Develop Reference

How to include util-linux in AOSP?

How do I include util-linux from here in AOSP? Where should I add this util-linux folder in AOSP so that I can build AOSP and these utils could be added in /system/bin/ or /system/xbin/? And is there any specific Makefile or Android.mk that I need to make it to compile with Android build?

I have added an application from util-linux package in AOSP.
Here's how I did it. I added the util-linux (2.34) from https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.34/util-linux-2.34.tar.gz in external of AOSP folder.
I just wanted to add chrt from util-linux. Therefore, I run the normal make command in util-linux to see what files are compiled for chrt. I took a note and created an Android.mk accordingly. I am sure there's a better way to do it hierarchically by making the library first and then make the chrt executable. However, this works too.
I added the following Android.mk at external\util-linux\. The Android.mk looks like the following:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := sohamchrt
LOCAL_SRC_FILES := schedutils/chrt.c lib/blkdev.c lib/canonicalize.c \
lib/crc32.c lib/crc32c.c lib/idcache.c lib/fileutils.c \
lib/ismounted.c lib/color-names.c lib/mangle.c lib/match.c lib/mbsalign.c \
lib/mbsedit.c lib/md5.c lib/pager.c lib/parse-date.c lib/pwdutils.c lib/randutils.c \
lib/setproctitle.c lib/strutils.c lib/timeutils.c lib/ttyutils.c lib/exec_shell.c \
lib/strv.c lib/sha1.c lib/signames.c lib/linux_version.c lib/loopdev.c \
lib/plymouth-ctrl.c lib/cpuset.c lib/path.c lib/procutils.c lib/sysfs.c
LOCAL_CFLAGS = -DHAVE_NANOSLEEP -include config.h \
-isystem bionic/libc/upstream-openbsd/android/include
LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
include $(BUILD_EXECUTABLE)
Now, when I run m -j8 iso_img, then Android tries to compile sohamchrt. I named the package sohamchrt because chrt is already provided by toybox which have limitations.
The problem is util-linux is not fully compatible with bionic. So, I needed to make some changes to some .c and .h files such as fileutils.c, include/c.h, etc.
After successful compilation, the binary sohamchrt appears in /system/bin when Android is running, and it works with no issues.
This is also a guide on how you can add a C source file for a userspace executable binary in AOSP.

It's always worth checking whether a library you want to add already exists at https://android.googlesource.com/. In your case, unfortunately, it does not.
As util-linux does not come with an Android.bp. You will have to understand how util-linux is built and how Soong works to create a custom Android.bp for integration. The correct folder to place it would be external/util-linux/.
Maybe you will want to take a shortcut and just add util-linux as prebuilt binaries. That will reduce the effort.
Please check licensing issues first, though.

How to build libvpx as static library

In my jni directory, I run the following command:
$ ./libvpx/configure --target=armv7-android-gcc --disable-examples --sdk-path=/home/peter/adt/android-ndk-r9/
This results in generating Android.mk in libvpx/build/make directory
Next, I create Android.mk in jni directory:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include libvpx/build/make/Android.mk
When I run ndk-build, it ends up creating libvpx.so.
However, I would really like to create a static library.
I started all over and ran the configuration with an extra flag:
$ ./libvpx/configure --target=armv7-android-gcc --disable-examples --sdk-path=/home/peter/adt/android-ndk-r9/ --enable-static
However, running ndk-build still results in creating libvpx.so.
Does any know how I can configure libvpx to create a static library? Thank you in advance for your help.

I was able to successfully build an arm static library, though I have not yet integrated it with an Android application as I am building libvpx as a component for another native library.
Note that in my case the Android.mk already existed in the directory tree and was unaffected by the configure script, which is apparently contrary to your experience. To build the static library I simply invoked configure and then make:
$ make clean
$ ./configure --target=armv7-android-gcc --disable-examples --sdk-path=/home/me/android-ndk-r9b/
$ make
In my case I had to do a clean build because I had some cruft left from an earlier build attempt that would break the build otherwise.
The result is libvpx.a and libvpx_g.a.

Linker trouble when using LuaJIT prebuilt static library with android under cygwin

I think I spent most of yesterday unsuccessfully wrestling with this, any help would greatly appreciated and make me extremely happy! Even a next step to try to find the root of the issue is something I'm stuck on at the moment!
I have an Android 2.2 project that's trying to reference a prebuilt LuaJIT static library but ndk-build gives me this error:
test_android.cpp:25: undefined reference to `luaL_newstate'
I built LuaJIT as liblua.a, I've placed that in the root of my JNI directory with the relevant headers. I've have one Android.mk as shown below:
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := lua
LOCAL_SRC_FILES := liblua.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := test
LOCAL_CFLAGS := -Werror
LOCAL_SRC_FILES := test_android.cpp
LOCAL_LDLIBS := -llog -lGLESv2
LOCAL_STATIC_LIBRARIES := lua
include $(BUILD_SHARED_LIBRARY)
In test_andrdoid.cpp I've got this code:
extern "C"
{
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
void test()
{
lua_State* lua = lua_open();
}
This seems like a linker error, for some reason the static library file is not being correctly referenced. But, to me, the makefile seems correct.
Any help would be greatly appreciated!
To start with: is there anyway to see how everything is being linked
together and if my shared library module is really get access
to the static library?
Additional Information
Here's extra information that I think could be relevant!
Building the library
Maybe it's the static lib file that's not correct? (Is there anywhere I could download a prebuilt one to check?). I made it with this script (from the LuaJIT website). I'm using the latest stable LuaJIT, 1.1.8
NDK=/cygdrive/c/android-ndk-r8b
NDKABI=8
NDKVER=$NDK/toolchains/arm-linux-androideabi-4.4.3
NDKP=$NDKVER/prebuilt/linux-x86/bin/arm-linux-androideabi-
NDKF="--sysroot $NDK/platforms/android-$NDKABI/arch-arm"
make linux HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF"
This builds fine and creates a liblua.a in the /src/ directory. (I ran nm on it and it lists out all the function prototypes I'd expect). I don't know if there's anything else I can do to ensure it's really a build for ARM?
NDKABI=8 means I'm targeting Android 2.2
Setting up the test Android Project
I create a brand new 2.2 android project using this command:
android create project --target 3 --name test --path . --activity TestActivity --package com.test
Target 3 maps to Android 2.2 on my system (using android list devices).
I create the jni folder and have a test_android.h and test_android.cpp. Then I use ndk-build to build them - which works fine when I'm not trying to reference LuaJIT. When I do try and use Lua I get the following error:
Full Error Message
Cygwin : Generating dependency file converter script
Compile++ thumb : test <= test_android.cpp
In file included from jni/test_android.h:3:0, from jni/test_android.cpp:2:
C:/android-ndk-r8b/platforms/android-8/arch-arm/usr/include/jni.h:592:13: note:
the mangling of 'va_list' has changed in GCC 4.4
Prebuilt : liblua.a <= jni/
StaticLibrary : libstdc++.a
SharedLibrary : libtest.so
obj/local/armeabi/objs/test/test_android.o: In function `test()':
C:\Users\Grrr\Documents\mycode\static_lib_test/jni/test_android.cpp:25: undefined reference to `luaL_newstate'
collect2: ld returned 1 exit status
/cygdrive/c/android-ndk-r8b/build/core/build-binary.mk:378: recipe for target `obj/local/armeabi/libtest.so' failed make: *** [obj/local/armeabi/libtest.so] Error 1
Most of the issues I've seen searching around are due to the local library include order, as I only have one library this shouldn't be an issue and suggests I've managed to get something more fundamental wrong :)
Update
I've since built normal Lua and added that as prebuilt static library and it works fine. I suspect its how I've built LuaJIT but I'm not sure how to correctly build it, or find a working prebuilt version.

The linking for this was fine, or at least the makefile was.
The problem was the LuaJIT library wasn't built for ARM (I used objdump -a lualib.a, to check this). I downloaded the latest LuaJIT, ran the script under linux and got an ARM library. Everything links nicely now!

Want to compile native Android binary I can run in terminal on the phone

I've been trying for a couple days to compile a native ARM Android binary that will execute on my phone using a terminal application. I want to generate the same type of binary as the standard Posix binaries installed on the phone like ls, mkdir etc. I've downloaded the Android NDK under Mac OS X and have been able to compile simple ELF binaries without errors. However, when I transfer them to the phone, they always segfault. That is, they segfault when compiled with -static in GCC. If I don't use -static, they complain about not being linked, etc. Put simply, they don't work.
My hypothesis is that they are not linking to the Android standard C library properly. Even though I am linking my binaries with the libc provided by the NDK, they still don't work. I read that Android uses the Bionic C library, and tried to download source for it but I'm not sure how to build a library from it (it's all ARM assembly, it seems).
Is it true that the Android C library on the phone is different from the one provided with the Android NDK? Will the one included with the NDK not allow me to compile native binaries I can execute through a terminal? Any guidance here is greatly appreciated!
Update:
I finally got this to work using GCC 4.7.0 on Mac OS X. I downloaded the Bionic headers and then compiled a dynamically linked binary using the C library that comes with the Android NDK. I was able to get a test app to work on the phone using the phone's C lib (the binary was 33K). I also tried to statically link against the NDK's C library, and that also worked.
In order to get this all working I had to pass -nostdlib to GCC and then manually add crtbegin_dynamic.o and crtend_android.o to GCC's command line. It works something like this:
$CC \
$NDK_PATH/usr/lib/crtbegin_dynamic.o \
hello.c -o hello \
$CFLAGS \
$NDK_PATH/usr/lib/crtend_android.o
For static binaries, use "crtbegin_static.o." This is explained in the crtbegin_dynamic.S/crtbegin_static.S source.
For this experiment, I only used plain 'ol GCC 4.7.0 and Binutils 2.22. I also compiled GCC with newlib, but I am not actually linking my ARM binaries with newlib at all. I am forcing GCC/ld to link directly to the libc provided with the Android NDK, or in the case of dynamic binaries, to the libc on the phone.

Just use the android-ndk. And build a Android.mk like so.
include $(BUILD_EXECUTABLE) is what tells it build a executable instead of a JNI .lib
Android.mk
ifneq ($(TARGET_SIMULATOR),true)
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_CFLAGS += -Wall
LOCAL_LDLIBS := -L$(LOCAL_PATH)/lib -llog -g
LOCAL_C_INCLUDES := bionic
LOCAL_C_INCLUDES += $(LOCAL_PATH)/include
LOCAL_SRC_FILES:= main.cpp
LOCAL_MODULE := mycmd
include $(BUILD_EXECUTABLE)
endif # TARGET_SIMULATOR != true

First, make sure you have the NDK:
http://developer.android.com/tools/sdk/ndk/index.html
Here is the easiest way to compile a C binary for your phone:
http://developer.android.com/tools/sdk/ndk/index.html
http://www.kandroid.org/ndk/docs/STANDALONE-TOOLCHAIN.html
Usually $NDK(may be different) =
Linux:
/home/<user>/android-ndk
Mac OS X:
/Users/<user>/android-ndk
In Terminal:
# create tool-chain - one line
# New method in ndk 12.
$NDK/build/tools/make_standalone_toolchain.py --arch arm --install-dir=/tmp/my-android-toolchain
# Old method.
#$NDK/build/tools/make-standalone-toolchain.sh --platform=android-3 --install-dir=/tmp/my-android-toolchain
# add to terminal PATH variable
export PATH=/tmp/my-android-toolchain/bin:$PATH
# make alias CC be the new gcc binary
export CC=arm-linux-androideabi-gcc
# compile your C code(I tried hello world)
$CC -o foo.o -c foo.c
# push binary to phone
adb push foo.o /data/local/tmp
# execute binary
adb /data/local/tmp/foo.o

Using CMake with the Android NDK is a nice way to compile Android console applications.
Download CMake and android-cmake (set it up like this). If your program is called main.c, then write the following in file CMakeLists.txt:
project(test)
cmake_minimum_required(VERSION 2.8)
add_executable(test ./main.c)
and run cmake -DCMAKE_TOOLCHAIN_FILE=$ANDTOOLCHAIN .
You will then have a Makefile for your program, you can run make to have your test executable.

In CMake, you can cross build using toolchain files.
From google developers:
cmake \
    -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
    -DANDROID_ABI=$ABI \
    -DANDROID_PLATFORM=android-$MINSDKVERSION \
    $OTHER_ARGS
CMake has its own built-in NDK support. Before CMake 3.21, this workflow is not supported by Android and is often broken with new NDK releases. Starting from CMake 3.21, the implementations are merged.
Starting from cmake 3.21 you can:
mkdir build
cd build
cmake ..
-DCMAKE_SYSTEM_NAME=Android
-DCMAKE_SYSTEM_VERSION=23 # API level. optional, recommanded
-DCMAKE_ANDROID_NDK=path/to/ndk
-DCMAKE_ANDROID_ARCH=arm # optional, recommanded
-DCMAKE_ANDROID_ARCH_ABI=armeabi # optional, recommanded
Note: in the command above, line endings (<line feed>) are not escaped, please don't copy-paste this command directly in your shell
See Cross Compiling for Android with the NDK for more information about variables, possible values, and determenation algorithms.

Try if if the agcc wrapper can help you as referenced in the Android-tricks blog. According to the blog post you want to use the bionic library, but the one already installed on the phone, not some separately compiled version.

Android-NDK build system (building hello-gl2)

I downloaded and installed Android-NDK on my Archlinux, using this package.
Got no issues building (and running) the sample hello-jni following the guide on this page, but if I try to do the same with hello-gl2 I get some errors; it looks like it cannot find some header files:
$ ../../ndk-build
/usr/bin/make -f /opt/android-ndk/build/core/build-local.mk
Compile++ thumb : gl2jni <= gl_code.cpp
/opt/android-ndk/samples/hello-gl2/jni/gl_code.cpp:22:23: error: GLES2/gl2.h: No such file or directory
/opt/android-ndk/samples/hello-gl2/jni/gl_code.cpp:23:26: error: GLES2/gl2ext.h: No such file or directory
--- SNIP ---
GLES2/gl2.h and GLES2/gl2ext.h are however present in $(NDK)/platforms/android-4/arch-arm/usr/include/, and it looks like$(NDK)/build/core/setup-toolchain.mk should set such include path.
Has anybody encountered the same issue? How can I compile this sample?
And then, are there other options to easily build Android-NDK applications? This build system seems quite complicated to me, and I'd prefer using cmake to build my applications.

make sure that APP_ABI and APP_PLATFORM is defined in your Application.mk and your APP_PLATFORM should be higher than android-5... check: gl.h & glext.h not found
for example, in Application.mk define:
APP_ABI := armeabi #armeabi-v7a
APP_STL := stlport_static
APP_PLATFORM := android-8

In my case it was missing the file default.properties with such content:
target=android-5
Put this file into the root project directory. It may help.

You need to use a higher SDK. Level 5 is the minimum to build OpenGL ES 2 code.