(var, head, field)                                  \
 282         for((var) = LIST_FIRST(head);                                   \
 283             (var)!= LIST_END(head);                                     \
 284             (var) = LIST_NEXT(var, field))
 285
 286 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 287         for ((var) = LIST_FIRST(head);                          \
 288             (var) && ((tvar) = LIST_NEXT(var, field), 1);               \
 289             (var) = (tvar))
 290
 291 /*
 292  * List functions.
 293  */
 294 #define LIST_INIT(head) do {                                            \
 295         LIST_FIRST(head) = LIST_END(head);                              \
 296 } while (0)
 297
 298 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 299         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 300                 (listelm)->field.le_next->field.le_prev =               \
 301                     &(elm)->field.le_next;                              \
 302         (listelm)->field.le_next = (elm);                               \
 303         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 304 } while (0)
 305
 306 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 307         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 308         (elm)->field.le_next = (listelm);                               \
 309         *(listelm)->field.le_prev = (elm);                              \
 310         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 311 } while (0)
 312
 313 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 314         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 315                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 316         (head)->lh_first = (elm);                                       \
 317         (elm)->field.le_prev = &(head)->lh_first;                       \
 318 } while (0)
 319
 320 #define LIST_REMOVE(elm, field) do {                                    \
 321         if ((elm)->field.le_next != NULL)                               \
 322                 (elm)->field.le_next->field.le_prev =                   \
 323                     (elm)->field.le_prev;                               \
 324         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 325         _Q_INVALIDATE((elm)->field.le_prev);                            \
 326         _Q_INVALIDATE((elm)->field.le_next);                            \
 327 } while (0)
 328
 329 #define LIST_REPLACE(elm, elm2, field) do {                             \
 330         if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)     \
 331                 (elm2)->field.le_next->field.le_prev =                  \
 332                     &(elm2)->field.le_next;                             \
 333         (elm2)->field.le_prev = (elm)->field.le_prev;                   \
 334         *(elm2)->field.le_prev = (elm2);                                \
 335         _Q_INVALIDATE((elm)->field.le_prev);                            \
 336         _Q_INVALIDATE((elm)->field.le_next);                            \
 337 } while (0)
 338
 339 /*
 340  * Simple queue definitions.
 341  */
 342 #define SIMPLEQ_HEAD(name, type)                                        \
 343 struct name {                                                           \
 344         struct type *sqh_first; /* first element */                     \
 345         struct type **sqh_last; /* addr of last next element */         \
 346 }
 347
 348 #define SIMPLEQ_HEAD_INITIALIZER(head)                                  \
 349         { NULL, &(head).sqh_first }
 350
 351 #define SIMPLEQ_ENTRY(type)                                             \
 352 struct {                                                                \
 353         struct type *sqe_next;  /* next element */                      \
 354 }
 355
 356 /*
 357  * Simple queue access methods.
 358  */
 359 #define SIMPLEQ_FIRST(head)         ((head)->sqh_first)
 360 #define SIMPLEQ_END(head)           NULL
 361 #define SIMPLEQ_EMPTY(head)         (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
 362 #define SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
 363
 364 #define SIMPLEQ_FOREACH(var, head, field)                               \
 365         for((var) = SIMPLEQ_FIRST(head);                                \
 366             (var) != SIMPLEQ_END(head);                                 \
 367             (var) = SIMPLEQ_NEXT(var, field))
 368
 369 #define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)                    \
 370         for ((var) = SIMPLEQ_FIRST(head);                               \
 371             (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1);            \
 372             (var) = (tvar))
 373
 374 /*
 375  * Simple queue functions.
 376  */
 377 #define SIMPLEQ_INIT(head) do {                                         \
 378         (head)->sqh_first = NULL;                                       \
 379         (head)->sqh_last = &(head)->sqh_first;                          \
 380 } while (0)
 381
 382 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do {                      \
 383         if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)        \
 384                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 385         (head)->sqh_first = (elm);                                      \
 386 } while (0)
 387
 388 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do {                      \
 389         (elm)->field.sqe_next = NULL;                                   \
 390         *(head)->sqh_last = (elm);                                      \
 391         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 392 } while (0)
 393
 394 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 395         if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
 396                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 397         (listelm)->field.sqe_next = (elm);                              \
 398 } while (0)
 399
 400 #define SIMPLEQ_REMOVE_HEAD(head, field) do {                   \
 401         if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
 402                 (head)->sqh_last = &(head)->sqh_first;                  \
 403 } while (0)
 404
 405 #define SIMPLEQ_REMOVE_AFTER(head, elm, field) do {                     \
 406         if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
 407             == NULL)                                                    \
 408                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 409 } while (0)
 410
 411 #define SIMPLEQ_CONCAT(head1, head2) do {                               \
 412         if (!SIMPLEQ_EMPTY((head2))) {                                  \
 413                 *(head1)->sqh_last = (head2)->sqh_first;                \
 414                 (head1)->sqh_last = (head2)->sqh_last;                  \
 415                 SIMPLEQ_INIT((head2));                                  \
 416         }                                                               \
 417 } while (0)
 418
 419 /*
 420  * XOR Simple queue definitions.
 421  */
 422 #define XSIMPLEQ_HEAD(name, type)                                       \
 423 struct name {                                                           \
 424         struct type *sqx_first; /* first element */                     \
 425         struct type **sqx_last; /* addr of last next element */         \
 426         unsigned long sqx_cookie;                                       \
 427 }
 428
 429 #define XSIMPLEQ_ENTRY(type)                                            \
 430 struct {                                                                \
 431         struct type *sqx_next;  /* next element */                      \
 432 }
 433
 434 /*
 435  * XOR Simple queue access methods.
 436  */
 437 #define XSIMPLEQ_XOR(head, ptr)     ((__typeof(ptr))((head)->sqx_cookie ^ \
 438                                         (unsigned long)(ptr)))
 439 #define XSIMPLEQ_FIRST(head)        XSIMPLEQ_XOR(head, ((head)->sqx_first))
 440 #define XSIMPLEQ_END(head)          NULL
 441 #define XSIMPLEQ_EMPTY(head)        (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
 442 #define XSIMPLEQ_NEXT(head, elm, field)    XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
 443
 444
 445 #define XSIMPLEQ_FOREACH(var, head, field)                              \
 446         for ((var) = XSIMPLEQ_FIRST(head);                              \
 447             (var) != XSIMPLEQ_END(head);                                \
 448             (var) = XSIMPLEQ_NEXT(head, var, field))
 449
 450 #define XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar)                   \
 451         for ((var) = XSIMPLEQ_FIRST(head);                              \
 452             (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1);     \
 453             (var) = (tvar))
 454
 455 /*
 456  * XOR Simple queue functions.
 457  */
 458 #define XSIMPLEQ_INIT(head) do {                                        \
 459         arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); \
 460         (head)->sqx_first = XSIMPLEQ_XOR(head, NULL);                   \
 461         (head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first);      \
 462 } while (0)
 463
 464 #define XSIMPLEQ_INSERT_HEAD(head, elm, field) do {                     \
 465         if (((elm)->field.sqx_next = (head)->sqx_first) ==              \
 466             XSIMPLEQ_XOR(head, NULL))                                   \
 467                 (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
 468         (head)->sqx_first = XSIMPLEQ_XOR(head, (elm));                  \
 469 } while (0)
 470
 471 #define XSIMPLEQ_INSERT_TAIL(head, elm, field) do {                     \
 472         (elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL);               \
 473         *(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); \
 474         (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);  \
 475 } while (0)
 476
 477 #define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 478         if (((elm)->field.sqx_next = (listelm)->field.sqx_next) ==      \
 479             XSIMPLEQ_XOR(head, NULL))                                   \
 480                 (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
 481         (listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm));          \
 482 } while (0)
 483
 484 #define XSIMPLEQ_REMOVE_HEAD(head, field) do {                          \
 485         if (((head)->sqx_first = XSIMPLEQ_XOR(head,                     \
 486             (head)->sqx_first)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) \
 487                 (head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
 488 } while (0)
 489
 490 #define XSIMPLEQ_REMOVE_AFTER(head, elm, field) do {                    \
 491         if (((elm)->field.sqx_next = XSIMPLEQ_XOR(head,                 \
 492             (elm)->field.sqx_next)->field.sqx_next)                     \
 493             == XSIMPLEQ_XOR(head, NULL))                                \
 494                 (head)->sqx_last =                                      \
 495                     XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);         \
 496 } while (0)
 497
 498
 499 /*
 500  * Tail queue definitions.
 501  */
 502 #define TAILQ_HEAD(name, type)                                          \
 503 struct name {                                                           \
 504         struct type *tqh_first; /* first element */                     \
 505         struct type **tqh_last; /* addr of last next element */         \
 506 }
 507
 508 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 509         { NULL, &(head).tqh_first }
 510
 511 #define TAILQ_ENTRY(type)                                               \
 512 struct {                                                                \
 513         struct type *tqe_next;  /* next element */                      \
 514         struct type **tqe_prev; /* address of previous next element */  \
 515 }
 516
 517 /*
 518  * Tail queue access methods.
 519  */
 520 #define TAILQ_FIRST(head)               ((head)->tqh_first)
 521 #define TAILQ_END(head)                 NULL
 522 #define TAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 523 #define TAILQ_LAST(head, headname)                                      \
 524         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 525 /* XXX */
 526 #define TAILQ_PREV(elm, headname, field)                                \
 527         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 528 #define TAILQ_EMPTY(head)                                               \
 529         (TAILQ_FIRST(head) == TAILQ_END(head))
 530
 531 #define TAILQ_FOREACH(var, head, field)                                 \
 532         for((var) = TAILQ_FIRST(head);                                  \
 533             (var) != TAILQ_END(head);                                   \
 534             (var) = TAILQ_NEXT(var, field))
 535
 536 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 537         for ((var) = TAILQ_FIRST(head);                                 \
 538             (var) != TAILQ_END(head) &&                                 \
 539             ((tvar) = TAILQ_NEXT(var, field), 1);                       \
 540             (var) = (tvar))
 541
 542
 543 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 544         for((var) = TAILQ_LAST(head, headname);                         \
 545             (var) != TAILQ_END(head);                                   \
 546             (var) = TAILQ_PREV(var, headname, field))
 547
 548 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 549         for ((var) = TAILQ_LAST(head, headname);                        \
 550             (var) != TAILQ_END(head) &&                                 \
 551             ((tvar) = TAILQ_PREV(var, headname, field), 1);             \
 552             (var) = (tvar))
 553
 554 /*
 555  * Tail queue functions.
 556  */
 557 #define TAILQ_INIT(head) do {                                           \
 558         (head)->tqh_first = NULL;                                       \
 559         (head)->tqh_last = &(head)->tqh_first;                          \
 560 } while (0)
 561
 562 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 563         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 564                 (head)->tqh_first->field.tqe_prev =                     \
 565                     &(elm)->field.tqe_next;                             \
 566         else                                                            \
 567                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 568         (head)->tqh_first = (elm);                                      \
 569         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 570 } while (0)
 571
 572 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 573         (elm)->field.tqe_next = NULL;                                   \
 574         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 575         *(head)->tqh_last = (elm);                                      \
 576         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 577 } while (0)
 578
 579 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 580         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 581                 (elm)->field.tqe_next->field.tqe_prev =                 \
 582                     &(elm)->field.tqe_next;                             \
 583         else                                                            \
 584                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 585         (listelm)->field.tqe_next = (elm);                              \
 586         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 587 } while (0)
 588
 589 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 590         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 591         (elm)->field.tqe_next = (listelm);                              \
 592         *(listelm)->field.tqe_prev = (elm);                             \
 593         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 594 } while (0)
 595
 596 #define TAILQ_REMOVE(head, elm, field) do {                             \
 597         if (((elm)->field.tqe_next) != NULL)                            \
 598                 (elm)->field.tqe_next->field.tqe_prev =                 \
 599                     (elm)->field.tqe_prev;                              \
 600         else                                                            \
 601                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 602         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 603         _Q_INVALIDATE((elm)->field.tqe_prev);                           \
 604         _Q_INVALIDATE((elm)->field.tqe_next);                           \
 605 } while (0)
 606
 607 #define TAILQ_REPLACE(head, elm, elm2, field) do {                      \
 608         if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)   \
 609                 (elm2)->field.tqe_next->field.tqe_prev =                \
 610                     &(elm2)->field.tqe_next;                            \
 611         else                                                            \
 612                 (head)->tqh_last = &(elm2)->field.tqe_next;             \
 613         (elm2)->field.tqe_prev = (elm)->field.tqe_prev;                 \
 614         *(elm2)->field.tqe_prev = (elm2);                               \
 615         _Q_INVALIDATE((elm)->field.tqe_prev);                           \
 616         _Q_INVALIDATE((elm)->field.tqe_next);                           \
 617 } while (0)
 618
 619 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 620         if (!TAILQ_EMPTY(head2)) {                                      \
 621                 *(head1)->tqh_last = (head2)->tqh_first;                \
 622                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 623                 (head1)->tqh_last = (head2)->tqh_last;                  \
 624                 TAILQ_INIT((head2));                                    \
 625         }                                                               \
 626 } while (0)
 627
 628 #endif  /* !_SYS_QUEUE_H_ */