grantpt - grant access to the slave pseudoterminal

Syntax	#include <stdlib.h> int grantpt(int fildes);
Description	The grantpt() function changes the access permissions and the owner of the slave pseudoterminal assigned to its master counterpart. fildes is a file descriptor that was returned when the master pseudoterminal was opened successfully. A program with the s bit set for root is called (/usr/lib/pt-chmod). The user ID of the slave device is the same as the effective user ID of the calling process, and the group ID is set to a reserved group ID. The access permissions are set such that for the slave pseudoterminal reading and writing are permitted for the owner and writing is permitted for the group.
Return val.	0 -1	if successful. if there is an error. errno is set to indicate the error.
Errors	grantpt() will fail if:
	EBADF	fildes is not a valid open file descriptor
	EINVAL	fildes is not assigned to a main pseudoterminal.
	EACCES	The corresponding slave device could not be accessed.
Notes	grantpt() will also fail if the application has implemented a signal handling routine to catch SIGCHLD signals.
See also	open(), ptsname(), setuid(), unlockpt(), stdlib.h.