How to open /dev/diag with super user permissions?

问题

I am developing an application for One Plus 6. This applications is using a shared library(lib.so) to perform some task. For the task it needs to open dev/diag first and then send some commands through code. Below is the code to open dev/diag:

fd = open("/dev/diag", O_RDWR|O_LARGEFILE|O_NONBLOCK);
if (fd < 0) {
    perror("open diag dev");
    return -8002;
}

I am able to build a executable with include $(BUILD_EXECUTABLE) written in Android.mk and with ndk-build command. I am able to run open the dev/diag with placing the executable in /system folder of android.

The thing that failing is to do the same with an android application. I have tried following:

Rooted the One Plus 6
Call Runtime.getRuntime().exec("su") in MainActivity::onCreate.
Give <uses-permission android:name="android.permission.ACCESS_SUPERUSER"/> in manifest.
Then call the required jni function.

Please suggest how can I enable su access on a function which is opening dev/diag for me?

I have also tried to do the same with running executable commands using ndk-build executable in /system e.g.

For READ:

    // Run the command
    Process process = Runtime.getRuntime().exec("su -c /system/lib get key");

    BufferedReader bufferedReader = new BufferedReader(
            new InputStreamReader(process.getInputStream()));

    // Grab the results
    StringBuilder log = new StringBuilder();
    String line;
    while ((line = bufferedReader.readLine()) != null) {
        log.append(line).append("\n");
    }

    String allLogs = log.toString();

For WRITE:

    Process suProcess = Runtime.getRuntime().exec("su");
    DataOutputStream os = new DataOutputStream(suProcess.getOutputStream());

    os.writeBytes("/system/lib set key " + value);
    // Close the terminal
    os.writeBytes("exit\n");

    os.flush();

and it is working fine. Still I am wondering how to do the same with shared library. Any help?

来源：https://stackoverflow.com/questions/55232995/how-to-open-dev-diag-with-super-user-permissions

标签

android

android-ndk

ndk-build