#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <pty.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>

/* Nonstandard, but vastly superior to the standard functions */

int openpty(int *pm, int *ps, char *name, const struct termios *tio, const struct winsize *ws)
{
	int m, s = -1, cs;
	char buf[20];

	m = open("/dev/ptmx", O_RDWR|O_NOCTTY);
	if (m < 0) return -1;

	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);

	if (!name) name = buf;

#ifdef TIOCGPTPEER
	int ret;

	/* Try to allocate slave fd solely based on the master fd in case the
	 * kernel supports it.
	 */
	s = ioctl(m, TIOCGPTPEER, O_RDWR|O_NOCTTY);
	if (s < 0)
		goto fail;

	/* Check the contents of the symlink in case devpts has been mounted in
	 * a non-standard location.
	 */
	ret = ttyname_r(s, name, sizeof buf);
	if (ret)
		goto fail;

	if (strncmp(name, "/dev/pts/", 9))
		goto fail;
#else
	int n = 0;

	if (ioctl(m, TIOCSPTLCK, &n) || ioctl (m, TIOCGPTN, &n))
		goto fail;

	snprintf(name, sizeof buf, "/dev/pts/%d", n);
	s = open(name, O_RDWR|O_NOCTTY);
	if (s < 0)
		goto fail;
#endif

	if (tio) tcsetattr(s, TCSANOW, tio);
	if (ws) ioctl(s, TIOCSWINSZ, ws);

	*pm = m;
	*ps = s;

	pthread_setcancelstate(cs, 0);
	return 0;
fail:
	close(m);
	if (s >= 0)
		close(s);
	pthread_setcancelstate(cs, 0);
	return -1;
}