create or replace function save_file(filename text, data bytea)
returns void language plperlu as $body$
  use strict;
  my ($filename, $data) = @_;
 $data =~ s!\\\\!'\\'!eg;
$data =~ s!\\(\d{ 3 })! chr(oct($ 1 )) !eg;
  open my $f, '>', $filename or die "can't create file '$filename'";
  binmode $f;
  print $f $data;
  close $f;
$body$;
revoke execute on function save_file(filename text, data bytea) from public;