lib/linklist.h

   1 /* Generic linked list
   2  * Copyright (C) 1997, 2000 Kunihiro Ishiguro
   3  *
   4  * This file is part of GNU Zebra.
   5  *
   6  * GNU Zebra is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * GNU Zebra is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #ifndef _ZEBRA_LINKLIST_H
  22 #define _ZEBRA_LINKLIST_H
  23
  24 /* listnodes must always contain data to be valid. Adding an empty node
  25  * to a list is invalid
  26  */
  27 struct listnode {
  28         struct listnode *next;
  29         struct listnode *prev;
  30
  31         /* private member, use getdata() to retrieve, do not access directly */
  32         void *data;
  33 };
  34
  35 struct list {
  36         struct listnode *head;
  37         struct listnode *tail;
  38
  39         /* invariant: count is the number of listnodes in the list */
  40         unsigned int count;
  41
  42         /*
  43          * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
  44          * Used as definition of sorted for listnode_add_sort
  45          */
  46         int (*cmp)(void *val1, void *val2);
  47
  48         /* callback to free user-owned data when listnode is deleted. supplying
  49          * this callback is very much encouraged!
  50          */
  51         void (*del)(void *val);
  52 };
  53
  54 #define listnextnode(X) ((X) ? ((X)->next) : NULL)
  55 #define listhead(X) ((X) ? ((X)->head) : NULL)
  56 #define listtail(X) ((X) ? ((X)->tail) : NULL)
  57 #define listcount(X) ((X)->count)
  58 #define list_isempty(X) ((X)->head == NULL && (X)->tail == NULL)
  59 /* return X->data only if X and X->data are not NULL */
  60 #define listgetdata(X) (assert(X), assert((X)->data != NULL), (X)->data)
  61
  62 /* Prototypes. */
  63 extern struct list *
  64 list_new(void); /* encouraged: set list.del callback on new lists */
  65
  66 extern void listnode_add(struct list *, void *);
  67 extern void listnode_add_sort(struct list *, void *);
  68 extern struct listnode *listnode_add_after(struct list *, struct listnode *,
  69                                            void *);
  70 extern struct listnode *listnode_add_before(struct list *, struct listnode *,
  71                                             void *);
  72 extern void listnode_move_to_tail(struct list *, struct listnode *);
  73 extern void listnode_delete(struct list *, void *);
  74 extern struct listnode *listnode_lookup(struct list *, void *);
  75 extern void *listnode_head(struct list *);
  76
  77 /*
  78  * The usage of list_delete is being transitioned to pass in
  79  * the double pointer to remove use after free's.
  80  * list_free usage is deprecated, it leads to memory leaks
  81  * of the linklist nodes.  Please use list_delete_and_null
  82  *
  83  * In Oct of 2018, rename list_delete_and_null to list_delete
  84  * and remove list_delete_original and the list_delete #define
  85  * Additionally remove list_free entirely
  86  */
  87 #if CONFDATE > 20181001
  88 CPP_NOTICE("list_delete without double pointer is deprecated, please fixup")
  89 #endif
  90 extern void list_delete_and_null(struct list **);
  91 extern void list_delete_original(struct list *);
  92 #define list_delete(X) list_delete_original((X))                        \
  93         CPP_WARN("Please transition to using list_delete_and_null")
  94 #define list_free(X) list_delete_original((X))                          \
  95         CPP_WARN("Please transition tousing list_delete_and_null")
  96
  97 extern void list_delete_all_node(struct list *);
  98
  99 /* For ospfd and ospf6d. */
 100 extern void list_delete_node(struct list *, struct listnode *);
 101
 102 /* For ospf_spf.c */
 103 extern void list_add_list(struct list *, struct list *);
 104
 105 /* List iteration macro.
 106  * Usage: for (ALL_LIST_ELEMENTS (...) { ... }
 107  * It is safe to delete the listnode using this macro.
 108  */
 109 #define ALL_LIST_ELEMENTS(list, node, nextnode, data)                          \
 110         (node) = listhead(list), ((data) = NULL);                              \
 111         (node) != NULL                                                         \
 112                 && ((data) = listgetdata(node), (nextnode) = node->next, 1);   \
 113         (node) = (nextnode), ((data) = NULL)
 114
 115 /* read-only list iteration macro.
 116  * Usage: as per ALL_LIST_ELEMENTS, but not safe to delete the listnode Only
 117  * use this macro when it is *immediately obvious* the listnode is not
 118  * deleted in the body of the loop. Does not have forward-reference overhead
 119  * of previous macro.
 120  */
 121 #define ALL_LIST_ELEMENTS_RO(list, node, data)                                 \
 122         (node) = listhead(list), ((data) = NULL);                              \
 123         (node) != NULL && ((data) = listgetdata(node), 1);                     \
 124         (node) = listnextnode(node), ((data) = NULL)
 125
 126 /* these *do not* cleanup list nodes and referenced data, as the functions
 127  * do - these macros simply {de,at}tach a listnode from/to a list.
 128  */
 129
 130 /* List node attach macro.  */
 131 #define LISTNODE_ATTACH(L, N)                                                  \
 132         do {                                                                   \
 133                 (N)->prev = (L)->tail;                                         \
 134                 (N)->next = NULL;                                              \
 135                 if ((L)->head == NULL)                                         \
 136                         (L)->head = (N);                                       \
 137                 else                                                           \
 138                         (L)->tail->next = (N);                                 \
 139                 (L)->tail = (N);                                               \
 140                 (L)->count++;                                                  \
 141         } while (0)
 142
 143 /* List node detach macro.  */
 144 #define LISTNODE_DETACH(L, N)                                                  \
 145         do {                                                                   \
 146                 if ((N)->prev)                                                 \
 147                         (N)->prev->next = (N)->next;                           \
 148                 else                                                           \
 149                         (L)->head = (N)->next;                                 \
 150                 if ((N)->next)                                                 \
 151                         (N)->next->prev = (N)->prev;                           \
 152                 else                                                           \
 153                         (L)->tail = (N)->prev;                                 \
 154                 (L)->count--;                                                  \
 155         } while (0)
 156
 157 #endif /* _ZEBRA_LINKLIST_H */