systemd-stable/udev/lib/libudev-device.c

/*
 * libudev - interface to udev device information
 *
 * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>

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

struct udev_device *device_init(struct udev *udev)
{
	struct udev_device *udev_device;

	if (udev == NULL)
		return NULL;

	udev_device = malloc(sizeof(struct udev_device));
	if (udev_device == NULL)
		return NULL;
	memset(udev_device, 0x00, sizeof(struct udev_device));
	udev_device->refcount = 1;
	udev_device->udev = udev;
	INIT_LIST_HEAD(&udev_device->link_list);
	INIT_LIST_HEAD(&udev_device->env_list);
	log_info(udev_device->udev, "udev_device: %p created\n", udev_device);
	return udev_device;
}

/**
 * udev_device_new_from_devpath:
 * @udev: udev library context
 * @devpath: sys device path
 *
 * Create new udev device, and fill in information from the sysfs
 * device and the udev database entry. The devpath must not contain
 * the sysfs mount path, and must contain a leading '/'.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the ressources of the udev device.
 *
 * Returns: a new udev device, or #NULL, if it does not exist
 **/
struct udev_device *udev_device_new_from_devpath(struct udev *udev, const char *devpath)
{
	char path[PATH_SIZE];
	struct stat statbuf;
	struct udev_device *udev_device;
	struct udevice *udevice;
	struct name_entry *name_loop;
	int err;

	if (udev == NULL)
		return NULL;
	if (devpath == NULL)
		return NULL;

	strlcpy(path, udev_get_sys_path(udev), sizeof(path));
	strlcat(path, devpath, sizeof(path));
	if (stat(path, &statbuf) != 0)
		return NULL;
	if (!S_ISDIR(statbuf.st_mode))
		return NULL;

	udev_device = device_init(udev);
	if (udev_device == NULL)
		return NULL;

	udevice = udev_device_init(NULL);
	if (udevice == NULL) {
		free(udev_device);
		return NULL;
	}

	/* resolve possible symlink to real path */
	strlcpy(path, devpath, sizeof(path));
	sysfs_resolve_link(path, sizeof(path));
	udev_device->devpath = strdup(path);
	log_info(udev, "device %p has devpath '%s'\n", udev_device, udev_device_get_devpath(udev_device));

	err = udev_db_get_device(udevice, path);
	if (err >= 0)
		log_info(udev, "device %p filled with udev database data\n", udev_device);

	if (udevice->name[0] != '\0')
		asprintf(&udev_device->devname, "%s/%s", udev_get_dev_path(udev), udevice->name);

	list_for_each_entry(name_loop, &udevice->symlink_list, node) {
		char name[PATH_SIZE];

		strlcpy(name, udev_get_dev_path(udev), sizeof(name));
		strlcat(name, "/", sizeof(name));
		strlcat(name, name_loop->name, sizeof(name));
		name_list_add(&udev_device->link_list, name, 0);
	}

	list_for_each_entry(name_loop, &udevice->env_list, node)
		name_list_add(&udev_device->env_list, name_loop->name, 0);

	udev_device_cleanup(udevice);
	return udev_device;
}

/**
 * udev_device_get_udev:
 *
 * Retrieve the udev library context the device was created with.
 *
 * Returns: the udev library context
 **/
struct udev *udev_device_get_udev(struct udev_device *udev_device)
{
	if (udev_device == NULL)
		return NULL;
	return udev_device->udev;
}

/**
 * udev_device_ref:
 * @udev_device: udev device
 *
 * Take a reference of a udev device.
 *
 * Returns: the passed udev device
 **/
struct udev_device *udev_device_ref(struct udev_device *udev_device)
{
	if (udev_device == NULL)
		return NULL;
	udev_device->refcount++;
	return udev_device;
}

/**
 * udev_device_unref:
 * @udev_device: udev device
 *
 * Drop a reference of a udev device. If the refcount reaches zero,
 * the ressources of the device will be released.
 *
 **/
void udev_device_unref(struct udev_device *udev_device)
{
	if (udev_device == NULL)
		return;
	udev_device->refcount--;
	if (udev_device->refcount > 0)
		return;
	free(udev_device->devpath);
	free(udev_device->devname);
	free(udev_device->subsystem);
	name_list_cleanup(&udev_device->link_list);
	name_list_cleanup(&udev_device->env_list);
	log_info(udev_device->udev, "udev_device: %p released\n", udev_device);
	free(udev_device);
}

/**
 * udev_device_get_devpath:
 * @udev_device: udev device
 *
 * Retrieve the sys path of the udev device. The path does not contain
 * the sys mount point.
 *
 * Returns: the sys path of the udev device
 **/
const char *udev_device_get_devpath(struct udev_device *udev_device)
{
	if (udev_device == NULL)
		return NULL;
	return udev_device->devpath;
}

/**
 * udev_device_get_devname:
 * @udev_device: udev device
 *
 * Retrieve the device node file name belonging to the udev device.
 * The path is an absolute path, and starts with the device directory.
 *
 * Returns: the device node file name of the udev device, or #NULL if no device node exists
 **/
const char *udev_device_get_devname(struct udev_device *udev_device)
{
	if (udev_device == NULL)
		return NULL;
	return udev_device->devname;
}

/**
 * udev_device_get_subsystem:
 * @udev_device: udev device
 *
 * Retrieve the subsystem string of the udev device. The string does not
 * contain any "/".
 *
 * Returns: the subsystem name of the udev device, or #NULL if it can not be determined
 **/
const char *udev_device_get_subsystem(struct udev_device *udev_device)
{
	char subsystem[NAME_SIZE];

	if (udev_device == NULL)
		return NULL;
	if (udev_device->subsystem != NULL)
		return udev_device->subsystem;
	if (util_get_sys_subsystem(udev_device->udev, udev_device->devpath, subsystem, sizeof(subsystem)) < 2)
		return NULL;
	udev_device->subsystem = strdup(subsystem);
	return udev_device->subsystem;
}

/**
 * udev_device_get_devlinks:
 * @udev_device: udev device
 * @cb: function to be called for every device link found
 * @data: data to be passed to the function
 *
 * Retrieve the device links pointing to the device file of the
 * udev device. For every device link, the passed function will be
 * called with the device link string.
 * The path is an absolute path, and starts with the device directory.
 * If the function returns 1, remaning device links will be ignored.
 *
 * Returns: the number of device links passed to the caller, or a negative value on error
 **/
int udev_device_get_devlinks(struct udev_device *udev_device,
			      int (*cb)(struct udev_device *udev_device, const char *value, void *data),
			      void *data)
{
	struct name_entry *name_loop;
	int count = 0;

	if (udev_device == NULL)
		return -1;
	list_for_each_entry(name_loop, &udev_device->link_list, node) {
		count++;
		if (cb(udev_device, name_loop->name, data) != 0)
			break;
	}
	return count;
}

/**
 * udev_device_get_properties:
 * @udev_device: udev device
 * @cb: function to be called for every property found
 * @data: data to be passed to the function
 *
 * Retrieve the property key/value pairs belonging to the
 * udev device. For every key/value pair, the passed function will be
 * called. If the function returns 1, remaning properties will be
 * ignored.
 *
 * Returns: the number of properties passed to the caller, or a negative value on error
 **/
int udev_device_get_properties(struct udev_device *udev_device,
				int (*cb)(struct udev_device *udev_device, const char *key, const char *value, void *data),
				void *data)
{
	struct name_entry *name_loop;
	int count = 0;

	if (udev_device == NULL)
		return -1;
	list_for_each_entry(name_loop, &udev_device->env_list, node) {
		char name[PATH_SIZE];
		char *val;

		strncpy(name, name_loop->name, PATH_SIZE);
		name[PATH_SIZE-1] = '\0';
		val = strchr(name, '=');
		if (val == NULL)
			continue;
		val[0] = '\0';
		val = &val[1];
		count++;
		if (cb(udev_device, name, val, data) != 0)
			break;
	}
	return count;
}