Running a native library on Android L. error: only position independent executables (PIE) are supported

Question

When I run native code on Android L (Nexus 5), I get the error.

error: only position independent executables (PIE) are supported.

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Answer 1

If you can live with only supporting Android 4.1+, just set APP_PLATFORM := android-16 and you'll be good to go. Behind the scenes it sets APP_PIE := true. Your binary will segfault on older SDKs.

If you also need to support lower SDK levels, you'll need to create two binaries. Some other answers I've seen have recommended maintaining two separate source trees with different APP_PLATFORMs, but you don't need to do that. It's possible to make a single Android.mk output both a PIE and a non-PIE binary.

NDK 10c and later:

Make sure that PIE is disabled by default since enabling it manually is easier than disabling it. PIE doesn't get enabled by default unless your APP_PLATFORM is >=16. Make sure that your APP_PLATFORM is either not set (defaulting to android-3, or android-14 since NDK 15), lower than android-16, or set APP_PIE := false.

The following Android.mk then creates a PIE and a non-PIE binary, but has a caveat (see below):

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

# Enable PIE manually. Will get reset on $(CLEAR_VARS). This
# is what enabling PIE translates to behind the scenes.
LOCAL_CFLAGS += -fPIE
LOCAL_LDFLAGS += -fPIE -pie

LOCAL_MODULE := mymod

LOCAL_SRC_FILES := \
    mymod.c

include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_MODULE := mymod-nopie

LOCAL_SRC_FILES := \
    mymod.c

include $(BUILD_EXECUTABLE)

You'll then have to add some sort of logic to invoke the correct binary in your code.

Unfortunately, this means you'll have to compile the executable module twice, which can be slow. You also need to specify LOCAL_SRC_FILES and any libraries twice, which can be frustrating and difficult to keep track of. What you can do is to compile the main executable as a static library, and build executables from nothing but that static library. Static libraries do not require PIE.

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := mymod-common

LOCAL_SRC_FILES := \
  mymod.c

include $(BUILD_STATIC_LIBRARY)

include $(CLEAR_VARS)

# Enable PIE manually. Will get reset on $(CLEAR_VARS). This
# is what enabling PIE translates to behind the scenes.
LOCAL_CFLAGS += -fPIE
LOCAL_LDFLAGS += -fPIE -pie

LOCAL_MODULE := mymod

LOCAL_STATIC_LIBRARIES := mymod-common

include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_MODULE := mymod-nopie

LOCAL_STATIC_LIBRARIES := mymod-common

include $(BUILD_EXECUTABLE)

This seems to work quite nicely, although a certain amount of boilerplate is still required.

NDK 10b:

NDK 10b enables PIE by default and doesn't let you disable it, except with terrible hacks. Really, just update to 10c. I'm leaving my old answer here for reference but I wouldn't recommend it to anyone.

LOCAL_PATH := $(call my-dir)

# Forcefully disable PIE globally. This makes it possible to
# build some binaries without PIE by adding the necessary flags
# manually. These will not get reset by $(CLEAR_VARS). PIE is
# force-enabled on NDK 10b so we'll need this even if APP_PIE
# is set to false.
TARGET_PIE := false
NDK_APP_PIE := false

include $(CLEAR_VARS)

# Enable PIE manually. Will get reset on $(CLEAR_VARS). This
# is what enabling PIE translates to behind the scenes.
LOCAL_CFLAGS += -fPIE
LOCAL_LDFLAGS += -fPIE -pie

LOCAL_MODULE := mymod

LOCAL_SRC_FILES := \
    mymod.c

include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_MODULE := mymod-nopie

LOCAL_SRC_FILES := \
    mymod.c

include $(BUILD_EXECUTABLE)