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For open/openat, if the flags parameter does not contain O_CREAT, the
3rd (variadic) mode_t parameter is irrelevant.  Many developers in the past
have passed mode_t (0, 044, 0644, or such), which might lead future people
to copy this broken idiom, and perhaps even believe this parameter has some
meaning or implication or application. Delete them all.
This comes out of a conversation where tb@ noticed that a strange (but
intentional) pledge behaviour is to always knock-out high-bits from
mode_t on a number of system calls as a safety factor, and his bewilderment
that this appeared to be happening against valid modes (at least visually),
but no sorry, they are all irrelevant junk.  They could all be 0xdeafbeef.
ok millert

/*	$OpenBSD: tty.c,v 1.19 2021/10/24 21:24:21 deraadt Exp $	*/

#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>

#include "sh.h"
#include "tty.h"

int		tty_fd = -1;	/* dup'd tty file descriptor */
int		tty_devtty;	/* true if tty_fd is from /dev/tty */
struct termios	tty_state;	/* saved tty state */

void
tty_close(void)
{
	if (tty_fd >= 0) {
		close(tty_fd);
		tty_fd = -1;
	}
}

/* Initialize tty_fd.  Used for saving/resetting tty modes upon
 * foreground job completion and for setting up tty process group.
 */
void
tty_init(int init_ttystate)
{
	int	do_close = 1;
	int	tfd;

	tty_close();
	tty_devtty = 1;

	tfd = open("/dev/tty", O_RDWR);
	if (tfd == -1) {
		tty_devtty = 0;
		warningf(false, "No controlling tty (open /dev/tty: %s)",
		    strerror(errno));

		do_close = 0;
		if (isatty(0))
			tfd = 0;
		else if (isatty(2))
			tfd = 2;
		else {
			warningf(false, "Can't find tty file descriptor");
			return;
		}
	}
	if ((tty_fd = fcntl(tfd, F_DUPFD_CLOEXEC, FDBASE)) == -1) {
		warningf(false, "%s: dup of tty fd failed: %s",
		    __func__, strerror(errno));
	} else if (init_ttystate)
		tcgetattr(tty_fd, &tty_state);
	if (do_close)
		close(tfd);
}