Fix dlclose for libraries with thread_local dtors

Mark library NODELETE once first pthread_atexit handler is registered.

According to the test runs it seems that glibc loader agrees on the fact
that it is too dangerous to unload a library on pthread_exit(). It only
does it on dlclose if there are no active thread local dtors left
associated with the dso.

(At this point we just have tests to demonstrate how it works)

Test: bionic-unit-tests --gtest_filter=dl*
Test: bionic-unit-tests-glibc --gtest_filter=dl*
Bug: android/ndk#360
Change-Id: I724ef89fc899788f95c47e6372c38b3313f18fed

tests/dlfcn_test.cpp

@@ -1317,6 +1317,77 @@ TEST(dlfcn, dt_runpath_absolute_path) {
   dlclose(handle);
 }
 
+TEST(dlfcn, dlclose_after_thread_local_dtor) {
+  bool is_dtor_triggered = false;
+
+  auto f = [](void* handle, bool* is_dtor_triggered) {
+    typedef void (*fn_t)(bool*);
+    fn_t fn = reinterpret_cast<fn_t>(dlsym(handle, "init_thread_local_variable"));
+    ASSERT_TRUE(fn != nullptr) << dlerror();
+
+    fn(is_dtor_triggered);
+
+    ASSERT_TRUE(!*is_dtor_triggered);
+  };
+
+  void* handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle == nullptr);
+
+  handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+
+  std::thread t(f, handle, &is_dtor_triggered);
+  t.join();
+
+  ASSERT_TRUE(is_dtor_triggered);
+  dlclose(handle);
+
+  handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle == nullptr);
+}
+
+TEST(dlfcn, dlclose_before_thread_local_dtor) {
+  bool is_dtor_triggered = false;
+
+  auto f = [](bool* is_dtor_triggered) {
+    void* handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW | RTLD_NOLOAD);
+    ASSERT_TRUE(handle == nullptr);
+
+    handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW);
+    ASSERT_TRUE(handle != nullptr) << dlerror();
+
+    typedef void (*fn_t)(bool*);
+    fn_t fn = reinterpret_cast<fn_t>(dlsym(handle, "init_thread_local_variable"));
+    ASSERT_TRUE(fn != nullptr) << dlerror();
+
+    fn(is_dtor_triggered);
+
+    dlclose(handle);
+
+    ASSERT_TRUE(!*is_dtor_triggered);
+
+    // Since we have thread_atexit dtors associated with handle - the library should
+    // still be availabe.
+    handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW | RTLD_NOLOAD);
+    ASSERT_TRUE(handle != nullptr) << dlerror();
+    dlclose(handle);
+  };
+
+  void* handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  dlclose(handle);
+
+  handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle == nullptr);
+
+  std::thread t(f, &is_dtor_triggered);
+  t.join();
+
+  ASSERT_TRUE(is_dtor_triggered);
+  handle = dlopen("libtest_thread_local_dtor.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+}
+
 TEST(dlfcn, RTLD_macros) {
 #if !defined(RTLD_LOCAL)
 #error no RTLD_LOCAL

tests/libs/Android.bp

@@ -635,6 +635,16 @@ cc_test_library {
     shared_libs: ["libtest_dlopen_from_ctor"],
 }
 
+// -----------------------------------------------------------------------------
+// Library with non-trivial thread_local variable to test dlclose()
+// -----------------------------------------------------------------------------
+cc_test_library {
+    name: "libtest_thread_local_dtor",
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["thread_local_dtor.cpp"],
+}
+
+
 // -----------------------------------------------------------------------------
 // Tool to use to align the shared libraries in a zip file.
 // -----------------------------------------------------------------------------

tests/libs/thread_local_dtor.cpp

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+namespace {
+
+class TestClass {
+ public:
+  TestClass(bool* flag) : flag_(flag) {}
+  ~TestClass() {
+    *flag_ = true;
+  }
+ private:
+  bool* flag_;
+};
+
+};  // namespace
+
+extern "C" void init_thread_local_variable(bool* flag) {
+  thread_local TestClass test(flag);
+}