libudev-device.c revision 07630cea1f3a845c09309f197ac7c4f11edd3b62
/***
This file is part of systemd.
Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
Copyright 2015 Tom Gundersen <teg@jklm.no>
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.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libudev.h"
#include "sd-device.h"
#include "device-private.h"
#include "device-util.h"
#include "libudev-device-internal.h"
#include "libudev-private.h"
/**
* SECTION:libudev-device
* @short_description: kernel sys devices
*
* Representation of kernel sys devices. Devices are uniquely identified
* by their syspath, every device has exactly one path in the kernel sys
* filesystem. Devices usually belong to a kernel subsystem, and have
* a unique name inside that subsystem.
*/
/**
* udev_device_get_seqnum:
* @udev_device: udev device
*
* This is only valid if the device was received through a monitor. Devices read from
* sys do not have a sequence number.
*
* Returns: the kernel event sequence number, or 0 if there is no sequence number available.
**/
{
const char *seqnum;
unsigned long long ret;
int r;
if (r == -ENOENT)
return 0;
else if (r < 0) {
errno = -r;
return 0;
}
if (r < 0) {
errno = -r;
return 0;
}
return ret;
}
/**
* udev_device_get_devnum:
* @udev_device: udev device
*
*
* Returns: the dev_t number.
**/
{
int r;
if (r < 0) {
errno = -r;
return makedev(0, 0);
}
return devnum;
}
/**
* udev_device_get_driver:
* @udev_device: udev device
*
* Get the kernel driver name.
*
* Returns: the driver name string, or #NULL if there is no driver attached.
**/
{
const char *driver;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return driver;
}
/**
* udev_device_get_devtype:
* @udev_device: udev device
*
* Retrieve the devtype string of the udev device.
*
* Returns: the devtype name of the udev device, or #NULL if it can not be determined
**/
{
const char *devtype;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return devtype;
}
/**
* 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 *subsystem;
int r;
if (r < 0) {
errno = -r;
return NULL;
} else if (!subsystem)
return subsystem;
}
/**
* udev_device_get_property_value:
* @udev_device: udev device
* @key: property name
*
* Get the value of a given property.
*
* Returns: the property string, or #NULL if there is no such property.
**/
_public_ const char *udev_device_get_property_value(struct udev_device *udev_device, const char *key)
{
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return value;
}
struct udev_device *udev_device;
if (!udev_device) {
return NULL;
}
return udev_device;
}
/**
* udev_device_new_from_syspath:
* @udev: udev library context
* @syspath: sys device path including sys directory
*
* Create new udev device, and fill in information from the sys
* device and the udev database entry. The syspath is the absolute
* path to the device, including the sys mount point.
*
* The initial refcount is 1, and needs to be decremented to
* release the resources of the udev device.
*
* Returns: a new udev device, or #NULL, if it does not exist
**/
struct udev_device *udev_device;
int r;
if (!udev_device)
return NULL;
if (r < 0) {
errno = -r;
return NULL;
}
return udev_device;
}
/**
* udev_device_new_from_devnum:
* @udev: udev library context
* @type: char or block device
*
* Create new udev device, and fill in information from the sys
* device and the udev database entry. The device is looked-up
* numbers are not unique across the two types.
*
* The initial refcount is 1, and needs to be decremented to
* release the resources of the udev device.
*
* Returns: a new udev device, or #NULL, if it does not exist
**/
_public_ struct udev_device *udev_device_new_from_devnum(struct udev *udev, char type, dev_t devnum)
{
struct udev_device *udev_device;
int r;
if (!udev_device)
return NULL;
if (r < 0) {
errno = -r;
return NULL;
}
return udev_device;
}
/**
* udev_device_new_from_device_id:
* @udev: udev library context
* @id: text string identifying a kernel device
*
* Create new udev device, and fill in information from the sys
* device and the udev database entry. The device is looked-up
* by a special string:
* b8:2 - block device major:minor
* c128:1 - char device major:minor
* n3 - network device ifindex
* +sound:card29 - kernel driver core subsystem:device name
*
* The initial refcount is 1, and needs to be decremented to
* release the resources of the udev device.
*
* Returns: a new udev device, or #NULL, if it does not exist
**/
{
struct udev_device *udev_device;
int r;
if (!udev_device)
return NULL;
if (r < 0) {
errno = -r;
return NULL;
}
return udev_device;
}
/**
* udev_device_new_from_subsystem_sysname:
* @udev: udev library context
* @subsystem: the subsystem of the device
* @sysname: the name of the device
*
* Create new udev device, and fill in information from the sys device
* and the udev database entry. The device is looked up by the subsystem
* and name string of the device, like "mem" / "zero", or "block" / "sda".
*
* The initial refcount is 1, and needs to be decremented to
* release the resources of the udev device.
*
* Returns: a new udev device, or #NULL, if it does not exist
**/
_public_ struct udev_device *udev_device_new_from_subsystem_sysname(struct udev *udev, const char *subsystem, const char *sysname)
{
struct udev_device *udev_device;
int r;
if (!udev_device)
return NULL;
if (r < 0) {
errno = -r;
return NULL;
}
return udev_device;
}
/**
* udev_device_new_from_environment
* @udev: udev library context
*
* Create new udev device, and fill in information from the
* current process environment. This only works reliable if
* the process is called from a udev rule. It is usually used
* for tools executed from IMPORT= rules.
*
* The initial refcount is 1, and needs to be decremented to
* release the resources of the udev device.
*
* Returns: a new udev device, or #NULL, if it does not exist
**/
{
struct udev_device *udev_device;
int r;
if (!udev_device)
return NULL;
if (r < 0) {
errno = -r;
return NULL;
}
return udev_device;
}
{
struct udev_device *parent;
int r;
if (!parent)
return NULL;
if (r < 0) {
errno = -r;
return NULL;
}
/* the parent is unref'ed with the child, so take a ref from libudev as well */
return parent;
}
/**
* udev_device_get_parent:
* @udev_device: the device to start searching from
*
* Find the next parent device, and fill in information from the sys
* device and the udev database entry.
*
* Returned device is not referenced. It is attached to the child
* device, and will be cleaned up when the child device is cleaned up.
*
* It is not necessarily just the upper level directory, empty or not
* recognized sys directories are ignored.
*
* It can be called as many times as needed, without caring about
* references.
*
* Returns: a new udev device, or #NULL, if it no parent exist.
**/
{
if (!udev_device->parent_set) {
udev_device->parent_set = true;
}
/* TODO: errno will differ here in case parent == NULL */
return udev_device->parent;
}
/**
* udev_device_get_parent_with_subsystem_devtype:
* @udev_device: udev device to start searching from
* @subsystem: the subsystem of the device
* @devtype: the type (DEVTYPE) of the device
*
* Find the next parent device, with a matching subsystem and devtype
* value, and fill in information from the sys device and the udev
* database entry.
*
* If devtype is #NULL, only subsystem is checked, and any devtype will
* match.
*
* Returned device is not referenced. It is attached to the child
* device, and will be cleaned up when the child device is cleaned up.
*
* It can be called as many times as needed, without caring about
* references.
*
* Returns: a new udev device, or #NULL if no matching parent exists.
**/
_public_ struct udev_device *udev_device_get_parent_with_subsystem_devtype(struct udev_device *udev_device, const char *subsystem, const char *devtype)
{
int r;
/* this relies on the fact that finding the subdevice of a parent or the
parent of a subdevice commute */
/* first find the correct sd_device */
if (r < 0) {
errno = -r;
return NULL;
}
/* then walk the chain of udev_device parents until the correspanding
one is found */
return udev_device;
}
return NULL;
}
/**
* udev_device_get_udev:
* @udev_device: udev device
*
* Retrieve the udev library context the device was created with.
*
* Returns: the udev library context
**/
{
return udev_device->udev;
}
/**
* udev_device_ref:
* @udev_device: udev device
*
* Take a reference of a udev device.
*
* Returns: the passed udev device
**/
{
if (udev_device)
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 resources of the device will be released.
*
* Returns: #NULL
**/
{
}
return NULL;
}
/**
* udev_device_get_devpath:
* @udev_device: udev device
*
* Retrieve the kernel devpath value of the udev device. The path
* does not contain the sys mount point, and starts with a '/'.
*
* Returns: the devpath of the udev device
**/
{
const char *devpath;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return devpath;
}
/**
* udev_device_get_syspath:
* @udev_device: udev device
*
* Retrieve the sys path of the udev device. The path is an
* absolute path and starts with the sys mount point.
*
* Returns: the sys path of the udev device
**/
{
const char *syspath;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return syspath;
}
/**
* udev_device_get_sysname:
* @udev_device: udev device
*
* Get the kernel device name in /sys.
*
* Returns: the name string of the device device
**/
{
const char *sysname;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return sysname;
}
/**
* udev_device_get_sysnum:
* @udev_device: udev device
*
* Get the instance number of the device.
*
* Returns: the trailing number string of the device name
**/
{
const char *sysnum;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return sysnum;
}
/**
* udev_device_get_devnode:
* @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 *devnode;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return devnode;
}
/**
* udev_device_get_devlinks_list_entry:
* @udev_device: udev device
*
* Retrieve the list of device links pointing to the device file of
* the udev device. The next list entry can be retrieved with
* udev_list_entry_get_next(), which returns #NULL if no more entries exist.
* The devlink path can be retrieved from the list entry by
* udev_list_entry_get_name(). The path is an absolute path, and starts with
* the device directory.
*
* Returns: the first entry of the device node link list
**/
_public_ struct udev_list_entry *udev_device_get_devlinks_list_entry(struct udev_device *udev_device)
{
!udev_device->devlinks_read) {
const char *devlink;
udev_device->devlinks_read = true;
}
}
/**
* udev_device_get_event_properties_entry:
* @udev_device: udev device
*
* device. The next list entry can be retrieved with udev_list_entry_get_next(),
* which returns #NULL if no more entries exist. The property name
* can be retrieved from the list entry by udev_list_entry_get_name(),
* the property value by udev_list_entry_get_value().
*
* Returns: the first entry of the property list
**/
_public_ struct udev_list_entry *udev_device_get_properties_list_entry(struct udev_device *udev_device)
{
udev_device->properties_read = true;
}
}
/**
* udev_device_get_action:
* @udev_device: udev device
*
* This is only valid if the device was received through a monitor. Devices read from
* sys do not have an action string. Usual actions are: add, remove, change, online,
* offline.
*
* Returns: the kernel action value, or #NULL if there is no action value available.
**/
int r;
if (r < 0 && r != -ENOENT) {
errno = -r;
return NULL;
}
return action;
}
/**
* udev_device_get_usec_since_initialized:
* @udev_device: udev device
*
* Return the number of microseconds passed since udev set up the
* device for the first time.
*
* This is only implemented for devices with need to store properties
* in the udev database. All other devices return 0 here.
*
* Returns: the number of microseconds since the device was first seen.
**/
_public_ unsigned long long int udev_device_get_usec_since_initialized(struct udev_device *udev_device)
{
int r;
if (r < 0) {
return 0;
}
return ts;
}
/**
* udev_device_get_sysattr_value:
* @udev_device: udev device
* @sysattr: attribute name
*
* The retrieved value is cached in the device. Repeated calls will return the same
* value and not open the attribute again.
*
* Returns: the content of a sys attribute file, or #NULL if there is no sys attribute value.
**/
_public_ const char *udev_device_get_sysattr_value(struct udev_device *udev_device, const char *sysattr)
{
const char *value;
int r;
if (r < 0) {
errno = -r;
return NULL;
}
return value;
}
/**
* udev_device_set_sysattr_value:
* @udev_device: udev device
* @sysattr: attribute name
* @value: new value to be set
*
* Update the contents of the sys attribute and the cached value of the device.
*
* Returns: Negative error code on failure or 0 on success.
**/
_public_ int udev_device_set_sysattr_value(struct udev_device *udev_device, const char *sysattr, char *value)
{
int r;
if (r < 0)
return r;
return 0;
}
/**
* udev_device_get_sysattr_list_entry:
* @udev_device: udev device
*
* Retrieve the list of available sysattrs, with value being empty;
* This just return all available sysfs attributes for a particular
* device without reading their values.
*
* Returns: the first entry of the property list
**/
_public_ struct udev_list_entry *udev_device_get_sysattr_list_entry(struct udev_device *udev_device)
{
if (!udev_device->sysattrs_read) {
const char *sysattr;
udev_device->sysattrs_read = true;
}
}
/**
* udev_device_get_is_initialized:
* @udev_device: udev device
*
* Check if udev has already handled the device and has set up
* device node permissions and context, or has renamed a network
* device.
*
* This is only implemented for devices with a device node
* or network interfaces. All other devices return 1 here.
*
* Returns: 1 if the device is set up. 0 otherwise.
**/
{
int r, initialized;
if (r < 0) {
errno = -r;
return 0;
}
return initialized;
}
/**
* udev_device_get_tags_list_entry:
* @udev_device: udev device
*
* Retrieve the list of tags attached to the udev device. The next
* list entry can be retrieved with udev_list_entry_get_next(),
* which returns #NULL if no more entries exist. The tag string
* can be retrieved from the list entry by udev_list_entry_get_name().
*
* Returns: the first entry of the tag list
**/
{
!udev_device->tags_read) {
const char *tag;
udev_device->tags_read = true;
}
}
/**
* udev_device_has_tag:
* @udev_device: udev device
* @tag: tag name
*
* Check if a given device has a certain tag associated.
*
* Returns: 1 if the tag is found. 0 otherwise.
**/
{
assert_return(udev_device, 0);
}