use Win32::API;
use Win32::API::Struct;

Win32::API::Struct->typedef( 'MYHANDLE', qw(
  LPCTSTR lpFileName;
  DWORD dwDesiredAccess;
  DWORD dwShareMode;
  LPSECURITY_ATTRIBUTES lpSecurityAttributes;
  DWORD dwCreationDisposition;
  DWORD dwFlagsAndAttributes;
  HANDLE hTemplateFile; 
));
  
my $handle = Win32::API::Struct->new( 'MYHANDLE' ); 

my $filename = './catalog.db';

my $dll = Win32::API->new(
      'db.dll', 'OpenBlockFile','PS'
) or die $!;

$dll->Call($filename, $handle) or die $!;