gitweb: Show submodule entries in the 'tree' view

Add S_ISGITLINK subroutine and S_IFGITLINK, S_IFINVALID constants.
Add support for "commit" (submodule) entries in the tree object to
mode_str ('m---------', following cgit), file_type and file_type_long
('submodule') subroutines.

There is only link to the history of submodule entry in the
supermodule (current repository) for now, because gitweb doesn't know
where to search for submodule repository objects.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -890,11 +890,25 @@ sub age_string {
 	return $age_str;
 }
 
+use constant {
+	S_IFINVALID => 0030000,
+	S_IFGITLINK => 0160000,
+};
+
+# submodule/subproject, a commit object reference
+sub S_ISGITLINK($) {
+	my $mode = shift;
+
+	return (($mode & S_IFMT) == S_IFGITLINK)
+}
+
 # convert file mode in octal to symbolic file mode string
 sub mode_str {
 	my $mode = oct shift;
 
-	if (S_ISDIR($mode & S_IFMT)) {
+	if (S_ISGITLINK($mode)) {
+		return 'm---------';
+	} elsif (S_ISDIR($mode & S_IFMT)) {
 		return 'drwxr-xr-x';
 	} elsif (S_ISLNK($mode)) {
 		return 'lrwxrwxrwx';
@@ -920,7 +934,9 @@ sub file_type {
 		$mode = oct $mode;
 	}
 
-	if (S_ISDIR($mode & S_IFMT)) {
+	if (S_ISGITLINK($mode)) {
+		return "submodule";
+	} elsif (S_ISDIR($mode & S_IFMT)) {
 		return "directory";
 	} elsif (S_ISLNK($mode)) {
 		return "symlink";
@@ -941,7 +957,9 @@ sub file_type_long {
 		$mode = oct $mode;
 	}
 
-	if (S_ISDIR($mode & S_IFMT)) {
+	if (S_ISGITLINK($mode)) {
+		return "submodule";
+	} elsif (S_ISDIR($mode & S_IFMT)) {
 		return "directory";
 	} elsif (S_ISLNK($mode)) {
 		return "symlink";
@@ -2707,6 +2725,20 @@ sub git_print_tree_entry {
 			              "history");
 		}
 		print "</td>\n";
+	} else {
+		# unknown object: we can only present history for it
+		# (this includes 'commit' object, i.e. submodule support)
+		print "<td class=\"list\">" .
+		      esc_path($t->{'name'}) .
+		      "</td>\n";
+		print "<td class=\"link\">";
+		if (defined $hash_base) {
+			print $cgi->a({-href => href(action=>"history",
+			                             hash_base=>$hash_base,
+			                             file_name=>"$basedir$t->{'name'}")},
+			              "history");
+		}
+		print "</td>\n";
 	}
 }