NAME

ptsname, ptsname_r — get the pathname of the slave pseudo-terminal device

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <stdlib.h>

char *
ptsname(int masterfd);

int
ptsname_r(int masterfd, char *buf, size_t buflen);

DESCRIPTION

The ptsname() function returns the pathname of the slave pseudo-terminal device that corresponds to the master pseudo-terminal device associated with masterfd. The ptsname() function is not reentrant or thread-safe.

The ptsname_r() function places the pathname of the slave pseudo-terminal device that corresponds to the master pseudo-terminal device associated with masterfd int the buf argument copying up to buflen characters. The buf is always NUL terminated.

RETURN VALUES

If successful, ptsname() returns a pointer to a nul-terminated string containing the pathname of the slave pseudo-terminal device. If an error occurs ptsname() will return NULL and errno is set to indicate the error.

If successful, ptsname_r() places a nul-terminated string containing the pathname of the slave pseudo-terminal device in buf and returns 0. If an error occurs ptsname_r() will return an error number indicating what went wrong.

ERRORS

The ptsname() and ptsname_r() functions will fail if:

[EACCESS]

the corresponding pseudo-terminal device could not be accessed.

[EBADF]

masterfd is not a valid descriptor.

[EINVAL]

masterfd is not associated with a master pseudo-terminal device.

In addition the ptsname_r() function will return:

[EINVAL]

the buf argument is NULL.

[ERANGE]

the name of the pseudo-terminal is longer than bufsiz characters plus the terminating NUL.

NOTES

The error returns of ptsname() are a NetBSD extension. The ptsname() function is equivalent to:

	static struct ptmget pm;
	return ioctl(masterfd, TIOCPTSNAME, &pm) == -1 ? NULL : pm.sn;

Both the ptsname() and ptsname_r() functions will also return the name of the slave pseudo-terminal if a file descriptor to the slave pseudo-terminal is passed to masterfd.

This is a convenient extension because it allows one to use the file descriptor obtained by open(2) /dev/tty to obtain the name of the pseudo-terminal for the current process.

SEE ALSO

ioctl(2), open(2), grantpt(3), posix_openpt(3), unlockpt(3)

STANDARDS

The ptsname() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”). Its first release was in X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”).