+# convert a filename (or any string) to HTML attribute
+
+my %ESCAPES = map { chr($_) => sprintf('::%02x', $_) } (0..255);
+$ESCAPES{'/'} = ':'; # common
+
+sub to_attr ($) {
+ my ($str) = @_;
+
+ # git would never do this to us:
+ return if index($str, '//') >= 0;
+
+ my $first = '';
+ utf8::encode($str); # to octets
+ if ($str =~ s/\A([^A-Ya-z])//ms) { # start with a letter
+ $first = sprintf('Z%02x', ord($1));
+ }
+ $str =~ s/([^A-Za-z0-9_\.\-])/$ESCAPES{$1}/egms;
+ utf8::decode($str); # allow wide chars
+ $first . $str;
+}
+
+# for the t= query parameter passed to overview DB
+sub ts2str ($) { strftime('%Y%m%d%H%M%S', gmtime($_[0])) };
+
+# human-friendly format
+sub fmt_ts ($) { strftime('%Y-%m-%d %k:%M', gmtime($_[0])) }
+