grantpt.3c (2010 09)

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grantpt(3C) grantpt(3C)
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.
SEE ALSO
open(2), unlockpt(3C), ptsname(3C), ptm(7), pts(7), ptem(7), ldterm(7).
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1