Fix dlsym(handle_of_main_executable, ...)

  According to man dlopen(3) and posix docs in the case when si is handle
  of the main executable we need to search not only in the executable and its
  dependencies but also in all libraries loaded with RTLD_GLOBAL.

  see also: http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlopen.html

Bug: http://b/21528224
Bug: http://b/17512583
Bug: https://code.google.com/p/android/issues/detail?id=173822
Change-Id: Ib2801367ba48b6f3704da89a6d9f5e6911430013
(cherry picked from commit f439b5a3186ca0fef1092f45770abc716da9d87a)

2 files changed, 34 insertions, 2 deletions

diff --git a/tests/dlfcn_test.cpp b/tests/dlfcn_test.cpp
index a5abda7..3c9b8e3 100644
--- a/tests/dlfcn_test.cpp
+++ b/tests/dlfcn_test.cpp
@@ -145,13 +145,28 @@ TEST(dlfcn, dlsym_from_sofile_with_preload) {
   dlclose(preload);
 }
 
+TEST(dlfcn, dlsym_handle_global_sym) {
+  // check that we do not look into global group
+  // when looking up symbol by handle
+  void* handle = dlopen("libtest_empty.so", RTLD_NOW);
+  dlopen("libtest_with_dependency.so", RTLD_NOW | RTLD_GLOBAL);
+  void* sym = dlsym(handle, "getRandomNumber");
+  ASSERT_TRUE(sym == nullptr);
+  ASSERT_SUBSTR("undefined symbol: getRandomNumber", dlerror());
+
+  sym = dlsym(handle, "DlSymTestFunction");
+  ASSERT_TRUE(sym == nullptr);
+  ASSERT_SUBSTR("undefined symbol: DlSymTestFunction", dlerror());
+  dlclose(handle);
+}
+
 TEST(dlfcn, dlsym_with_dependencies) {
   void* handle = dlopen("libtest_with_dependency.so", RTLD_NOW);
-  ASSERT_TRUE(handle != NULL);
+  ASSERT_TRUE(handle != nullptr);
   dlerror();
   // This symbol is in DT_NEEDED library.
   void* sym = dlsym(handle, "getRandomNumber");
-  ASSERT_TRUE(sym != NULL);
+  ASSERT_TRUE(sym != nullptr) << dlerror();
   int (*fn)(void);
   fn = reinterpret_cast<int (*)(void)>(sym);
   EXPECT_EQ(4, fn());
@@ -583,6 +598,15 @@ TEST(dlfcn, dlopen_check_rtld_global) {
   // RTLD_GLOBAL implies RTLD_NODELETE, let's check that
   void* sym_after_dlclose = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
   ASSERT_EQ(sym, sym_after_dlclose);
+
+  // Check if dlsym() for main program's handle searches RTLD_GLOBAL
+  // shared libraries after symbol was not found in the main executable
+  // and dependent libraries.
+  void* handle_for_main_executable = dlopen(nullptr, RTLD_NOW);
+  sym = dlsym(handle_for_main_executable, "dlopen_testlib_simple_func");
+  ASSERT_TRUE(sym != nullptr) << dlerror();
+
+  dlclose(handle_for_main_executable);
 }
 
 // libtest_with_dependency_loop.so -> libtest_with_dependency_loop_a.so ->
diff --git a/tests/libs/Android.mk b/tests/libs/Android.mk
index 15fa55c..a5ef622 100644
--- a/tests/libs/Android.mk
+++ b/tests/libs/Android.mk
@@ -405,6 +405,14 @@ module := libtest_dlsym_from_this_grandchild
 include $(LOCAL_PATH)/Android.build.testlib.mk
 
 # -----------------------------------------------------------------------------
+# Empty library
+# -----------------------------------------------------------------------------
+libtest_empty_src_files := empty.cpp
+
+module := libtest_empty
+include $(LOCAL_PATH)/Android.build.testlib.mk
+
+# -----------------------------------------------------------------------------
 # Library with weak undefined function
 # -----------------------------------------------------------------------------
 libtest_dlopen_weak_undefined_func_src_files := \