bird/lib/lists.h
Maria Matejka ebd5751cde Babel: Seqno requests are properly decoupled from neighbors when the underlying interface disappears
When an interface disappears, all the neighbors are freed as well. Seqno
requests were anyway not decoupled from them, leading to strange
segfaults. This fix adds a proper seqno request list inside neighbors to
make sure that no pointer to neighbor is kept after free.
2021-05-30 13:29:21 +02:00

88 lines
2.6 KiB
C

/*
* BIRD Library -- Linked Lists
*
* (c) 1998 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#ifndef _BIRD_LISTS_H_
#define _BIRD_LISTS_H_
/*
* I admit the list structure is very tricky and also somewhat awkward,
* but it's both efficient and easy to manipulate once one understands the
* basic trick: The list head always contains two synthetic nodes which are
* always present in the list: the head and the tail. But as the `next'
* entry of the tail and the `prev' entry of the head are both NULL, the
* nodes can overlap each other:
*
* head head_node.next
* null head_node.prev tail_node.next
* tail tail_node.prev
*/
typedef struct node {
struct node *next, *prev;
} node;
typedef union list { /* In fact two overlayed nodes */
struct { /* Head node */
struct node head_node;
void *head_padding;
};
struct { /* Tail node */
void *tail_padding;
struct node tail_node;
};
struct { /* Split to separate pointers */
struct node *head;
struct node *null;
struct node *tail;
};
} list;
#define NODE (node *)
#define HEAD(list) ((void *)((list).head))
#define TAIL(list) ((void *)((list).tail))
#define NODE_NEXT(n) ((void *)((NODE (n))->next))
#define NODE_VALID(n) ((NODE (n))->next)
#define WALK_LIST(n,list) for(n=HEAD(list); NODE_VALID(n); n=NODE_NEXT(n))
#define WALK_LIST2(n,nn,list,pos) \
for(nn=(list).head; NODE_VALID(nn) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=nn->next)
#define WALK_LIST_DELSAFE(n,nxt,list) \
for(n=HEAD(list); nxt=NODE_NEXT(n); n=(void *) nxt)
#define WALK_LIST2_DELSAFE(n,nn,nxt,list,pos) \
for(nn=HEAD(list); (nxt=nn->next) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=nxt)
/* WALK_LIST_FIRST supposes that called code removes each processed node */
#define WALK_LIST_FIRST(n,list) \
while(n=HEAD(list), (NODE (n))->next)
#define WALK_LIST_FIRST2(n,pos,list) \
while(n=SKIP_BACK(typeof(*n),pos,HEAD(list)), (n)->pos.next)
#define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \
n=(void *)((NODE (n))->prev))
#define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \
for(n=TAIL(list); prv=(void *)((NODE (n))->prev); n=(void *) prv)
#define EMPTY_LIST(list) (!(list).head->next)
#ifndef _BIRD_LISTS_C_
#define LIST_INLINE static inline
#include "lib/lists.c"
#undef LIST_INLINE
#else /* _BIRD_LISTS_C_ */
#define LIST_INLINE
void add_tail(list *, node *);
void add_head(list *, node *);
void rem_node(node *);
void add_tail_list(list *, list *);
void init_list(list *);
void insert_node(node *, node *);
uint list_length(list *);
#endif
#endif