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.

HISTORY

       udev_device_get_devlinks_list_entry(), udev_device_get_properties_list_entry(),
       udev_device_get_tags_list_entry(), udev_device_get_sysattr_list_entry(),
       udev_device_get_property_value(), udev_device_has_tag(), udev_device_get_sysattr_value(),
       and udev_device_set_sysattr_value() were added in version 221.

       udev_device_has_current_tag() and udev_device_get_current_tags_list_entry() were added in
       version 247.

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)