1 #include <unistd.h>
2 #include <errno.h>
3 #include <sys/ioctl.h>
4 #include "syscall.h"
5 
isatty(int fd)6 int isatty(int fd)
7 {
8 	struct winsize wsz;
9 	unsigned long r = syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
10 	if (r == 0) return 1;
11 	if (errno != EBADF) errno = ENOTTY;
12 	return 0;
13 }
14