Initial implementation of __cxa_thread_atexit_impl

  This is initial implementations; does not yet handle
  dlclose - undefined behavior, needs linker support to
  handle it right.

Bug: 19800080
Bug: 16696563
Change-Id: I7a3e21ed7f7ec01e62ea1b7cb2ab253590ea0686

3 files changed, 75 insertions, 1 deletions

diff --git a/libc/Android.mk b/libc/Android.mk
index 6f430cc..ebc59de 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -533,6 +533,9 @@ libc_pthread_src_files := \
     bionic/pthread_setschedparam.cpp \
     bionic/pthread_sigmask.cpp \
 
+libc_thread_atexit_impl_src_files := \
+    bionic/__cxa_thread_atexit_impl.cpp \
+
 libc_arch_static_src_files := \
     bionic/dl_iterate_phdr_static.cpp \
 
@@ -1002,6 +1005,24 @@ $(eval $(call patch-up-arch-specific-flags,LOCAL_CFLAGS,libc_common_cflags))
 $(eval $(call patch-up-arch-specific-flags,LOCAL_SRC_FILES,libc_bionic_src_files))
 include $(BUILD_STATIC_LIBRARY)
 
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := $(libc_thread_atexit_impl_src_files)
+LOCAL_CFLAGS := $(libc_common_cflags) -fno-data-sections -Wframe-larger-than=2048
+
+LOCAL_CONLYFLAGS := $(libc_common_conlyflags)
+LOCAL_CPPFLAGS := $(libc_common_cppflags) -Wold-style-cast
+LOCAL_C_INCLUDES := $(libc_common_c_includes)
+LOCAL_MODULE := libc_thread_atexit_impl
+# TODO: Clang tries to use __tls_get_addr which is not supported yet
+# remove after it is implemented.
+LOCAL_CLANG := false
+LOCAL_ADDITIONAL_DEPENDENCIES := $(libc_common_additional_dependencies)
+LOCAL_CXX_STL := none
+LOCAL_SYSTEM_SHARED_LIBRARIES :=
+LOCAL_ADDRESS_SANITIZER := false
+LOCAL_NATIVE_COVERAGE := $(bionic_coverage)
+
+include $(BUILD_STATIC_LIBRARY)
 
 # ========================================================
 # libc_pthread.a - pthreads parts that previously lived in
@@ -1206,6 +1227,7 @@ LOCAL_WHOLE_STATIC_LIBRARIES := \
     libc_pthread \
     libc_stack_protector \
     libc_syscalls \
+    libc_thread_atexit_impl \
     libc_tzcode \
 
 LOCAL_WHOLE_STATIC_LIBRARIES_arm := libc_aeabi
diff --git a/libc/bionic/__cxa_thread_atexit_impl.cpp b/libc/bionic/__cxa_thread_atexit_impl.cpp
new file mode 100644
index 0000000..9ae6dfd
--- /dev/null
+++ b/libc/bionic/__cxa_thread_atexit_impl.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2015 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 <sys/cdefs.h>
+
+struct thread_local_dtor {
+  void (*func) (void *);
+  void *arg;
+  void *dso_handle; // unused...
+  thread_local_dtor* next;
+};
+
+__thread thread_local_dtor* thread_local_dtors = nullptr;
+
+extern "C" int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle) {
+  thread_local_dtor* dtor = new thread_local_dtor();
+
+  dtor->func = func;
+  dtor->arg = arg;
+  dtor->dso_handle = dso_handle;
+  dtor->next = thread_local_dtors;
+
+  thread_local_dtors = dtor;
+
+  return 0;
+}
+
+extern "C" __LIBC_HIDDEN__ void __cxa_thread_finalize() {
+  while (thread_local_dtors != nullptr) {
+    thread_local_dtor* current = thread_local_dtors;
+    thread_local_dtors = current->next;
+
+    current->func(current->arg);
+    delete current;
+  }
+}
diff --git a/libc/bionic/pthread_exit.cpp b/libc/bionic/pthread_exit.cpp
index c2232a9..1de85f5 100644
--- a/libc/bionic/pthread_exit.cpp
+++ b/libc/bionic/pthread_exit.cpp
@@ -37,6 +37,7 @@
 extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t);
 extern "C" __noreturn void __exit(int);
 extern "C" int __set_tid_address(int*);
+extern "C" void __cxa_thread_finalize();
 
 /* CAVEAT: our implementation of pthread_cleanup_push/pop doesn't support C++ exceptions
  *         and thread cancelation
@@ -59,10 +60,13 @@ void __pthread_cleanup_pop(__pthread_cleanup_t* c, int execute) {
 }
 
 void pthread_exit(void* return_value) {
+  // Call dtors for thread_local objects first.
+  __cxa_thread_finalize();
+
   pthread_internal_t* thread = __get_thread();
   thread->return_value = return_value;
 
-  // Call the cleanup handlers first.
+  // Call the cleanup handlers.
   while (thread->cleanup_stack) {
     __pthread_cleanup_t* c = thread->cleanup_stack;
     thread->cleanup_stack = c->__cleanup_prev;