Re: What's the correct new API to request pcap_linux to not open an eventfd

[Bill Fenner via tcpdump-workers <tcpdump-workers () lists tcpdump org>]

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>
>
> From: Bill Fenner <fenner () gmail com>
>
> Date: Tue, 5 Jul 2022 09:28:14 -0400
>
> Hi Denis,
>
> Thanks for pointing out the manpage update.  I had old man pages (my work
> is being done in the context of the 1.10 release).  What confused me is the
> asymmetry of the API.  If you call pcap_setnonblock() on an
> un-activated socket, it sets a flag and doesn't return an error.  But
> pcap_getnonblock() returns an error, so you can not check the value on an
> un-activated socket.
>
> This is not a flaw, necessarily, just confusing.
>
> Now that I understand this flow (I did not realize there were two different
> implementations of pcap_setnonblock(), because I was focused on
> pcap-linux.c and not on the important stuff in pcap.c) I think it's
> straightforward to defer the opening of the eventfd to pcap_activate(), so
> that we can avoid opening the eventfd altogether in nonblock mode.  I'll
> see if I can update my changes accordingly.  Thank you for pointing out the
> extra detail that helped me to understand.
>
>   Bill
>
> --- End Message ---
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