|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
UDEV_DEVICE_NEW_FROM_SYSPATH(3)vice_new_from_syspathVICE_NEW_FROM_SYSPATH(3)
udev_device_new_from_syspath, udev_device_new_from_devnum,
udev_device_new_from_subsystem_sysname,
udev_device_new_from_device_id, udev_device_new_from_environment,
udev_device_ref, udev_device_unref - Create, acquire and release a
udev device object
#include <libudev.h>
struct udev_device *udev_device_new_from_syspath(struct udev *udev,
const char *syspath);
struct udev_device *udev_device_new_from_devnum(struct udev *udev,
char type,
dev_t devnum);
struct udev_device
*udev_device_new_from_subsystem_sysname(struct udev *udev,
const char *subsystem,
const char *sysname);
struct udev_device *udev_device_new_from_device_id(struct udev *udev,
const char *id);
struct udev_device
*udev_device_new_from_environment(struct udev *udev);
struct udev_device *udev_device_ref(struct udev_device *udev_device);
struct udev_device
*udev_device_unref(struct udev_device *udev_device);
udev_device_new_from_syspath, udev_device_new_from_devnum,
udev_device_new_from_subsystem_sysname,
udev_device_new_from_device_id, and udev_device_new_from_environment
allocate a new udev device object and returns a pointer to it. This
object is opaque and must not be accessed by the caller via different
means than functions provided by libudev. Initially, the reference
count of the device is 1. You can acquire further references, and
drop gained references via udev_device_ref() and udev_device_unref().
Once the reference count hits 0, the device object is destroyed and
freed.
udev_device_new_from_syspath, udev_device_new_from_devnum,
udev_device_new_from_subsystem_sysname, and
udev_device_new_from_device_id create the device object based on
information found in /sys, annotated with properties from the
udev-internal device database. A syspath is any subdirectory of /sys,
with the restriction that a subdirectory of /sys/devices (or a
symlink to one) represents a real device and as such must contain a
uevent file. udev_device_new_from_devnum takes a device type, which
can be b for block devices or c for character devices, as well as a
devnum (see makedev(3)). udev_device_new_from_subsystem_sysname
looks up devices based on the provided subsystem and sysname (see
udev_device_get_subsystem(3) and udev_device_get_sysname(3)) and
udev_device_new_from_device_id looks up devices based on the provided
device ID, which is a special string in one of the following four
forms:
Table 1. Device ID strings
┌──────────────┬──────────────────────────┐
│Example │ Explanation │
├──────────────┼──────────────────────────┤
│b8:2 │ block device major:minor │
├──────────────┼──────────────────────────┤
│c128:1 │ char device major:minor │
├──────────────┼──────────────────────────┤
│n3 │ network device ifindex │
├──────────────┼──────────────────────────┤
│+sound:card29 │ kernel driver core │
│ │ subsystem:device name │
└──────────────┴──────────────────────────┘
udev_device_new_from_environment creates a device from the current
environment (see environ(7)). Each key-value pair is interpreted in
the same way as if it was received in an uevent (see
udev_monitor_receive_device(3)). The keys DEVPATH, SUBSYSTEM, ACTION,
and SEQNUM are mandatory.
On success, udev_device_new_from_syspath(),
udev_device_new_from_devnum(),
udev_device_new_from_subsystem_sysname(),
udev_device_new_from_device_id() and
udev_device_new_from_environment() return a pointer to the allocated
udev device. On failure, NULL is returned, and errno is set
appropriately. udev_device_ref() returns the argument that it was
passed, unmodified. udev_device_unref() always returns NULL.
udev_new(3), udev_device_get_syspath(3), udev_device_has_tag(3),
udev_enumerate_new(3), udev_monitor_new_from_netlink(3),
udev_list_entry(3), systemd(1),
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2017-07-05. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
systemd 234 UDEV_DEVICE_NEW_FROM_SYSPATH(3)
Pages that refer to this page: libudev(3), udev_device_get_syspath(3), udev_device_has_tag(3), udev_enumerate_add_match_subsystem(3), udev_enumerate_new(3), udev_enumerate_scan_devices(3), udev_list_entry(3), udev_monitor_filter_update(3), udev_monitor_new_from_netlink(3), udev_monitor_receive_device(3), systemd.directives(7), systemd.index(7)