3 files changed, 5 insertions, 2 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) = @_;
  
diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 09afdaf1..83ae99bc 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -528,7 +528,7 @@ sub attach_link ($$$$;$) {
          $desc = $fn unless defined $desc;
          $desc = '' unless defined $desc;
          my $sfn;
-        if (defined $fn && $fn =~ /\A[[:alnum:]][\w\.-]+[[:alnum:]]\z/) {
+        if (defined $fn && $fn =~ /\A$PublicInbox::Hval::FN\z/o) {
                  $sfn = $fn;
          } elsif ($ct eq 'text/plain') {
                  $sfn = 'a.txt';
diff --git a/lib/PublicInbox/WWW.pm b/lib/PublicInbox/WWW.pm
index b6f18f8d..50b6950c 100644
--- a/lib/PublicInbox/WWW.pm
+++ b/lib/PublicInbox/WWW.pm
@@ -28,7 +28,7 @@ use PublicInbox::UserContent;
  our $INBOX_RE = qr!\A/([\w\-][\w\.\-]*)!;
  our $MID_RE = qr!([^/]+)!;
  our $END_RE = qr!(T/|t/|t\.mbox(?:\.gz)?|t\.atom|raw|)!;
-our $ATTACH_RE = qr!(\d[\.\d]*)-([[:alnum:]][\w\.-]+[[:alnum:]])!i;
+our $ATTACH_RE = qr!([0-9][0-9\.]*)-($PublicInbox::Hval::FN)!;
  our $OID_RE = qr![a-f0-9]{7,40}!;
  
  sub new {