now stuck in dlsym/dereferencing type-punned pointer will break strict-aliasing rules beautiness :-)

3 files changed, 44 insertions, 4 deletions

diff --git a/include/wolf/library/loader.h b/include/wolf/library/loader.h
index a2ee16e..2218677 100644
--- a/include/wolf/library/loader.h
+++ b/include/wolf/library/loader.h
@@ -70,10 +70,22 @@ wolf_error_t wolf_library_unload( wolf_library_p library );
  * @param buf       the buffer which will hold the error message
  * @param buflen    the size of the buffer
  *
- * @returns         a pointer to buf for convenience
+ * @return          a pointer to buf for convenience
  */
 char *wolf_library_errmsg( const wolf_error_t error, const wolf_library_p library, char *buf, size_t buflen );
 
+/**
+ * Gets a symbol (usually a function) from the library object. It has to be
+ * casted properly to the function you are expecting to call.
+ *
+ * @param library   the library object
+ * @param name      name of the symbol to retrieve
+ * @param error     WOLF_OK if the symbol could be loaded
+ *
+ * @return          a pointer to the retrieved symbol
+ */
+void *wolf_library_get( const wolf_library_p library, const char *name, wolf_error_t *error );
+
 /** @} */ /* @addtogroup wolf_library */
 
 #endif /* ifndef WOLF_LOADER_H */
diff --git a/src/library/loader.c b/src/library/loader.c
index ad83bda..cf5f0e3 100644
--- a/src/library/loader.c
+++ b/src/library/loader.c
@@ -85,12 +85,22 @@ wolf_error_t wolf_library_unload( wolf_library_p l ) {
 	return WOLF_OK;
 }
 
-char *wolf_library_errmsg( const wolf_error_t error, const wolf_library_p l, char *buf, size_t buflen ) {
+char *wolf_library_errmsg( const wolf_error_t error, const wolf_library_p library, char *buf, size_t buflen ) {
 	(void)wolf_error_msg( error, buf, buflen );
 	strncat( buf, " - ", buflen - strlen( buf ) );
 	if( error == WOLF_ERR_INTERNAL ) {
-		strncat( buf, l->errbuf, buflen - strlen( buf ) );
+		strncat( buf, library->errbuf, buflen - strlen( buf ) );
 	}
 
 	return buf;
 }
+
+void *wolf_library_get( const wolf_library_p l, const char *name, wolf_error_t *error ) {
+	void *ret;
+
+	ret = dlsym( l->handle, name );
+
+	*error = WOLF_OK;	
+	return ret;
+}
+
diff --git a/tests/library/test_loader.c b/tests/library/test_loader.c
index 6088c92..b9bce9d 100644
--- a/tests/library/test_loader.c
+++ b/tests/library/test_loader.c
@@ -19,12 +19,17 @@
 
 #include <stdlib.h>		/* for EXIT_SUCCESS, EXIT_FAILURE */
 #include <stdio.h>		/* for fprintf */
+#include <assert.h>		/* for assert */
 
 int main( void ) {
 	wolf_library_p library;
 	wolf_error_t error;
 	char errbuf[512];
+	typedef int (*multiply_by_two_func)( int );
+	multiply_by_two_func func;
+	int res = 0;
 
+	/* open the libray */
 	library = wolf_library_load( "./testlib.so.0.0.0", &error );
 	if( error != WOLF_OK ) {
 		fprintf( stderr, "Error %d loading the library: %s\n",
@@ -32,7 +37,20 @@ int main( void ) {
 		return EXIT_FAILURE;
 	}
 
-	wolf_library_unload( library );
+	/* fetch a known symbol (multiply_by_two) */
+	*(void **)(&func) = wolf_library_get( library, "multiply_by_two", &error );
+
+	/* call it */
+	res = func( 2 );
+	assert( res == 4 );
+
+	/* close library */
+	error = wolf_library_unload( library );
+	if( error != WOLF_OK ) {
+		fprintf( stderr, "Error %d unloading the library: %s\n",
+			error, wolf_library_errmsg( error, library, errbuf, 512 ) );
+		return EXIT_FAILURE;
+	}
 
 	return EXIT_SUCCESS;
 }