[PATCH 3/3] libcap-ng: fix built failure with some external toolchains due to missing pthread

[Christopher Larson <kergoth@gmail.com>]

From: Christopher Larson <chris_larson@mentor.com>

The libcap-ng build doesn't pass -pthread and can fail to link.

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
---
 meta/recipes-support/libcap-ng/libcap-ng.inc       |  1 +
 .../libcap-ng/revert-pthread_atfork-fix.patch      | 56 ++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 meta/recipes-support/libcap-ng/libcap-ng/revert-pthread_atfork-fix.patch

diff --git a/meta/recipes-support/libcap-ng/libcap-ng.inc b/meta/recipes-support/libcap-ng/libcap-ng.inc
index aec83896e4..46d37e6807 100644
--- a/meta/recipes-support/libcap-ng/libcap-ng.inc
+++ b/meta/recipes-support/libcap-ng/libcap-ng.inc
@@ -9,6 +9,7 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=94d55d512a9ba36caa9b7df079bae19f \
 
 SRC_URI = "http://people.redhat.com/sgrubb/libcap-ng/libcap-ng-${PV}.tar.gz \
            file://python.patch \
+           file://revert-pthread_atfork-fix.patch \
 "
 
 SRC_URI[md5sum] = "57dc267e2949cdecb651a929f9206572"
diff --git a/meta/recipes-support/libcap-ng/libcap-ng/revert-pthread_atfork-fix.patch b/meta/recipes-support/libcap-ng/libcap-ng/revert-pthread_atfork-fix.patch
new file mode 100644
index 0000000000..d3f7790b1e
--- /dev/null
+++ b/meta/recipes-support/libcap-ng/libcap-ng/revert-pthread_atfork-fix.patch
@@ -0,0 +1,56 @@
+From 81dc82393fae9851397fa5d94094434aa1d5c3d1 Mon Sep 17 00:00:00 2001
+From: Christopher Larson <chris_larson@mentor.com>
+Date: Thu, 14 Nov 2019 21:13:24 +0500
+Subject: [PATCH] Revert "Fix usage of pthread_atfork a whole different way"
+
+This reverts commit 08a09cba90f3d960c080a20833fb8c0908f1cea6.
+
+The fix was breaking builds with some toolchains.
+
+Signed-off-by: Christopher Larson <chris_larson@mentor.com>
+---
+ src/Makefile.am |  2 +-
+ src/cap-ng.c    | 12 +++++++++++-
+ 2 files changed, 12 insertions(+), 2 deletions(-)
+
+diff --git a/src/Makefile.am b/src/Makefile.am
+index 5a66d4e..d46d02b 100644
+--- a/src/Makefile.am
++++ b/src/Makefile.am
+@@ -34,5 +34,5 @@ noinst_HEADERS = captab.h
+ libcap_ng_la_SOURCES = cap-ng.c lookup_table.c
+ libcap_ng_la_LIBADD =
+ libcap_ng_la_DEPENDENCIES = $(libcap_ng_la_SOURCES) ../config.h
+-libcap_ng_la_LDFLAGS = -Wl,-z,relro
++libcap_ng_la_LDFLAGS = -Wl,-z,relro -Wl,-z,nodelete
+ 
+diff --git a/src/cap-ng.c b/src/cap-ng.c
+index 35fcd7a..ed31afa 100644
+--- a/src/cap-ng.c
++++ b/src/cap-ng.c
+@@ -155,6 +155,15 @@ static __thread struct cap_ng m =	{ 1,
+ 					CAPNG_NEW,
+ 					{0, 0} };
+ 
++
++/*
++ * The pthread_atfork function is being made weak so that we can use it
++ * if the program is linked with pthreads and not requiring it for
++ * everything that uses libcap-ng.
++ */
++extern int __attribute__((weak)) pthread_atfork(void (*prepare)(void),
++	void (*parent)(void), void (*child)(void));
++
+ /*
+  * Reset the state so that init gets called to erase everything
+  */
+@@ -166,7 +175,8 @@ static void deinit(void)
+ static void init_lib(void) __attribute__ ((constructor));
+ static void init_lib(void)
+ {
+-	pthread_atfork(NULL, NULL, deinit);
++	if (pthread_atfork)
++		pthread_atfork(NULL, NULL, deinit);
+ }
+ 
+ static void init(void)
-- 
2.11.1