Bug in Constants.pm causes 500 error when running agent

[Saint Aardvark]

I'm running OCS Inventory version 1.3.2 on CentOS Linux, 5.4; the
package comes from the Fedora EPEL project. The client is version
1.0.1 (yes, that's old, but I'm having unrelated problems with version
1.1.2 on CentOS, and from what I can see the problem isn't related to
the client).

When I run the OCS Inventory client and point it at the server, I get
a 500 error from Apache and this message logged in Apache's error_log:

----
DBD::mysql::db do failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '|CHECKSUM|1),
        NAME='bogus',
        WORKGROUP='example.com',
        USERDOMAIN=NULL,' at line 4 at /usr/lib/perl5/vendor_perl/5.8.8/Apache/Ocsinventory/Server/Inventory/Update/Hardware.pm line 35.
----

(Actual hostnames deleted.) I added some debugging statements to
Hardware.pm, and here's a bit more context from the query
being run:

----
UPDATE hardware SET USERAGENT='OCS-NG_linux_client_v15',
        LASTDATE=NOW(),
        LASTCOME=NOW(),
        CHECKSUM=(|CHECKSUM|1),
        NAME='bogus',
        WORKGROUP='example.com',
        USERDOMAIN=NULL,
----

The relevant bit of Hardware.pm is:

----
  $dbh->do("UPDATE hardware SET USERAGENT=".$dbh->quote($ua).",
        LASTDATE=NOW(),
        LASTCOME=NOW(),
        CHECKSUM=(".(defined($base->{CHECKSUM})?$base->{CHECKSUM}:CHECKSUM_MAX_VALUE)."|CHECKSUM|1),
        NAME=".$dbh->quote($base->{NAME}).",
        WORKGROUP=".$dbh->quote($base->{WORKGROUP}).",
----

In turn, CHECKSUM_MAX_VALUE is defined in
Ocsinventory/Server/Constants.pm:

----
my $checksum_max_value = &get_checksum();
use constant CHECKSUM_MAX_VALUE => $checksum_max_value;

[snip]

sub get_checksum {
  my $checksum;

  for my $section (keys %DATA_MAP){
    $checksum|=$DATA_MAP{$section}->{mask};
  }
  return $checksum;
}
----

By adding more debugging statements, I figured out that the subroutine
get_checksum() *was* returning a sane value (262143), but the "use
constant" statement was *not* using it. This problem can be reduced
to the test case:

----
$ perl -e'$bar = &get_bar(); print "\$bar == |$bar|\n"; use constant FOO => $bar; print "FOO == |" . FOO . "|\n"; sub get_bar { return 1;}'
$bar == |1|
FOO == ||
----

The problem appears to be that a "use constant" statement is
evaluated/set at *compile* time, and the variable assignment is done
at *run* time. This PerlMonks thread has more details:

 http://www.perlmonks.org/bare/?node_id=843110

I'm not sure what the correct solution would be, but a stupid
workaround for me is just to insert this into Hardware.pm:

 use constant CHECKSUM_MAX_VALUE => 262143;

Thanks very much, and please let me know if you need any further information.