#!perl

use Win32API::File qw(:Func :FILE_ :FILE_SHARE_);
sub FILE_FLAG_BACKUP_SEMANTICS () { 0x0200_0000 }
sub FSCTL_GET_RETRIEVAL_POINTERS () { 0x90073 }

my $f = $0;
$f =~ s,/,\\,go;

# CreateFile->Call
#    FH, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANT
+ICS, NULL;

  my $fh= createFile( "$f", {
        Access => 'r',
        Share => FILE_SHARE_READ,
        Create => 'e',
        #Attributes=>"hst",
        Flags=>FILE_FLAG_BACKUP_SEMANTICS()
        } ) or  die "Can't create file, $0: $^E\n";
  

  my $vcn = 0 ; # virtual cluster number ...

  my $inBuf = pack ('L2',$vcn,0); # LARGE: Quad hence L2 !!! ;
  my $outBuf = pack ('L8',0); # ExCount,StartVCN,NextVCN,LCN
  my $dwByteReturned = 0; # DWORD;

  printf "Control code: %x\n",FSCTL_GET_RETRIEVAL_POINTERS;
  DeviceIoControl($fh,
    FSCTL_GET_RETRIEVAL_POINTERS,
    $inBuf,length($inBuf),
    $outBuf,length($outBuf),
    $dwBytesReturned,
    []);
  my $error = Win32::GetLastError();
  print "error-no: $error\n";
  warn "DeviceIoControl->Call: ", Win32::FormatMessage($error) if ($er
+ror);
  printf "BytesReturned: %u\n",$dwBytesReturned;
  printf "outBuf %s\n",unpack 'H*',substr($outBuf,0,80);


1;
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