Obtain the Master Port Name of a Pseudo Terminal

Question

How do you get the master port name when I create a Pseudo Terminal? I know I can use ptsname() to obtain the slave port name but what about the master?

int fdm, fds;
char slave_port_name[256];
int open_res = openpty(&fdm, &fds, slave_port_name, NULL, NULL);

system("ls -l /dev/");
printf("Master Port Name: %s, file descriptor: %d\n", ??? How to get master portname?, fdm);
printf("Slave Port Name: %s, file descriptor: %d\n", slave_port_name, fds);

Answer 1

You can't - there is no name for the master in the open_pt interface (there is a name for the masters in BSD style pty, however). You can't "open" the master device a second time, but you can dup the fd and pass it around if you need to (why do you need to, though?)