isatty_.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 30 行

/*
char id_isatty[] = "@(#)isatty_.c	1.1";
 *
 * determine if stream is associated with a tty (async port)
 *
 * calling sequence:
 *	logical	isatty, val
 *	val = isatty (lunit)
 * where:
 *	val will be .TRUE. if lunit is associated with a 'tty'
 */

#include	"../libI77/fiodefs.h"

extern unit units[];	/* logical units table from iolib */

long isatty_(u)
long *u;
{
	int	i;
	unit	*lu;

	if (*u < 0 || *u >= MXUNIT)
		return(0);
	lu = &units[*u];
	if (!lu->ufd)
		return(0);
	return((long)(isatty(fileno(lu->ufd)) != 0));
}