mirror of
https://github.com/openvswitch/ovs
synced 2025-10-15 14:17:18 +00:00
c7ecbf1e9c
Previously, list_moved() only worked with non-empty lists, but this was a caveat that was really easy to miss. parse_ofp_group_mod_file() had a bug because it didn't honor that restriction. This commit fixes the problem, by modifying the list_moved() interface to be harder to use incorrectly and then updating the callers. Reported-by: Simon Horman <simon.horman@netronome.com> Signed-off-by: Ben Pfaff <blp@nicira.com> Acked-by: Thomas Graf <tgraf@noironetworks.com>
272 lines
8.7 KiB
C
272 lines
8.7 KiB
C
/*
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* Copyright (c) 2008, 2009, 2010, 2011, 2013, 2015 Nicira, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef LIST_H
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#define LIST_H 1
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/* Doubly linked list. */
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#include <stdbool.h>
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#include <stddef.h>
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#include "util.h"
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#include "openvswitch/list.h"
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static inline void list_init(struct ovs_list *);
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static inline void list_poison(struct ovs_list *);
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/* List insertion. */
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static inline void list_insert(struct ovs_list *, struct ovs_list *);
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static inline void list_splice(struct ovs_list *before, struct ovs_list *first,
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struct ovs_list *last);
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static inline void list_push_front(struct ovs_list *, struct ovs_list *);
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static inline void list_push_back(struct ovs_list *, struct ovs_list *);
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static inline void list_replace(struct ovs_list *, const struct ovs_list *);
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static inline void list_moved(struct ovs_list *, const struct ovs_list *orig);
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static inline void list_move(struct ovs_list *dst, struct ovs_list *src);
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/* List removal. */
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static inline struct ovs_list *list_remove(struct ovs_list *);
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static inline struct ovs_list *list_pop_front(struct ovs_list *);
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static inline struct ovs_list *list_pop_back(struct ovs_list *);
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/* List elements. */
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static inline struct ovs_list *list_front(const struct ovs_list *);
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static inline struct ovs_list *list_back(const struct ovs_list *);
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/* List properties. */
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static inline size_t list_size(const struct ovs_list *);
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static inline bool list_is_empty(const struct ovs_list *);
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static inline bool list_is_singleton(const struct ovs_list *);
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static inline bool list_is_short(const struct ovs_list *);
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#define LIST_FOR_EACH(ITER, MEMBER, LIST) \
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for (INIT_CONTAINER(ITER, (LIST)->next, MEMBER); \
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&(ITER)->MEMBER != (LIST); \
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ASSIGN_CONTAINER(ITER, (ITER)->MEMBER.next, MEMBER))
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#define LIST_FOR_EACH_CONTINUE(ITER, MEMBER, LIST) \
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for (INIT_CONTAINER(ITER, (ITER)->MEMBER.next, MEMBER); \
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&(ITER)->MEMBER != (LIST); \
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ASSIGN_CONTAINER(ITER, (ITER)->MEMBER.next, MEMBER))
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#define LIST_FOR_EACH_REVERSE(ITER, MEMBER, LIST) \
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for (INIT_CONTAINER(ITER, (LIST)->prev, MEMBER); \
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&(ITER)->MEMBER != (LIST); \
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ASSIGN_CONTAINER(ITER, (ITER)->MEMBER.prev, MEMBER))
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#define LIST_FOR_EACH_REVERSE_CONTINUE(ITER, MEMBER, LIST) \
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for (ASSIGN_CONTAINER(ITER, (ITER)->MEMBER.prev, MEMBER); \
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&(ITER)->MEMBER != (LIST); \
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ASSIGN_CONTAINER(ITER, (ITER)->MEMBER.prev, MEMBER))
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#define LIST_FOR_EACH_SAFE(ITER, NEXT, MEMBER, LIST) \
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for (INIT_CONTAINER(ITER, (LIST)->next, MEMBER); \
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(&(ITER)->MEMBER != (LIST) \
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? INIT_CONTAINER(NEXT, (ITER)->MEMBER.next, MEMBER), 1 \
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: 0); \
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(ITER) = (NEXT))
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/* Inline implementations. */
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/* Initializes 'list' as an empty list. */
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static inline void
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list_init(struct ovs_list *list)
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{
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list->next = list->prev = list;
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}
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/* Initializes 'list' with pointers that will (probably) cause segfaults if
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* dereferenced and, better yet, show up clearly in a debugger. */
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static inline void
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list_poison(struct ovs_list *list)
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{
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memset(list, 0xcc, sizeof *list);
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}
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/* Inserts 'elem' just before 'before'. */
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static inline void
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list_insert(struct ovs_list *before, struct ovs_list *elem)
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{
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elem->prev = before->prev;
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elem->next = before;
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before->prev->next = elem;
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before->prev = elem;
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}
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/* Removes elements 'first' though 'last' (exclusive) from their current list,
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then inserts them just before 'before'. */
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static inline void
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list_splice(struct ovs_list *before, struct ovs_list *first, struct ovs_list *last)
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{
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if (first == last) {
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return;
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}
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last = last->prev;
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/* Cleanly remove 'first'...'last' from its current list. */
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first->prev->next = last->next;
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last->next->prev = first->prev;
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/* Splice 'first'...'last' into new list. */
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first->prev = before->prev;
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last->next = before;
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before->prev->next = first;
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before->prev = last;
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}
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/* Inserts 'elem' at the beginning of 'list', so that it becomes the front in
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'list'. */
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static inline void
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list_push_front(struct ovs_list *list, struct ovs_list *elem)
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{
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list_insert(list->next, elem);
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}
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/* Inserts 'elem' at the end of 'list', so that it becomes the back in
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* 'list'. */
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static inline void
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list_push_back(struct ovs_list *list, struct ovs_list *elem)
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{
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list_insert(list, elem);
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}
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/* Puts 'elem' in the position currently occupied by 'position'.
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* Afterward, 'position' is not part of a list. */
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static inline void
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list_replace(struct ovs_list *element, const struct ovs_list *position)
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{
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element->next = position->next;
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element->next->prev = element;
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element->prev = position->prev;
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element->prev->next = element;
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}
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/* Adjusts pointers around 'list' to compensate for 'list' having been moved
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* around in memory (e.g. as a consequence of realloc()), with original
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* location 'orig'.
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*
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* ('orig' likely points to freed memory, but this function does not
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* dereference 'orig', it only compares it to 'list'. In a very pedantic
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* language lawyer sense, this still yields undefined behavior, but it works
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* with actual compilers.) */
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static inline void
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list_moved(struct ovs_list *list, const struct ovs_list *orig)
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{
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if (list->next == orig) {
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list_init(list);
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} else {
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list->prev->next = list->next->prev = list;
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}
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}
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/* Initializes 'dst' with the contents of 'src', compensating for moving it
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* around in memory. The effect is that, if 'src' was the head of a list, now
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* 'dst' is the head of a list containing the same elements. */
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static inline void
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list_move(struct ovs_list *dst, struct ovs_list *src)
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{
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*dst = *src;
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list_moved(dst, src);
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}
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/* Removes 'elem' from its list and returns the element that followed it.
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Undefined behavior if 'elem' is not in a list. */
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static inline struct ovs_list *
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list_remove(struct ovs_list *elem)
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{
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elem->prev->next = elem->next;
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elem->next->prev = elem->prev;
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return elem->next;
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}
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/* Removes the front element from 'list' and returns it. Undefined behavior if
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'list' is empty before removal. */
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static inline struct ovs_list *
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list_pop_front(struct ovs_list *list)
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{
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struct ovs_list *front = list->next;
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list_remove(front);
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return front;
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}
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/* Removes the back element from 'list' and returns it.
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Undefined behavior if 'list' is empty before removal. */
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static inline struct ovs_list *
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list_pop_back(struct ovs_list *list)
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{
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struct ovs_list *back = list->prev;
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list_remove(back);
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return back;
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}
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/* Returns the front element in 'list_'.
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Undefined behavior if 'list_' is empty. */
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static inline struct ovs_list *
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list_front(const struct ovs_list *list_)
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{
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struct ovs_list *list = CONST_CAST(struct ovs_list *, list_);
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ovs_assert(!list_is_empty(list));
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return list->next;
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}
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/* Returns the back element in 'list_'.
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Undefined behavior if 'list_' is empty. */
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static inline struct ovs_list *
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list_back(const struct ovs_list *list_)
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{
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struct ovs_list *list = CONST_CAST(struct ovs_list *, list_);
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ovs_assert(!list_is_empty(list));
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return list->prev;
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}
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/* Returns the number of elements in 'list'.
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Runs in O(n) in the number of elements. */
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static inline size_t
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list_size(const struct ovs_list *list)
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{
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const struct ovs_list *e;
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size_t cnt = 0;
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for (e = list->next; e != list; e = e->next) {
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cnt++;
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}
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return cnt;
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}
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/* Returns true if 'list' is empty, false otherwise. */
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static inline bool
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list_is_empty(const struct ovs_list *list)
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{
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return list->next == list;
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}
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/* Returns true if 'list' has exactly 1 element, false otherwise. */
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static inline bool
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list_is_singleton(const struct ovs_list *list)
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{
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return list_is_short(list) && !list_is_empty(list);
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}
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/* Returns true if 'list' has 0 or 1 elements, false otherwise. */
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static inline bool
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list_is_short(const struct ovs_list *list)
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{
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return list->next == list->prev;
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}
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#endif /* list.h */
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