systemd/libudev/libudev-list.c

/*
 * libudev - interface to udev device information
 *
 * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

#include "libudev.h"
#include "libudev-private.h"

/**
 * SECTION:libudev-list
 * @short_description: list operation
 *
 * Libudev list operations.
 */

/**
 * udev_list_entry:
 *
 * Opaque object representing one entry in a list. An entry contains
 * contains a name, and optionally a value.
 */
struct udev_list_entry {
	struct udev_list_node node;
	struct udev *udev;
	struct udev_list_node *list;
	char *name;
	char *value;
	int num;
};

/* the list's head points to itself if empty */
void udev_list_init(struct udev_list_node *list)
{
	list->next = list;
	list->prev = list;
}

int udev_list_is_empty(struct udev_list_node *list)
{
	return list->next == list;
}

static void udev_list_node_insert_between(struct udev_list_node *new,
					  struct udev_list_node *prev,
					  struct udev_list_node *next)
{
	next->prev = new;
	new->next = next;
	new->prev = prev;
	prev->next = new;
}

void udev_list_node_append(struct udev_list_node *new, struct udev_list_node *list)
{
	udev_list_node_insert_between(new, list->prev, list);
}

void udev_list_node_remove(struct udev_list_node *entry)
{
	struct udev_list_node *prev = entry->prev;
	struct udev_list_node *next = entry->next;

	next->prev = prev;
	prev->next = next;

	entry->prev = NULL;
	entry->next = NULL;
}

/* return list entry which embeds this node */
static struct udev_list_entry *list_node_to_entry(struct udev_list_node *node)
{
	char *list;

	list = (char *)node;
	list -= offsetof(struct udev_list_entry, node);
	return (struct udev_list_entry *)list;
}

/* insert entry into a list as the last element  */
void udev_list_entry_append(struct udev_list_entry *new, struct udev_list_node *list)
{
	/* inserting before the list head make the node the last node in the list */
	udev_list_node_insert_between(&new->node, list->prev, list);
	new->list = list;
}

/* remove entry from a list */
void udev_list_entry_remove(struct udev_list_entry *entry)
{
	udev_list_node_remove(&entry->node);
	entry->list = NULL;
}

/* insert entry into a list, before a given existing entry */
void udev_list_entry_insert_before(struct udev_list_entry *new, struct udev_list_entry *entry)
{
	udev_list_node_insert_between(&new->node, entry->node.prev, &entry->node);
	new->list = entry->list;
}

struct udev_list_entry *udev_list_entry_add(struct udev *udev, struct udev_list_node *list,
					    const char *name, const char *value,
					    unsigned int flags)
{
	struct udev_list_entry *entry_loop = NULL;
	struct udev_list_entry *entry_new;

	if (flags & UDEV_LIST_UNIQUE) {
		udev_list_entry_foreach(entry_loop, udev_list_get_entry(list)) {
			if (strcmp(entry_loop->name, name) == 0) {
				dbg(udev, "'%s' is already in the list\n", name);
				free(entry_loop->value);
				if (value == NULL) {
					entry_loop->value = NULL;
					dbg(udev, "'%s' value unset\n", name);
					return entry_loop;
				}
				entry_loop->value = strdup(value);
				if (entry_loop->value == NULL)
					return NULL;
				dbg(udev, "'%s' value replaced with '%s'\n", name, value);
				return entry_loop;
			}
		}
	}

	if (flags & UDEV_LIST_SORT) {
		udev_list_entry_foreach(entry_loop, udev_list_get_entry(list)) {
			if (strcmp(entry_loop->name, name) > 0)
				break;
		}
	}

	entry_new = malloc(sizeof(struct udev_list_entry));
	if (entry_new == NULL)
		return NULL;
	memset(entry_new, 0x00, sizeof(struct udev_list_entry));
	entry_new->udev = udev;
	entry_new->name = strdup(name);
	if (entry_new->name == NULL) {
		free(entry_new);
		return NULL;
	}

	if (value != NULL) {
		entry_new->value = strdup(value);
		if (entry_new->value == NULL) {
			free(entry_new->name);
			free(entry_new);
			return NULL;
		}
	}

	if (entry_loop != NULL)
		udev_list_entry_insert_before(entry_new, entry_loop);
	else
		udev_list_entry_append(entry_new, list);

	dbg(udev, "'%s=%s' added\n", entry_new->name, entry_new->value);
	return entry_new;
}

void udev_list_entry_delete(struct udev_list_entry *entry)
{
	udev_list_node_remove(&entry->node);
	free(entry->name);
	free(entry->value);
	free(entry);
}

void udev_list_cleanup_entries(struct udev *udev, struct udev_list_node *list)
{
	struct udev_list_entry *entry_loop;
	struct udev_list_entry *entry_tmp;

	udev_list_entry_foreach_safe(entry_loop, entry_tmp, udev_list_get_entry(list))
		udev_list_entry_delete(entry_loop);
}

struct udev_list_entry *udev_list_get_entry(struct udev_list_node *list)
{
	if (udev_list_is_empty(list))
		return NULL;
	return list_node_to_entry(list->next);
}

/**
 * udev_list_entry_get_next:
 * @list_entry: current entry
 *
 * Returns: the next entry from the list, #NULL is no more entries are found.
 */
UDEV_EXPORT struct udev_list_entry *udev_list_entry_get_next(struct udev_list_entry *list_entry)
{
	struct udev_list_node *next;

	if (list_entry == NULL)
		return NULL;
	next = list_entry->node.next;
	/* empty list or no more entries */
	if (next == list_entry->list)
		return NULL;
	return list_node_to_entry(next);
}

/**
 * udev_list_entry_get_by_name:
 * @list_entry: current entry
 * @name: name string to match
 *
 * Returns: the entry where @name matched, #NULL if no matching entry is found.
 */
UDEV_EXPORT struct udev_list_entry *udev_list_entry_get_by_name(struct udev_list_entry *list_entry, const char *name)
{
	struct udev_list_entry *entry;

	udev_list_entry_foreach(entry, list_entry) {
		if (strcmp(udev_list_entry_get_name(entry), name) == 0) {
			dbg(entry->udev, "found '%s=%s'\n", entry->name, entry->value);
			return entry;
		}
	}
	return NULL;
}

/**
 * udev_list_entry_get_name:
 * @list_entry: current entry
 *
 * Returns: the name string of this entry.
 */
UDEV_EXPORT const char *udev_list_entry_get_name(struct udev_list_entry *list_entry)
{
	if (list_entry == NULL)
		return NULL;
	return list_entry->name;
}

/**
 * udev_list_entry_get_value:
 * @list_entry: current entry
 *
 * Returns: the value string of this entry.
 */
UDEV_EXPORT const char *udev_list_entry_get_value(struct udev_list_entry *list_entry)
{
	if (list_entry == NULL)
		return NULL;
	return list_entry->value;
}

int udev_list_entry_get_num(struct udev_list_entry *list_entry)
{
	if (list_entry == NULL)
		return -EINVAL;
	return list_entry->num;
}

void udev_list_entry_set_num(struct udev_list_entry *list_entry, int num)
{
	if (list_entry == NULL)
		return;
	list_entry->num = num;
}