perform in chunks, don’t read the entire file into memory ahead

dot.mkshrc

@@ -1,5 +1,5 @@
 # $Id$
-# $MirOS: src/bin/mksh/dot.mkshrc,v 1.115 2017/08/08 20:22:16 tg Exp $
+# $MirOS: src/bin/mksh/dot.mkshrc,v 1.116 2017/08/08 20:38:08 tg Exp $
 #-
 # Copyright (c) 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010,
 #		2011, 2012, 2013, 2014, 2015, 2016, 2017
@@ -109,7 +109,8 @@ function hd_mksh {
 	\\builtin typeset dasc line i
 	\\builtin set +U
 
-	\\builtin cat "$@" | if \\builtin read -arN -1 line; then
+	\\builtin cat "$@" | {
+		while \\builtin read -arn 512 line; do
 			\\builtin typeset -i1 'line[*]'
 			i=0
 			while (( i < ${#line[*]} )); do
@@ -130,13 +131,14 @@ function hd_mksh {
 				(( (pos++ & 15) == 7 )) && \
 				    \\builtin print -nr -- '- '
 			done
+		done
 		while (( pos & 15 )); do
 			\\builtin print -nr '   '
 			(( (pos++ & 15) == 7 )) && \
 			    \\builtin print -nr -- '- '
 		done
 		(( hv == 2147483647 )) || \\builtin print -r -- "$dasc|"
-	fi
+	}
 }
 
 # Berkeley C shell compatible dirs, popd, and pushd functions