Android 7.1添加一个 系统底层服务

------CustomCamera.cpp

#include "CustomCamera.h"
#include 
#include 
namespace android {
    static struct sigaction oldact;
	static pthread_key_t sigbuskey;
	// 把自己注册到系统中
	int CustomCamera::instantiate() {
	ALOGW("CustomCamera instantiate");
    int r = defaultServiceManager()->addService(
				String16("custom_camera"), new CustomCamera());//服务添加到 Binder Driver 中服务名为 custom_camera
		ALOGW("CustomCamera r = %d/n", r);
		return r;
	}
	// 构造函数
	CustomCamera::CustomCamera()
	{
		ALOGW("CustomCamera created");
		pthread_key_create(&sigbuskey, NULL);
	}
	// 析构函数
	CustomCamera::~CustomCamera()
	{
		pthread_key_delete(sigbuskey);
		ALOGW("CustomCamera  destroyed");
	}
	// 这个是服务具体的本地实现，功能实现都应该放在这里面，通过传入执行代码（ code ） // 的不同来执行不同的操作，上层隐射为不同的 api 。
	status_t CustomCamera::onTransact(
			uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags){
		switch(code) {
			case 0: {// 根据 code 的不同执行不同的操作
					pid_t pid = data.readInt32();
					int num = data.readInt32();
					num = num + 1000;
					reply->writeInt32(num);
					return NO_ERROR;
				}
				break;
			default:
				return BBinder::onTransact(code, data, reply, flags);
		}
	}};
//namespace

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "../libcustomcamera/CustomCamera.h"
using namespace android;
int main(int arGC, char** argv)
{
	sp proc(ProcessState::self());
	sp sm = defaultServiceManager();//取得 ServiceManager
	ALOGW("CustomCamera ServiceManager: %p", sm.get());
	CustomCamera::instantiate();//把自己添加到 ServiceManager中
	ProcessState::self()->startThreadPool();//启动缓冲池
	IPCThreadState::self()->joinThreadPool();//这里是把服务添加到 Binder闭合循环进程中
}

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := ../libcustomcamera/CustomCamera.cpp \
        customcamera.cpp \
LOCAL_CFLAGS := -D__STDC_CONSTANT_MacROS -Wl,-Map=test.map -g -Wno-unused-parameter -Wno-unused-variable
LOCAL_CONLYFLAGS := -std=c11
LOCAL_SHARED_LIBRARIES := libcutils \
                libsysutils \
        libutils \
        libbinder \
        libui \
        libgui \
        liblog
LOCAL_LDLIBS := -llog
LOCAL_MODULE := custom_camera
LOCAL_MODULE_TAGS := optional
LOCAL_C_INCLUDES += $(LOCAL_PATH)
#编译为可执行文件
include $(BUILD_EXECUTABLE)

~:source build/envsetup.sh 
~:lunch XX

PRODUCT_COPY_FILES += \
    /custom_camera:system/bin/custom_camera
例如如下面的代码就是拷贝custom_camera 到system/文件夹下
PRODUCT_COPY_FILES += \
    out/target/product/msm8953_64/system/bin/custom_camera:system/bin/custom_camera

    #修改权限 增加的代码
     chmod 0777 /system/bin/custom_camera
    #系统代码不必关注
     chmod 0660 /sys/devices/soc.0/78b7000.i2c/i2c-3/3-0020/input/input0/secure_touch_enable

#启动我们的服务,开机启动
service custom_camera /system/bin/custom_camera
    class core
    user root
    group root
    oneshot

//在应用程序中测试服务的代码：
    private void test(){
                try{
                        IBinder binder = ServiceManager.getService("custom_camera");// 取得服务
                        Parcel data = Parcel.obtain();
                        Parcel reply = Parcel.obtain();
                        if(binder == null)
                        Log.d(TAG,"failed to get custom_camera");
                        data.writeInt(Process.myPid());// 固定操作
                        data.writeInt(100);// 传入参数
                        binder.transact(0, data, reply, 0);// 执行远程调用
                        Log.d(TAG," custom_camer aresult="+reply.readInt());// 验证结果
                }catch(Exception e){
                         Log.d(TAG,e.toString());
                }

#主要是修改 neverallow 内容
#-mcu_service
system/sepolicy/domain.te
#/system/bin/custom_camera  u:object_r:custom_camera_service_exec:s0
system/sepolicy/file_contexts
# custom_camera               u:custom_camera_service_exec:s0
system/sepolicy/custom_camera.te # 拷贝别的te修改名字就行
# custom_camera               u:object_r:custom_camera_service_service:s0
system/sepolicy/service_contexts #  与 file_contexts 相对应