use Win32API::File;
use Win32;
use Win32::API;
{
my $api;
die "PeekNamedPipe"
    if ! ($api= Win32::API::More->Import("kernel32", "
BOOL PeekNamedPipe(
  HANDLE hNamedPipe,
  LPVOID lpBuffer,
  DWORD nBufferSize,
  LPDWORD lpBytesRead,
  LPDWORD lpTotalBytesAvail,
  LPDWORD lpBytesLeftThisMessage
);"));
}
##########################
my ($TotalBytesAvail, $ret) = (0);
my $hnd = Win32API::File::FdGetOsFHandle($rfh->fileno()); #get Win32 kernel handle from Perl land
if($hnd == Win32API::File::INVALID_HANDLE_VALUE()) {
    die "bad hnd";
}
$ret = PeekNamedPipe($hnd, undef, 0, undef, $TotalBytesAvail, undef);
if(!$ret) {
    my $err = Win32::GetLastError();
    die "PNP failed $err $^E";
 }
if($TotalBytesAvail) {
    #can safely read
}