Re: cat-file timing window on Cygwin

[Adam Dinwoodie <adam@dinwoodie.org>]

On Sun, Aug 27, 2017 at 03:06:31AM +0100, Ramsay Jones wrote:
> On 26/08/17 22:11, Adam Dinwoodie wrote:
> > On Sat, Aug 26, 2017 at 11:53:37AM -0700, Jeff King wrote:
> >> Interesting. I find it a little hard to believe there's so obvious a bug
> >> as "fflush(NULL) flushes stdin", but well...that's what it seems like.
> >>
> >> If that's truly what it is, this is the minimal reproduction I came up
> >> with:
> >>
> >> -- >8 --
> >> #include <stdio.h>
> >>
> >> int main(void)
> >> {
> >> 	char buf[256];
> >> 	while (fgets(buf, sizeof(buf), stdin)) {
> >> 		fprintf(stdout, "got: %s", buf);
> >> 		fflush(NULL);
> >> 	}
> >> 	return 0;
> >> }
> >> -- 8< --
> >>
> >> If this really is the bug, then doing something like "seq 10 | ./a.out"
> >> would drop some of the input lines.
> > 
> > ...yep.  It does.  Specifically, I consistently only get the firsts
> > line:
> > 
> >     $ seq 10 | ./a.exe
> >     got: 1
> >     
> >     $ 
> > 
> > If I introduce a delay between the lines of stdin (which I tested by
> > just typing stdin from the keyboard), it works as expected.
> > 
> > Looks like this one will need to go to the Cygwin mailing list; I'll
> > take it there shortly.  Thank you all for your help getting this far!
> 
> This is apparently fixed in cygwin v2.8.3 [see commit 78ade082fe,
> ('Revert "errno: Stop using _impure_ptr->_errno completely"', 19-07-2017),
> commit 9cc89b0438 ("cygwin: Use errno instead of _impure_ptr->_errno", 19-07-2017), commit a674199fc9 ("cygwin: Bump DLL version to 2.8.3",
> 19-07-2017) and commit d2ae2f00b8 ("cygwin: add fflush fix to release
> notes", 19-07-2017)].
> 
> I haven't had a chance to try v2.8.3 yet (it's 3am and I'm about to
> go get some sleep).

Cygwin 2.8.3 hasn't been released yet, but I've just tested the latest
development snapshot with Jeff's simple test case, and it works as
expected, so I'm going to assume the Git test will start passing once
that version of the Cygwin DLL is released too.