# Backport sys/queue.h from OpenBSD.

--- glibc-2.3.5/misc/sys/queue.h.orig	1999-06-08 21:03:17 +0000
+++ glibc-2.3.5/misc/sys/queue.h	2004-04-08 12:08:21 +0000
@@ -10,7 +10,7 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
+ * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
@@ -26,29 +26,47 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)queue.h	8.3 (Berkeley) 12/13/93
+ *	@(#)queue.h	8.5 (Berkeley) 8/20/94
  */
 
-#ifndef	_SYS_QUEUE_H
-#define	_SYS_QUEUE_H 1
+#ifndef	_SYS_QUEUE_H_
+#define	_SYS_QUEUE_H_
 
 /*
- * This file defines three types of data structures: lists, tail queues,
- * and circular queues.
+ * This file defines five types of data structures: singly-linked lists, 
+ * lists, simple queues, tail queues, and circular queues.
+ *
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction.  Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
  *
  * A list is headed by a single forward pointer (or an array of forward
  * pointers for a hash table header). The elements are doubly linked
  * so that an arbitrary element can be removed without a need to
- * traverse the list. New elements can be added to the list after
- * an existing element or at the head of the list. A list may only be
- * traversed in the forward direction.
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
  *
  * A tail queue is headed by a pair of pointers, one to the head of the
  * list and the other to the tail of the list. The elements are doubly
  * linked so that an arbitrary element can be removed without a need to
- * traverse the list. New elements can be added to the list after
- * an existing element, at the head of the list, or at the end of the
- * list. A tail queue may only be traversed in the forward direction.
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
  *
  * A circle queue is headed by a pair of pointers, one to the head of the
  * list and the other to the tail of the list. The elements are doubly
@@ -62,6 +80,78 @@
  */
 
 /*
+ * Singly-linked List definitions.
+ */
+#define SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+ 
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+ 
+#define SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+ 
+/*
+ * Singly-linked List access methods.
+ */
+#define	SLIST_FIRST(head)	((head)->slh_first)
+#define	SLIST_END(head)		NULL
+#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for((var) = SLIST_FIRST(head);					\
+	    (var) != SLIST_END(head);					\
+	    (var) = SLIST_NEXT(var, field))
+
+#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
+	for ((varp) = &SLIST_FIRST((head));				\
+	    ((var) = *(varp)) != SLIST_END(head);			\
+	    (varp) = &SLIST_NEXT((var), field))
+
+/*
+ * Singly-linked List functions.
+ */
+#define	SLIST_INIT(head) {						\
+	SLIST_FIRST(head) = SLIST_END(head);				\
+}
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
+	(slistelm)->field.sle_next = (elm);				\
+} while (0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.sle_next = (head)->slh_first;			\
+	(head)->slh_first = (elm);					\
+} while (0)
+
+#define	SLIST_REMOVE_NEXT(head, elm, field) do {			\
+	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
+} while (0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	(head)->slh_first = (head)->slh_first->field.sle_next;		\
+} while (0)
+
+#define SLIST_REMOVE(head, elm, type, field) do {			\
+	if ((head)->slh_first == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	}								\
+	else {								\
+		struct type *curelm = (head)->slh_first;		\
+		while( curelm->field.sle_next != (elm) )		\
+			curelm = curelm->field.sle_next;		\
+		curelm->field.sle_next =				\
+		    curelm->field.sle_next->field.sle_next;		\
+	}								\
+} while (0)
+
+/*
  * List definitions.
  */
 #define LIST_HEAD(name, type)						\
@@ -69,6 +159,9 @@ struct name {								\
 	struct type *lh_first;	/* first element */			\
 }
 
+#define LIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
 #define LIST_ENTRY(type)						\
 struct {								\
 	struct type *le_next;	/* next element */			\
@@ -76,35 +169,124 @@ struct {								\
 }
 
 /*
+ * List access methods
+ */
+#define	LIST_FIRST(head)		((head)->lh_first)
+#define	LIST_END(head)			NULL
+#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
+#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
+
+#define LIST_FOREACH(var, head, field)					\
+	for((var) = LIST_FIRST(head);					\
+	    (var)!= LIST_END(head);					\
+	    (var) = LIST_NEXT(var, field))
+
+/*
  * List functions.
  */
-#define	LIST_INIT(head) {						\
-	(head)->lh_first = NULL;					\
-}
+#define	LIST_INIT(head) do {						\
+	LIST_FIRST(head) = LIST_END(head);				\
+} while (0)
 
-#define LIST_INSERT_AFTER(listelm, elm, field) {			\
+#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
 	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
 		(listelm)->field.le_next->field.le_prev =		\
 		    &(elm)->field.le_next;				\
 	(listelm)->field.le_next = (elm);				\
 	(elm)->field.le_prev = &(listelm)->field.le_next;		\
-}
+} while (0)
 
-#define LIST_INSERT_HEAD(head, elm, field) {				\
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	(elm)->field.le_next = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &(elm)->field.le_next;		\
+} while (0)
+
+#define LIST_INSERT_HEAD(head, elm, field) do {				\
 	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
 		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 	(head)->lh_first = (elm);					\
 	(elm)->field.le_prev = &(head)->lh_first;			\
-}
+} while (0)
 
-#define LIST_REMOVE(elm, field) {					\
+#define LIST_REMOVE(elm, field) do {					\
 	if ((elm)->field.le_next != NULL)				\
-		(elm)->field.le_next->field.le_prev = 			\
+		(elm)->field.le_next->field.le_prev =			\
 		    (elm)->field.le_prev;				\
 	*(elm)->field.le_prev = (elm)->field.le_next;			\
+} while (0)
+
+#define LIST_REPLACE(elm, elm2, field) do {				\
+	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
+		(elm2)->field.le_next->field.le_prev =			\
+		    &(elm2)->field.le_next;				\
+	(elm2)->field.le_prev = (elm)->field.le_prev;			\
+	*(elm2)->field.le_prev = (elm2);				\
+} while (0)
+
+/*
+ * Simple queue definitions.
+ */
+#define SIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqh_first;	/* first element */			\
+	struct type **sqh_last;	/* addr of last next element */		\
+}
+
+#define SIMPLEQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).sqh_first }
+
+#define SIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqe_next;	/* next element */			\
 }
 
 /*
+ * Simple queue access methods.
+ */
+#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
+#define	SIMPLEQ_END(head)	    NULL
+#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
+#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
+
+#define SIMPLEQ_FOREACH(var, head, field)				\
+	for((var) = SIMPLEQ_FIRST(head);				\
+	    (var) != SIMPLEQ_END(head);					\
+	    (var) = SIMPLEQ_NEXT(var, field))
+
+/*
+ * Simple queue functions.
+ */
+#define	SIMPLEQ_INIT(head) do {						\
+	(head)->sqh_first = NULL;					\
+	(head)->sqh_last = &(head)->sqh_first;				\
+} while (0)
+
+#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(head)->sqh_first = (elm);					\
+} while (0)
+
+#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqe_next = NULL;					\
+	*(head)->sqh_last = (elm);					\
+	(head)->sqh_last = &(elm)->field.sqe_next;			\
+} while (0)
+
+#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(listelm)->field.sqe_next = (elm);				\
+} while (0)
+
+#define SIMPLEQ_REMOVE_HEAD(head, elm, field) do {			\
+	if (((head)->sqh_first = (elm)->field.sqe_next) == NULL)	\
+		(head)->sqh_last = &(head)->sqh_first;			\
+} while (0)
+
+/*
  * Tail queue definitions.
  */
 #define TAILQ_HEAD(name, type)						\
@@ -113,55 +295,99 @@ struct name {								\
 	struct type **tqh_last;	/* addr of last next element */		\
 }
 
+#define TAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).tqh_first }
+
 #define TAILQ_ENTRY(type)						\
 struct {								\
 	struct type *tqe_next;	/* next element */			\
 	struct type **tqe_prev;	/* address of previous next element */	\
 }
 
+/* 
+ * tail queue access methods 
+ */
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#define	TAILQ_END(head)			NULL
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+#define TAILQ_LAST(head, headname)					\
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
+/* XXX */
+#define TAILQ_PREV(elm, headname, field)				\
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+#define	TAILQ_EMPTY(head)						\
+	(TAILQ_FIRST(head) == TAILQ_END(head))
+
+#define TAILQ_FOREACH(var, head, field)					\
+	for((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_NEXT(var, field))
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
+	for((var) = TAILQ_LAST(head, headname);				\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_PREV(var, headname, field))
+
 /*
  * Tail queue functions.
  */
-#define	TAILQ_INIT(head) {						\
+#define	TAILQ_INIT(head) do {						\
 	(head)->tqh_first = NULL;					\
 	(head)->tqh_last = &(head)->tqh_first;				\
-}
+} while (0)
 
-#define TAILQ_INSERT_HEAD(head, elm, field) {				\
+#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
 	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
-		(elm)->field.tqe_next->field.tqe_prev =			\
+		(head)->tqh_first->field.tqe_prev =			\
 		    &(elm)->field.tqe_next;				\
 	else								\
 		(head)->tqh_last = &(elm)->field.tqe_next;		\
 	(head)->tqh_first = (elm);					\
 	(elm)->field.tqe_prev = &(head)->tqh_first;			\
-}
+} while (0)
 
-#define TAILQ_INSERT_TAIL(head, elm, field) {				\
+#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
 	(elm)->field.tqe_next = NULL;					\
 	(elm)->field.tqe_prev = (head)->tqh_last;			\
 	*(head)->tqh_last = (elm);					\
 	(head)->tqh_last = &(elm)->field.tqe_next;			\
-}
+} while (0)
 
-#define TAILQ_INSERT_AFTER(head, listelm, elm, field) {			\
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
 	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
-		(elm)->field.tqe_next->field.tqe_prev = 		\
+		(elm)->field.tqe_next->field.tqe_prev =			\
 		    &(elm)->field.tqe_next;				\
 	else								\
 		(head)->tqh_last = &(elm)->field.tqe_next;		\
 	(listelm)->field.tqe_next = (elm);				\
 	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
-}
+} while (0)
 
-#define TAILQ_REMOVE(head, elm, field) {				\
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
+	(elm)->field.tqe_next = (listelm);				\
+	*(listelm)->field.tqe_prev = (elm);				\
+	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
+} while (0)
+
+#define TAILQ_REMOVE(head, elm, field) do {				\
 	if (((elm)->field.tqe_next) != NULL)				\
-		(elm)->field.tqe_next->field.tqe_prev = 		\
+		(elm)->field.tqe_next->field.tqe_prev =			\
 		    (elm)->field.tqe_prev;				\
 	else								\
 		(head)->tqh_last = (elm)->field.tqe_prev;		\
 	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
-}
+} while (0)
+
+#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
+		(elm2)->field.tqe_next->field.tqe_prev =		\
+		    &(elm2)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm2)->field.tqe_next;		\
+	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
+	*(elm2)->field.tqe_prev = (elm2);				\
+} while (0)
 
 /*
  * Circular queue definitions.
@@ -172,6 +398,9 @@ struct name {								\
 	struct type *cqh_last;		/* last element */		\
 }
 
+#define CIRCLEQ_HEAD_INITIALIZER(head)					\
+	{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
+
 #define CIRCLEQ_ENTRY(type)						\
 struct {								\
 	struct type *cqe_next;		/* next element */		\
@@ -179,63 +408,98 @@ struct {								\
 }
 
 /*
+ * Circular queue access methods 
+ */
+#define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
+#define	CIRCLEQ_LAST(head)		((head)->cqh_last)
+#define	CIRCLEQ_END(head)		((void *)(head))
+#define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
+#define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
+#define	CIRCLEQ_EMPTY(head)						\
+	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
+
+#define CIRCLEQ_FOREACH(var, head, field)				\
+	for((var) = CIRCLEQ_FIRST(head);				\
+	    (var) != CIRCLEQ_END(head);					\
+	    (var) = CIRCLEQ_NEXT(var, field))
+
+#define CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
+	for((var) = CIRCLEQ_LAST(head);					\
+	    (var) != CIRCLEQ_END(head);					\
+	    (var) = CIRCLEQ_PREV(var, field))
+
+/*
  * Circular queue functions.
  */
-#define	CIRCLEQ_INIT(head) {						\
-	(head)->cqh_first = (void *)(head);				\
-	(head)->cqh_last = (void *)(head);				\
-}
+#define	CIRCLEQ_INIT(head) do {						\
+	(head)->cqh_first = CIRCLEQ_END(head);				\
+	(head)->cqh_last = CIRCLEQ_END(head);				\
+} while (0)
 
-#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {		\
+#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
 	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
 	(elm)->field.cqe_prev = (listelm);				\
-	if ((listelm)->field.cqe_next == (void *)(head))		\
+	if ((listelm)->field.cqe_next == CIRCLEQ_END(head))		\
 		(head)->cqh_last = (elm);				\
 	else								\
 		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
 	(listelm)->field.cqe_next = (elm);				\
-}
+} while (0)
 
-#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {		\
+#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
 	(elm)->field.cqe_next = (listelm);				\
 	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
-	if ((listelm)->field.cqe_prev == (void *)(head))		\
+	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))		\
 		(head)->cqh_first = (elm);				\
 	else								\
 		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
 	(listelm)->field.cqe_prev = (elm);				\
-}
+} while (0)
 
-#define CIRCLEQ_INSERT_HEAD(head, elm, field) {				\
+#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
 	(elm)->field.cqe_next = (head)->cqh_first;			\
-	(elm)->field.cqe_prev = (void *)(head);				\
-	if ((head)->cqh_last == (void *)(head))				\
+	(elm)->field.cqe_prev = CIRCLEQ_END(head);			\
+	if ((head)->cqh_last == CIRCLEQ_END(head))			\
 		(head)->cqh_last = (elm);				\
 	else								\
 		(head)->cqh_first->field.cqe_prev = (elm);		\
 	(head)->cqh_first = (elm);					\
-}
+} while (0)
 
-#define CIRCLEQ_INSERT_TAIL(head, elm, field) {				\
-	(elm)->field.cqe_next = (void *)(head);				\
+#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.cqe_next = CIRCLEQ_END(head);			\
 	(elm)->field.cqe_prev = (head)->cqh_last;			\
-	if ((head)->cqh_first == (void *)(head))			\
+	if ((head)->cqh_first == CIRCLEQ_END(head))			\
 		(head)->cqh_first = (elm);				\
 	else								\
 		(head)->cqh_last->field.cqe_next = (elm);		\
 	(head)->cqh_last = (elm);					\
-}
+} while (0)
 
-#define	CIRCLEQ_REMOVE(head, elm, field) {				\
-	if ((elm)->field.cqe_next == (void *)(head))			\
+#define	CIRCLEQ_REMOVE(head, elm, field) do {				\
+	if ((elm)->field.cqe_next == CIRCLEQ_END(head))			\
 		(head)->cqh_last = (elm)->field.cqe_prev;		\
 	else								\
 		(elm)->field.cqe_next->field.cqe_prev =			\
 		    (elm)->field.cqe_prev;				\
-	if ((elm)->field.cqe_prev == (void *)(head))			\
+	if ((elm)->field.cqe_prev == CIRCLEQ_END(head))			\
 		(head)->cqh_first = (elm)->field.cqe_next;		\
 	else								\
 		(elm)->field.cqe_prev->field.cqe_next =			\
 		    (elm)->field.cqe_next;				\
-}
-#endif	/* sys/queue.h */
+} while (0)
+
+#define CIRCLEQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==		\
+	    CIRCLEQ_END(head))						\
+		(head).cqh_last = (elm2);				\
+	else								\
+		(elm2)->field.cqe_next->field.cqe_prev = (elm2);	\
+	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==		\
+	    CIRCLEQ_END(head))						\
+		(head).cqh_first = (elm2);				\
+	else								\
+		(elm2)->field.cqe_prev->field.cqe_next = (elm2);	\
+} while (0)
+
+#endif	/* !_SYS_QUEUE_H_ */