executing su command from android activity

Question

i am trying to execute the following method:

public void runAsRoot(String[] cmds) throws Exception {
        Process p = Runtime.getRuntime().exec("su");
        DataOutputStream os = new DataOutputStream(p.getOutputStream());
        InputStream is = p.getInputStream();
        for (String tmpCmd : cmds) {
            os.writeBytes(tmpCmd+"\n");
            int readed = 0;
            byte[] buff = new byte[4096];

            // if cmd requires an output
            // due to the blocking behaviour of read(...)
            boolean cmdRequiresAnOutput = true;
            if (cmdRequiresAnOutput) {
                while( is.available() <= 0) {
                    try { Thread.sleep(200); } catch(Exception ex) {}
                }

                while( is.available() > 0) {
                    readed = is.read(buff);
                    if ( readed <= 0 ) break;
                    String seg = new String(buff,0,readed);
                    Log.i("#>", seg);
                }
            }
        }        
        os.writeBytes("exit\n");
        os.flush();
    }

i invoked this method using the following input:

String[] cmds = {"/system/bin/sendevent /dev/input/event0 1 107 0 \n", "sleep 1", "/system/bin/sendevent /dev/input/event0 1 107 1 \n"};
                try {
                    runAsRoot(cmds);
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

but in logcat i receiving following errors:

07-06 15:19:27.007: E/su(6547): sudb - Opening database
07-06 15:19:27.007: E/(6547): Couldn't open database: unable to open database file
07-06 15:19:27.017: E/su(6547): sudb - Could not open database, prompt user
07-06 15:19:47.082: E/su(6547): select failed with 2: No such file or directory
07-06 15:19:47.082: W/su(6547): request rejected (10060->0 /system/bin/sh)

Any idea whats the issue?

Answer 1

It looks like there's an issue with the su binary, not with your app. Check if you can succesfully run a rooted shell from 'adb shell'. If 'adb shell' gives you a rooted shell from start, run 'su 1000' to lose root privileges and then run 'su' to try getting into a rooted shell again. If that fails, su isn't working.

Oh and on a related note: Be sure to run su in another Thread, maybe via a Handler or AsyncTask, so it won't block your UI thread.