See SetFilePointer() in Win32API::File (which comes standard with Win32 Perl).

Note that using Perl file handles with this may present a problem. You might be able to simply seek before each call to SetFilePointer(): 

use Win32API::File qw( SetFilePointer GetOsFHandle );
sub BigTell {
    my( $fh )= @_;
    seek( $fh, 0, 1 );    # Flush buffers
    my $osf= GetOsFHandle( $fh );
    my $hi= 0;
    my $lo= SetFilePointer( $osf, 0, $hi, 1 );
    return pack "NN", $hi, $lo;
}
sub BigSeek {
    my( $fh, $pos, $whence )= @_;
    my $osf= GetOsFHandle( $fh );
    seek($fh,0,1);    # Flush buffers
    my( $posHi, $posLo )= unpack "NN", $pos;
    $posLo= SetFilePointer( $osf, $posLo, $posHi, $whence )
      or  return;
    return pack "NN", $posHi, $posLo;
}

[download]
Note that I chose a format for the "big pointer" such that string comparisons are meaningful.

Unfortunately I don't have time at the moment to test this. However, if you have problems with it, reply and I'll likely be able to help.

On the other hand, please reply if this turns out to work well as it'd make a good addition to Win32API::File. (:

Updated to fix a typo.

        - tye (but my friends call me "Tye")

In reply to (tye)Re: 4Gb filesize limit by tye
in thread 4Gb filesize limit by ruffing

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