+sub checkmodified {
+ my $lastmod;
+ for (@_) {
+ my $mod = stat $_ or next;
+ $mod = $mod->mtime or next;
+ $lastmod = $mod if $mod gt $lastmod;
+ }
+
+ for ($ENV{HTTP_IF_MODIFIED_SINCE} || ()) {
+ next if str2time($_) < $lastmod;
+ $header{status} = '304 Same old';
+ exit;
+ }
+
+ $header{'Last-Modified'} = time2str($lastmod);
+}
+