From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: Setting termios VMIN > 0 and VTIME > 0 on non blocking file
Date: Tue, 17 Mar 2020 13:16:03 +0100 [thread overview]
Message-ID: <20200317121603.GI512788@calimero.vinschen.de> (raw)
In-Reply-To: <20200316093514.GG512788@calimero.vinschen.de>
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Hi Åke,
On Mar 16 10:35, Corinna Vinschen wrote:
> On Mar 14 11:36, Åke Rehnman via Cygwin wrote:
> > On 2020-03-14 11:23, Åke Rehnman wrote:
> > > > > BTW there is a gremlin in the "else if (ev)" line....
> > > > A gremlin? Would you mind to explain? Btw., if you find a bug
> > > > in the code, we do take patches :) https://cygwin.com/contrib.html
> > > If we have an error event in ev it will make a blocking read even if
> > > VTIME==0.
>
> Ah, yeah, I was aware of that, I just ignored it for now since I'm not
> sure what the best way to handle that is.
>
> Two options come to mind, either ignoring these errors entirely, or
> returning -1 with errno set to EIO, along the lines of the Linux test
> for tty_io_error() at the start of tty_read.
>
> However, I have a sinking feeling that the function needs a rewrite
> anyway.
>
> For instance, consider reading in blocking mode, which may result in
> running the for loop more than once. If the first loop successfully
> read 4 bytes, and the second loop runs into an error from
> ClearCommError, the function will return -1 with errno set, completely
> ignoring the fact that 4 bytes have been read already.
>
> It should return 4 in this case, and only the next run of
> fhandler_serial::raw_read *might* return -1.
>
> This code really shows its age...
I have revamped the fhandler_serial::raw_read function, but I need
somebody for testing. Any chance you volunteer for that job?
We may need a couple of days to iron out all problems, but I think
the code is more sound now than the original function. I even
added a couple of comments to the code (*gasp*) so there's stuff
to discuss and to see why I did it that way.
For a quicker turn around we can also use Freenode IRC, see
https://cygwin.com/irc.html
Interested?
Thanks,
Corinna
--
Corinna Vinschen
Cygwin Maintainer
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next prev parent reply other threads:[~2020-03-17 12:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.1473.1583981776.15804.cygwin@cygwin.com>
2020-03-11 20:48 ` Åke Rehnman
2020-03-11 21:55 ` Brian Inglis
2020-03-12 1:01 ` Norton Allen
2020-03-12 1:04 ` Åke Rehnman
2020-03-12 1:08 ` Norton Allen
2020-03-12 1:39 ` Åke Rehnman
2020-03-12 8:05 ` Thomas Dickey
2020-03-12 11:01 ` Åke Rehnman
2020-03-12 19:48 ` Achim Gratz
2020-03-12 11:40 ` Corinna Vinschen
2020-03-12 13:32 ` Åke Rehnman
2020-03-12 14:13 ` Corinna Vinschen
2020-03-12 16:42 ` Åke Rehnman
2020-03-13 10:02 ` Corinna Vinschen
2020-03-12 14:20 ` Åke Rehnman
2020-03-12 14:44 ` Corinna Vinschen
2020-03-12 15:08 ` Corinna Vinschen
2020-03-12 17:04 ` Åke Rehnman
2020-03-13 10:12 ` Corinna Vinschen
2020-03-14 10:23 ` Åke Rehnman
2020-03-14 10:36 ` Åke Rehnman
2020-03-16 9:35 ` Corinna Vinschen
2020-03-17 12:16 ` Corinna Vinschen [this message]
2020-03-17 15:54 ` Åke Rehnman
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