From: "Åke Rehnman" <ake.rehnman@gmail.com>
To: cygwin@cygwin.com
Subject: Re: Setting termios VMIN > 0 and VTIME > 0 on non blocking file
Date: Tue, 17 Mar 2020 16:54:35 +0100 [thread overview]
Message-ID: <ac1d31f7-a945-5a0f-2fa0-1e9646b14bcc@gmail.com> (raw)
In-Reply-To: <20200317121603.GI512788@calimero.vinschen.de>
On 2020-03-17 13:16, Corinna Vinschen wrote:
> 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?
Sure, bring it on!
/Ake
prev parent reply other threads:[~2020-03-17 15:54 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
2020-03-17 15:54 ` Åke Rehnman [this message]
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