Implement symbol visibility.

* configure.ac: New option --enable-ld-version-script.
(GPGRT_USE_VISIBILITY): New ac_define.
(HAVE_LD_VERSION_SCRIPT): New am_conditional.
* src/gpg-error.vers: New.
* src/gpgrt-int.h: New.
* src/visibility.c, src/visibility.h: New.  Lot of changes to symbold
names.
--

This is only doe for the old API.  The estream API needs to be added.

21 files changed, 485 insertions, 52 deletions

diff --git a/configure.ac b/configure.ac
index 7390bc1..64b2752 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,5 @@
 # configure.ac for libgpg-error
-# Copyright (C) 2003, 2004, 2006, 2010, 2013 g10 Code GmbH
+# Copyright (C) 2003, 2004, 2006, 2010, 2013, 2014 g10 Code GmbH
 #
 # This file is part of libgpg-error.
 #
@@ -250,6 +250,110 @@ if test "$gcry_cv_gcc_attribute_aligned" = "yes" ; then
      [Defined if a GCC style "__attribute__ ((aligned (n))" is supported])
 fi
 
+#
+# Check for ELF visibility support.
+#
+AC_CACHE_CHECK(whether the visibility attribute is supported,
+       gcry_cv_visibility_attribute,
+       [gcry_cv_visibility_attribute=no
+        AC_LANG_CONFTEST([AC_LANG_SOURCE(
+          [[int foo __attribute__ ((visibility ("hidden"))) = 1;
+            int bar __attribute__ ((visibility ("protected"))) = 1;
+          ]])])
+
+        if ${CC-cc} -Werror -S conftest.c -o conftest.s \
+                  1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD ; then
+            if grep '\.hidden.*foo' conftest.s >/dev/null 2>&1 ; then
+                if grep '\.protected.*bar' conftest.s >/dev/null 2>&1; then
+                    gcry_cv_visibility_attribute=yes
+                fi
+            fi
+        fi
+       ])
+if test "$gcry_cv_visibility_attribute" = "yes"; then
+    AC_CACHE_CHECK(for broken visibility attribute,
+       gcry_cv_broken_visibility_attribute,
+       [gcry_cv_broken_visibility_attribute=yes
+        AC_LANG_CONFTEST([AC_LANG_SOURCE(
+          [[int foo (int x);
+            int bar (int x) __asm__ ("foo")
+                            __attribute__ ((visibility ("hidden")));
+            int bar (int x) { return x; }
+          ]])])
+
+        if ${CC-cc} -Werror -S conftest.c -o conftest.s \
+                  1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD ; then
+           if grep '\.hidden@<:@ 	_@:>@foo' conftest.s >/dev/null 2>&1;
+            then
+               gcry_cv_broken_visibility_attribute=no
+           fi
+        fi
+       ])
+fi
+if test "$gcry_cv_visibility_attribute" = "yes"; then
+    AC_CACHE_CHECK(for broken alias attribute,
+       gcry_cv_broken_alias_attribute,
+       [gcry_cv_broken_alias_attribute=yes
+        AC_LANG_CONFTEST([AC_LANG_SOURCE(
+          [[extern int foo (int x) __asm ("xyzzy");
+            int bar (int x) { return x; }
+            extern __typeof (bar) foo __attribute ((weak, alias ("bar")));
+            extern int dfoo;
+            extern __typeof (dfoo) dfoo __asm ("abccb");
+            int dfoo = 1;
+          ]])])
+
+        if ${CC-cc} -Werror -S conftest.c -o conftest.s \
+                  1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD ; then
+           if grep 'xyzzy' conftest.s >/dev/null 2>&1 && \
+              grep 'abccb' conftest.s >/dev/null 2>&1; then
+              gcry_cv_broken_alias_attribute=no
+           fi
+        fi
+        ])
+fi
+if test "$gcry_cv_visibility_attribute" = "yes"; then
+    AC_CACHE_CHECK(if gcc supports -fvisibility=hidden,
+       gcry_cv_gcc_has_f_visibility,
+       [gcry_cv_gcc_has_f_visibility=no
+        _gcc_cflags_save=$CFLAGS
+        CFLAGS="-fvisibility=hidden"
+        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],[])],
+                          gcry_cv_gcc_has_f_visibility=yes)
+        CFLAGS=$_gcc_cflags_save;
+       ])
+fi
+if test "$gcry_cv_visibility_attribute" = "yes" \
+   && test "$gcry_cv_broken_visibility_attribute" != "yes" \
+   && test "$gcry_cv_broken_alias_attribute" != "yes" \
+   && test "$gcry_cv_gcc_has_f_visibility" = "yes"
+ then
+   AC_DEFINE(GPGRT_USE_VISIBILITY, 1,
+             [Define to use the GNU C visibility attribute.])
+   CFLAGS="$CFLAGS -fvisibility=hidden"
+fi
+
+#
+# Check whether ld supports a version script.
+# (Actually not a check but a list of systems which are known to support it.)
+#
+have_ld_version_script=no
+case "${host}" in
+    *-*-linux*)
+	have_ld_version_script=yes
+        ;;
+    *-*-gnu*)
+	have_ld_version_script=yes
+        ;;
+esac
+AC_ARG_ENABLE([ld-version-script],
+              AC_HELP_STRING([--enable-ld-version-script],
+                             [enable/disable use of linker version script.
+                              (default is system dependent)]),
+              [have_ld_version_script=$enableval],
+              [ : ] )
+AM_CONDITIONAL(HAVE_LD_VERSION_SCRIPT, test "$have_ld_version_script" = "yes")
+
 
 #
 # Check for thread library.
diff --git a/src/Makefile.am b/src/Makefile.am
index 20871a4..55a9bb9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -76,7 +76,7 @@ EXTRA_DIST = mkstrtable.awk err-sources.h.in err-codes.h.in \
 	mkerrcodes.awk mkerrcodes1.awk mkerrcodes2.awk mkerrcodes.c \
 	mkheader.c gpg-error.h.in mkw32errmap.c w32-add.h w32ce-add.h \
 	err-sources.h err-codes.h gpg-error-config.in gpg-error.m4 \
-	gpg-error.def.in versioninfo.rc.in \
+	gpg-error.vers gpg-error.def.in versioninfo.rc.in \
 	$(lock_obj_pub)
 
 BUILT_SOURCES = err-sources.h err-codes.h code-to-errno.h code-from-errno.h \
@@ -90,6 +90,10 @@ CLEANFILES = err-sources.h err-codes.h code-to-errno.h code-from-errno.h \
 	mkw32errmap.map.c err-sources-sym.h err-codes-sym.h errnos-sym.h \
 	gpg-extra/errno.h mkheader $(tmp_files) lock-obj-pub.native.h
 
+
+#
+# {{{ Begin Windows part
+#
 if HAVE_W32_SYSTEM
 arch_sources = w32-gettext.c w32-lock.c w32-lock-obj.h w32-thread.c
 RCCOMPILE = $(RC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) \
@@ -115,7 +119,13 @@ uninstall-def-file:
 libgpg_error_la_DEPENDENCIES = $(gpg_error_res) gpg-error.def
 intllibs =
 
+#
+# }}} End Windows part
+#
 else
+#
+# {{{ Begin Unix part
+#
 arch_sources = posix-lock.c posix-lock-obj.h posix-thread.c
 gpg_error_res =
 no_undefined =
@@ -126,16 +136,29 @@ uninstall-def-file:
 intllibs = @LTLIBINTL@
 
 endif
+#
+# }}} End Unix part
+#
 
+if HAVE_LD_VERSION_SCRIPT
+  libgpg_error_vers_opt = -Wl,--version-script=$(srcdir)/gpg-error.vers
+else
+  libgpg_error_vers_opt =
+endif
 
-libgpg_error_la_LDFLAGS = -version-info \
-  @LIBGPG_ERROR_LT_CURRENT@:@LIBGPG_ERROR_LT_REVISION@:@LIBGPG_ERROR_LT_AGE@ \
-  $(no_undefined) $(export_symbols)
+libgpg_error_la_LDFLAGS = \
+  $(no_undefined) $(export_symbols) $(libgpg_error_vers_opt) \
+  -version-info \
+  @LIBGPG_ERROR_LT_CURRENT@:@LIBGPG_ERROR_LT_REVISION@:@LIBGPG_ERROR_LT_AGE@
 
 libgpg_error_la_SOURCES = gpg-error.h gettext.h $(arch_sources) \
-	init.c init.h version.c lock.h thread.h \
-	estream.c estream.h estream-printf.c estream-printf.h \
-	strsource.c strerror.c code-to-errno.c code-from-errno.c
+	gpgrt-int.h init.c init.h version.c lock.h thread.h \
+	estream.c estream-printf.c estream-printf.h \
+	strsource.c strerror.c code-to-errno.c code-from-errno.c \
+	visibility.c visibility.h
+
+# libgpg_error_la_DEPENDENCIES = \
+#        $(srcdir)/gpg-error.vers
 
 # Note that RCCOMPILE needs the same defines as ..._la_CPPFLAGS but
 # without the extra_cppflags because they may include am -idirafter
diff --git a/src/code-from-errno.c b/src/code-from-errno.c
index 96fcf20..6064270 100644
--- a/src/code-from-errno.c
+++ b/src/code-from-errno.c
@@ -7,12 +7,12 @@
    modify it under the terms of the GNU Lesser General Public License
    as published by the Free Software Foundation; either version 2.1 of
    the License, or (at your option) any later version.
- 
+
    libgpg-error is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
- 
+
    You should have received a copy of the GNU Lesser General Public
    License along with libgpg-error; if not, write to the Free
    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
@@ -22,7 +22,7 @@
 #include <config.h>
 #endif
 
-#include <errno.h> 
+#include <errno.h>
 
 #include <gpg-error.h>
 
@@ -32,7 +32,7 @@
    GPG_ERR_UNKNOWN_ERRNO if the system error is not mapped (report
    this).  */
 gpg_err_code_t
-gpg_err_code_from_errno (int err)
+_gpg_err_code_from_errno (int err)
 {
   int idx;
 
@@ -52,7 +52,7 @@ gpg_err_code_from_errno (int err)
    returns GPG_ERR_UNKNOWN_ERRNO if the system error is not mapped
    (report this) and GPG_ERR_MISSING_ERRNO if ERRNO has the value 0. */
 gpg_err_code_t
-gpg_err_code_from_syserror (void)
+_gpg_err_code_from_syserror (void)
 {
   int err = errno;
   int idx;
diff --git a/src/code-to-errno.c b/src/code-to-errno.c
index 5873aad..6ba6d87 100644
--- a/src/code-to-errno.c
+++ b/src/code-to-errno.c
@@ -7,12 +7,12 @@
    modify it under the terms of the GNU Lesser General Public License
    as published by the Free Software Foundation; either version 2.1 of
    the License, or (at your option) any later version.
- 
+
    libgpg-error is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
- 
+
    You should have received a copy of the GNU Lesser General Public
    License along with libgpg-error; if not, write to the Free
    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
@@ -29,7 +29,7 @@
 /* Retrieve the system error for the error code CODE.  This returns 0
    if CODE is not a system error code.  */
 int
-gpg_err_code_to_errno (gpg_err_code_t code)
+_gpg_err_code_to_errno (gpg_err_code_t code)
 {
   if (!(code & GPG_ERR_SYSTEM_ERROR))
     return 0;
diff --git a/src/estream.c b/src/estream.c
index 2e31b51..5a1a80b 100644
--- a/src/estream.c
+++ b/src/estream.c
@@ -101,7 +101,7 @@
 # include "../common/util.h"
 #endif
 
-#include "estream.h"
+#include "gpgrt-int.h"
 #include "estream-printf.h"
 
 
@@ -1143,8 +1143,6 @@ es_func_w32_read (void *cookie, void *buffer, size_t size)
               else
                 {
                   _set_errno (map_w32_to_errno (ec));
-                  log_debug ("estream: ReadFile returned %d\n",
-                             (int)GetLastError ());
                   bytes_read = -1;
                 }
             }
diff --git a/src/estream.h b/src/estream.h
index dd17031..cfb7eec 100644
--- a/src/estream.h
+++ b/src/estream.h
@@ -1,4 +1,4 @@
-/* estream.h - Interanl defiinitions for the Extended Stream I/O Library
+/* gpgrt-int.h - Internal definitions
  * Copyright (C) 2014 g10 Code GmbH
  *
  * This file is part of libgpg-error.
diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index 2ea482a..97bc00f 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -1,5 +1,25 @@
-/* gpg-error.def.in - Exported symbols
- *   Needs to be processed by CPP.
+/* libgpg-error.def - Exported symbols for W32
+ * Copyright (C) 2014 g10 Code GmbH
+ *
+ * This file is part of libgpg-error.
+ *
+ * libgpg-error is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * libgpg-error is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Note: This file should be updated manually and the ordinals shall
+ * never be changed.  Also check gpg-error.vers and visibility.h.
+ *
+ * This file needs to be pre-processed.
  */
 
 #include <config.h>
@@ -10,7 +30,7 @@ EXPORTS
  gpg_strsource                @3
  gpg_err_code_from_errno      @4
  gpg_err_code_to_errno        @5
- gpg_err_init		      @6
+ /* Not anymore used.  */
  gpg_err_code_from_syserror   @7
  gpg_err_set_errno            @8
 #ifdef HAVE_W32CE_SYSTEM
@@ -26,7 +46,7 @@ EXPORTS
    _gpg_w32_gettext_localename @16
    _gpg_w32_gettext_use_utf8   @17
 #endif
- gpg_err_deinit		      @18
+ /* Not anymore used. */
  gpg_error_check_version      @19
 
  gpgrt_lock_init              @20
@@ -34,3 +54,7 @@ EXPORTS
  gpgrt_lock_unlock            @22
  gpgrt_lock_destroy           @23
  gpgrt_yield                  @24
+
+
+
+;; end of file with public symbols for Windows.
diff --git a/src/gpg-error.vers b/src/gpg-error.vers
new file mode 100644
index 0000000..8e67081
--- /dev/null
+++ b/src/gpg-error.vers
@@ -0,0 +1,42 @@
+# libgpg-error.vers - What symbols to export              -*- std -*-
+# Copyright (C) 2014 g10 Code GmbH
+#
+# This file is part of libgpg-error.
+#
+# libgpg-error is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation; either version 2.1 of the
+# License, or (at your option) any later version.
+#
+# libgpg-error is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, see <http://www.gnu.org/licenses/>.
+#
+# NOTE: When adding new functions, please make sure to add them to
+#       visibility.h and gpg-error.def.in as well.
+
+
+GPG_ERROR_1.0 {
+  global:
+    gpg_strerror;
+    gpg_strerror_r;
+    gpg_strsource;
+    gpg_err_code_from_errno;
+    gpg_err_code_to_errno;
+    gpg_err_code_from_syserror;
+    gpg_err_set_errno;
+    gpg_error_check_version;
+
+    gpgrt_lock_init;
+    gpgrt_lock_lock;
+    gpgrt_lock_unlock;
+    gpgrt_lock_destroy;
+    gpgrt_yield;
+
+  local:
+    *;
+};
diff --git a/src/gpgrt-int.h b/src/gpgrt-int.h
new file mode 100644
index 0000000..044fe74
--- /dev/null
+++ b/src/gpgrt-int.h
@@ -0,0 +1,49 @@
+/* gpgrt-int.h - Internal definitions
+ * Copyright (C) 2014 g10 Code GmbH
+ *
+ * This file is part of libgpg-error.
+ *
+ * libgpg-error is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * libgpg-error is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _GPGRT_GPGRT_INT_H
+#define _GPGRT_GPGRT_INT_H
+
+#include "gpg-error.h"
+#include "visibility.h"
+
+/* Local error function prototypes.  */
+const char *_gpg_strerror (gpg_error_t err);
+int _gpg_strerror_r (gpg_error_t err, char *buf, size_t buflen);
+const char *_gpg_strsource (gpg_error_t err);
+gpg_err_code_t _gpg_err_code_from_errno (int err);
+int _gpg_err_code_to_errno (gpg_err_code_t code);
+gpg_err_code_t _gpg_err_code_from_syserror (void);
+void _gpg_err_set_errno (int err);
+
+const char *_gpg_error_check_version (const char *req_version);
+
+gpg_err_code_t _gpgrt_lock_init (gpgrt_lock_t *lockhd);
+gpg_err_code_t _gpgrt_lock_lock (gpgrt_lock_t *lockhd);
+gpg_err_code_t _gpgrt_lock_unlock (gpgrt_lock_t *lockhd);
+gpg_err_code_t _gpgrt_lock_destroy (gpgrt_lock_t *lockhd);
+gpg_err_code_t _gpgrt_yield (void);
+
+
+/* Local prototypes for estream.  */
+int _gpgrt_es_init (void);
+
+
+
+#endif /*_GPGRT_GPGRT_INT_H*/
diff --git a/src/init.c b/src/init.c
index 40fa2a8..b7cc2fd 100644
--- a/src/init.c
+++ b/src/init.c
@@ -26,10 +26,8 @@
 #include <string.h>
 #include <errno.h>
 
-#include <gpg-error.h>
-
+#include "gpgrt-int.h"
 #include "gettext.h"
-#include "estream.h"
 #include "init.h"
 
 #ifdef HAVE_W32CE_SYSTEM
@@ -365,7 +363,7 @@ _gpg_w32ce_strerror (int err)
 
 
 void
-gpg_err_set_errno (int err)
+_gpg_err_set_errno (int err)
 {
 #ifdef HAVE_W32CE_SYSTEM
   SetLastError (err);
@@ -430,7 +428,7 @@ DllMain (HINSTANCE hinst, DWORD reason, LPVOID reserved)
 #else /*!HAVE_W32_SYSTEM*/
 
 void
-gpg_err_set_errno (int err)
+_gpg_err_set_errno (int err)
 {
   errno = err;
 }
diff --git a/src/posix-lock.c b/src/posix-lock.c
index 5b0cab5..22bb734 100644
--- a/src/posix-lock.c
+++ b/src/posix-lock.c
@@ -114,7 +114,7 @@ get_lock_object (gpgrt_lock_t *lockhd)
 
 
 gpg_err_code_t
-gpgrt_lock_init (gpgrt_lock_t *lockhd)
+_gpgrt_lock_init (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = (_gpgrt_lock_t*)lockhd;
   int rc;
@@ -149,7 +149,7 @@ gpgrt_lock_init (gpgrt_lock_t *lockhd)
 
 
 gpg_err_code_t
-gpgrt_lock_lock (gpgrt_lock_t *lockhd)
+_gpgrt_lock_lock (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = get_lock_object (lockhd);
   int rc;
@@ -172,7 +172,7 @@ gpgrt_lock_lock (gpgrt_lock_t *lockhd)
 
 
 gpg_err_code_t
-gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
+_gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = get_lock_object (lockhd);
   int rc;
@@ -197,7 +197,7 @@ gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
 /* Note: Use this function only if no other thread holds or waits for
    this lock.  */
 gpg_err_code_t
-gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
+_gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = get_lock_object (lockhd);
   int rc;
diff --git a/src/posix-thread.c b/src/posix-thread.c
index a739e40..bef0386 100644
--- a/src/posix-thread.c
+++ b/src/posix-thread.c
@@ -45,7 +45,7 @@
 
 
 gpg_err_code_t
-gpgrt_yield (void)
+_gpgrt_yield (void)
 {
 #if USE_POSIX_THREADS
 # ifdef _POSIX_PRIORITY_SCHEDULING
diff --git a/src/strerror.c b/src/strerror.c
index dc56040..b0efb3d 100644
--- a/src/strerror.c
+++ b/src/strerror.c
@@ -7,12 +7,12 @@
    modify it under the terms of the GNU Lesser General Public License
    as published by the Free Software Foundation; either version 2.1 of
    the License, or (at your option) any later version.
- 
+
    libgpg-error is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
- 
+
    You should have received a copy of the GNU Lesser General Public
    License along with libgpg-error; if not, write to the Free
    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
@@ -35,7 +35,7 @@
 /* Return a pointer to a string containing a description of the error
    code in the error value ERR.  This function is not thread-safe.  */
 const char *
-gpg_strerror (gpg_error_t err)
+_gpg_strerror (gpg_error_t err)
 {
   gpg_err_code_t code = gpg_err_code (err);
 
@@ -134,7 +134,7 @@ system_strerror_r (int no, char *buf, size_t buflen)
    large enough, ERANGE is returned and BUF contains as much of the
    beginning of the error string as fits into the buffer.  */
 int
-gpg_strerror_r (gpg_error_t err, char *buf, size_t buflen)
+_gpg_strerror_r (gpg_error_t err, char *buf, size_t buflen)
 {
   gpg_err_code_t code = gpg_err_code (err);
   const char *errstr;
diff --git a/src/strsource.c b/src/strsource.c
index 66d783c..6604eb0 100644
--- a/src/strsource.c
+++ b/src/strsource.c
@@ -2,17 +2,17 @@
    Copyright (C) 2003 g10 Code GmbH
 
    This file is part of libgpg-error.
- 
+
    libgpg-error is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public License
    as published by the Free Software Foundation; either version 2.1 of
    the License, or (at your option) any later version.
- 
+
    libgpg-error is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
- 
+
    You should have received a copy of the GNU Lesser General Public
    License along with libgpg-error; if not, write to the Free
    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
@@ -30,7 +30,7 @@
 /* Return a pointer to a string containing a description of the error
    source in the error value ERR.  */
 const char *
-gpg_strsource (gpg_error_t err)
+_gpg_strsource (gpg_error_t err)
 {
   gpg_err_source_t source = gpg_err_source (err);
   return dgettext (PACKAGE, msgstr + msgidx[msgidxof (source)]);
diff --git a/src/version.c b/src/version.c
index 5b40537..8bfe625 100644
--- a/src/version.c
+++ b/src/version.c
@@ -113,7 +113,7 @@ compare_versions (const char *my_version, const char *req_version)
  * and the version string is simply returned.
  */
 const char *
-gpg_error_check_version (const char *req_version)
+_gpg_error_check_version (const char *req_version)
 {
   if (req_version && req_version[0] == 1 && req_version[1] == 1)
     return cright_blurb ();
diff --git a/src/visibility.c b/src/visibility.c
new file mode 100644
index 0000000..f7832ae
--- /dev/null
+++ b/src/visibility.c
@@ -0,0 +1,104 @@
+/* visibility.c - Wrapper for all public functions.
+ * Copyright (C) 2014  g10 Code GmbH
+ *
+ * This file is part of libgpg-error.
+ *
+ * libgpg-error is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * libgpg-error is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdarg.h>
+
+#define _GPGRT_INCL_BY_VISIBILITY_C 1
+#include "gpgrt-int.h"
+
+const char *
+gpg_strerror (gpg_error_t err)
+{
+  return _gpg_strerror (err);
+}
+
+int
+gpg_strerror_r (gpg_error_t err, char *buf, size_t buflen)
+{
+  return _gpg_strerror_r (err, buf, buflen);
+}
+
+const char *
+gpg_strsource (gpg_error_t err)
+{
+  return _gpg_strsource (err);
+}
+
+gpg_err_code_t
+gpg_err_code_from_errno (int err)
+{
+  return _gpg_err_code_from_errno (err);
+}
+
+int
+gpg_err_code_to_errno (gpg_err_code_t code)
+{
+  return _gpg_err_code_to_errno (code);
+}
+
+gpg_err_code_t
+gpg_err_code_from_syserror (void)
+{
+  return _gpg_err_code_from_syserror ();
+}
+
+void
+gpg_err_set_errno (int err)
+{
+  _gpg_err_set_errno (err);
+}
+
+
+const char *
+gpg_error_check_version (const char *req_version)
+{
+  return _gpg_error_check_version (req_version);
+}
+
+
+gpg_err_code_t
+gpgrt_lock_init (gpgrt_lock_t *lockhd)
+{
+  return _gpgrt_lock_init (lockhd);
+}
+
+gpg_err_code_t
+gpgrt_lock_lock (gpgrt_lock_t *lockhd)
+{
+  return _gpgrt_lock_lock (lockhd);
+}
+
+gpg_err_code_t
+gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
+{
+  return _gpgrt_lock_unlock (lockhd);
+}
+
+gpg_err_code_t
+gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
+{
+  return _gpgrt_lock_destroy (lockhd);
+}
+
+gpg_err_code_t
+gpgrt_yield (void)
+{
+  return _gpgrt_yield ();
+}
diff --git a/src/visibility.h b/src/visibility.h
new file mode 100644
index 0000000..95d7d76
--- /dev/null
+++ b/src/visibility.h
@@ -0,0 +1,91 @@
+/* visibility.h - Set visibility attribute
+ * Copyright (C) 2014  g10 Code GmbH
+ *
+ * This file is part of libgpg-error.
+ *
+ * libgpg-error is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * libgpg-error is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _GPGRT_VISIBILITY_H
+#define _GPGRT_VISIBILITY_H
+
+/* Include the main header here so that public symbols are mapped to
+   the internal underscored ones.  */
+#ifdef _GPGRT_INCL_BY_VISIBILITY_C
+# include "gpgrt-int.h"
+#endif
+
+
+/* Our use of the ELF visibility feature works by passing
+   -fvisibiliy=hidden on the command line and by explicitly marking
+   all exported functions as visible.
+
+   NOTE: When adding new functions, please make sure to add them to
+         gpg-error.vers and gpg-error.def.in as well.  */
+
+#ifdef _GPGRT_INCL_BY_VISIBILITY_C
+
+# ifdef GPGRT_USE_VISIBILITY
+#  define MARK_VISIBLE(name) \
+     extern __typeof__ (name) name __attribute__ ((visibility("default")));
+# else
+#  define MARK_VISIBLE(name) /* */
+# endif
+
+MARK_VISIBLE (gpg_strerror)
+MARK_VISIBLE (gpg_strerror_r)
+MARK_VISIBLE (gpg_strsource)
+MARK_VISIBLE (gpg_err_code_from_errno)
+MARK_VISIBLE (gpg_err_code_to_errno)
+MARK_VISIBLE (gpg_err_code_from_syserror)
+MARK_VISIBLE (gpg_err_set_errno)
+
+MARK_VISIBLE (gpg_error_check_version)
+
+MARK_VISIBLE (gpgrt_lock_init)
+MARK_VISIBLE (gpgrt_lock_lock)
+MARK_VISIBLE (gpgrt_lock_unlock)
+MARK_VISIBLE (gpgrt_lock_destroy)
+MARK_VISIBLE (gpgrt_yield)
+
+
+
+#undef MARK_VISIBLE
+
+#else /*!_GPGRT_INCL_BY_VISIBILITY_C*/
+
+/* To avoid accidental use of the public functions inside Libgpg-error,
+   we redefine them to catch such errors.  */
+
+#define gpg_strerror                _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpg_strerror_r              _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpg_strsource               _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpg_err_code_from_errno     _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpg_err_code_to_errno       _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpg_err_code_from_syserror  _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpg_err_set_errno           _gpgrt_USE_UNDERSCORED_FUNCTION
+
+#define gpg_error_check_version     _gpgrt_USE_UNDERSCORED_FUNCTION
+
+#define gpgrt_lock_init             _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_lock_lock             _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_lock_unlock           _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_lock_destroy          _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_yield                 _gpgrt_USE_UNDERSCORED_FUNCTION
+
+
+
+#endif /*!_GPGRT_INCL_BY_VISIBILITY_C*/
+
+#endif /*_GPGRT_VISIBILITY_H*/
diff --git a/src/w32-lock.c b/src/w32-lock.c
index 56a0ed5..3aac1ae 100644
--- a/src/w32-lock.c
+++ b/src/w32-lock.c
@@ -50,7 +50,7 @@ get_lock_object (gpgrt_lock_t *lockhd)
 
 
 gpg_err_code_t
-gpgrt_lock_init (gpgrt_lock_t *lockhd)
+_gpgrt_lock_init (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = (_gpgrt_lock_t*)lockhd;
 
@@ -76,7 +76,7 @@ gpgrt_lock_init (gpgrt_lock_t *lockhd)
 
 
 gpg_err_code_t
-gpgrt_lock_lock (gpgrt_lock_t *lockhd)
+_gpgrt_lock_lock (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = get_lock_object (lockhd);
 
@@ -106,7 +106,7 @@ gpgrt_lock_lock (gpgrt_lock_t *lockhd)
 
 
 gpg_err_code_t
-gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
+_gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = get_lock_object (lockhd);
 
@@ -120,7 +120,7 @@ gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
 /* Note: Use this function only if no other thread holds or waits for
    this lock.  */
 gpg_err_code_t
-gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
+_gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
 {
   _gpgrt_lock_t *lock = get_lock_object (lockhd);
 
diff --git a/src/w32-thread.c b/src/w32-thread.c
index f86be35..53d26b4 100644
--- a/src/w32-thread.c
+++ b/src/w32-thread.c
@@ -37,7 +37,7 @@
 
 
 gpg_err_code_t
-gpgrt_yield (void)
+_gpgrt_yield (void)
 {
   Sleep (0);
   return 0;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 277a78b..388e1d5 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -31,7 +31,7 @@ TESTS = t-version t-strerror t-syserror t-lock
 
 INCLUDES = -I$(top_builddir)/src $(extra_includes)
 
-
+AM_LDFLAGS = -no-install
 LDADD = $(gpg_error_lib)
 
 noinst_PROGRAMS = $(TESTS)
diff --git a/tests/t-strerror.c b/tests/t-strerror.c
index e02b302..9289066 100644
--- a/tests/t-strerror.c
+++ b/tests/t-strerror.c
@@ -2,17 +2,17 @@
    Copyright (C) 2003 g10 Code GmbH
 
    This file is part of libgpg-error.
- 
+
    libgpg-error is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public License
    as published by the Free Software Foundation; either version 2.1 of
    the License, or (at your option) any later version.
- 
+
    libgpg-error is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
- 
+
    You should have received a copy of the GNU Lesser General Public
    License along with libgpgme-error; if not, write to the Free
    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA