Allow static C++ destructors to be properly called on dlclose().

With this patch, _and_ an upcoming build/ patch, the destruction
of static C++ objects contained in shared libraries will happen
properly when dlclose() is called.

Note that this change introduces crtbegin_so.S and crtend_so.S which
are currently ignored by the build system.

+ move definition of __dso_handle to the right place
  (before that, all shared libraries used the __dso_handle
   global variable from the C library).

  Note that we keep a 'weak' __dso_handle in aeabi.c to avoid
  breaking the build until the next patch to build/core/combo/
  appears. We will be able to remove that later.

+ move bionic/aeabi.c to arch-arm/bionic/ (its proper location)

Change-Id: Ie771aa204e3acbdf02fd30ebd4150373a1398f39
NOTE: The NDK will need to be modified to enable this feature in
      the shared libraries that are generated through it.

1 files changed, 16 insertions, 6 deletions

diff --git a/libc/Android.mk b/libc/Android.mk
index 79c89ed..6b2334e 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -317,7 +317,6 @@ libc_common_src_files := \
 # =========================================================
 ifeq ($(TARGET_ARCH),arm)
 libc_common_src_files += \
-	bionic/eabi.c \
 	bionic/bionic_clone.c \
 	arch-arm/bionic/__get_pc.S \
 	arch-arm/bionic/__get_sp.S \
@@ -325,6 +324,7 @@ libc_common_src_files += \
 	arch-arm/bionic/_setjmp.S \
 	arch-arm/bionic/atomics_arm.S \
 	arch-arm/bionic/clone.S \
+	arch-arm/bionic/eabi.c \
 	arch-arm/bionic/ffs.S \
 	arch-arm/bionic/kill.S \
 	arch-arm/bionic/libgcc_compat.c \
@@ -421,7 +421,6 @@ libc_common_src_files += \
 	string/strncmp.c \
 	string/memcmp.c \
 	string/strlen.c \
-	bionic/eabi.c \
 	bionic/pthread.c \
 	bionic/pthread-rwlocks.c \
 	bionic/pthread-timers.c \
@@ -490,6 +489,10 @@ else
     libc_common_cflags += -DANDROID_SMP=0
 endif
 
+# Needed to access private/__dso_handle.S from
+# crtbegin_xxx.S and crtend_xxx.S
+#
+libc_crt_target_cflags += -I$(LOCAL_PATH)/private
 
 # Define some common includes
 # ========================================================
@@ -504,10 +507,17 @@ libc_common_c_includes := \
 # executables)
 # ==========================================================================
 
-ifeq ($(TARGET_ARCH),x86)
-# we only need begin_so/end_so for x86, since it needs an appropriate .init
-# section in the shared library with a function to call all the entries in
-# .ctors section. ARM uses init_array, and does not need the function.
+ifneq ($(filter arm x86,$(TARGET_ARCH)),)
+# ARM and x86 need crtbegin_so/crtend_so.
+#
+# For x86, the .init section must point to a function that calls all
+# entries in the .ctors section. (on ARM this is done through the
+# .init_array section instead).
+#
+# For both platforms, the .fini_array section must point to a function
+# that will call __cxa_finalize(&__dso_handle) in order to ensure that
+# static C++ destructors are properly called on dlclose().
+#
 GEN := $(TARGET_OUT_STATIC_LIBRARIES)/crtbegin_so.o
 $(GEN): $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin_so.S
 	@mkdir -p $(dir $@)