b933281ed5
WALK_LIST_DELSAFE (in ev_run_list) is not safe with regard to deletion of next node. When some events are rescheduled during event execution, it may lead to deletion of next node and some events are skipped. Such skipped nodes remain in temporary list on stack and the last of them contains 'next' pointer to stack area. When this event is later scheduled, it damages stack area trying to remove it from the list, which leads to random crashes with funny backtraces :-) .
65 lines
1.9 KiB
C
65 lines
1.9 KiB
C
/*
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* BIRD Library -- Linked Lists
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*
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* (c) 1998 Martin Mares <mj@ucw.cz>
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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#ifndef _BIRD_LISTS_H_
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#define _BIRD_LISTS_H_
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/*
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* I admit the list structure is very tricky and also somewhat awkward,
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* but it's both efficient and easy to manipulate once one understands the
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* basic trick: The list head always contains two synthetic nodes which are
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* always present in the list: the head and the tail. But as the `next'
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* entry of the tail and the `prev' entry of the head are both NULL, the
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* nodes can overlap each other:
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*
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* head head_node.next
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* null head_node.prev tail_node.next
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* tail tail_node.prev
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*/
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typedef struct node {
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struct node *next, *prev;
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} node;
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typedef struct list { /* In fact two overlayed nodes */
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struct node *head, *null, *tail;
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} list;
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#define NODE (node *)
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#define HEAD(list) ((void *)((list).head))
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#define TAIL(list) ((void *)((list).tail))
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#define WALK_LIST(n,list) for(n=HEAD(list);(NODE (n))->next; \
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n=(void *)((NODE (n))->next))
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#define WALK_LIST_DELSAFE(n,nxt,list) \
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for(n=HEAD(list); nxt=(void *)((NODE (n))->next); n=(void *) nxt)
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/* WALK_LIST_FIRST supposes that called code removes each processed node */
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#define WALK_LIST_FIRST(n,list) \
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while(n=HEAD(list), (NODE (n))->next)
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#define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \
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n=(void *)((NODE (n))->prev))
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#define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \
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for(n=TAIL(list); prv=(void *)((NODE (n))->prev); n=(void *) prv)
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#define EMPTY_LIST(list) (!(list).head->next)
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void add_tail(list *, node *);
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void add_head(list *, node *);
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void rem_node(node *);
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void add_tail_list(list *, list *);
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void init_list(list *);
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void insert_node(node *, node *);
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#ifndef _BIRD_LISTS_C_
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#define LIST_INLINE extern inline
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#include "lib/lists.c"
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#undef LIST_INLINE
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#else
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#define LIST_INLINE
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#endif
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#endif
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