// positionsLocked returns the positions in the blockfile of all packets matched by
// the passed-in query. b.mu must be locked.
func (b *BlockFile) positionsLocked(ctx context.Context, q query.Query) (base.Positions, error) {
if b.i == nil || b.f == nil {
// If we're closed, just return nothing.
return nil, nil
}
return q.LookupIn(ctx, b.i)
}
