определить состояние конкретного сиденья (determine state of a specific seat)
Имя (Name)
sd_seat_get_active, sd_seat_get_sessions, sd_seat_can_tty,
sd_seat_can_graphical - Determine state of a specific seat
Синопсис (Synopsis)
#include <systemd/sd-login.h>
int sd_seat_get_active(const char *seat, char **session,
uid_t *uid);
int sd_seat_get_sessions(const char *seat, char ***ret_sessions,
uid_t **ret_uids,
unsigned int *ret_n_uids);
int sd_seat_can_tty(const char *seat);
int sd_seat_can_graphical(const char *seat);
Описание (Description)
sd_seat_get_active() may be used to determine which session is
currently active on a seat, if there is any. Returns the session
identifier and the user identifier of the Unix user the session
is belonging to. Either the session or the user identifier
parameter can be passed NULL, in case only one of the parameters
shall be queried. The returned string needs to be freed with the
libc free(3) call after use.
sd_seat_get_sessions() may be used to determine all sessions on
the specified seat. Returns two arrays, one (NULL terminated)
with the session identifiers of the sessions and one with the
user identifiers of the Unix users the sessions belong to. An
additional parameter may be used to return the number of entries
in the latter array. This value is the same as the return value
if the return value is nonnegative. The output parameters may be
passed as NULL in case these output values are not needed. The
arrays and the strings referenced by them need to be freed with
the libc free(3) call after use. Note that instead of an empty
array NULL may be returned and should be considered equivalent to
an empty array.
sd_seat_can_tty() may be used to determine whether a specific
seat provides TTY functionality, i.e. is useful as a text
console.
sd_seat_can_graphical() may be used to determine whether a
specific seat provides graphics functionality, i.e. is useful as
a graphics display.
If the seat parameter of any of these functions is passed as
NULL, the operation is executed for the seat of the session of
the calling process, if there is any.
Возвращаемое значение (Return value)
On success, sd_seat_get_active() returns 0 or a positive integer.
On success, sd_seat_get_sessions() returns the number of entries
in the session identifier array. If the test succeeds,
sd_seat_can_tty() and sd_seat_can_graphical() return a positive
integer, if it fails 0. On failure, these calls return a negative
errno-style error code.
Errors
Returned errors may indicate the following problems:
-ENODATA
The given field is not specified for the described seat.
-ENXIO
The specified seat is unknown.
-EINVAL
An input parameter was invalid (out of range, or NULL, where
that is not accepted).
-ENOMEM
Memory allocation failed.
Примечание (Note)
These APIs are implemented as a shared library, which can be
compiled and linked to with the libsystemd pkg-config(1) file.
История (History)
In the past, sd_seat_can_multi_session() was used to check
whether the seat supports multiple sessions. All seats support
that now, so that function has been deprecated and always returns
true.
Смотри также (See also)
systemd(1), sd-login(3), sd_session_get_seat(3)
