The function
openpty ();
attempts to obtain the next available pseudo-terminal from the system (see
pty(4)).
If it successfully finds one, it subsequently changes the
ownership of the slave device to the real UID of the current process,
the group membership to the group
``tty''
(if such a group exists in the system), the access permissions for
reading and writing by the owner, and for writing by the group, and
invalidates any current use of the line by calling
revoke(2).
If the argument
Fa name
is not
NULL
openpty ();
copies the pathname of the slave pty to this area.
The caller is
responsible for allocating the required space in this array.
If the arguments
Fa termp
or
Fa winp
are not
NULL
openpty ();
initializes the termios and window size settings from the structures
these arguments point to, respectively.
Upon return, the open file descriptors for the master and slave side
of the pty are returned in the locations pointed to by
Fa amaster
and
Fa aslave ,
respectively.
The
forkpty ();
function first calls
openpty ();
to obtain the next available pseudo-terminal from the system.
Upon success,
it forks off a new process.
In the child process, it closes the descriptor
for the master side of the pty, and calls
login_tty3
for the slave pty.
In the parent process, it closes the descriptor for the
slave side of the pty.
The arguments
Fa amaster ,
Fa name ,
Fa termp ,
and
Fa winp
have the same meaning as described for
openpty (.);
RETURN VALUES
The
openpty ();
function returns 0 on success, or -1 on failure.
The
forkpty ();
function returns -1 on failure, 0 in the slave process, and the process ID of
the slave process in the parent process.
ERRORS
The
openpty ();
function may fail and set the global variable
errno
for any of the errors specified for the
grantpt(3),
posix_openpt3,
ptsname(3),
and
unlockpt(3)
functions and the
revoke(2)
system call.
In addition to this,
forkpty ();
may set it to any value as described for
fork(2).