[PATCH libdrm] configure: Support symbol visibility when available

[Emil Velikov]

On 30/07/14 14:48, Thierry Reding wrote:
> From: Thierry Reding <treding at nvidia.com>
> 
> Checks whether or not the compiler supports the -fvisibility option. If
> so it sets the VISIBILITY_CFLAGS variable which can be added to the per
> directory AM_CFLAGS where appropriate.
> 
> By default all symbols will be hidden via the VISIBILITY_CFLAGS. The
> drm_public macro can be used to mark symbols that should be exported.
> 
Thank you Thierry. Finally we can cleanup some of the exports that libdrm*
erroneously provides :)

Reviewed-by: Emil Velikov <emil.l.velikov at gmail.com>

> Signed-off-by: Thierry Reding <treding at nvidia.com>
> ---
> Changes in v3:
> - distribute libdrm.h
> 
>  Makefile.am  |  1 +
>  configure.ac | 20 ++++++++++++++++++++
>  libdrm.h     | 34 ++++++++++++++++++++++++++++++++++
>  3 files changed, 55 insertions(+)
>  create mode 100644 libdrm.h
> 
> diff --git a/Makefile.am b/Makefile.am
> index 826c30d0c0d9..65680da963eb 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -69,6 +69,7 @@ libdrm_la_SOURCES =				\
>  	xf86drmSL.c				\
>  	xf86drmMode.c				\
>  	xf86atomic.h				\
> +	libdrm.h				\
>  	libdrm_lists.h
>  
>  libdrmincludedir = ${includedir}
> diff --git a/configure.ac b/configure.ac
> index 1c78c4520c49..f7c7177bfb2a 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -366,6 +366,26 @@ AC_ARG_WITH([kernel-source],
>  	    [kernel_source="$with_kernel_source"])
>  AC_SUBST(kernel_source)
>  
> +dnl Add flags for gcc and g++
> +if test "x$GCC" = xyes; then
> +    # Enable -fvisibility=hidden if using a gcc that supports it
> +    save_CFLAGS="$CFLAGS"
> +    AC_MSG_CHECKING([whether $CC supports -fvisibility=hidden])
> +    VISIBILITY_CFLAGS="-fvisibility=hidden"
> +    CFLAGS="$CFLAGS $VISIBILITY_CFLAGS"
> +    AC_LINK_IFELSE([AC_LANG_PROGRAM()], AC_MSG_RESULT([yes]),
> +                   [VISIBILITY_CFLAGS=""; AC_MSG_RESULT([no])]);
> +
> +    # Restore CFLAGS; VISIBILITY_CFLAGS are added to it where needed.
> +    CFLAGS=$save_CFLAGS
> +
> +    if test "x$VISIBILITY_CFLAGS" != x; then
> +        AC_DEFINE(HAVE_VISIBILITY, 1, [Compiler has -fvisibility support])
> +    fi
> +
> +    AC_SUBST([VISIBILITY_CFLAGS])
> +fi
> +
>  AC_SUBST(WARN_CFLAGS)
>  AC_CONFIG_FILES([
>  	Makefile
> diff --git a/libdrm.h b/libdrm.h
> new file mode 100644
> index 000000000000..23926e6f6741
> --- /dev/null
> +++ b/libdrm.h
> @@ -0,0 +1,34 @@
> +/*
> + * Copyright © 2014 NVIDIA Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#ifndef LIBDRM_LIBDRM_H
> +#define LIBDRM_LIBDRM_H
> +
> +#if defined(HAVE_VISIBILITY)
> +#  define drm_private __attribute__((visibility("hidden")))
> +#  define drm_public __attribute__((visibility("default")))
> +#else
> +#  define drm_private
> +#  define drm_public
> +#endif
> +
> +#endif
>