53e1b68390
This follows what the kernel is doing, c.f. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5fd54ace4721fc5ce2bb5aef6318fcf17f421460.
352 lines
10 KiB
C
352 lines
10 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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/***
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This file is part of systemd.
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Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include "alloc-util.h"
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#include "libudev-private.h"
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/**
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* SECTION:libudev-list
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* @short_description: list operation
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*
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* Libudev list operations.
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*/
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/**
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* udev_list_entry:
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*
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* Opaque object representing one entry in a list. An entry contains
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* contains a name, and optionally a value.
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*/
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struct udev_list_entry {
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struct udev_list_node node;
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struct udev_list *list;
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char *name;
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char *value;
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int num;
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};
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/* the list's head points to itself if empty */
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void udev_list_node_init(struct udev_list_node *list)
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{
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list->next = list;
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list->prev = list;
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}
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int udev_list_node_is_empty(struct udev_list_node *list)
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{
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return list->next == list;
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}
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static void udev_list_node_insert_between(struct udev_list_node *new,
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struct udev_list_node *prev,
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struct udev_list_node *next)
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{
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next->prev = new;
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new->next = next;
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new->prev = prev;
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prev->next = new;
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}
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void udev_list_node_append(struct udev_list_node *new, struct udev_list_node *list)
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{
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udev_list_node_insert_between(new, list->prev, list);
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}
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void udev_list_node_remove(struct udev_list_node *entry)
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{
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struct udev_list_node *prev = entry->prev;
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struct udev_list_node *next = entry->next;
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next->prev = prev;
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prev->next = next;
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entry->prev = NULL;
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entry->next = NULL;
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}
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/* return list entry which embeds this node */
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static inline struct udev_list_entry *list_node_to_entry(struct udev_list_node *node)
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{
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return container_of(node, struct udev_list_entry, node);
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}
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void udev_list_init(struct udev *udev, struct udev_list *list, bool unique)
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{
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memzero(list, sizeof(struct udev_list));
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list->udev = udev;
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list->unique = unique;
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udev_list_node_init(&list->node);
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}
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/* insert entry into a list as the last element */
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static void udev_list_entry_append(struct udev_list_entry *new, struct udev_list *list)
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{
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/* inserting before the list head make the node the last node in the list */
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udev_list_node_insert_between(&new->node, list->node.prev, &list->node);
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new->list = list;
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}
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/* insert entry into a list, before a given existing entry */
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static void udev_list_entry_insert_before(struct udev_list_entry *new, struct udev_list_entry *entry)
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{
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udev_list_node_insert_between(&new->node, entry->node.prev, &entry->node);
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new->list = entry->list;
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}
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/* binary search in sorted array */
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static int list_search(struct udev_list *list, const char *name)
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{
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unsigned int first, last;
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first = 0;
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last = list->entries_cur;
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while (first < last) {
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unsigned int i;
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int cmp;
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i = (first + last)/2;
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cmp = strcmp(name, list->entries[i]->name);
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if (cmp < 0)
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last = i;
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else if (cmp > 0)
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first = i+1;
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else
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return i;
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}
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/* not found, return negative insertion-index+1 */
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return -(first+1);
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}
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struct udev_list_entry *udev_list_entry_add(struct udev_list *list, const char *name, const char *value)
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{
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struct udev_list_entry *entry;
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int i = 0;
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if (list->unique) {
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/* lookup existing name or insertion-index */
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i = list_search(list, name);
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if (i >= 0) {
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entry = list->entries[i];
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free(entry->value);
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if (value == NULL) {
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entry->value = NULL;
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return entry;
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}
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entry->value = strdup(value);
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if (entry->value == NULL)
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return NULL;
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return entry;
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}
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}
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/* add new name */
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entry = new0(struct udev_list_entry, 1);
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if (entry == NULL)
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return NULL;
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entry->name = strdup(name);
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if (entry->name == NULL)
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return mfree(entry);
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if (value != NULL) {
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entry->value = strdup(value);
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if (entry->value == NULL) {
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free(entry->name);
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return mfree(entry);
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}
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}
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if (list->unique) {
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/* allocate or enlarge sorted array if needed */
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if (list->entries_cur >= list->entries_max) {
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struct udev_list_entry **entries;
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unsigned int add;
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add = list->entries_max;
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if (add < 1)
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add = 64;
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entries = realloc(list->entries, (list->entries_max + add) * sizeof(struct udev_list_entry *));
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if (entries == NULL) {
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free(entry->name);
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free(entry->value);
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return mfree(entry);
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}
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list->entries = entries;
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list->entries_max += add;
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}
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/* the negative i returned the insertion index */
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i = (-i)-1;
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/* insert into sorted list */
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if ((unsigned int)i < list->entries_cur)
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udev_list_entry_insert_before(entry, list->entries[i]);
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else
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udev_list_entry_append(entry, list);
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/* insert into sorted array */
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memmove(&list->entries[i+1], &list->entries[i],
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(list->entries_cur - i) * sizeof(struct udev_list_entry *));
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list->entries[i] = entry;
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list->entries_cur++;
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} else {
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udev_list_entry_append(entry, list);
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}
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return entry;
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}
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void udev_list_entry_delete(struct udev_list_entry *entry)
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{
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if (entry->list->entries != NULL) {
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int i;
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struct udev_list *list = entry->list;
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/* remove entry from sorted array */
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i = list_search(list, entry->name);
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if (i >= 0) {
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memmove(&list->entries[i], &list->entries[i+1],
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((list->entries_cur-1) - i) * sizeof(struct udev_list_entry *));
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list->entries_cur--;
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}
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}
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udev_list_node_remove(&entry->node);
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free(entry->name);
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free(entry->value);
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free(entry);
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}
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void udev_list_cleanup(struct udev_list *list)
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{
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struct udev_list_entry *entry_loop;
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struct udev_list_entry *entry_tmp;
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list->entries = mfree(list->entries);
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list->entries_cur = 0;
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list->entries_max = 0;
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udev_list_entry_foreach_safe(entry_loop, entry_tmp, udev_list_get_entry(list))
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udev_list_entry_delete(entry_loop);
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}
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struct udev_list_entry *udev_list_get_entry(struct udev_list *list)
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{
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if (udev_list_node_is_empty(&list->node))
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return NULL;
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return list_node_to_entry(list->node.next);
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}
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/**
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* udev_list_entry_get_next:
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* @list_entry: current entry
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*
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* Get the next entry from the list.
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*
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* Returns: udev_list_entry, #NULL if no more entries are available.
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*/
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_public_ struct udev_list_entry *udev_list_entry_get_next(struct udev_list_entry *list_entry)
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{
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struct udev_list_node *next;
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if (list_entry == NULL)
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return NULL;
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next = list_entry->node.next;
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/* empty list or no more entries */
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if (next == &list_entry->list->node)
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return NULL;
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return list_node_to_entry(next);
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}
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/**
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* udev_list_entry_get_by_name:
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* @list_entry: current entry
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* @name: name string to match
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*
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* Lookup an entry in the list with a certain name.
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*
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* Returns: udev_list_entry, #NULL if no matching entry is found.
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*/
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_public_ struct udev_list_entry *udev_list_entry_get_by_name(struct udev_list_entry *list_entry, const char *name)
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{
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int i;
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if (list_entry == NULL)
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return NULL;
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if (!list_entry->list->unique)
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return NULL;
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i = list_search(list_entry->list, name);
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if (i < 0)
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return NULL;
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return list_entry->list->entries[i];
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}
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/**
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* udev_list_entry_get_name:
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* @list_entry: current entry
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*
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* Get the name of a list entry.
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*
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* Returns: the name string of this entry.
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*/
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_public_ const char *udev_list_entry_get_name(struct udev_list_entry *list_entry)
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{
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if (list_entry == NULL)
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return NULL;
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return list_entry->name;
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}
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/**
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* udev_list_entry_get_value:
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* @list_entry: current entry
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*
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* Get the value of list entry.
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*
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* Returns: the value string of this entry.
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*/
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_public_ const char *udev_list_entry_get_value(struct udev_list_entry *list_entry)
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{
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if (list_entry == NULL)
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return NULL;
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return list_entry->value;
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}
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int udev_list_entry_get_num(struct udev_list_entry *list_entry)
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{
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if (list_entry == NULL)
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return -EINVAL;
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return list_entry->num;
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}
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void udev_list_entry_set_num(struct udev_list_entry *list_entry, int num)
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{
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if (list_entry == NULL)
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return;
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list_entry->num = num;
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}
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