Add a SANITIZE_HOST flag.

We had discussed the idea of making all host tools default to using
ASAN. Even if we don't make it the default, this makes it easy for the
user to switch all host binaries over.

Change-Id: I64a5c741b1b4e9aefed3a6be8dcd4f386e06b29c
diff --git a/core/binary.mk b/core/binary.mk
index 7fd7e32..752a5c3 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -191,19 +191,7 @@
 b_lib :=
 endif
 
-ifeq ($(strip $(LOCAL_ADDRESS_SANITIZER)),true)
-  my_clang := true
-  # Frame pointer based unwinder in ASan requires ARM frame setup.
-  LOCAL_ARM_MODE := arm
-  my_cflags += $(ADDRESS_SANITIZER_CONFIG_EXTRA_CFLAGS)
-  my_ldflags += $(ADDRESS_SANITIZER_CONFIG_EXTRA_LDFLAGS)
-  ifdef LOCAL_IS_HOST_MODULE
-      my_ldflags += -fsanitize=address
-  else
-      my_shared_libraries += $(ADDRESS_SANITIZER_CONFIG_EXTRA_SHARED_LIBRARIES)
-      my_static_libraries += $(ADDRESS_SANITIZER_CONFIG_EXTRA_STATIC_LIBRARIES)
-  endif
-endif
+include $(BUILD_SYSTEM)/config_sanitizers.mk
 
 ifeq ($(strip $($(LOCAL_2ND_ARCH_VAR_PREFIX)WITHOUT_$(my_prefix)CLANG)),true)
   my_clang :=
diff --git a/core/config_sanitizers.mk b/core/config_sanitizers.mk
new file mode 100644
index 0000000..a1964a9
--- /dev/null
+++ b/core/config_sanitizers.mk
@@ -0,0 +1,32 @@
+##############################################
+## Perform configuration steps for sanitizers.
+##############################################
+
+# Configure SANITIZE_HOST.
+ifdef LOCAL_IS_HOST_MODULE
+ifeq ($(SANITIZE_HOST),true)
+ifneq ($(strip $(LOCAL_CLANG)),false)
+ifneq ($(strip $(LOCAL_ADDRESS_SANITIZER)),false)
+    LOCAL_ADDRESS_SANITIZER := true
+endif
+endif
+endif
+endif
+
+# Configure address sanitizer.
+ifeq ($(strip $(LOCAL_ADDRESS_SANITIZER)),true)
+  my_clang := true
+  # Frame pointer based unwinder in ASan requires ARM frame setup.
+  LOCAL_ARM_MODE := arm
+  my_cflags += $(ADDRESS_SANITIZER_CONFIG_EXTRA_CFLAGS)
+  my_ldflags += $(ADDRESS_SANITIZER_CONFIG_EXTRA_LDFLAGS)
+  ifdef LOCAL_IS_HOST_MODULE
+      my_ldflags += -fsanitize=address
+      # -nodefaultlibs (provided with libc++) prevents the driver from linking
+      # libraries needed with -fsanitize=address. http://b/18650275
+      my_ldlibs += -ldl -lpthread
+  else
+      my_shared_libraries += $(ADDRESS_SANITIZER_CONFIG_EXTRA_SHARED_LIBRARIES)
+      my_static_libraries += $(ADDRESS_SANITIZER_CONFIG_EXTRA_STATIC_LIBRARIES)
+  endif
+endif