1 files changed, 3 insertions, 0 deletions
diff --git a/lib/PublicInbox/Hval.pm b/lib/PublicInbox/Hval.pm
index 95a0f709..2b443970 100644
--- a/lib/PublicInbox/Hval.pm
+++ b/lib/PublicInbox/Hval.pm
@@ -13,6 +13,9 @@ our @EXPORT_OK = qw/ascii_html obfuscate_addrs to_filename src_escape
                  to_attr from_attr/;
  my $enc_ascii = find_encoding('us-ascii');
  
+# safe-ish acceptable filename pattern for portability
+our $FN = '[a-zA-Z0-9][a-zA-Z0-9_\-\.]+[a-zA-Z0-9]'; # needs \z anchor
+
  sub new {
          my ($class, $raw, $href) = @_;