Re: [PATCHv4] gethostname: fix build on mingw

[Matthias Bolte]

2010/3/22 Eric Blake <address@hidden>:
> Since commit 4e86671a, gethostname failed to compile on mingw.
> Gnulib's sys/socket.h includes winsock2.h, which then includes
> unistd.h prior to declaring gethostname.  The fix is to ensure
> that our replacement unistd.h does not declare any replacements
> until we are sure that winsock2.h is completely included.
>
> * lib/unistd.in.h (includes): Work around fact that mingw
> <winsock2.h> re-includes <unistd.h>, by avoiding any
> redeclarations if we are being included by <winsock2.h>.
> Reported by Matthias Bolte.
>
> Signed-off-by: Eric Blake <address@hidden>
> ---
>
> Try 4.  This time, try localizing all the changes to just our
> replacement <unistd.h>.  Detect whether we are being indirectly
> included by <winsock2.h>, so that clients should not have to
> adjust their calling patterns (although they DO need to explcitly
> include <unistd.h> if they plan on using gethostname, rather
> than relying on the nonstandard <winsock2.h> to provide it).
>
>  ChangeLog       |    8 ++++++++
>  lib/unistd.in.h |   28 +++++++++++++++++++++++++---
>  2 files changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/ChangeLog b/ChangeLog
> index cc3ef5a..22dfca0 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,11 @@
> +2010-03-22  Eric Blake  <address@hidden>
> +
> +       gethostname: fix build on mingw
> +       * lib/unistd.in.h (includes): Work around fact that mingw
> +       <winsock2.h> re-includes <unistd.h>, by avoiding any
> +       redeclarations if we are being included by <winsock2.h>.
> +       Reported by Matthias Bolte.
> +
>  2010-03-20  Bruno Haible  <address@hidden>
>
>        * m4/unlink.m4 (gl_FUNC_UNLINK): Fix last commit.
> diff --git a/lib/unistd.in.h b/lib/unistd.in.h
> index b74484a..b2b92c8 100644
> --- a/lib/unistd.in.h
> +++ b/lib/unistd.in.h
> @@ -15,7 +15,23 @@
>    along with this program; if not, write to the Free Software Foundation,
>    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
>
> -#ifndef _GL_UNISTD_H
> +/* Special invocation convention:
> +   - On mingw, several headers, including <winsock2.h>, include <unistd.h>,
> +     but we need to ensure that both the system <unistd.h> and <winsock2.h>
> +     are completely included before we replace gethostname.  */
> +#if @UNISTD_H_HAVE_WINSOCK2_H@ && !defined _GL_WINSOCK2_H_WITNESS \
> +  && defined _WINSOCK2_H
> +/* <unistd.h> is being indirectly included for the first time from
> +   <winsock2.h>; avoid declaring any overrides.  */
> +# if @HAVE_UNISTD_H

An @ is missing here.

> +# address@hidden@ @NEXT_UNISTD_H@
> +# else
> +#  error unexpected; report this to address@hidden
> +# endif
> +# define _GL_WINSOCK2_H_WITNESS
> +
> +/* Normal invocation.  */
> +#elif !defined _GL_UNISTD_H
>
>  #if __GNUC__ >= 3
> address@hidden@
> @@ -26,7 +42,14 @@
>  # @INCLUDE_NEXT@ @NEXT_UNISTD_H@
>  #endif
>
> -#ifndef _GL_UNISTD_H
> +/* Get all possible declarations of gethostname().  */
> +#if @UNISTD_H_HAVE_WINSOCK2_H@ && !defined _GL_INCLUDING_WINSOCK2_H
> +# define _GL_INCLUDING_WINSOCK2_H
> +# include <winsock2.h>
> +# undef _GL_INCLUDING_WINSOCK2_H
> +#endif
> +
> +#if !defined _GL_UNISTD_H && !defined _GL_INCLUDING_WINSOCK2_H
>  #define _GL_UNISTD_H
>
>  /* NetBSD 5.0 mis-defines NULL.  Also get size_t.  */
> @@ -76,7 +99,6 @@
>  #if @GNULIB_GETHOSTNAME@
>  /* Get all possible declarations of gethostname().  */
>  # if @UNISTD_H_HAVE_WINSOCK2_H@
> -#  include <winsock2.h>
>  #  if !defined _GL_SYS_SOCKET_H
>  #   undef socket
>  #   define socket               socket_used_without_including_sys_socket_h
> --
> 1.6.6.1
>

ACK.

This one fixes the issue.

Matthias