booster: Fix build problems with various libtool versions

We've been facing a problem on some test systems where the
booster.so is built by libtool as an executable rather than
a dynamically loadable library.

This problem is probably caused by it seeing a _init function in
the source. This is the name of the libc initiliazation
function so it could be the source of the problem.

In any case, ld-preloadable libraries must not have a function
called _init, instead they need to have __attribute ((constructor))
as the attribute for any and all functions the library wants
executed before the program's main(). Our earlier approach was
inherently problematic.
This commit also cleans up the booster Makefile for better
build behaviour. Credit: Harsha.

Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

2 files changed, 20 insertions, 12 deletions

diff --git a/booster/src/Makefile.am b/booster/src/Makefile.am
index a5158591226..6402c8d7977 100644
--- a/booster/src/Makefile.am
+++ b/booster/src/Makefile.am
@@ -1,18 +1,21 @@
-xlatordir = $(libdir)/glusterfs/$(PACKAGE_VERSION)/xlator/performance
-
-ldpreload_PROGRAMS = glusterfs-booster.so
+ldpreload_LTLIBRARIES = libglusterfs-booster.la
 ldpreloaddir = $(libdir)/glusterfs/
 noinst_HEADERS = booster_fstab.h booster-fd.h
-glusterfs_booster_so_SOURCES = booster.c booster_stat.c booster_fstab.c booster-fd.c
-glusterfs_booster_so_CFLAGS = -I$(top_srcdir)/libglusterfsclient/src/ -D_GNU_SOURCE -D$(GF_HOST_OS) -fPIC -Wall \
-	-pthread $(GF_BOOSTER_CFLAGS)
-glusterfs_booster_so_CPPFLAGS = -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE  \
+libglusterfs_booster_la_SOURCES = booster.c booster_stat.c booster_fstab.c booster-fd.c
+libglusterfs_booster_la_CFLAGS = -I$(top_srcdir)/libglusterfsclient/src/ -D_GNU_SOURCE -D$(GF_HOST_OS) -fPIC -Wall \
+	-pthread $(GF_BOOSTER_CFLAGS) -shared -nostartfiles
+libglusterfs_booster_la_CPPFLAGS = -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE  \
 	-I$(top_srcdir)/libglusterfsclient/src \
 	-I$(top_srcdir)/libglusterfs/src -DDATADIR=\"$(localstatedir)\" \
 	-DCONFDIR=\"$(sysconfdir)/glusterfs\"
-glusterfs_booster_so_LDFLAGS = -shared -nostartfiles
-glusterfs_booster_so_LDADD = -L$(top_builddir)/libglusterfs/src -lglusterfs \
-	-L$(top_builddir)/libglusterfsclient/src -lglusterfsclient  
 
-CLEANFILES = 
+libglusterfs_booster_la_LDFLAGS = -module -avoidversion
+libglusterfs_booster_la_LIBADD =  $(top_builddir)/libglusterfs/src/libglusterfs.la $(top_builddir)/libglusterfsclient/src/libglusterfsclient.la
+
+CLEANFILES =
+
+uninstall-local:
+	rm -f $(DESTDIR)$(ldpreloaddir)/glusterfs-booster.so
 
+install-data-hook:
+	ln -sf libglusterfs-booster.so $(DESTDIR)$(ldpreloaddir)/glusterfs-booster.so
diff --git a/booster/src/booster.c b/booster/src/booster.c
index 26cf6b6113f..0ed914b1f0d 100644
--- a/booster/src/booster.c
+++ b/booster/src/booster.c
@@ -49,6 +49,11 @@
 #define GF_UNIT_KB 1024
 #endif
 
+/* attr constructor registers this function with libc's
+ * _init function as a function that must be called before
+ * the main() of the program.
+ */
+static void booster_lib_init (void) __attribute__((constructor));
 
 extern fd_t *
 fd_ref (fd_t *fd);
@@ -2194,7 +2199,7 @@ out:
 }
 
 void
-_init (void)
+booster_lib_init (void)
 {
 
         RESOLVE (open);