internal: add NM_BACKPORT_SYMBOL()

Add a macro to insert the necessary compiler/linker magic to add a
copy of an existing symbol to an older version. Also, update
check-exports.sh to be able to check for such symbols by listed them
commented-out in the appropriate section.

(Based on a patch from Thomas Haller.)

2 files changed, 14 insertions, 3 deletions

diff --git a/include/nm-utils-internal.h b/include/nm-utils-internal.h
index 7ca44f3c4b..cc95def0ab 100644
--- a/include/nm-utils-internal.h
+++ b/include/nm-utils-internal.h
@@ -160,4 +160,17 @@ NM_DEFINE_SINGLETON_DESTRUCTOR(TYPE)
 
 /*****************************************************************************/
 
+#define _NM_BACKPORT_SYMBOL_IMPL(VERSION, RETURN_TYPE, ORIG_FUNC, VERSIONED_FUNC, ARGS_TYPED, ARGS) \
+RETURN_TYPE VERSIONED_FUNC ARGS_TYPED; \
+RETURN_TYPE VERSIONED_FUNC ARGS_TYPED \
+{ \
+    return ORIG_FUNC ARGS; \
+} \
+__asm__(".symver "G_STRINGIFY(VERSIONED_FUNC)","G_STRINGIFY(ORIG_FUNC)"@"G_STRINGIFY(VERSION))
+
+#define NM_BACKPORT_SYMBOL(VERSION, RETURN_TYPE, FUNC, ARGS_TYPED, ARGS) \
+_NM_BACKPORT_SYMBOL_IMPL(VERSION, RETURN_TYPE, FUNC, _##FUNC##_##VERSION, ARGS_TYPED, ARGS)
+
+/*****************************************************************************/
+
 #endif
diff --git a/tools/check-exports.sh b/tools/check-exports.sh
index dfd882c15b..335312fad9 100755
--- a/tools/check-exports.sh
+++ b/tools/check-exports.sh
@@ -18,9 +18,7 @@ get_syms() {
 }
 
 get_syms_from_def() {
-    # be strict and only parse entries that start with one \t and end with a ';'
-    sed -n 's/^\t\([_a-zA-Z0-9]\+\);$/\1/p' "$1" |
-    grep '^\*$' -v |
+    sed -n 's/^\t\(\([_a-zA-Z0-9]\+\)\|#\s*\([_a-zA-Z0-9]\+@[_a-zA-Z0-9]\+\)\);$/\2\3/p' "$1" |
     sort
 }