The destructor for Person::OwnedByPerl would call free_person(), while Person::OwnedByLibrary would have no destructor.

That would solve the problem of not freeing memory which doesn't belong to you. It wouldn't solve the problem of holdning a Perl reference to an object which used memory already freed by Record::DESTROY call.

Of course, you could also store that information of whether to free the person or not on the XS level

I think that has the same problem. If I create Perl code like: 
sub find_person {
   my $record = new Record();
   my $person = $record->get_person();
   return $person;
}

my $p = find_person();

my $name = $p->name();

[download]
... then I would have an invalid-read. ... and Valgrind confirms it for me.

In reply to Re^2: Managing C library memory in XS by petermogensen
in thread Managing C library memory in XS by petermogensen

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