Re: fcntl(F_SETFD) on a file or socket handle

["Dmitry Timoshkov" <dmitry at baikal dot ru>]

"Corinna Vinschen" <cygwin@cygwin.com> wrote:

> > Analyzing Cygwin code, it seems I have found the source of the problem (had no
> > time to confirm it running offending code though).
> > 
> > It's in the fhandler_base::set_inheritance() called from fhandler_base::set_close_on_exec().
> > 
> > DuplicateHandle()/CloseHandle() invalidates original system handle associated
> > with the Cygwin internal file descriptor (fd) while an operation on the fd is
> > possibly still in progress.
> 
> Thanks for the hint.
> 
> That should unlikely be the cause, except you're running plain win95. 
> If you take a look into fhandler_socket.cc, you'll see that the
> fhandler_socket class defines it's own set_close_on_exec() method
> which doesn't call set_inheritance() when running Winsock2.

I see that fhandler_socket::fcntl() calls fhandler_base::fcntl() in
all cases different from F_SETFL. Perhaps my understanding of things
in C++ is not enough (I'm an old hand plain C programmer).

> OTOH, there seem to be a bug in 1.3.2 which could result in using
> Winsock1.1 methods even if Winsock2 is available.  Hmm, but the
> cause should be exactly the other way around:  Due to the error,
> Winsock1.1 methods are used for inheritance but w/o calling
> set_inheritance() before... However, you're reporting that problem is
> in the snapshots as well...
> 
> Are you using win95, perhaps?

No, I'm using Win2000 SP2.

>  Could you please start the application
> under strace and check, which Winsock version is used?  Just look
> for a block of lines with the text "wsock_init" like that:
> 
>  2326  339805 [main] ssh-agent 1760 wsock_init: res 0
>   157  339962 [main] ssh-agent 1760 wsock_init: wVersion 514
>    81  340043 [main] ssh-agent 1760 wsock_init: wHighVersion 514
>    78  340121 [main] ssh-agent 1760 wsock_init: szDescription WinSock 2.0
>    78  340199 [main] ssh-agent 1760 wsock_init: szSystemStatus Running
>    77  340276 [main] ssh-agent 1760 wsock_init: iMaxSockets 0
>    74  340350 [main] ssh-agent 1760 wsock_init: iMaxUdpDg 0
>    74  340424 [main] ssh-agent 1760 wsock_init: lpVendorInfo 0

I have the same numbers as in your trace.

--
Dmitry.



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