www: avoid uninitialized vars from shadowed Message-IDs

For /all/ (extindex) and like, Message-ID reuse from client
errors or list-injected footers can cause threading weirdness.
Avoid auto-vivification in the mapping table and dereferencing
of unknown messages.

1 files changed, 21 insertions, 18 deletions

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index fc0cd77e..c80a675e 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -281,8 +281,15 @@ sub eml_entry {
 sub pad_link ($$;$) {
         my ($mid, $level, $s) = @_;
         $s ||= '...';
-        my $id = id_compress($mid, 1);
-        (' 'x19).indent_for($level).th_pfx($level)."<a\nhref=#r$id>($s)</a>\n";
+        my $href = defined($mid) ?
+                ("<a\nhref=#r".id_compress($mid, 1).">($s)</a>\n") :
+                "($s)\n";
+        (' 'x19).indent_for($level).th_pfx($level).$href;
+}
+
+sub _skel_hdr {
+        # my ($mapping, $mid) = @_;
+        ($_[0]->{$_[1] // \'bogus'} // [ "(?)\n" ])->[0];
 }
 
 sub _th_index_lite {
@@ -314,10 +321,11 @@ sub _th_index_lite {
                                 my $s = ($idx - 1). ' preceding siblings ...';
                                 $rv .= pad_link($pmid, $level, $s);
                         } elsif ($idx == 2) {
-                                my $ppmid = $siblings->[0]->{mid};
-                                $rv .= $pad . $mapping->{$ppmid}->[0];
+                                $rv .= $pad . _skel_hdr($mapping,
+                                                $siblings->[0] ?
+                                                $siblings->[0]->{mid} : undef);
                         }
-                        $rv .= $pad . $mapping->{$pmid}->[0];
+                        $rv .= $pad . _skel_hdr($mapping, $pmid);
                 }
         }
         my $s_s = nr_to_s($nr_s, 'sibling', 'siblings');
@@ -327,26 +335,26 @@ sub _th_index_lite {
         $attr =~ s!<a\nhref=[^>]+>([^<]+)</a>!$1!s; # no point linking to self
         $rv .= "<b>@ $attr";
         if ($nr_c) {
-                my $cmid = $children->[0]->{mid};
-                $rv .= $pad . $mapping->{$cmid}->[0];
+                my $cmid = $children->[0] ? $children->[0]->{mid} : undef;
+                $rv .= $pad . _skel_hdr($mapping, $cmid);
                 if ($nr_c > 2) {
                         my $s = ($nr_c - 1). ' more replies';
                         $rv .= pad_link($cmid, $level + 1, $s);
                 } elsif (my $cn = $children->[1]) {
-                        $rv .= $pad . $mapping->{$cn->{mid}}->[0];
+                        $rv .= $pad . _skel_hdr($mapping, $cn->{mid});
                 }
         }
 
         my $next = $siblings->[$idx+1] if $siblings && $idx >= 0;
         if ($next) {
                 my $nmid = $next->{mid};
-                $rv .= $pad . $mapping->{$nmid}->[0];
+                $rv .= $pad . _skel_hdr($mapping, $nmid);
                 my $nnext = $nr_s - $idx;
                 if ($nnext > 2) {
                         my $s = ($nnext - 1).' subsequent siblings';
                         $rv .= pad_link($nmid, $level, $s);
                 } elsif (my $nn = $siblings->[$idx + 2]) {
-                        $rv .= $pad . $mapping->{$nn->{mid}}->[0];
+                        $rv .= $pad . _skel_hdr($mapping, $nn->{mid});
                 }
         }
         $rv .= $pad ."<a\nhref=#r$id>$s_s, $s_c; $ctx->{s_nr}</a>\n";
@@ -453,8 +461,8 @@ EOF
         $ctx->{skel} = \$skel;
         $ctx->{prev_attr} = '';
         $ctx->{prev_level} = 0;
-        $ctx->{root_anchor} = anchor_for($mid);
-        $ctx->{mapping} = {};
+        $ctx->{root_anchor} = 'm' . id_compress($mid, 1);
+        $ctx->{mapping} = {}; # mid -> [ header_summary, node, idx, level ]
         $ctx->{s_nr} = ($nr > 1 ? "$nr+ messages" : 'only message')
                        .' in thread';
 
@@ -869,11 +877,6 @@ sub linkify_ref_no_over {
         "&lt;<a\nhref=\"../$href/\">$html</a>&gt;";
 }
 
-sub anchor_for {
-        my ($msgid) = @_;
-        'm' . id_compress($msgid, 1);
-}
-
 sub ghost_parent {
         my ($upfx, $mid) = @_;
 
@@ -1274,7 +1277,7 @@ sub thread_adj_level {
 sub ghost_index_entry {
         my ($ctx, $level, $node) = @_;
         my ($beg, $end) = thread_adj_level($ctx,  $level);
-        $beg . '<pre>'. ghost_parent($ctx->{-upfx}, $node->{mid})
+        $beg . '<pre>'. ghost_parent($ctx->{-upfx}, $node->{mid} // '?')
                 . '</pre>' . $end;
 }