parameterize the prefix length and ensure we don't have files with names too short

diff --git a/dm6 b/dm6
index a5d56a6545a59258d2742e7dcfcedd0a4be5d843..b0ff96b84b633c717bf0516038f74e6ae2be494d 100755 (executable)
--- a/dm6
+++ b/dm6
@@ -69,10 +69,13 @@ sub link_files {
 my $link_dir = shift @ARGV;
 (-d $link_dir) or usage;
 
+my $prefix_length = 3;
+
 sub slash_prefix {
        my ($file) = @_;
-       my $prefix = substr($file, 0, 3);
-       my $suffix = substr($file, 3);
+       $file .= '_' x (length($file) + 1 - $prefix_length) if length($file) + 1 < $prefix_length;
+       my $prefix = substr($file, 0, $prefix_length);
+       my $suffix = substr($file, $prefix_length);
        $prefix =~ s:(.):$1/:osg;
        chop($prefix);
        return ($prefix, $suffix);