Re: [PATCH] gethostname: fix build on mingw

[Matthias Bolte]

2010/3/20 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.  Therefore, unistd.h
> cannot replace gethostname until winsock2.h is complete, also
> fixing things if a .c includes <unistd.h> (or even <winsock2.h>)
> prior to <sys/socket.h>.
>
> * lib/sys_socket.in.h (includes): Set witness when including
> winsock2.h.
> * lib/unistd.in.h (includes): Likewise, after hoisting <winsock2.h>
> inclusion.  Don't replace anything when included by winsock2.h.
> Reported by Matthias Bolte.
>
> Signed-off-by: Eric Blake <address@hidden>
> ---
>
> I think this is more robust, but would appreciate another round
> of testing before I push.
>
>  ChangeLog           |    9 +++++++++
>  lib/sys_socket.in.h |    7 ++++++-
>  lib/unistd.in.h     |   15 +++++++++++++--
>  3 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/ChangeLog b/ChangeLog
> index de054fa..2125639 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,12 @@
> +2010-03-19  Eric Blake  <address@hidden>
> +
> +       gethostname: fix build on mingw
> +       * lib/sys_socket.in.h (includes): Set witness when including
> +       winsock2.h.
> +       * lib/unistd.in.h (includes): Don't replace anything when included
> +       by winsock2.h.
> +       Reported by Matthias Bolte.
> +
>  2010-02-17  Eric Blake  <address@hidden>
>
>        manywarnings: add more warnings
> diff --git a/lib/sys_socket.in.h b/lib/sys_socket.in.h
> index 006a901..b34b506 100644
> --- a/lib/sys_socket.in.h
> +++ b/lib/sys_socket.in.h
> @@ -28,7 +28,10 @@
>    - On Cygwin 1.5.x we have a sequence of nested includes
>      <sys/socket.h> -> <cygwin/socket.h> -> <asm/socket.h> -> <cygwin/if.h>,
>      and the latter includes <sys/socket.h>.  In this situation, the functions
> -     are not yet declared, therefore we cannot provide the C++ aliases.  */
> +     are not yet declared, therefore we cannot provide the C++ aliases.
> +   - On mingw, <sys/socket.h> -> <winsock2.h> -> <unistd.h>, and the latter
> +     includes <winsock2.h>.  In this situation, functions like gethostname
> +     are not yet declared, therefore we must defer.  */
>
> address@hidden@ @NEXT_SYS_SOCKET_H@
>
> @@ -129,7 +132,9 @@ struct sockaddr_storage
>
>
>  # if @HAVE_WINSOCK2_H@
> +#  define _GL_INCLUDING_WINSOCK2_H
>  #  include <winsock2.h>
> +#  undef _GL_INCLUDING_WINSOCK2_H
>  # endif
>  # if @HAVE_WS2TCPIP_H@
>  #  include <ws2tcpip.h>
> diff --git a/lib/unistd.in.h b/lib/unistd.in.h
> index b74484a..a57ba37 100644
> --- a/lib/unistd.in.h
> +++ b/lib/unistd.in.h
> @@ -26,7 +26,19 @@
>  # @INCLUDE_NEXT@ @NEXT_UNISTD_H@
>  #endif
>
> -#ifndef _GL_UNISTD_H
> +/* On mingw, <winsock2.h> includes <unistd.h> prior to declaring
> +   gethostname, but we want to replace gethostname.  We must ensure
> +   that <winsock2.h> is completely included first.  */
> +#if @GNULIB_GETHOSTNAME@
> +/* Get all possible declarations of gethostname().  */
> +# if @UNISTD_H_HAVE_WINSOCK2_H@
> +#  define _GL_INCLUDING_WINSOCK2_H
> +#  include <winsock2.h>
> +#  undef _GL_INCLUDING_WINSOCK2_H
> +# endif
> +#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 +88,6 @@
>  #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
>

This patch doesn't solve the problem with gethostname. The same error
as before occurs.

Matthias