Hidl 学习总结 3

1、需求分析

2、接口实现

3、代码编写

4、调试过程中遇到的坑

1、需求分析

项目中需要监听gpio改变的事件，驱动测上报Input事件，需要在framework添加逻辑通知给app，为了解耦，考虑能够更好的移植，app单独监听该input事件。

2、接口实现

1、APP注册 callback给 Hidl Service
2、Hidl Service监听相关文件节点后回调 APP Callback

参考之前Hidl 学习总结1

3、代码编写

APP代码编写

package com.example.test2;import androidx.appcompat.app.AppCompatActivity;
import vendor.hardware.test.V1_0.ITest;
import vendor.hardware.test.V1_0.ITestCmdCallback;import android.hidl.base.V1_0.DebugInfo;
import android.os.Bundle;
import android.os.IHwBinder;
import android.os.NativeHandle;
import android.os.RemoteException;import java.util.ArrayList;public class MainActivity extends AppCompatActivity {private TestCmdCallback mCallback;ITest mTest;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);try {mTest = ITest.getService(false);mCallback = new TestCmdCallback();android.util.Log.i("zmao","get services success **** !");int ret = mTest.registCallback(mCallback);android.util.Log.i("zmao","register callback ret = " + ret);} catch(Exception e) {android.util.Log.i("zmao","exception " + e);}}@Overrideprotected void onResume() {super.onResume();}public class TestCmdCallback extends ITestCmdCallback.Stub {public void callback(String rsp) {android.util.Log.i("zmao","TestCmdCallback rsp = " + rsp);}}
}

Hidl 服务代码编写

void EventObserver::startObserver(void *observer){int fd; /*需要轮询的fds*/fd_set readfds;/*需要轮询的fds数量*/int maxfds;struct input_event event;struct timeval timeout;timeout.tv_sec = 10;timeout.tv_usec = 0;EventCallback* mObserver = (EventCallback*)observer;fd = open("/dev/input/event3", O_RDWR | O_NONBLOCK);if(fd < 0){ALOGE("startObserver error");} else {ALOGE("startObserver success");}//清零FD_ZERO(&readfds);/*将标准输入的文件描述符添加到集合中, 如果是多个添加多个文件描述符*/FD_SET(fd, &readfds);maxfds = fd + 1; //最大文件描述符fd + 1while(1){int ret = select(maxfds, &readfds, NULL, NULL, NULL);if(ret > 0){/*只有发生过的fd才会在文件readfds中*/if(FD_ISSET(fd, &readfds)){while(read(fd, &event, sizeof(event)) == sizeof(event)){ALOGE("get envent: type = 0x%x, Code = 0x%x value = 0x%x \n",event.type, event.code, event.value);//ALOGE("get envent: type = %s, Code = %s value = 0x%x \n",eventTypeToString(event.type), eventCodeToString(event.code), event.value);if(mObserver->mCallback != nullptr){mObserver->mCallback->callback("gpio is change");ALOGE("mCallback is called");}}}//将文件描述符重置FD_ZERO(&readfds);FD_SET(fd, &readfds); } else if (ret == 0){if(FD_ISSET(fd, &readfds)){ALOGE("select time out \n");}} else {ALOGE("poll err \n");}}
}

关闭Selinux 调试Log 如下

   Line 70180: 04-10 18:38:32.399 443 443 E SELinux : avc: denied { find } for interface=vendor.hardware.test::ITest sid=u:r:untrusted_app_32:s0:c238,c256,c512,c768 pid=9203 scontext=u:r:untrusted_app_32:s0:c238,c256,c512,c768 tcontext=u:object_r:default_android_hwservice:s0 tclass=hwservice_manager permissive=1
   Line 70181: 04-10 18:38:32.399 443 443 I auditd : avc: denied { find } for interface=vendor.hardware.test::ITest sid=u:r:untrusted_app_32:s0:c238,c256,c512,c768 pid=9203 scontext=u:r:untrusted_app_32:s0:c238,c256,c512,c768 tcontext=u:object_r:default_android_hwservice:s0 tclass=hwservice_manager permissive=1
   Line 70183: 04-10 18:38:32.400 9203 9203 I android_os_HwBinder: HwBinder: Starting thread pool for getting: vendor.hardware.test@1.0::ITest/default
   Line 70185: 04-10 18:38:32.401 9203 9203 I zmao : get services success **** !
   Line 70186: 04-10 18:38:32.401 16251 16251 E vendor.hardware.test@1.0-service: zmao registCallback success!
   Line 70186: 04-10 18:38:32.401 16251 16251 E vendor.hardware.test@1.0-service: zmao registCallback success!
   Line 70187: 04-10 18:38:32.401 16251 16251 E vendor.hardware.test@1.0-service: registCallback sucess
   Line 70188: 04-10 18:38:32.402 9203 9203 I zmao : register callback ret = 0
   Line 115875: 04-10 18:39:00.883 16251 16252 E vendor.hardware.test@1.0-service: get envent: type = 0x1, Code = 0x1 value = 0x1
   Line 115879: 04-10 18:39:00.884 16251 16252 E vendor.hardware.test@1.0-service: mCallback is called
   Line 115880: 04-10 18:39:00.884 16251 16252 E vendor.hardware.test@1.0-service: get envent: type = 0x1, Code = 0x1 value = 0x0
   Line 115881: 04-10 18:39:00.884 16251 16252 E vendor.hardware.test@1.0-service: mCallback is called
   Line 115882: 04-10 18:39:00.884 16251 16252 E vendor.hardware.test@1.0-service: get envent: type = 0x0, Code = 0x0 value = 0x0
   Line 115883: 04-10 18:39:00.885 16251 16252 E vendor.hardware.test@1.0-service: mCallback is called
   Line 115898: 04-10 18:39:00.886 9203 19019 I zmao : TestCmdCallback rspgpio is change
   Line 115905: 04-10 18:39:00.887 9203 19019 I zmao : TestCmdCallback rspgpio is change
   Line 115906: 04-10 18:39:00.887 9203 19019 I zmao : TestCmdCallback rspgpio is change