in reply to Re: fcntl on Windows
in thread fcntl on Windows

The point was not to figure out how to do it.. I know how to do it.. Here is my 'test' code.

#!/usr/bin/perl
use IO::Socket;

$sock = IO::Socket::INET->new( PeerAddr => '192.168.0.4',
                               PeerPort => 4000,
                               Proto    => 'tcp'
                              );

$flags = fcntl($sock, F_GETFL, 0)
        or die "Can't get flags for socket: $!\n";
fcntl($sock, F_SETFL, $flags | O_NONBLOCK)
        or die "Can't make socket nonblocking: $!\n";

print $sock "logn 0607daimuntemp123\n";

while(1) {
  sleep 1;
  $str = <$sock>;
  chomp $str;

  print $str . "\n";

  if( $str =~ /^$/ ) {
    print "null\n";
  }
}

[download]


When run, it results in this error:
fcntl is not implemented at sam.pl line 10.

Daimun

Replies are listed 'Best First'.
Re: Re: Re: fcntl on Windows
by Adam (Vicar) on Mar 21, 2001 at 00:59 UTC
    You forgot the line: 
    use Fcntl;

    [download]
    Easy mistake to make. That should fix it.

    Update:
    I tried your code (plus the use statement and a few print statements) on my NT box with Perl 5.6 and got this rather annoying message: 

    Your vendor has not defined Fcntl macro F_GETFL, used at C:\temp.pl li
+ne 10.

    [download]
    That means the Fcntl implementation in my install is incomplete. I suspect this is going to be true across Windows installations, so you might want to write a wrapper around Fcntl that defaults to Fcntl but fills in the holes when they are missing.
[reply]
[d/l]
[select]
      I apologize for the back-and-forth, but.. with that fix (Which I had already tried..) - I get:

      Your vendor has not defined Fcntl macro F_GETFL, used at ...

      If I then change F_GETFL to something random like F_GETFALLY or the such, I again get:

      fcntl is not implemented ...

      But.. again, it all works perfectly on the unix side. Frustrating me, indeed.

      Daimun
[reply]
      Trying to tap the well of knowledge here..
      What other ways are there to do what fcntl does? I'm not clear on what my other options might be.

      Daimun
[reply]
        Ooops. We are chasing a red herring. As "Programming Perl 2ed"(166) explains:
        fcntl will produce a fatal error if used on a machine that doesn't implement fcntl(2). On machines that do implement it, you can do such things as modify the close-on-exec flags, modify the non-blocking I/O flags, emulate the lockf(3) function...
        In otherwords, you are SOL on Windows machines. Your best alternative is to loop on select with a very small timeout. The use of polling to achieve non-blocking is not-uncommon, but it is probably slower and more processor intensive (I don't really know.) So then you will want to implement this twice, once for when $^O eq 'MSWin32' and once for when it doesn't.
[reply]

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