ifupdown: code to deconstruct the state_list gracefully

(patch by Gabriel L. Somlo <somlo@cmu.edu>)

1 files changed, 27 insertions, 8 deletions

diff --git a/libbb/llist.c b/libbb/llist.c
index 0a5978a26..2b34f762c 100644
--- a/libbb/llist.c
+++ b/libbb/llist.c
@@ -45,21 +45,40 @@ void llist_add_to_end(llist_t ** list_head, void *data)
 /* Remove first element from the list and return it */
 void *llist_pop(llist_t ** head)
 {
-        void *data;
+        void *data, *next;
 
         if (!*head)
-                data = *head;
-        else {
-                void *next = (*head)->link;
+                return NULL;
 
-                data = (*head)->data;
-                free(*head);
-                *head = next;
-        }
+        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))