device.go

// +build linux,cgo

package udev

/*
  #cgo LDFLAGS: -ludev
  #include <libudev.h>
  #include <linux/types.h>
  #include <stdlib.h>
	#include <linux/kdev_t.h>
*/
import "C"
import "errors"
import "github.com/jkeiser/iter"

// Device wraps a libudev device object
type Device struct {
	ptr *C.struct_udev_device
	u   *Udev
}

// Lock the udev context
func (d *Device) lock() {
	d.u.m.Lock()
}

// Unlock the udev context
func (d *Device) unlock() {
	d.u.m.Unlock()
}

func deviceUnref(d *Device) {
	C.udev_device_unref(d.ptr)
}

// Parent returns the parent Device, or nil if the receiver has no parent Device
func (d *Device) Parent() *Device {
	d.lock()
	defer d.unlock()
	ptr := C.udev_device_get_parent(d.ptr)
	if ptr != nil {
		C.udev_device_ref(ptr)
	}
	return d.u.newDevice(ptr)
}

// ParentWithSubsystemDevtype returns the parent Device with the given subsystem and devtype,
// or nil if the receiver has no such parent device
func (d *Device) ParentWithSubsystemDevtype(subsystem, devtype string) *Device {
	d.lock()
	defer d.unlock()
	ss, dt := C.CString(subsystem), C.CString(devtype)
	defer freeCharPtr(ss)
	defer freeCharPtr(dt)
	ptr := C.udev_device_get_parent_with_subsystem_devtype(d.ptr, ss, dt)
	if ptr != nil {
		C.udev_device_ref(ptr)
	}
	return d.u.newDevice(ptr)
}

// Devpath returns the kernel devpath value of the udev device.
// The path does not contain the sys mount point, and starts with a '/'.
func (d *Device) Devpath() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_devpath(d.ptr))
}

// Subsystem returns the subsystem string of the udev device.
// The string does not contain any "/".
func (d *Device) Subsystem() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_subsystem(d.ptr))
}

// Devtype returns the devtype string of the udev device.
func (d *Device) Devtype() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_devtype(d.ptr))
}

// Sysname returns the sysname of the udev device (e.g. ttyS3, sda1...).
func (d *Device) Sysname() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_sysname(d.ptr))
}

// Syspath returns the sys path of the udev device.
// The path is an absolute path and starts with the sys mount point.
func (d *Device) Syspath() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_syspath(d.ptr))
}

// Sysnum returns the trailing number of of the device name
func (d *Device) Sysnum() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_sysnum(d.ptr))
}

// Devnode returns the device node file name belonging to the udev device.
// The path is an absolute path, and starts with the device directory.
func (d *Device) Devnode() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_devnode(d.ptr))
}

// IsInitialized checks 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.
func (d *Device) IsInitialized() bool {
	d.lock()
	defer d.unlock()
	return C.udev_device_get_is_initialized(d.ptr) != 0
}

// Devlinks retrieves the map of device links pointing to the device file of the udev device.
// The path is an absolute path, and starts with the device directory.
func (d *Device) Devlinks() (r map[string]struct{}) {
	d.lock()
	defer d.unlock()
	r = make(map[string]struct{})
	for l := C.udev_device_get_devlinks_list_entry(d.ptr); l != nil; l = C.udev_list_entry_get_next(l) {
		r[C.GoString(C.udev_list_entry_get_name(l))] = struct{}{}
	}
	return
}

// DevlinkIterator returns an Iterator over the device links pointing to the device file of the udev device.
// The Iterator is using the github.com/jkeiser/iter package.
// Values are returned as an interface{} and should be cast to string.
func (d *Device) DevlinkIterator() iter.Iterator {
	d.lock()
	defer d.unlock()
	l := C.udev_device_get_devlinks_list_entry(d.ptr)
	return iter.Iterator{
		Next: func() (item interface{}, err error) {
			d.lock()
			defer d.unlock()
			if l != nil {
				item = C.GoString(C.udev_list_entry_get_name(l))
				l = C.udev_list_entry_get_next(l)
			} else {
				err = iter.FINISHED
			}
			return
		},
		Close: func() {
		},
	}
}

// Properties retrieves a map[string]string of key/value device properties of the udev device.
func (d *Device) Properties() (r map[string]string) {
	d.lock()
	defer d.unlock()
	r = make(map[string]string)
	for l := C.udev_device_get_properties_list_entry(d.ptr); l != nil; l = C.udev_list_entry_get_next(l) {
		r[C.GoString(C.udev_list_entry_get_name(l))] = C.GoString(C.udev_list_entry_get_value(l))
	}
	return
}

// PropertyIterator returns an Iterator over the key/value device properties of the udev device.
// The Iterator is using the github.com/jkeiser/iter package.
// Values are returned as an interface{} and should be cast to []string,
// which will have length 2 and represent a Key/Value pair.
func (d *Device) PropertyIterator() iter.Iterator {
	d.lock()
	defer d.unlock()
	l := C.udev_device_get_properties_list_entry(d.ptr)
	return iter.Iterator{
		Next: func() (item interface{}, err error) {
			d.lock()
			defer d.unlock()
			if l != nil {
				item = []string{
					C.GoString(C.udev_list_entry_get_name(l)),
					C.GoString(C.udev_list_entry_get_value(l)),
				}
				l = C.udev_list_entry_get_next(l)
			} else {
				err = iter.FINISHED
			}
			return
		},
		Close: func() {
		},
	}
}

// Tags retrieves the Set of tags attached to the udev device.
func (d *Device) Tags() (r map[string]struct{}) {
	d.lock()
	defer d.unlock()
	r = make(map[string]struct{})
	for l := C.udev_device_get_tags_list_entry(d.ptr); l != nil; l = C.udev_list_entry_get_next(l) {
		r[C.GoString(C.udev_list_entry_get_name(l))] = struct{}{}
	}
	return
}

// TagIterator returns an Iterator over the tags attached to the udev device.
// The Iterator is using the github.com/jkeiser/iter package.
// Values are returned as an interface{} and should be cast to string.
func (d *Device) TagIterator() iter.Iterator {
	d.lock()
	defer d.unlock()
	l := C.udev_device_get_tags_list_entry(d.ptr)
	return iter.Iterator{
		Next: func() (item interface{}, err error) {
			d.lock()
			defer d.unlock()
			if l != nil {
				item = C.GoString(C.udev_list_entry_get_name(l))
				l = C.udev_list_entry_get_next(l)
			} else {
				err = iter.FINISHED
			}
			return
		},
		Close: func() {
		},
	}
}

// Sysattrs returns a Set with the systems attributes of the udev device.
func (d *Device) Sysattrs() (r map[string]struct{}) {
	d.lock()
	defer d.unlock()
	r = make(map[string]struct{})
	for l := C.udev_device_get_sysattr_list_entry(d.ptr); l != nil; l = C.udev_list_entry_get_next(l) {
		r[C.GoString(C.udev_list_entry_get_name(l))] = struct{}{}
	}
	return
}

// SysattrIterator returns an Iterator over the systems attributes of the udev device.
// The Iterator is using the github.com/jkeiser/iter package.
// Values are returned as an interface{} and should be cast to string.
func (d *Device) SysattrIterator() iter.Iterator {
	d.lock()
	defer d.unlock()
	l := C.udev_device_get_sysattr_list_entry(d.ptr)
	return iter.Iterator{
		Next: func() (item interface{}, err error) {
			d.lock()
			defer d.unlock()
			if l != nil {
				item = C.GoString(C.udev_list_entry_get_name(l))
				l = C.udev_list_entry_get_next(l)
			} else {
				err = iter.FINISHED
			}
			return
		},
		Close: func() {
		},
	}
}

// PropertyValue retrieves the value of a device property
func (d *Device) PropertyValue(key string) string {
	d.lock()
	defer d.unlock()
	k := C.CString(key)
	defer freeCharPtr(k)
	return C.GoString(C.udev_device_get_property_value(d.ptr, k))
}

// Driver returns the driver for the receiver
func (d *Device) Driver() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_driver(d.ptr))
}

// Devnum returns the device major/minor number.
func (d *Device) Devnum() Devnum {
	d.lock()
	defer d.unlock()
	return Devnum{C.udev_device_get_devnum(d.ptr)}
}

// Action returns the action for the event.
// 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.
func (d *Device) Action() string {
	d.lock()
	defer d.unlock()
	return C.GoString(C.udev_device_get_action(d.ptr))
}

// Seqnum returns the sequence number of the event.
// This is only valid if the device was received through a monitor.
// Devices read from sys do not have a sequence number.
func (d *Device) Seqnum() uint64 {
	d.lock()
	defer d.unlock()
	return uint64(C.udev_device_get_seqnum(d.ptr))
}

// UsecSinceInitialized returns 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.
func (d *Device) UsecSinceInitialized() uint64 {
	d.lock()
	defer d.unlock()
	return uint64(C.udev_device_get_usec_since_initialized(d.ptr))
}

// SysattrValue retrieves the content of a sys attribute file, and returns an empty string if there is no sys attribute value.
// The retrieved value is cached in the device.
// Repeated calls will return the same value and not open the attribute again.
func (d *Device) SysattrValue(sysattr string) string {
	d.lock()
	defer d.unlock()
	s := C.CString(sysattr)
	defer freeCharPtr(s)
	return C.GoString(C.udev_device_get_sysattr_value(d.ptr, s))
}

// SetSysattrValue sets the content of a sys attribute file, and returns an error if this fails.
func (d *Device) SetSysattrValue(sysattr, value string) (err error) {
	d.lock()
	defer d.unlock()
	sa, val := C.CString(sysattr), C.CString(value)
	defer freeCharPtr(sa)
	defer freeCharPtr(val)
	if C.udev_device_set_sysattr_value(d.ptr, sa, val) < 0 {
		err = errors.New("udev: udev_device_set_sysattr_value failed")
	}
	return
}

// HasTag checks if the udev device has the tag specified
func (d *Device) HasTag(tag string) bool {
	d.lock()
	defer d.unlock()
	t := C.CString(tag)
	defer freeCharPtr(t)
	return C.udev_device_has_tag(d.ptr, t) != 0
}