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Date: Sat, 12 Mar 2016 20:39:46 +0100
From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: Problem with line buffering and getc function on 1.7.33.
Message-ID: <20160312193946.GB3567@calimero.vinschen.de>
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References: <a0c23290b3a8502552dcf149fbfa5f90@mail.kylheku.com> <56E34346.9010000@gmail.com> <11ca145175d5b7d15db927c0c1f28b18@mail.kylheku.com>
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On Mar 11 16:05, Kaz Kylheku wrote:
> We can reproduce the problem with just file streams using
> a much simpler program:
>=20
> #include <stdio.h>
>=20
> int main(void)
> {
>   FILE *out =3D fopen("file", "w+");
>   setvbuf(out, (char *) NULL, _IOLBF, 0);
>   getc(out);
>   clearerr(out);
>   fseek(out, 0, SEEK_SET);
>   putc('a', out);
>   putc('b', out);
>   putc('c', out);
>   putc('d', out);
>   putc('e', out);
>   putc('\n', out);
>   fclose(out);
>   return 0;
> }
>=20
> The contents of file end up being "\n": one empty
> line, instead of "abcde\n":
>=20
>   $ cat file
>=20
>   $

Thanks for the testcase.  I can reproduce the issue and I see where the
problem occurs, but I'm still puzzled.  Comparing the code in our newlib
C library with its BSD counterparts, I could swear the same behaviour
happens on OpenBSD as well.  If not (which needs testing), I wonder why
and where newlib's actually different.  Right now I don't see the
difference.


Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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