+# like format_sanitized_subject in git.git pretty.c with '%f' format string
+sub to_filename ($) {
+ my ($s, undef) = split(/\n/, $_[0]);
+ $s =~ s/[^A-Za-z0-9_\.]+/-/g;
+ $s =~ tr/././s;
+ $s =~ s/[\.\-]+\z//;
+ $s =~ s/\A[\.\-]+//;
+ $s
+}
+
+# convert a filename (or any string) to HTML attribute
+
+my %ESCAPES = map { chr($_) => sprintf('::%02x', $_) } (0..255);
+$ESCAPES{'/'} = ':'; # common
+
+sub to_attr ($) {
+ my ($str) = @_;
+
+ # git would never do this to us:
+ return if index($str, '//') >= 0;
+
+ my $first = '';
+ if ($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;
+ $first . $str;
+}
+
+# reverse the result of to_attr
+sub from_attr ($) {
+ my ($str) = @_;
+ my $first = '';
+ if ($str =~ s/\AZ([a-f0-9]{2})//ms) {
+ $first = chr(hex($1));
+ }
+ $str =~ s!::([a-f0-9]{2})!chr(hex($1))!egms;
+ $str =~ tr!:!/!;
+ $first . $str;
+}
+