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#ifndef _LIBSEAT_H
#define _LIBSEAT_H
#include <stdarg.h>
/*
* An opaque struct containing an opened seat, created by libseat_open-seat and
* destroyed by libseat_close_seat.
*/
struct libseat;
/*
* A seat event listener, given to libseat_open_seat.
*/
struct libseat_seat_listener {
/*
* The seat has been enabled, and is now valid for use. Re-open all seat
* devices to ensure that they are operational, as existing fds may have
* had their functionality blocked or revoked.
*
* Must be non-NULL.
*/
void (*enable_seat)(struct libseat *seat, void *userdata);
/*
* The seat has been disabled. This event signals that the application
* is going to lose its seat access. The event *must* be acknowledged
* with libseat_disable_seat shortly after receiving this event.
*
* If the recepient fails to acknowledge the event in time, seat devices
* may be forcibly revoked by the seat provider.
*
* Must be non-NULL.
*/
void (*disable_seat)(struct libseat *seat, void *userdata);
};
/*
* Opens a seat, taking control of it if possible and returning a pointer to
* the libseat instance. If LIBSEAT_BACKEND is set, the specified backend is
* used. Otherwise, the first successful backend will be used.
*
* The seat listener specified is used to signal events on the seat, and must
* be non-NULL. The userdata pointer will be provided in all calls to the seat
* listener.
*
* The available backends, if enabled at compile-time, are: seatd, logind and
* builtin.
*
* To use builtin, the process must have CAP_SYS_ADMIN or be root at the time
* of the call. These privileges can be dropped at any point after the call.
*
* The returned pointer must be destroyed with libseat_close_seat.
*
* Returns a pointer to an opaque libseat struct on success. Returns NULL and
* sets errno on error.
*/
struct libseat *libseat_open_seat(struct libseat_seat_listener *listener, void *userdata);
/*
* Disables a seat, used in response to a disable_seat event. After disabling
* the seat, the seat devices must not be used until enable_seat is received,
* and all requests on the seat will fail during this period.
*
* Returns 0 on success. -1 and sets errno on error.
*/
int libseat_disable_seat(struct libseat *seat);
/*
* Closes the seat. This frees the libseat structure.
*
* Returns 0 on success. Returns -1 and sets errno on error.
*/
int libseat_close_seat(struct libseat *seat);
/*
* Opens a device on the seat, returning its device ID and placing the fd in
* the specified pointer.
*
* This will only succeed if the seat is active and the device is of a type
* permitted for opening on the backend, such as drm and evdev.
*
* The device may be revoked in some situations, such as in situations where a
* seat session switch is being forced.
*
* Returns the device id on success. Returns -1 and sets errno on error.
*/
int libseat_open_device(struct libseat *seat, const char *path, int *fd);
/*
* Closes a device that has been opened on the seat using the device_id from
* libseat_open_device.
*
* Returns 0 on success. Returns -1 and sets errno on error.
*/
int libseat_close_device(struct libseat *seat, int device_id);
/*
* Retrieves the name of the seat that is currently made available through the
* provided libseat instance.
*
* The returned string is owned by the libseat instance, and must not be
* modified. It remains valid as long as the seat is open.
*/
const char *libseat_seat_name(struct libseat *seat);
/*
* Requests that the seat switches session to the specified session number.
* For seats that are VT-bound, the session number matches the VT number, and
* switching session results in a VT switch.
*
* A call to libseat_switch_session does not imply that a switch will occur,
* and the caller should assume that the session continues unaffected.
*
* Returns 0 on success. Returns -1 and sets errno on error.
*/
int libseat_switch_session(struct libseat *seat, int session);
/*
* Retrieve the pollable connection fd for a given libseat instance. Used to
* poll the libseat connection for events that need to be dispatched.
*
* Returns a pollable fd on success. Returns -1 and sets errno on error.
*/
int libseat_get_fd(struct libseat *seat);
/*
* Reads and dispatches events on the libseat connection fd.
*
* The specified timeout dictates how long libseat might wait for data if none
* is available: 0 means that no wait will occur, -1 means that libseat might
* wait indefinitely for data to arrive, while > 0 is the maximum wait in
* milliseconds that might occur.
*
* Returns a positive number signifying processed internal messages on success.
* Returns 0-if no messages were processed. Returns -1 and sets errno on error.
*/
int libseat_dispatch(struct libseat *seat, int timeout);
#endif
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