[PATCH libdrm] configure: Support symbol visibility when available

[Emil Velikov]

On 30/07/14 15:31, Rob Clark wrote:
> On Wed, Jul 30, 2014 at 9:48 AM, Thierry Reding
> <thierry.reding at gmail.com> 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.
> 
> hmm, maybe dumb question, I might possibly have missed some discussion
> on this, but if we merged this without a heap of patches to export
> libdrm and libdrm_foo syms, wouldn't everything be hidden?
> 
> Maybe we should introduce drm_public first.. then once stuff is
> converted to use it actually start hiding things?
> 
This adds the tool, but it's up-to the individual libraries/makefiles to make
use of it.

All you need is:
 - append $(VISIBILITY_CFLAGS) to libdrm_freedreno_CFLAGS
 - prefix each exported function definition with DRM_PUBLIC
 - ***
 - profit :P

-Emil

> 
> BR,
> -R
> 
>> 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
>> --
>> 2.0.3
>>
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