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