923edabe6c
queue functions. This includes a private queue.h header derived from FreeBSD. It is simpler to just use our own header rather than try to deal with macros that may or may not be present in various queue.h incarnations.
159 lines
3.7 KiB
C
159 lines
3.7 KiB
C
/*
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* Copyright (c) 2007-2008, 2010-2012 Todd C. Miller <Todd.Miller@courtesan.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <config.h>
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#include <sys/types.h>
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#include <stdio.h>
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#ifdef STDC_HEADERS
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# include <stdlib.h>
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# include <stddef.h>
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#else
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# ifdef HAVE_STDLIB_H
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# include <stdlib.h>
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# endif
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#endif /* STDC_HEADERS */
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#include "missing.h"
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#include "list.h"
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#ifdef DEBUG
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# include "fatal.h"
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#endif
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struct list_proto {
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struct list_proto *prev;
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struct list_proto *next;
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};
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struct list_head_proto {
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struct list_proto *first;
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struct list_proto *last;
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};
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/*
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* Pop the last element off the end of vh.
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* Returns the popped element.
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*/
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void *
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tq_pop(void *vh)
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{
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struct list_head_proto *h = (struct list_head_proto *)vh;
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void *last = NULL;
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if (!tq_empty(h)) {
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last = (void *)h->last;
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if (h->first == h->last) {
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h->first = NULL;
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h->last = NULL;
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} else {
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h->last = h->last->prev;
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h->last->next = NULL;
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}
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}
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return last;
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}
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/*
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* Convert from a semi-circle queue to normal doubly-linked list
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* with a head node.
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*/
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void
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list2tq(void *vh, void *vl)
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{
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struct list_head_proto *h = (struct list_head_proto *)vh;
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struct list_proto *l = (struct list_proto *)vl;
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if (l != NULL) {
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#ifdef DEBUG
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if (l->prev == NULL) {
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warningx_nodebug("list2tq called with non-semicircular list");
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abort();
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}
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#endif
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h->first = l;
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h->last = l->prev; /* l->prev points to the last member of l */
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l->prev = NULL; /* zero last ptr now that we have a head */
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} else {
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h->first = NULL;
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h->last = NULL;
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}
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}
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/*
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* Append one queue (or single entry) to another using the
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* circular properties of the prev pointer to simplify the logic.
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*/
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void
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list_append(void *vl1, void *vl2)
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{
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struct list_proto *l1 = (struct list_proto *)vl1;
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struct list_proto *l2 = (struct list_proto *)vl2;
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void *tail = l2->prev;
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l1->prev->next = l2;
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l2->prev = l1->prev;
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l1->prev = tail;
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}
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/*
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* Append the list of entries to the head node and convert
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* from a semi-circle queue to normal doubly-linked list.
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*/
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void
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tq_append(void *vh, void *vl)
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{
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struct list_head_proto *h = (struct list_head_proto *)vh;
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struct list_proto *l = (struct list_proto *)vl;
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void *tail = l->prev;
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if (h->first == NULL)
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h->first = l;
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else
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h->last->next = l;
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l->prev = h->last;
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h->last = tail;
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}
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/*
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* Remove element from the tail_queue
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*/
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void
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tq_remove(void *vh, void *vl)
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{
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struct list_head_proto *h = (struct list_head_proto *)vh;
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struct list_proto *l = (struct list_proto *)vl;
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if (h->first == l && h->last == l) {
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/* Single element in the list. */
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h->first = NULL;
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h->last = NULL;
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} else {
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/* At least two elements in the list. */
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if (h->first == l) {
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h->first = l->next;
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h->first->prev = h->first;
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} else if (h->last == l) {
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h->last = l->prev;
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h->last->next = NULL;
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} else {
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l->prev->next = l->next;
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l->next->prev = l->prev;
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}
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}
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}
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