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 listnextnode_unchecked(X) ((X)->next)
  56 #define listhead(X) ((X) ? ((X)->head) : NULL)
  57 #define listtail(X) ((X) ? ((X)->tail) : NULL)
  58 #define listcount(X) ((X)->count)
  59 #define list_isempty(X) ((X)->head == NULL && (X)->tail == NULL)
  60 /* return X->data only if X and X->data are not NULL */
  61 #define listgetdata(X) (assert(X), assert((X)->data != NULL), (X)->data)
  62
  63 /*
  64  * Create a new linked list.
  65  *
  66  * Returns:
  67  *    the created linked list
  68  */
  69 extern struct list *list_new(void);
  70
  71 /*
  72  * Add a new element to the tail of a list.
  73  *
  74  * Runtime is O(1).
  75  *
  76  * list
  77  *    list to operate on
  78  *
  79  * data
  80  *    element to add
  81  */
  82 extern void listnode_add(struct list *list, void *data);
  83
  84 /*
  85  * Insert a new element into a list with insertion sort.
  86  *
  87  * If list->cmp is set, this function is used to determine the position to
  88  * insert the new element. If it is not set, this function is equivalent to
  89  * listnode_add.
  90  *
  91  * Runtime is O(N).
  92  *
  93  * list
  94  *    list to operate on
  95  *
  96  * val
  97  *    element to add
  98  */
  99 extern void listnode_add_sort(struct list *list, void *val);
 100
 101 /*
 102  * Insert a new element into a list after another element.
 103  *
 104  * Runtime is O(1).
 105  *
 106  * list
 107  *    list to operate on
 108  *
 109  * pp
 110  *    listnode to insert after
 111  *
 112  * data
 113  *    data to insert
 114  *
 115  * Returns:
 116  *    pointer to newly created listnode that contains the inserted data
 117  */
 118 extern struct listnode *listnode_add_after(struct list *list,
 119                                            struct listnode *pp, void *data);
 120
 121 /*
 122  * Insert a new element into a list before another element.
 123  *
 124  * Runtime is O(1).
 125  *
 126  * list
 127  *    list to operate on
 128  *
 129  * pp
 130  *    listnode to insert before
 131  *
 132  * data
 133  *    data to insert
 134  *
 135  * Returns:
 136  *    pointer to newly created listnode that contains the inserted data
 137  */
 138 extern struct listnode *listnode_add_before(struct list *list,
 139                                             struct listnode *pp, void *data);
 140
 141 /*
 142  * Move a node to the tail of a list.
 143  *
 144  * Runtime is O(1).
 145  *
 146  * list
 147  *    list to operate on
 148  *
 149  * node
 150  *    node to move to tail
 151  */
 152 extern void listnode_move_to_tail(struct list *list, struct listnode *node);
 153
 154 /*
 155  * Delete an element from a list.
 156  *
 157  * Runtime is O(N).
 158  *
 159  * list
 160  *    list to operate on
 161  *
 162  * data
 163  *    data to insert into list
 164  */
 165 extern void listnode_delete(struct list *list, void *data);
 166
 167 /*
 168  * Find the listnode corresponding to an element in a list.
 169  *
 170  * list
 171  *    list to operate on
 172  *
 173  * data
 174  *    data to search for
 175  *
 176  * Returns:
 177  *    pointer to listnode storing the given data if found, NULL otherwise
 178  */
 179 extern struct listnode *listnode_lookup(struct list *list, void *data);
 180
 181 /*
 182  * Retrieve the element at the head of a list.
 183  *
 184  * list
 185  *    list to operate on
 186  *
 187  * Returns:
 188  *    data at head of list, or NULL if list is empty
 189  */
 190 extern void *listnode_head(struct list *list);
 191
 192 /*
 193  * Duplicate a list.
 194  *
 195  * list
 196  *    list to duplicate
 197  *
 198  * Returns:
 199  *    copy of the list
 200  */
 201 extern struct list *list_dup(struct list *l);
 202
 203 /*
 204  * Sort a list in place.
 205  *
 206  * The sorting algorithm used is quicksort. Runtimes are equivalent to those of
 207  * quicksort plus N. The sort is not stable.
 208  *
 209  * For portability reasons, the comparison function takes a pointer to pointer
 210  * to void. This pointer should be dereferenced to get the actual data pointer.
 211  * It is always safe to do this.
 212  *
 213  * list
 214  *    list to sort
 215  *
 216  * cmp
 217  *    comparison function for quicksort. Should return less than, equal to or
 218  *    greater than zero if the first argument is less than, equal to or greater
 219  *    than the second argument.
 220  */
 221 extern void list_sort(struct list *list,
 222                       int (*cmp)(const void **, const void **));
 223
 224 /*
 225  * The usage of list_delete is being transitioned to pass in
 226  * the double pointer to remove use after free's.
 227  * list_free usage is deprecated, it leads to memory leaks
 228  * of the linklist nodes.  Please use list_delete_and_null
 229  *
 230  * In Oct of 2018, rename list_delete_and_null to list_delete
 231  * and remove list_delete_original and the list_delete #define
 232  * Additionally remove list_free entirely
 233  */
 234 #if defined(VERSION_TYPE_DEV) && CONFDATE > 20181001
 235 CPP_NOTICE("list_delete without double pointer is deprecated, please fixup")
 236 #endif
 237
 238 /*
 239  * Delete a list and NULL its pointer.
 240  *
 241  * If non-null, list->del is called with each data element.
 242  *
 243  * plist
 244  *    pointer to list pointer; this will be set to NULL after the list has been
 245  *    deleted
 246  */
 247 extern void list_delete_and_null(struct list **plist);
 248
 249 /*
 250  * Delete a list.
 251  *
 252  * If non-null, list->del is called with each data element.
 253  *
 254  * plist
 255  *    pointer to list pointer
 256  */
 257 extern void list_delete_original(struct list *list);
 258 #define list_delete(X)                                                         \
 259         list_delete_original((X))                                              \
 260                 CPP_WARN("Please transition to using list_delete_and_null")
 261 #define list_free(X)                                                           \
 262         list_delete_original((X))                                              \
 263                 CPP_WARN("Please transition tousing list_delete_and_null")
 264
 265 /*
 266  * Delete all nodes from a list without deleting the list itself.
 267  *
 268  * If non-null, list->del is called with each data element.
 269  *
 270  * list
 271  *    list to operate on
 272  */
 273 extern void list_delete_all_node(struct list *list);
 274
 275 /*
 276  * Delete a node from a list.
 277  *
 278  * list->del is not called with the data associated with the node.
 279  *
 280  * Runtime is O(1).
 281  *
 282  * list
 283  *    list to operate on
 284  *
 285  * node
 286  *    the node to delete
 287  */
 288 extern void list_delete_node(struct list *list, struct listnode *node);
 289
 290 /*
 291  * Append a list to an existing list.
 292  *
 293  * Runtime is O(N) where N = listcount(add).
 294  *
 295  * list
 296  *    list to append to
 297  *
 298  * add
 299  *    list to append
 300  */
 301 extern void list_add_list(struct list *list, struct list *add);
 302
 303 /* List iteration macro.
 304  * Usage: for (ALL_LIST_ELEMENTS (...) { ... }
 305  * It is safe to delete the listnode using this macro.
 306  */
 307 #define ALL_LIST_ELEMENTS(list, node, nextnode, data)                          \
 308         (node) = listhead(list), ((data) = NULL);                              \
 309         (node) != NULL                                                         \
 310                 && ((data) = listgetdata(node), (nextnode) = node->next, 1);   \
 311         (node) = (nextnode), ((data) = NULL)
 312
 313 /* read-only list iteration macro.
 314  * Usage: as per ALL_LIST_ELEMENTS, but not safe to delete the listnode Only
 315  * use this macro when it is *immediately obvious* the listnode is not
 316  * deleted in the body of the loop. Does not have forward-reference overhead
 317  * of previous macro.
 318  */
 319 #define ALL_LIST_ELEMENTS_RO(list, node, data)                                 \
 320         (node) = listhead(list), ((data) = NULL);                              \
 321         (node) != NULL && ((data) = listgetdata(node), 1);                     \
 322         (node) = listnextnode(node), ((data) = NULL)
 323
 324 /* these *do not* cleanup list nodes and referenced data, as the functions
 325  * do - these macros simply {de,at}tach a listnode from/to a list.
 326  */
 327
 328 /* List node attach macro.  */
 329 #define LISTNODE_ATTACH(L, N)                                                  \
 330         do {                                                                   \
 331                 (N)->prev = (L)->tail;                                         \
 332                 (N)->next = NULL;                                              \
 333                 if ((L)->head == NULL)                                         \
 334                         (L)->head = (N);                                       \
 335                 else                                                           \
 336                         (L)->tail->next = (N);                                 \
 337                 (L)->tail = (N);                                               \
 338                 (L)->count++;                                                  \
 339         } while (0)
 340
 341 /* List node detach macro.  */
 342 #define LISTNODE_DETACH(L, N)                                                  \
 343         do {                                                                   \
 344                 if ((N)->prev)                                                 \
 345                         (N)->prev->next = (N)->next;                           \
 346                 else                                                           \
 347                         (L)->head = (N)->next;                                 \
 348                 if ((N)->next)                                                 \
 349                         (N)->next->prev = (N)->prev;                           \
 350                 else                                                           \
 351                         (L)->tail = (N)->prev;                                 \
 352                 (L)->count--;                                                  \
 353         } while (0)
 354
 355 #endif /* _ZEBRA_LINKLIST_H */