andorid4.4 USB默认权限修改

川长思鸟来 2022-05-29 04:57 368阅读 0赞

最近在Android4.4上调试一个Usb指纹模块，记录下系统默认权限修改.

Usb Device具体操作流程这里就不写了，网上有很多例子，

正常流程:首先是UsbManager申请权限,这时会出现一个提示框,如下图:

![20180317133649530][]

勾选默认情况下用于该设备后，点击确定。这时会在/data/system/users/0/目录下生成一个xml文件

usb\_device\_manager.xml

内容如下:

![20180317133817754][]

会保存package应用程序的包名，设备vid,pid,以及相关协议.

知道这些后，开始跟踪代码找相关函数.

UsbManager的requestPermission最后是调用Usbservice的requestDevicePermission函数然后到UsbSettingsManager里的requestPermission函数，这个最后的requestPermissionDialog就是调用Systemui的UsbPermissionActivity弹出的第一个申请权限的对话框.

由于我要在裁剪过的系统里进行修改，这里面已经删除了SystemUi所以，只能在requestPermissionDialog之前进行处理.

查看Systemui中UsbPermissionActivity申请权限点击后主要作了两件事

intent = new Intent(UsbManager.ACTION_USB_DEVICE_ATTACHED);
                        intent.putExtra(UsbManager.EXTRA_DEVICE, mDevice);
    
                        // grant permission for the device
                        service.grantDevicePermission(mDevice, uid);
                        // set or clear default setting
                        if (alwaysUse) {
                            service.setDevicePackage(
                                    mDevice, mResolveInfo.activityInfo.packageName, userId);
                        } else {
                            service.setDevicePackage(mDevice, null, userId);
                        }

首先调用UsbService的grantDevicePermission，然后调用了setDevicePackage

对应查看UsbSettingsManager的两个函数，然后对UsbSettingsManager进行了如下修改

修改构造函数

public UsbSettingsManager(Context context, UserHandle user) {
            if (DEBUG) Slog.v(TAG, "Creating settings for " + user);
    
            try {
                mUserContext = context.createPackageContextAsUser("android", 0, user);
            } catch (NameNotFoundException e) {
                throw new RuntimeException("Missing android package");
            }
    
            mContext = context;
            mPackageManager = mUserContext.getPackageManager();
    
            mUser = user;
            mSettingsFile = new AtomicFile(new File(
                    Environment.getUserSystemDirectory(user.getIdentifier()),
                    "usb_device_manager.xml"));
    
            synchronized (mLock) {
                if (UserHandle.OWNER.equals(user)) {
                    upgradeSingleUserLocked();
                }
                readSettingsLocked();
            }
    
    		//add by hclydao
            DeviceFilter myfilter = new DeviceFilter(pid, vid,0, 0, 0);
    		String pak = mDevicePreferenceMap.get(myfilter);
    		if(pak == null) {
    			mDevicePreferenceMap.put(myfilter, mypakname);//mypakname是应用程序包名 String类型
    			writeSettingsLocked();
    		}
                //add end
            mPackageMonitor.register(mUserContext, null, true);
        }

其中pid,vid在之前测试的usb\_device\_manager.xml中可以找到，一般产家都会直接提供,这里的操作是直接启动后，直接将相关信息写到usb\_device\_manager.xml文件中,这里相当于调用了一次setDevicePackage.

然后修改requestPermission函数

public void requestPermission(UsbDevice device, String packageName, PendingIntent pi) { 
          Intent intent = new Intent();
            // respond immediately if permission has already been granted
          if (hasPermission(device)) {
                intent.putExtra(UsbManager.EXTRA_DEVICE, device);
                intent.putExtra(UsbManager.EXTRA_PERMISSION_GRANTED, true);
                try {
                    pi.send(mUserContext, 0, intent);
                } catch (PendingIntent.CanceledException e) {
                    if (DEBUG) Slog.d(TAG, "requestPermission PendingIntent was cancelled");
                }
                return;
            }
    		//hclydao
    		if(packageName.equals(mypakname)) {
    			int uid = Binder.getCallingUid();
                SparseBooleanArray uidList = new SparseBooleanArray(1);
                mDevicePermissionMap.put(device.getDeviceName(), uidList);
    			uidList.put(uid, true);
    
                intent.putExtra(UsbManager.EXTRA_DEVICE, device);
                intent.putExtra(UsbManager.EXTRA_PERMISSION_GRANTED, true);
                try {
                    pi.send(mUserContext, 0, intent);
                } catch (PendingIntent.CanceledException e) {
                    if (DEBUG) Slog.d(TAG, "requestPermission PendingIntent was cancelled");
                }
                return;
    		}
    
            // start UsbPermissionActivity so user can choose an activity
            intent.putExtra(UsbManager.EXTRA_DEVICE, device);
            requestPermissionDialog(intent, packageName, pi);
        }

如果当前申请权限的包名与默认设置的包名一致就直接给权限返回.直接相当于调用了一次grantDevicePermission

修改完成后，编译系统更新，解决问题.

======================================  
作者：hclydao  
[http://blog.csdn.net/hclydao][http_blog.csdn.net_hclydao]  
版权没有，但是转载请保留此段声明

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[20180317133649530]: /images/20220529/f6deb1c0550a4128ae7caca19970b2a6.png
[20180317133817754]: /images/20220529/4d08aea9a4844225afbb810b688ef109.png
[http_blog.csdn.net_hclydao]: http://blog.csdn.net/hclydao