www: support POST /$INBOX/$MSGID/?x=m&q=

This allows filtering the contents of any existing thread using
a search query.  It uses the existing THREADID column in Xapian
so we can internally add a Xapian OP_FILTER to the results.

This new functionality is orthogonal to the existing `t=1'
parameter which gives mairix-style thread expansion.  It doesn't
make sense to use `t=1' with this functionality, but it's not
disallowed, either.

The indentation change in Over->next_by_mid is to ensure
DBI->prepare_cached can share across both ->next_by_mid
and ->mid2tid.

I also noticed the existing regex for `POST /$INBOX/?x=m&q=' was
allowing extra characters.  With an added \z, it's now as strict
was originally intended and AFAIK nothing was generating invalid
URLs for it

Reported-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Link: https://public-inbox.org/meta/aaniyhk7wfm4e6m5mbukcrhevzoc6ftctyrfwvmz4fkykwwtlj@mverfng6ytas/T/

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/PublicInbox/Mbox.pm b/lib/PublicInbox/Mbox.pm
index 18db9d38..e1abf7ec 100644
--- a/lib/PublicInbox/Mbox.pm
+++ b/lib/PublicInbox/Mbox.pm
@@ -229,6 +229,11 @@ sub mbox_all {
                 return PublicInbox::WWW::need($ctx, 'Overview');
 
         my $qopts = $ctx->{qopts} = { relevance => -2 }; # ORDER BY docid DESC
+
+        # {threadid} limits results to a given thread
+        # {threads} collapses results from messages in the same thread,
+        # allowing us to use ->expand_thread w/o duplicates in our own code
+        $qopts->{threadid} = $over->mid2tid($ctx->{mid}) if defined($ctx->{mid});
         $qopts->{threads} = 1 if $q->{t};
         $srch->query_approxidate($ctx->{ibx}->git, $q_string);
         my $mset = $srch->mset($q_string, $qopts);