busybox/libbb/llist.c

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/* vi: set sw=4 ts=4: */
/*
* linked list helper functions.
*
* Copyright (C) 2003 Glenn McGrath
* Copyright (C) 2005 Vladimir Oleynik
* Copyright (C) 2005 Bernhard Fischer
* Copyright (C) 2006 Rob Landley <rob@landley.net>
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include <stdlib.h>
#include "libbb.h"
/* Add data to the start of the linked list. */
void llist_add_to(llist_t **old_head, void *data)
{
llist_t *new_head = xmalloc(sizeof(llist_t));
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new_head->data = data;
new_head->link = *old_head;
*old_head = new_head;
}
/* Add data to the end of the linked list. */
void llist_add_to_end(llist_t **list_head, void *data)
{
llist_t *new_item = xmalloc(sizeof(llist_t));
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new_item->data = data;
new_item->link = NULL;
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if (!*list_head)
*list_head = new_item;
else {
llist_t *tail = *list_head;
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while (tail->link)
tail = tail->link;
tail->link = new_item;
}
}
/* Remove first element from the list and return it */
void *llist_pop(llist_t **head)
{
void *data, *next;
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if (!*head)
return NULL;
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data = (*head)->data;
next = (*head)->link;
free(*head);
*head = next;
return data;
}
/* Unlink arbitrary given element from the list */
void llist_unlink(llist_t **head, llist_t *elm)
{
llist_t *crt;
if (!(elm && *head))
return;
if (elm == *head) {
*head = (*head)->link;
return;
}
for (crt = *head; crt; crt = crt->link) {
if (crt->link == elm) {
crt->link = elm->link;
return;
}
}
}
/* Recursively free all elements in the linked list. If freeit != NULL
* call it on each datum in the list */
void llist_free(llist_t *elm, void (*freeit) (void *data))
{
while (elm) {
void *data = llist_pop(&elm);
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if (freeit)
freeit(data);
}
}
#ifdef UNUSED
/* Reverse list order. */
llist_t *llist_rev(llist_t *list)
{
llist_t *rev = NULL;
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while (list) {
llist_t *next = list->link;
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list->link = rev;
rev = list;
list = next;
}
return rev;
}
#endif