From c92a3ca5c2cd5366714da916e4f31f606901b727 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Wed, 12 Aug 2020 12:30:30 +0200
Subject: [PATCH] build: fix generating "NetworkManager.ver" with LTO

We use a linker version script "NetworkManager.ver", to hide
symbols from NetworkManager that are not used. That is important
due to our habit of using internal helper libraries that we link
statically everywhere, without handpicking the symbols we actually
need. We want the tooling to get rid of unnecessary symbols.

However, NetworkManager loads shared libraries for settings and device
plugins. These libraries require symbols from the NetworkManager binary,
but which one depends on build options. Hence, we also generate
"NetworkManager.ver" by the "tools/create-exports-NetworkManager.sh"
script.

For that the script uses "nm" to find symbols that are undefined in the
plugin libraries but defined in NetworkManager. With autotools the
script looked at "./src/.libs/libNetworkManager.a" to find the present
symbols. Note that for meson that already didn't work, and we build
instead an intermediate NetworkManager binary first (with all symbols
exposed). With LTO, "nm" doesn't find all symbols in
"./src/.libs/libNetworkManager.a", and consequently they are not
exported and dropped/hidden.

This also causes unit tests to fail with LTO, because our test script
"tools/check-exports.sh" catches such bugs.

Fix that by also with autotools generate a complete "NetworkManager-all-sym"
binary that is used to generate "NetworkManager.ver", before rebuilding
"NetworkManager" again.
---
 .gitignore                             |  1 +
 Makefile.am                            | 21 ++++++++++++++++++++-
 src/meson.build                        |  6 +++---
 tools/create-exports-NetworkManager.sh |  6 +-----
 4 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/.gitignore b/.gitignore
index 919b1830c9..8c08337548 100644
--- a/.gitignore
+++ b/.gitignore
@@ -217,6 +217,7 @@ test-*.trs
 /po/remove-potcdate.sin
 
 /src/NetworkManager
+/src/NetworkManager-all-sym
 /src/NetworkManager.ver
 /src/devices/bluetooth/tests/nm-bt-test
 /src/devices/tests/test-acd
diff --git a/Makefile.am b/Makefile.am
index 5841cbe72a..0f2f5da0f7 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2406,7 +2406,26 @@ $(src_libNetworkManagerTest_la_OBJECTS): $(libnm_core_lib_h_pub_mkenums)
 
 ###############################################################################
 
-src/NetworkManager.ver: src/libNetworkManager.la $(core_plugins)
+noinst_PROGRAMS += src/NetworkManager-all-sym
+
+src_NetworkManager_all_sym_CPPFLAGS = $(src_cppflags)
+
+src_NetworkManager_all_sym_SOURCES = \
+	src/main.c
+
+src_NetworkManager_all_sym_LDADD = \
+	src/libNetworkManager.la \
+	$(GLIB_LIBS) \
+	$(NULL)
+
+src_NetworkManager_all_sym_LDFLAGS = \
+	-rdynamic \
+	$(SANITIZER_EXEC_LDFLAGS) \
+	$(NULL)
+
+$(src_NetworkManager_all_sym_OBJECTS): $(libnm_core_lib_h_pub_mkenums)
+
+src/NetworkManager.ver: src/NetworkManager-all-sym $(core_plugins)
 	$(AM_V_GEN) NM="$(NM)" "$(srcdir)/tools/create-exports-NetworkManager.sh" --called-from-build "$(srcdir)"
 
 CLEANFILES += src/NetworkManager.ver
diff --git a/src/meson.build b/src/meson.build
index b2ea2ba0a1..5fc03d8d59 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -267,8 +267,8 @@ symbol_map_name = 'NetworkManager.ver'
 # add dependencies with link_whole, only supported in meson >= 0.46.
 # Create an executable with full symbols that we use in place of the
 # library to enumerate the symbols.
-network_manager_sym = executable(
-  'nm-full-symbols',
+network_manager_all_sym = executable(
+  'NetworkManager-all-sym',
   'main.c',
   dependencies: nm_deps,
   c_args: daemon_c_flags,
@@ -280,7 +280,7 @@ network_manager_sym = executable(
 ver_script = custom_target(
   symbol_map_name,
   output: symbol_map_name,
-  depends: [network_manager_sym, core_plugins],
+  depends: [network_manager_all_sym, core_plugins],
   command: [create_exports_networkmanager, '--called-from-build', source_root],
 )
 
diff --git a/tools/create-exports-NetworkManager.sh b/tools/create-exports-NetworkManager.sh
index 47061f9dda..f439bd3112 100755
--- a/tools/create-exports-NetworkManager.sh
+++ b/tools/create-exports-NetworkManager.sh
@@ -40,11 +40,7 @@ call_nm() {
 }
 
 get_symbols_nm () {
-    if [ -z "$from_meson" ]; then
-        base=./src/.libs/libNetworkManager.a
-    else
-        base=./src/nm-full-symbols
-    fi
+    base=./src/NetworkManager-all-sym
     call_nm "$base" |
         sed -n 's/^[tTDGRBS] //p' |
         _sort