sub readline {

# 'select'-compatible function for reading one line of input from 
#    a filehandle.
#    
#    readline() expects one argument -- filehandle S
#
#    sample call:       $mystring = readline('S')
#

    my $filehandle = $_[0];
    my $c='';
    my $retstr='';
    my $endoffile=0;

    while ($c ne "\n" && ! $endoffile) {
	if (sysread($filehandle, $c, 1) > 0) {
	    $retstr = $retstr . $c;
	}
	else {
	    $endoffile=1;
	}
    }
    
    return $retstr;
}