src/unistd/isatty.c


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#include <unistd.h>
#include <errno.h>
#include <sys/ioctl.h>
#include "syscall.h"

int isatty(int fd)
{
	struct winsize wsz;
	/* +1 converts from error status (0/-1) to boolean (1/0) */
	return syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz) + 1;
}