如何在App层添加System Service

最新推荐文章于 2024-01-18 10:51:34 发布

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最新推荐文章于 2024-01-18 10:51:34 发布

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分类专栏： Android Framework 文章标签： Framework Android

本文链接：https://blog.youkuaiyun.com/ffmpeg4976/article/details/50753992

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本文介绍如何在Android系统中通过ServiceManager注册自定义服务，并提供了一个具体的例子，包括创建AIDL接口、实现服务类以及在ServiceManager中添加服务的过程。

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基本原理就是调用ServiceManager中的接口

    /**
     * Place a new @a service called @a name into the service
     * manager.
     *
     * @param name the name of the new service
     * @param service the service object
     */
    public static void addService(String name, IBinder service) {
        try {
            getIServiceManager().addService(name, service, false);
        } catch (RemoteException e) {
            Log.e(TAG, "error in addService", e);
        }

}

首先，需要写一个aidl，这个接口能生成符合System Service的Stub和Proxy，他们都继承于IBinder

/** @hide */

interface IMyExample {

int checkPermission(String permissionName, int uid);
}

这东西被aidl的解释语言搞成了IMyExample.java(./target/common/obj/JAVA_LIBRARIES/framework_intermediates/src/core/java/com/xxxx/IMyExample .java)

* This file is auto-generated. DO NOT MODIFY.

*/
package com.mobvoi;
/** @hide */

public interface IMyExample extends android.os.IInterface

{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements com.mobvoi.IMobvoiPermissionManager
{

public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}

public static com.mobvoi.IMyExample asInterface(android.os.IBinder obj)

{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);

if (((iin!=null)&&(iin instanceof com.mobvoi.IMyExample ))) {

return ((com.mobvoi.IMyExample )iin);

}

return new com.mobvoi.IMyExample.Stub.Proxy(obj);

}
@Override public android.os.IBinder asBinder()
{
return this;
}
@Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
{
switch (code)
{
case INTERFACE_TRANSACTION:
{
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_checkPermission:
{
data.enforceInterface(DESCRIPTOR);
java.lang.String _arg0;
_arg0 = data.readString();
int _arg1;
_arg1 = data.readInt();
int _result = this.checkPermission(_arg0, _arg1);
reply.writeNoException();
reply.writeInt(_result);
return true;
}
}
return super.onTransact(code, data, reply, flags);
}

private static class Proxy implements com.mobvoi.IMyExample

{
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote)
{
mRemote = remote;
}
@Override public android.os.IBinder asBinder()
{
return mRemote;
}
public java.lang.String getInterfaceDescriptor()
{
return DESCRIPTOR;
}
/**
* [Permission Controller Functions]
*/
@Override public int checkPermission(java.lang.String permissionName, int uid) throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
int _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
_data.writeString(permissionName);
_data.writeInt(uid);
mRemote.transact(Stub.TRANSACTION_checkPermission, _data, _reply, 0);
_reply.readException();
_result = _reply.readInt();
}
finally {
_reply.recycle();
_data.recycle();
}
return _result;
}
}
static final int TRANSACTION_checkPermission = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
}
/**
* [Permission Controller Functions]
*/
public int checkPermission(java.lang.String permissionName, int uid) throws android.os.RemoteException;
}

写一个类去实现这个SystemService

public class MyExample extends IMyExample .Stub {

public MyExample (Context context) {

    }

    @Override
    public int checkPermission(String permissionName, int uid) throws RemoteException {

       }

}

在某个地方添加到ServiceManager里面

ServiceManager.addService(“Service Name”, MyExample );

另外，还要在SELinux中注册一下，这种机制也是为了避免App随便给系统添加服务

sepolicy/service/ service_contexts

Mmsstats u:object_r:system_app_service:s0

MyExample u:object_r:system_app_service:s0

sepolicy/proxy/ service_contexts