How do I build a native (command line) executable to run on Android?
As of NDK r8d, this can be solved in a much simpler way.
-
Create a project with the following directory hierarchy:
project/ jni/ Android.mk Application.mk *.c, *.cpp, *.h, etc. -
Fill in Android.mk with the following content. The most important thing is the last line. Check the NDK doc for the meaning of the other variables.
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := name-of-your-executable LOCAL_SRC_FILES := a.cpp b.cpp c.cpp etc.cpp LOCAL_CPPFLAGS := -std=gnu++0x -Wall -fPIE # whatever g++ flags you like LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog -fPIE -pie # whatever ld flags you like include $(BUILD_EXECUTABLE) # <-- Use this to build an executable. -
Go to the
project/directory, and simply typendk-buildThe result will be placed in
project/libs/<arch>/name-of-your-executable.
http://www.bekatul.info/content/native-c-application-android [broken (Nov 9, 2015)]
Wayback Machine link
To summarize the article...
The test code is :
#include <stdio.h>//for printf
#include <stdlib.h>//for exit
int main(int argc, char **argv)
{
int i = 1;
i+=2;
printf("Hello, world (i=%d)!\n", i);
return 0;
exit(0);
}
The Makefile is :
APP := test
ROOT := /home/dd/android
INSTALL_DIR := /data/tmp
NDK_PLATFORM_VER := 8
ANDROID_NDK_ROOT := $(ROOT)/android-ndk-r5
ANDROID_NDK_HOST := linux-x86
ANDROID_SDK_ROOT := $(ROOT)/android-sdk-linux_86
PREBUILD := $(ANDROID_NDK_ROOT)/toolchains/arm-eabi-4.4.0/prebuilt/$(ANDROID_NDK_HOST)
BIN := $(PREBUILD)/bin/
LIB := $(ANDROID_NDK_ROOT)/platforms/android-$(NDK_PLATFORM_VER)/arch-arm/usr/lib
INCLUDE := $(ANDROID_NDK_ROOT)/platforms/android-$(NDK_PLATFORM_VER)/arch-arm/usr/include
CC := $(BIN)/arm-eabi-gcc
GDB_CLIENT := $(BIN)/arm-eabi-gdb
LIBCRT := $(LIB)/crtbegin_dynamic.o
LINKER := /system/bin/linker
DEBUG := -g
CFLAGS := $(DEBUG) -fno-short-enums -I$(INCLUDE)
CFLAGS += -Wl,-rpath-link=$(LIB),-dynamic-linker=$(LINKER) -L$(LIB)
CFLAGS += -nostdlib -lc
all: $(APP)
$(APP): $(APP).c
$(CC) -o $@ $< $(CFLAGS) $(LIBCRT)
install: $(APP)
$(ANDROID_SDK_ROOT)/platform-tools/adb push $(APP) $(INSTALL_DIR)/$(APP)
$(ANDROID_SDK_ROOT)/platform-tools/adb shell chmod 777 $(INSTALL_DIR)/$(APP)
shell:
$(ANDROID_SDK_ROOT)/platform-tools/adb shell
run:
$(ANDROID_SDK_ROOT)/platform-tools/adb shell $(INSTALL_DIR)/$(APP)
debug-install:
$(ANDROID_SDK_ROOT)/platform-tools/adb push $(PREBUILD)/../gdbserver $(INSTALL_DIR)/gdbserver
$(ANDROID_SDK_ROOT)/platform-tools/adb shell chmod 777 $(INSTALL_DIR)/gdbserver
debug-go:
$(ANDROID_SDK_ROOT)/platform-tools/adb forward tcp:1234: tcp:1234
$(ANDROID_SDK_ROOT)/platform-tools/adb shell $(INSTALL_DIR)/gdbserver :1234 $(INSTALL_DIR)/$(APP)
debug:
$(GDB_CLIENT) $(APP)
clean:
@rm -f $(APP).o $(APP)
The author stored those files on his/hers local linux computer at:
/home/dd/android/dev/native/test.c
/home/dd/android/dev/native/Makefile
The author then compiled and tested it with:
dd@abil:~/android/dev/native$ make clean; make; make install; make run
/home/dd/android/android-ndk-r5/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/bin//arm-eabi-gcc -c -fno-short-enums -I/home/dd/android/android-ndk-r5/platforms/android-9/arch-arm/usr/include test.c -o test.o
/home/dd/android/android-ndk-r5/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/bin//arm-eabi-g++ -Wl,--entry=main,-dynamic-linker=/system/bin/linker,-rpath-link=/home/dd/android/android-ndk-r5/platforms/android-9/arch-arm/usr/lib -L/home/dd/android/android-ndk-r5/platforms/android-9/arch-arm/usr/lib -nostdlib -lc -o test test.o
/home/dd/android/android-sdk-linux_86/platform-tools/adb push test /data/tmp/test
45 KB/s (2545 bytes in 0.054s)
/home/dd/android/android-sdk-linux_86/platform-tools/adb shell chmod 777 /data/tmp/test
/home/dd/android/android-sdk-linux_86/platform-tools/adb shell /data/tmp/test
Hello, world (i=3)!
SDK and NDK used were:
source code: /home/dd/android/dev/native
android ndk: /home/dd/android/android-ndk-r5
android sdk: /home/dd/android/android-sdk-linux_86
However, the debug guide was the really good part ! Copy and pasted ...
Set the compile for enable debugging:
DEBUG = -g
CFLAGS := $(DEBUG) -fno-short-enums -I$(ANDROID_NDK_ROOT)/platforms/android-$(NDK_PLATFORM_VER)/arch-arm/usr/include
copy the gdbserver file ($(PREBUILD)/../gdbserver) to the emulator, add the target in Makefile than to make it easy:
debug-install:
$(ANDROID_SDK_ROOT)/platform-tools/adb push $(PREBUILD)/../gdbserver $(INSTALL_DIR)/gdbserver
$(ANDROID_SDK_ROOT)/platform-tools/adb shell chmod 777 $(INSTALL_DIR)/gdbserver
Now we will debug it @ port 1234:
debug-go:
$(ANDROID_SDK_ROOT)/platform-tools/adb forward tcp:1234: tcp:1234
$(ANDROID_SDK_ROOT)/platform-tools/adb shell $(INSTALL_DIR)/gdbserver :1234 $(INSTALL_DIR)/$(APP)
Then execute it:
dd@abil:~/android/dev/native$ make clean; make; make install; make debug-install; make debug-go
/home/dd/android/android-ndk-r5/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/bin//arm-eabi-gcc -c -g -fno-short-enums -I/home/dd/android/android-ndk-r5/platforms/android-9/arch-arm/usr/include test.c -o test.o
/home/dd/android/android-ndk-r5/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/bin//arm-eabi-g++ -Wl,--entry=main,-dynamic-linker=/system/bin/linker,-rpath-link=/home/dd/android/android-ndk-r5/platforms/android-9/arch-arm/usr/lib -L/home/dd/android/android-ndk-r5/platforms/android-9/arch-arm/usr/lib -nostdlib -lc -o test test.o
/home/dd/android/android-sdk-linux_86/platform-tools/adb push test /data/tmp/test
71 KB/s (3761 bytes in 0.051s)
/home/dd/android/android-sdk-linux_86/platform-tools/adb shell chmod 777 /data/tmp/test
/home/dd/android/android-sdk-linux_86/platform-tools/adb push /home/dd/android/android-ndk-r5/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/../gdbserver /data/tmp/gdbserver
895 KB/s (118600 bytes in 0.129s)
/home/dd/android/android-sdk-linux_86/platform-tools/adb shell chmod 777 /data/tmp/gdbserver
/home/dd/android/android-sdk-linux_86/platform-tools/adb forward tcp:1234: tcp:1234
/home/dd/android/android-sdk-linux_86/platform-tools/adb shell /data/tmp/gdbserver :1234 /data/tmp/test
Process /data/tmp/test created; pid = 472
Listening on port 1234
Now open other console and execute the debugger:
dd@abil:~/android/dev/native$ make debug
/home/dd/android/android-ndk-r5/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/bin//arm-eabi-gdb test
GNU gdb 6.6
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "--host=x86_64-linux-gnu --target=arm-elf-linux"...
(gdb) target remote :1234
Remote debugging using :1234
warning: Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.
0xb0001000 in ?? ()
(gdb) b main
Breakpoint 1 at 0x82fc: file test.c, line 6.
(gdb) c
Continuing.
Error while mapping shared library sections:
/system/bin/linker: No such file or directory.
Error while mapping shared library sections:
libc.so: Success.
Breakpoint 1, main (argc=33512, argv=0x0) at test.c:6
6 int i = 1;
(gdb) n
7 i+=2;
(gdb) p i
$1 = 1
(gdb) n
9 printf("Hello, world (i=%d)!\n", i);
(gdb) p i
$2 = 3
(gdb) c
Continuing.
Program exited normally.
(gdb) quit
Well it is ok. And the other console will give additional output like so:
Remote debugging from host 127.0.0.1
gdb: Unable to get location for thread creation breakpoint: requested event is not supported
Hello, world (i=3)!
Child exited with retcode = 0
Child exited with status 0
GDBserver exiting
Here's an example project that follows the KennyTM's answer. You can create it from scratch or modify another project, for example, hello-jni in the NDK samples.
jni/main.c:
#include <stdio.h>
int main() {
printf("hello\n");
return 0;
}
jni/Application.mk:
#APP_ABI := all
APP_ABI := armeabi-v7a
jni/Android.mk:
LOCAL_PATH := $(call my-dir)
# first target: the hello-jni example
# it shows how to build multiple targets
# {{ you may comment it out
include $(CLEAR_VARS)
LOCAL_MODULE := hello-jni
LOCAL_SRC_FILES := hello-jni.c
LOCAL_LDLIBS := -llog -L$(LOCAL_PATH)/lib -lmystuff # link to libmystuff.so
include $(BUILD_SHARED_LIBRARY)
#}} you may comment it out
# second target
include $(CLEAR_VARS)
LOCAL_MODULE := hello
LOCAL_SRC_FILES := main.c
include $(BUILD_EXECUTABLE) # <-- Use this to build an executable.
I have to note that you will not see any logging in the stdout output, you will have to use adb logcat to see it.
So if you want logging:
jni/main.c:
#include <stdio.h>
#include <android/log.h>
int main() {
printf("hello\n");
__android_log_print(ANDROID_LOG_DEBUG , "~~~~~~", "log %i", 0); // the 3rd arg is a printf-style format string
return 0;
}
and the corresponding section in jni/Android.mk becomes:
LOCAL_PATH := $(call my-dir)
#...
include $(CLEAR_VARS)
LOCAL_MODULE := hello
LOCAL_SRC_FILES := main.c
LOCAL_LDLIBS := -llog # no need to specify path for liblog.so
include $(BUILD_EXECUTABLE) # <-- Use this to build an executable.