export and check last-modified header

Avoid resending unaltered pages.

diff --git a/common.inc.plp b/common.inc.plp
index b3a9a70520660bf4fffeb0319a2b826275a8e34b..d51e3e672870520d126a6e0fc10d4f5c02128357 100644 (file)
--- a/common.inc.plp
+++ b/common.inc.plp
@@ -6,6 +6,8 @@ no  warnings 'qw';  # you know what you doing
 no  warnings 'uninitialized';  # save some useless checks for more legible code
 use open IO => ':utf8';
 
+use File::stat 'stat';
+use HTTP::Date;
 use Shiar_Sheet::KeySigns qw(%sign);  # dependant on $get{ascii}
 
 our $style;
@@ -36,9 +38,33 @@ sub stylesheet {
        ) } @_;
 }
 
+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);
+}
+
 sub Html {
        my ($meta) = @_;
 
+       # announce and check data modification
+       checkmodified(
+               $ENV{SCRIPT_FILENAME},
+               (grep { /^Shiar_/ } values %INC),
+               $meta->{data} ? @{ $meta->{data} } : (),
+       );
+
        # default fallbacks
        $meta->{stylesheet} ||= [qw'light dark circus mono red terse'];
        $meta->{charset} ||= 'utf-8';