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, 23 insertions, 1 deletions

diff --git a/lib/PublicInbox/Over.pm b/lib/PublicInbox/Over.pm
index d6409b2a..82034b30 100644
--- a/lib/PublicInbox/Over.pm
+++ b/lib/PublicInbox/Over.pm
@@ -282,13 +282,35 @@ SELECT eidx_key FROM inboxes WHERE ibx_id = ?
         $rows;
 }
 
+sub mid2tid {
+        my ($self, $mid) = @_;
+        my $dbh = dbh($self);
+
+        my $sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT id FROM msgid WHERE mid = ? LIMIT 1
+
+        $sth->execute($mid);
+        my $id = $sth->fetchrow_array or return;
+        $sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT num FROM id2num WHERE id = ? AND num > ?
+ORDER BY num ASC LIMIT 1
+
+        $sth->execute($id, 0);
+        my $num = $sth->fetchrow_array or return;
+        $sth = $dbh->prepare(<<'');
+SELECT tid FROM over WHERE num = ? LIMIT 1
+
+        $sth->execute($num);
+        $sth->fetchrow_array;
+}
+
 sub next_by_mid {
         my ($self, $mid, $id, $prev) = @_;
         my $dbh = dbh($self);
 
         unless (defined $$id) {
                 my $sth = $dbh->prepare_cached(<<'', undef, 1);
-        SELECT id FROM msgid WHERE mid = ? LIMIT 1
+SELECT id FROM msgid WHERE mid = ? LIMIT 1
 
                 $sth->execute($mid);
                 $$id = $sth->fetchrow_array;