/*      $OpenBSD: pty.c,v 1.1 2024/06/03 08:02:22 anton Exp $   */

#include <sys/ioctl.h>

#include <err.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

#include "pty.h"

int
pty_open(struct pty *pty)
{
        int master, slave;

        master = posix_openpt(O_RDWR);
        if (master == -1) {
                warn("posix_openpt");
                return 1;
        }
        if (grantpt(master) == -1) {
                warn("grantpt");
                return 1;
        }
        if (unlockpt(master) == -1) {
                warn("unlockpt");
                return 1;
        }

        slave = open(ptsname(master), O_RDWR);
        if (slave == -1) {
                warn("%s", ptsname(master));
                return 1;
        }

        pty->master = master;
        pty->slave = slave;
        return 0;
}

void
pty_close(struct pty *pty)
{
        close(pty->slave);
        close(pty->master);
}

/*
 * Disconnect the controlling tty, if present.
 */
int
pty_detach(struct pty *pty)
{
        int fd;

        fd = open("/dev/tty", O_RDWR | O_NOCTTY);
        if (fd >= 0) {
                (void)ioctl(fd, TIOCNOTTY, NULL);
                close(fd);
        }
        return 0;
}

/*
 * Connect the slave as the controlling tty.
 */
int
pty_attach(struct pty *pty)
{
        if (ioctl(pty->slave, TIOCSCTTY, NULL) == -1) {
                warn("TIOCSCTTY");
                return 1;
        }
        return 0;
}

int
pty_drain(struct pty *pty)
{
        for (;;) {
                char *buf = &pty->buf.storage[pty->buf.len];
                size_t bufsize = sizeof(pty->buf.storage) - pty->buf.len;
                ssize_t n;

                n = read(pty->master, buf, bufsize);
                if (n == -1) {
                        warn("read");
                        return 1;
                }
                if (n == 0)
                        break;

                /* Ensure space for NUL-terminator. */
                if ((size_t)n >= bufsize) {
                        warnx("pty buffer too small");
                        return 1;
                }
                pty->buf.len += n;
        }

        return 0;
}