?RCS: $Id: d_eofpipe.U 1 2006-08-24 12:32:52Z rmanfredi $
?RCS:
?RCS: Copyright (c) 1991-1997, 2004-2006, Raphael Manfredi
?RCS: 
?RCS: You may redistribute only under the terms of the Artistic Licence,
?RCS: as specified in the README file that comes with the distribution.
?RCS: You may reuse parts of this distribution only within the terms of
?RCS: that same Artistic Licence; a copy of which may be found at the root
?RCS: of the source tree for dist 4.0.
?RCS:
?RCS: $Log: d_eofpipe.U,v $
?RCS: Revision 3.0.1.1  1994/10/29  16:12:40  ram
?RCS: patch36: call ./bsd explicitely instead of relying on PATH
?RCS:
?RCS: Revision 3.0  1993/08/18  12:05:57  ram
?RCS: Baseline for dist 3.0 netwide release.
?RCS:
?MAKE:d_eofpipe: cat +cc +ccflags +libs rm Oldconfig Guess echo n c
?MAKE:	-pick add $@ %<
?S:d_eofpipe:
?S:	This variable conditionally defines the EOFPIPE symbol, which
?S:	indicates to the C program that select will correctly detect the EOF
?S:	condition when pipe is closed from the other end.
?S:.
?C:EOFPIPE:
?C:	This symbol, if defined, indicates that EOF condition will be detected
?C:	by the reader of the pipe when it is closed by the writing process.
?C:	That is, a select() call on that file descriptor will not block when
?C:	only an EOF remains (typical behaviour for BSD systems).
?C:.
?H:#$d_eofpipe EOFPIPE		/**/
?H:.
?F:!mpipe
: see if pipe correctly gives the EOF condition
echo " "
case "$d_eofpipe" in
'')
	echo "Let's see if your pipes return EOF to select() upon closing..." >&4
	$cat >pipe.c <<'EOP'
int main()
{
	int pd[2];
	int mask;

	pipe(pd);
	if (0 == fork()) {
		close(pd[0]);
		close(pd[1]);
		exit(0);
	}

	close(pd[1]);
	mask = 1 << pd[0];
	alarm(2);
	select(32, &mask, (int *) 0, (int *) 0, (char *) 0);
	if (0 == read(pd[0], &mask, 1))
		exit(0);
	
	exit(1);
}
EOP
	if $cc $ccflags -o pipe pipe.c $libs >/dev/null 2>&1; then
?X: Use a script to avoid the possible 'alarm call' message
		echo "./pipe || exit 1" > mpipe
		chmod +x mpipe
		./mpipe >/dev/null 2>&1
		case $? in
		0) d_eofpipe="$define";;
		*) d_eofpipe="$undef";;
		esac
	else
		echo "(The test program did not compile correctly -- Guessing.)"
		if ./bsd; then
			d_eofpipe="$define"
		else
			d_eofpipe="$undef"
		fi
	fi
	case "$d_eofpipe" in
	"$define") echo "Yes, they do.";;
	*) echo "No, they don't! (sigh)";;
	esac
	;;
*)
	$echo $n "Your pipes $c"
	case "$d_eofpipe" in
	"$define") echo "allow select() to see EOF upon closing.";;
	*) echo "won't let select() see EOF on closing.";;
	esac
	;;
esac
$rm -f *pipe* core

