config: ignore extindex entries with newlines in paths

git 2.11 and earlier could not handle git directories with
newlines in them, nor does libgit2 support them.

Followup-to: d87dd0e679587043 ("config: reject `\n' in `inboxdir'")

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index 228de4ff..26ac298e 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -510,6 +510,10 @@ sub _fill_ei ($$) {
         my $pfx = "extindex.$name";
         my $d = $self->{"$pfx.topdir"} // return;
         -d $d or return;
+        if (index($d, "\n") >= 0) {
+                warn "E: `$d' must not contain `\\n'\n";
+                return;
+        }
         my $es = PublicInbox::ExtSearch->new($d);
         for my $k (qw(indexlevel indexsequentialshard)) {
                 my $v = _one_val($self, $pfx, $k) // next;