added more documentation and dlopen/dlclose, must backport shared library building from SMERP first

5 files changed, 65 insertions, 8 deletions

diff --git a/docs/libraries/README b/docs/libraries/README
index c33ea38..3b49ed4 100644
--- a/docs/libraries/README
+++ b/docs/libraries/README
@@ -12,6 +12,12 @@ helpers:
 http://www.cse.iitb.ac.in/dbms/Data/Courses/CS631/PostgreSQL-Resources/postgresql-8.1.4/src/Makefile.shlib
 http://root.cern.ch/root/Makefile.html
 
+Some more unsorted links:
+- http://www.linuxjournal.com/article/3687: on C/C++ dlopen usage
+- http://msdn.microsoft.com/en-us/library/ms684175(VS.85).aspx: LoadLibrary on Windows
+- http://en.wikipedia.org/wiki/Dynamic_loading
+- On MacX: http://developer.apple.com/mac/library/releasenotes/DeveloperTools/RN-dyld/index.html
+
 Goal:
 - we want abstractions for varying versions of dlopen/LoadLibrary(Ex) etc.
 - only basic functionality, no module magic versions or other stuff, should
diff --git a/include/wolf/library/loader.h b/include/wolf/library/loader.h
index 233cd8c..85195a7 100644
--- a/include/wolf/library/loader.h
+++ b/include/wolf/library/loader.h
@@ -54,8 +54,13 @@ wolf_library_p wolf_library_load( const char *name, wolf_error_t *error );
  * Free up resources used by the library object.
  *
  * @param demon     the library object to free
+ *
+ * @return          WOLF_OK if library has been unloaded,
+ *                  WOLF_ERR_INTERNAL_STATE if the library handle is in an illegal state
+ *                  (like double freeing the same library)
  */
-void wolf_library_unload( wolf_library_p library );
+
+wolf_error_t wolf_library_unload( wolf_library_p library );
 
 #if 0
 
diff --git a/makefiles/gmake/compiler.mk b/makefiles/gmake/compiler.mk
index 222a453..0962f11 100644
--- a/makefiles/gmake/compiler.mk
+++ b/makefiles/gmake/compiler.mk
@@ -272,8 +272,8 @@ endif
 CFLAGS = $(COMPILE_FLAGS) $(PLATFORM_COMPILE_FLAGS) $(INCLUDE_DIRS) $(PTHREADS_CFLAGS)
 CCPPFLAGS = $(CCPP_COMPILE_FLAGS) $(PLATFORM_COMPILE_FLAGS) $(INCLUDE_DIRS) $(PTHREADS_CFLAGS)
 
-LDFLAGS = $(INCLUDE_LDFLAGS) $(PTHREADS_LDFLAGS) $(LDFLAGS_NET) $(LDFLAGS_LT)
-LIBS = $(INCLUDE_LIBS) $(PTHREADS_LIBS) $(LIBS_NET) $(LIBS_LT)
+LDFLAGS = $(INCLUDE_LDFLAGS) $(PTHREADS_LDFLAGS) $(LDFLAGS_NET) $(LDFLAGS_LT) $(LDFLAGS_DL)
+LIBS = $(INCLUDE_LIBS) $(PTHREADS_LIBS) $(LIBS_NET) $(LIBS_LT) $(LIBS_DL)
 LINK = $(CC)
 CCPP_LINK = $(CCPP)
 
diff --git a/src/library/loader.c b/src/library/loader.c
index e0bb055..1f8ce20 100644
--- a/src/library/loader.c
+++ b/src/library/loader.c
@@ -16,20 +16,62 @@
 */
 
 #include "library/loader.h"
+#include "port/sys_internal.h"
 #include "port/unused.h"
 
 #include "port/stdlib.h"		/* for malloc, free */
 
+#ifdef HAVE_DLFCN
+#include <dlfcn.h>                      /* for dlopen. dlclose functions */
+#endif
+
 struct wolf_library_t {
-	char dummy;			/**< dummy */
+	void *handle;			/**< the OS handle for the library */
 };
 
 wolf_library_p wolf_library_load( const char *name, wolf_error_t *error ) {
-	WOLF_UNUSED( name );
+	wolf_library_p l;
+	int flags = 0;
+
+	l = (struct wolf_library_t *)malloc( sizeof ( struct wolf_library_t ) );
+	if( l == NULL ) {
+		*error = WOLF_ERR_OUT_OF_MEMORY;
+		return NULL;
+	}
+
+#if defined HAVE_DLFCN
+	/* TODO: Apache has a flags variable and a direct parameter version, find out why..
+	 * also make up our bind how many flags we should "leak" to the application layer
+	 */
+	flags = RTLD_NOW | RTLD_LOCAL;
+
+	l->handle = dlopen( name, flags );
+	if( l->handle == NULL ) {
+		*error = WOLF_ERR_INTERNAL;
+		return NULL;
+	}
+#else
+#error Not using DLFCN as shared loader. Port first!
+#endif
+
 	*error = WOLF_OK;
-	return NULL;
+	return l;
 }
 
-void wolf_library_unload( wolf_library_p library ) {
-	WOLF_UNUSED( library );
+wolf_error_t wolf_library_unload( wolf_library_p l ) {
+	int res = 0;
+
+	if( l == NULL || l->handle == NULL ) {
+		return WOLF_ERR_INVALID_STATE;
+	}
+
+	res = dlclose( l->handle );
+	if( res != 0 ) {
+		return WOLF_ERR_INVALID_STATE;
+	}
+
+	free( l );
+	l = NULL;
+
+	return WOLF_OK;
 }
diff --git a/tests/library/test_loader.c b/tests/library/test_loader.c
index ac4f79c..d2b9329 100644
--- a/tests/library/test_loader.c
+++ b/tests/library/test_loader.c
@@ -25,6 +25,10 @@ int main( void ) {
 	wolf_error_t error;
 
 	library = wolf_library_load( "testlib.so", &error );
+	if( library == NULL ) {
+		fprintf( stderr, "Error loading the library: %d\n", error );
+		return EXIT_FAILURE;
+	}
 
 	wolf_library_unload( library );