From b16a9009730c94eb255445de02f5a0f75cc2d1de Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 10 Nov 2019 20:39:57 +0000
Subject: [PATCH 1/1] WIP

---
 build-aux/subdirmk-setup | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/build-aux/subdirmk-setup b/build-aux/subdirmk-setup
index 59430c7..ea9cb5b 100755
--- a/build-aux/subdirmk-setup
+++ b/build-aux/subdirmk-setup
@@ -36,17 +36,40 @@ sub build_tree () {
 
 sub target_varname ($$) {
     my ($var_prefix, $target) = @_;
-    return $vprefix.'TARGETS'.($target eq 'all' ? '' : "_$target");
+    return $var_prefix.'TARGETS'.($target eq 'all' ? '' : "_$target");
+}
+
+our $writing_output;
+our %output_files;
+
+sub close_any_output_file() {
+    return unless defined $writing_output;
+    O->error and die "error writing $writing_output.tmp: $! (?)\n";
+    close O or die "error closing $writing_output.tmp: $!\n";
+    $writing_output = undef;
+}
+
+sub start_output_file ($) {
+    close_any_output_file();
+    ($writing_output) = @_;
+    die if $output_files{$writing_output}++;
+    my $tmp = "$writing_output.tmp";
+    open O, ">", $tmp or die "create $tmp: $!\n";
+}
+
+sub o {
+    die unless defined $writing_output;
+    print O @_ or die "error writing $writing_output.tmp: $!\n";
 }
 
 sub write_makefile ($$) {
     my ($dir_prefix,$depth) = @_;
     start_output_file("${dir_prefix}Makefile");
     my $cd = $depth ? join('/', ('..',) x $depth) : '.';
-    o <<END;
+    o sprintf <<'END', $cd, $dir_prefix;
 default: all
-%:
-	\$(MAKE) -C $cd ${dir_prefix}$@
+%%:
+	$(MAKE) -C %s %s$@
 END
 }
 
@@ -55,7 +78,7 @@ sub filter_subdir_mk ($$$$$) {
 	$var_prefix, $targets) = @_;
 
     my $in = "${srcdir}/${dir_prefix}Subdir.mk.in";
-    open I, '<' $in or die "open $in: $!\n";
+    open I, '<', $in or die "open $in: $!\n";
     my $caps_re = qr{[A-Z][0-9_A-Z]*(?=\W)};
     my $lc_e = qr{[a-z][-+,0-9_a-z]*(?=\W)};
     my $esclit = '&';
-- 
2.30.2