Fix unload of recursively linked library

Expanded test for recursive libs. Fixed bug with unnecessary
  soinfo_free of already loaded library.

(cherry picked from commit a6ac54a215d6b64f5cc5a59b66c1dbfbb41ea9f5)

Change-Id: I6907c723d9fbdf6b2777f3f236b1e29b0843edd6

linker/linker.cpp

@@ -843,6 +843,7 @@ static soinfo* load_library(LoadTaskList& load_tasks, const char* name, int dlfl
   }
 
   if ((dlflags & RTLD_NOLOAD) != 0) {
+    DL_ERR("library \"%s\" wasn't loaded and RTLD_NOLOAD prevented it", name);
     return nullptr;
   }
 
@@ -950,7 +951,6 @@ static bool find_libraries(const char* const library_names[], size_t library_nam
     soinfo* needed_by = task->get_needed_by();
 
     if (is_recursive(si, needed_by)) {
-      soinfo_free(si);
       return false;
     }
 

tests/dlfcn_test.cpp

@@ -207,8 +207,19 @@ TEST(dlfcn, dlopen_check_order) {
 // libtest_with_dependency_loop_a.so
 TEST(dlfcn, dlopen_check_loop) {
   void* handle = dlopen("libtest_with_dependency_loop.so", RTLD_NOW);
-  ASSERT_TRUE(handle == NULL);
+  ASSERT_TRUE(handle == nullptr);
   ASSERT_STREQ("dlopen failed: recursive link to \"libtest_with_dependency_loop_a.so\"", dlerror());
+  // This symbol should never be exposed
+  void* f = dlsym(RTLD_DEFAULT, "dlopen_test_invalid_function");
+  ASSERT_TRUE(f == nullptr);
+  ASSERT_SUBSTR("undefined symbol: dlopen_test_invalid_function", dlerror());
+
+  // dlopen second time to make sure that the library wasn't loaded even though dlopen returned null.
+  // This may happen if during cleanup the root library or one of the depended libs were not removed
+  // from soinfo list.
+  handle = dlopen("libtest_with_dependency_loop.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle == nullptr);
+  ASSERT_STREQ("dlopen failed: library \"libtest_with_dependency_loop.so\" wasn't loaded and RTLD_NOLOAD prevented it", dlerror());
 }
 
 TEST(dlfcn, dlopen_failure) {

tests/libs/Android.mk

@@ -195,7 +195,7 @@ include $(TEST_PATH)/Android.build.mk
 #
 # libtest_with_dependency_loop -> a -> b -> c -> a
 # -----------------------------------------------------------------------------
-libtest_with_dependency_loop_src_files := empty.cpp
+libtest_with_dependency_loop_src_files := dlopen_testlib_invalid.cpp
 
 libtest_with_dependency_loop_shared_libraries := \
     libtest_with_dependency_loop_a
@@ -208,7 +208,7 @@ include $(TEST_PATH)/Android.build.mk
 # -----------------------------------------------------------------------------
 # libtest_with_dependency_loop_a.so
 # -----------------------------------------------------------------------------
-libtest_with_dependency_loop_a_src_files := empty.cpp
+libtest_with_dependency_loop_a_src_files := dlopen_testlib_invalid.cpp
 
 libtest_with_dependency_loop_a_shared_libraries := \
     libtest_with_dependency_loop_b_tmp
@@ -223,7 +223,7 @@ include $(TEST_PATH)/Android.build.mk
 #
 # this is temporary placeholder - will be removed
 # -----------------------------------------------------------------------------
-libtest_with_dependency_loop_b_tmp_src_files := empty.cpp
+libtest_with_dependency_loop_b_tmp_src_files := dlopen_testlib_invalid.cpp
 libtest_with_dependency_loop_b_tmp_ldflags := -Wl,-soname=libtest_with_dependency_loop_b.so
 
 module := libtest_with_dependency_loop_b_tmp
@@ -234,7 +234,7 @@ include $(TEST_PATH)/Android.build.mk
 # -----------------------------------------------------------------------------
 # libtest_with_dependency_loop_b.so
 # -----------------------------------------------------------------------------
-libtest_with_dependency_loop_b_src_files := empty.cpp
+libtest_with_dependency_loop_b_src_files := dlopen_testlib_invalid.cpp
 libtest_with_dependency_loop_b_shared_libraries := libtest_with_dependency_loop_c
 
 module := libtest_with_dependency_loop_b
@@ -245,7 +245,7 @@ include $(TEST_PATH)/Android.build.mk
 # -----------------------------------------------------------------------------
 # libtest_with_dependency_loop_c.so
 # -----------------------------------------------------------------------------
-libtest_with_dependency_loop_c_src_files := empty.cpp
+libtest_with_dependency_loop_c_src_files := dlopen_testlib_invalid.cpp
 
 libtest_with_dependency_loop_c_shared_libraries := \
     libtest_with_dependency_loop_a

tests/libs/dlopen_testlib_invalid.cpp

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+
+// This file is used for libraries that are not supposed to
+// be successfully loaded/linked - therefore, this function should
+// not be visible via dlsym - (we are going to use this fact in tests)
+extern "C" int dlopen_test_invalid_function() {
+  abort();
+}