UDEV_DEVICE_HAS_TAG(3) udev_device_has_tag UDEV_DEVICE_HAS_TAG(3)
NAME
udev_device_has_tag, udev_device_has_current_tag,
udev_device_get_devlinks_list_entry,
udev_device_get_properties_list_entry, udev_device_get_tags_list_entry,
udev_device_get_current_tags_list_entry,
udev_device_get_sysattr_list_entry, udev_device_get_property_value,
udev_device_get_sysattr_value, udev_device_set_sysattr_value - Retrieve
or set device attributes
SYNOPSIS
#include <libudev.h>
int udev_device_has_tag(struct udev_device *udev_device,
const char *tag);
int udev_device_has_current_tag(struct udev_device *udev_device,
const char *tag);
struct udev_list_entry
*udev_device_get_devlinks_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_properties_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_tags_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_current_tags_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_sysattr_list_entry(struct udev_device *udev_device);
const char
*udev_device_get_property_value(struct udev_device *udev_device,
const char *key);
const char
*udev_device_get_sysattr_value(struct udev_device *udev_device,
const char *sysattr);
int udev_device_set_sysattr_value(struct udev_device *udev_device,
const char *sysattr,
const char *value);
DESCRIPTION
udev_device_has_tag() returns a valuer larger than zero if the
specified device object has the indicated tag assigned to it, and zero
otherwise. See udev(7) for details on the tags concept.
udev_device_has_current_tag() executes a similar check, however only
determines whether the indicated tag was set as result of the most
recent event seen for the device. Tags are "sticky", i.e. once set for
a device they remain on the device until the device is unplugged, even
if the rules run for later events of the same device do not set them
anymore. Any tag for which udev_device_has_current_tag() returns true
will hence also return true when passed to udev_device_has_tag(), but
the opposite might not be true, in case a tag is no longer configured
by the rules applied to the most recent device even.
udev_device_get_tags_list_entry() returns a udev_list_entry object,
encapsulating a list of tags set for the specified device. Similar,
udev_device_get_current_tags_list_entry() returns a list of tags set
for the specified device as effect of the most recent device event seen
(see above for details on the difference).
RETURN VALUE
On success, udev_device_has_tag() and udev_device_has_current_tag()
return positive or 0, depending on whether the device has the given tag
or not. On failure, a negative error code is returned.
On success, udev_device_get_devlinks_list_entry(),
udev_device_get_properties_list_entry(),
udev_device_get_tags_list_entry(),
udev_device_get_current_tags_list_entry() and
udev_device_get_sysattr_list_entry() return a pointer to the first
entry of the retrieved list. If that list is empty, or if an error
occurred, NULL is returned.
On success, udev_device_get_property_value() and
udev_device_get_sysattr_value() return a pointer to a constant string
of the requested value. On error, NULL is returned. Attributes that may
contain NUL bytes should not be retrieved with
udev_device_get_sysattr_value(); instead, read them directly from the
files within the device's syspath.
On success, udev_device_set_sysattr_value() returns an integer greater
than, or equal to, 0. On failure, a negative error code is returned.
Values that contain NUL bytes should not be set with this function;
instead, write them directly to the files within the device's syspath.
SEE ALSO
udev(7), udev_new(3), udev_device_new_from_syspath(3),
udev_device_get_syspath(3), udev_enumerate_new(3),
udev_monitor_new_from_netlink(3), udev_list_entry(3), systemd(1),
systemd 252 UDEV_DEVICE_HAS_TAG(3)
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