[PATCH v2] libtraceevent: Add trace.conf for ld.so if needed

[PATCH v2] libtraceevent: Add trace.conf for ld.so if needed

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

It can not be guaranteed that the system the library is being installed on
has ld.so set to search the location of where libtraceevent.so is installed.

During the install process, check if the path is found in ld.so.conf.d/ and
if not, test if an executable can be built and find the library. If it can
not, then add the path to ld.so.conf.d/trace.conf, and run ldconfig again.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 Changes since v1:
   Noticed while making this change to libtracefs, that some uses of
    $(libdir_SQ) should have been $(libdir)

 Makefile | 29 ++++++++++++++++++++++++++++-
 test.c   |  7 +++++++
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 test.c

diff --git a/Makefile b/Makefile
index 9044536..fd91383 100644
--- a/Makefile
+++ b/Makefile
@@ -23,6 +23,8 @@ $(call allow-override,CC,$(CROSS_COMPILE)gcc)
 $(call allow-override,AR,$(CROSS_COMPILE)ar)
 $(call allow-override,NM,$(CROSS_COMPILE)nm)
 $(call allow-override,PKG_CONFIG,pkg-config)
+$(call allow-override,LD_SO_CONF_PATH,/etc/ld.so.conf.d/)
+$(call allow-override,LDCONFIG,ldconfig)
 
 EXT = -std=gnu99
 INSTALL = install
@@ -241,10 +243,35 @@ define do_install_pkgconfig_file
 	fi
 endef
 
+
+ifeq ("$(DESTDIR)", "")
+# If DESTDIR is not defined, then test if after installing the library
+# and running ldconfig, if the library is visible by ld.so.
+# If not, add the path to /etc/ld.so.conf.d/trace.conf and run ldconfig again.
+define install_ld_config
+	$(LDCONFIG); \
+	if ! grep "^$(libdir)$$" $(LD_SO_CONF_PATH)/* &> /dev/null ; then \
+		$(CC) -o $(OUTPUT)test $(srctree)/test.c -I $(includedir_SQ) \
+			-L $(libdir_SQ) -ltraceevent; \
+		if ! $(OUTPUT)test > /dev/null; then \
+			echo $(libdir_SQ) >> $(LD_SO_CONF_PATH)/trace.conf; \
+			$(LDCONFIG); \
+		fi; \
+		$(RM) $(OUTPUT)test; \
+	fi
+endef
+else
+# If installing to a location for another machine or package, do not bother
+# with running ldconfig.
+define install_ld_config
+endef
+endif # DESTDIR = ""
+
 install_lib: all_cmd install_plugins install_headers install_pkgconfig
 	$(call QUIET_INSTALL, $(LIB_TARGET)) \
 		$(call do_install_mkdir,$(libdir_SQ)); \
-		cp -fpR $(LIB_INSTALL) $(DESTDIR)$(libdir_SQ)
+		cp -fpR $(LIB_INSTALL) $(DESTDIR)$(libdir_SQ); \
+		$(call install_ld_config)
 
 install_pkgconfig: $(PKG_CONFIG_FILE)
 	$(call QUIET_INSTALL, $(PKG_CONFIG_FILE)) \
diff --git a/test.c b/test.c
new file mode 100644
index 0000000..7566fac
--- /dev/null
+++ b/test.c
@@ -0,0 +1,7 @@
+#include <event-parse.h>
+
+int main ()
+{
+	tep_load_plugins(NULL);
+	return 0;
+}
-- 
2.25.4