[PATCH 29/95] lei_mirror: defend against infinite loops

[Eric Wong]

A reference chain of 1000 ought to be enough, I think...
---
 lib/PublicInbox/LeiMirror.pm | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index 0f46d355..1d6ed51c 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -538,9 +538,13 @@ sub clone_all {
        # resolve references, deepest, first:
        while (scalar keys %$todo) {
                for my $x (keys %$todo) {
+                       my $nr;
                        # resolve multi-level references
                        while (defined(my $nxt = $m->{$x}->{reference})) {
                                exists($todo->{$nxt}) or last;
+                               die <<EOM if ++$nr > 1000;
+E: dependency loop detected (`$x' => `$nxt')
+EOM
                                $x = $nxt;
                        }
                        my $y = delete $todo->{$x} // next; # already done