stailq - Man Page

Standard C library (libc, -lc)

#include <sys/queue.h>

STAILQ_ENTRY(TYPE);

STAILQ_HEAD(HEADNAME, TYPE);
STAILQ_HEAD STAILQ_HEAD_INITIALIZER(STAILQ_HEAD head);
void STAILQ_INIT(STAILQ_HEAD *head);

int STAILQ_EMPTY(STAILQ_HEAD *head);

void STAILQ_INSERT_HEAD(STAILQ_HEAD *head,
                         struct TYPE *elm, STAILQ_ENTRY NAME);
void STAILQ_INSERT_TAIL(STAILQ_HEAD *head,
                         struct TYPE *elm, STAILQ_ENTRY NAME);
void STAILQ_INSERT_AFTER(STAILQ_HEAD *head, struct TYPE *listelm,
                         struct TYPE *elm, STAILQ_ENTRY NAME);

struct TYPE *STAILQ_FIRST(STAILQ_HEAD *head);
struct TYPE *STAILQ_NEXT(struct TYPE *elm, STAILQ_ENTRY NAME);

STAILQ_FOREACH(struct TYPE *var, STAILQ_HEAD *head, STAILQ_ENTRY NAME);

void STAILQ_REMOVE(STAILQ_HEAD *head, struct TYPE *elm, TYPE,
                         STAILQ_ENTRY NAME);
void STAILQ_REMOVE_HEAD(STAILQ_HEAD *head,
                         STAILQ_ENTRY NAME);

void STAILQ_CONCAT(STAILQ_HEAD *head1, STAILQ_HEAD *head2);

Note: Identical macros prefixed with SIMPLEQ instead of STAILQ exist; see Versions.

These macros define and operate on singly linked tail queues.

In the macro definitions, TYPE is the name of a user-defined structure, that must contain a field of type STAILQ_ENTRY, named NAME. The argument HEADNAME is the name of a user-defined structure that must be declared using the macro STAILQ_HEAD().

STAILQ_HEAD(HEADNAME, TYPE) head;

struct HEADNAME *headp;

STAILQ_EMPTY() returns nonzero if the queue is empty, and zero if the queue contains at least one entry.

STAILQ_FIRST(), and STAILQ_NEXT() return a pointer to the first or next TYPE structure, respectively.

STAILQ_HEAD_INITIALIZER() returns an initializer that can be assigned to the queue head.

Some BSDs provide SIMPLEQ instead of STAILQ. They are identical, but for historical reasons they were named differently on different BSDs. STAILQ originated on FreeBSD, and SIMPLEQ originated on NetBSD. For compatibility reasons, some systems provide both sets of macros. glibc provides both STAILQ and SIMPLEQ, which are identical except for a missing SIMPLEQ equivalent to STAILQ_CONCAT().

STAILQ_FOREACH() doesn't allow var to be removed or freed within the loop, as it would interfere with the traversal. STAILQ_FOREACH_SAFE(), which is present on the BSDs but is not present in glibc, fixes this limitation by allowing var to safely be removed from the list and freed from within the loop without interfering with the traversal.

BSD.

4.4BSD.

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/queue.h>

struct entry {
    int data;
    STAILQ_ENTRY(entry) entries;        /* Singly linked tail queue */
};

STAILQ_HEAD(stailhead, entry);

int
main(void)
{
    struct entry *n1, *n2, *n3, *np;
    struct stailhead head;                  /* Singly linked tail queue
                                               head */

    STAILQ_INIT(&head);                     /* Initialize the queue */

    n1 = malloc(sizeof(struct entry));      /* Insert at the head */
    STAILQ_INSERT_HEAD(&head, n1, entries);

    n1 = malloc(sizeof(struct entry));      /* Insert at the tail */
    STAILQ_INSERT_TAIL(&head, n1, entries);

    n2 = malloc(sizeof(struct entry));      /* Insert after */
    STAILQ_INSERT_AFTER(&head, n1, n2, entries);

    STAILQ_REMOVE(&head, n2, entry, entries); /* Deletion */
    free(n2);

    n3 = STAILQ_FIRST(&head);
    STAILQ_REMOVE_HEAD(&head, entries);     /* Deletion from the head */
    free(n3);

    n1 = STAILQ_FIRST(&head);
    n1->data = 0;
    for (unsigned int i = 1; i < 5; i++) {
        n1 = malloc(sizeof(struct entry));
        STAILQ_INSERT_HEAD(&head, n1, entries);
        n1->data = i;
    }
                                            /* Forward traversal */
    STAILQ_FOREACH(np, &head, entries)
        printf("%i\n", np->data);
                                            /* TailQ deletion */
    n1 = STAILQ_FIRST(&head);
    while (n1 != NULL) {
        n2 = STAILQ_NEXT(n1, entries);
        free(n1);
        n1 = n2;
    }
    STAILQ_INIT(&head);

    exit(EXIT_SUCCESS);
}

insque(3), queue(7)

queue(7).

The man pages simpleq(3), SIMPLEQ_EMPTY(3), SIMPLEQ_ENTRY(3), SIMPLEQ_FIRST(3), SIMPLEQ_FOREACH(3), SIMPLEQ_HEAD(3), SIMPLEQ_HEAD_INITIALIZER(3), SIMPLEQ_INIT(3), SIMPLEQ_INSERT_AFTER(3), SIMPLEQ_INSERT_HEAD(3), SIMPLEQ_INSERT_TAIL(3), SIMPLEQ_NEXT(3), SIMPLEQ_REMOVE(3), SIMPLEQ_REMOVE_HEAD(3), STAILQ_CONCAT(3), STAILQ_EMPTY(3), STAILQ_ENTRY(3), STAILQ_FIRST(3), STAILQ_FOREACH(3), STAILQ_HEAD(3), STAILQ_HEAD_INITIALIZER(3), STAILQ_INIT(3), STAILQ_INSERT_AFTER(3), STAILQ_INSERT_HEAD(3), STAILQ_INSERT_TAIL(3), STAILQ_NEXT(3), STAILQ_REMOVE(3) and STAILQ_REMOVE_HEAD(3) are aliases of stailq(3).