Only copy headers if they've changed.

util/copy-if-different.pl

+#!/usr/local/bin/perl
+
+use strict;
+
+use Fcntl;
+
+
+# copy-if-different.pl
+
+# Copy to the destination if the source is not the same as it.
+
+my $stripcr = 0;
+
+my @filelist;
+
+foreach my $arg (@ARGV) {
+	$arg =~ s|\\|/|g;	# compensate for bug/feature in cygwin glob...
+	foreach (glob $arg)
+		{
+		push @filelist, $_;
+		}
+}
+
+my $fnum = @filelist;
+
+if ($fnum <= 1)
+	{
+	die "Need at least two filenames";
+	}
+
+my $dest = pop @filelist;
+
+if ($fnum > 2 && ! -d $dest)
+	{
+	die "Destination must be a directory";
+	}
+
+foreach (@filelist)
+	{
+        my $dfile;
+	if (-d $dest)
+		{
+		$dfile = $_;
+		$dfile =~ s|^.*[/\\]([^/\\]*)$|$1|;
+		$dfile = "$dest/$dfile";
+		}
+	else
+		{
+		$dfile = $dest;
+		}
+
+	my $buf;
+	if (-f $dfile)
+		{
+		sysopen(IN, $_, O_RDONLY|O_BINARY) || die "Can't Open $_";
+		sysopen(OUT, $dfile, O_RDONLY|O_BINARY)
+		  || die "Can't Open $dfile";
+		while (sysread IN, $buf, 10240)
+			{
+			my $b2;
+			goto copy if !sysread(OUT, $b2, 10240) || $buf ne $b2;
+			}
+		goto copy if sysread(OUT, $buf, 1);
+		close(IN);
+		close(OUT);
+		print "NOT copying: $_ to $dfile\n";
+		next;
+		}
+      copy:
+	sysopen(IN, $_, O_RDONLY|O_BINARY) || die "Can't Open $_";
+	sysopen(OUT, $dfile, O_WRONLY|O_CREAT|O_TRUNC|O_BINARY)
+					|| die "Can't Open $dfile";
+	while (sysread IN, $buf, 10240)
+		{
+		syswrite(OUT, $buf, length($buf));
+		}
+	close(IN);
+	close(OUT);
+	print "Copying: $_ to $dfile\n";
+	}
+

util/mk1mf.pl

@@ -1353,7 +1353,7 @@ sub do_copy_rule
 		if ($n =~ /bss_file/)
 			{ $pp=".c"; }
 		else	{ $pp=$p; }
-		$ret.="$to${o}$n$pp: \$(SRC_D)$o$_$pp $to\n\t\$(CP) \"\$(SRC_D)$o$_$pp\" \"$to${o}$n$pp\"\n\n";
+		$ret.="$to${o}$n$pp: \$(SRC_D)$o$_$pp $to\n\t\$(SRC_D)${o}util${o}copy-if-different.pl \"\$(SRC_D)$o$_$pp\" \"$to${o}$n$pp\"\n\n";
 		}
 	return($ret);
 	}