usr/src/usr.bin/f77/libU77/isatty_.c

/*
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));
}