#include <libudev.h>
udev_device_has_tag()
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).
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.
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),