src/third_party/musl/src/misc/login_tty.c

#include <utmp.h>
#include <sys/ioctl.h>
#include <unistd.h>

int login_tty(int fd)
{
	setsid();
	if (ioctl(fd, TIOCSCTTY, (char *)0)) return -1;
	dup2(fd, 0);
	dup2(fd, 1);
	dup2(fd, 2);
	if (fd>2) close(fd);
	return 0;
}