Fwd: Re: [PATCH] Be truthful about reporting whether readahead is available

Corinna Vinschen corinna-cygwin@cygwin.com
Tue Apr 5 18:47:00 GMT 2016

On Apr  5 18:50, Thomas Wolff wrote:
> >>Von: Corinna Vinschen <corinna-cygwin@cygwin.com>
> >>An: cygwin-patches@cygwin.com
> >>Cc: Thomas Wolff <towo@towo.net>
> >>Datum: 5. April 2016 um 15:55
> >>Betreff: Re: [PATCH] Be truthful about reporting whether readahead is
> >>available
> >>
> >>Thomas?
> >>
> >>Any input?
> >>
> Yes, let's fix the patch so. Sorry for the flaw.

No worries.

> Thomas
> >>
> >>On Apr 5 10:52, Johannes Schindelin wrote:
> >>
> >>>In 7346568 (Make requested console reports work, 2016-03-16), code was
> >>>introduced to report the current cursor position. It works by using a
> >>>pointer that either points to the next byte in the readahead buffer, or
> >>>to a NUL byte if the buffer is depleted, or the pointer is NULL.
> >>>
> >>>These conditions are heeded in the fhandler_console::read() method, but
> >>>the condition that the pointer can point at the end of the readahead
> >>>buffer was not handled properly in the get_cons_readahead_valid()
> >>>method.
> >>>
> >>>This poses a problem e.g. in Git for Windows (which uses a slightly
> >>>modified MSYS2 runtime which is in turn a slightly modified Cygwin
> >>>runtime) when vim queries the cursor position and immediately goes on to
> >>>read console input, erroneously thinking that the readahead buffer is
> >>>valid when it is already depleted instead. This condition results in an
> >>>apparent freeze that can be helped only by pressing keys repeatedly.
> >>>
> >>>The full Git for Windows bug report is here:
> >>>
> >>>https://github.com/git-for-windows/git/issues/711
> >>>
> >>>Let's just teach the get_cons_readahead_valid() method to handle a
> >>>depleted readahead buffer correctly.

Patch applied.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat
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