NAME
grantpt — grant access to the STREAMS slave pty
SYNOPSIS
int grantpt (int fildes);
DESCRIPTION
The passed parameter,
fildes,
is a file descriptor that is returned from a successful open of
a STREAMS master pty (pseudo-terminal) device. The
grantpt()
function modifies the ownership and mode of the slave pty
device special file associated with its master pty counterpart.
A
setuid()
root program is spawned to change ownership and mode of the pty slave
device file in the following way: The group ID is set to a reserved
group named "tty". The slave user ID is set to the effective owner of the
calling process. The permissions of the slave device are set so that the
owner is allowed read and write access and the group is allowed write
access.
RETURN VALUE
Upon successful completion, the
grantpt()
function returns a value of 0 (zero). Otherwise, it returns a value of -1.
Failure may result under the following conditions:
The file descriptor specified by the
fildes
parameter is not an open file descriptor.
The file descriptor specified
by the
fildes
parameter is not associated with a STREAMS master pty device.
The corresponding slave pty device cannot be accessed.
WARNINGS
The
grantpt()
function may also fail if the application has installed a signal handler
to catch the SIGCHLD (death of a child) signal.
EXAMPLES
The following example shows how
grantpt()
is typically used.
int fd_master, fd_slave;
char *slave;
...
fd_master = open("/dev/ptmx", O_RDWR);
grantpt(fd_master);
unlockpt(fd_master);
slave = ptsname(fd_master);
fd_slave = open(slave, O_RDWR);
ioctl(fd_slave, I_PUSH, "ptem");
ioctl(fd_slave, I_PUSH, "ldterm");
AUTHOR
grantpt()
was developed by HP and OSF.
