RE: cat-file timing window on Cygwin

> -----Original Message-----
> From: Ramsay Jones
> Sent: Sunday, August 27, 2017 11:48 AM
> To: Adam Dinwoodie
> Cc: Jeff King; git@vger.kernel.org; Johannes Schindelin
> Subject: Re: cat-file timing window on Cygwin
> 
> 
> 
> On 27/08/17 12:33, Adam Dinwoodie wrote:
> > 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,
> 
> Heh, yes, I found that out myself this afternoon. ;-)
> 
> >                                         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.
> 
> Hmm, I'm not keen on installing "snapshot"(s), so I think I 
> will wait for the release to test it. (However, as a matter 
> of interest, how would I obtain/install/test this snapshot 
> release - is it a 'low-risk' exercise?)