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Old 01-03-2004, 09:14 PM   #1
Registered: Sep 2003
Posts: 104

Rep: Reputation: 20
Set/Unset Non-Blocking sockets?

I am working on an irc bot (big suprise?) and I need to set/unet non blocking sockets, I know how to set it with:

// ...

int sd, v;

// ...

v = fcntl(sd, F_GETFD, 0);
fcntl(sd, F_SETFD, v | O_NONBLOCK);

// ...
Anyway, any help would be appreciated
Old 01-03-2004, 11:43 PM   #2
Registered: Mar 2003
Posts: 804

Rep: Reputation: 30
since you have the previous flags saved in the variable v, all you have to do is:
fcntl(sd, F_SETFD, v);

but as an aside, lets say you had done this:

v = fcntl(sd, F_GETFD, 0);

now if you wanted to remove the nonblocking flag from v, you would go


that would clear the O_NONBLOCK flag. remember flags are just bits that
have been "turned on", meaning set to 1. to turn off a bit you just set it back to 0.
the '~' complements O_NONBLOCK, setting all the bits that were 0 to 1, and the
bits that were 1 to 0. then when you '&=' it with v this has the effect of setting
the bit in v for O_NONBLOCK to 0.
Old 01-04-2004, 01:31 AM   #3
Registered: Sep 2003
Posts: 104

Original Poster
Rep: Reputation: 20
-sighs-, I knew it was something like that, and why I didn't think to just use v, I don't know, anyway thanks.. Though, I found that the problem was not from the ``blocking'' sockets... so back to the drawing board.


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