I have a program that reads from a socket I created with IO::Socket::INET. Most of the time, I want the calls to sysread and $sock->accept() to block. But just one time I need to check if I've received anything over the socket. If there is nothing there, I don't want it to block forever, I want it to move on. In Windows, I think the only way to get a non-blocking socket is to use the ioctl function like: 
my $true = 1;
ioctl($sock,0x8004667e,\$true);

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I found this lovely gem on this site and it's worked well. My first thought to solve my problem was to make my socket non-blocking with ioctl, read from it, then change it back to blocking with a similar ioctl call. Unfortunately, this doesn't work. I tried setting $true to 0, -1, and undef and all have the same effect, they make the socket non-blocking. So my question is this: Is there any way to reverse the non-blockingness caused by an ioctl call? I have tried other methods (like an alarm), but these don't work in Windows. When perl is blocked in a sysread, I can't get it to catch sig int or sig alrm. Please help!

In reply to ioctl for non-blocking and blocking in Windows by Anonymous Monk

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