CODEWITHSUNDEEP
androidroot
iamnp
iamnp

Reputation: 508

android open file in root directory

Is there any way to write and read text files on rooted Android phone in root directories (ex. /data/)?

InputStream instream = openFileInput("/data/somefile");

doesn't work

Upvotes: 0

Views: 2969

Answers (2)

user4400167
user4400167

Reputation:

You can only access to /data folder is you're root user.

Call to SU binary and write bytes (these bytes are the command) over SU binary via OutputStream and read command output via InputStream, it's easy:
Call to cat command to read files.

try {
    Process process = Runtime.getRuntime().exec("su");
    InputStream in = process.getInputStream();
    OutputStream out = process.getOutputStream();
    String cmd = "cat /data/someFile";
    out.write(cmd.getBytes());
    out.flush();
    out.close();
    byte[] buffer = new byte[1024 * 12]; //Able to read up to 12 KB (12288 bytes)
    int length = in.read(buffer);
    String content = new String(buffer, 0, length);
    //Wait until reading finishes
    process.waitFor();
    //Do your stuff here with "content" string
    //The "content" String has the content of /data/someFile
} catch (IOException e) {
    Log.e(TAG, "IOException, " + e.getMessage());
} catch (InterruptedException e) {
    Log.e(TAG, "InterruptedException, " + e.getMessage());
}

Don't use OutputStream for write files, OutputStream is used for execute commands inside SU binary, and InputStream is used for get output of command.

Upvotes: 3

Jug6ernaut
Jug6ernaut

Reputation: 8325

To be able to do what you are asking you must do all of the operations via the SU binary.

like...

try {
      Process process = Runtime.getRuntime().exec("su");
      process.waitFor();
    } catch (IOException e) {
      e.printStackTrace();
    } catch (InterruptedException e) {
      e.printStackTrace();
    }

Reading will be easier then writing, for writing easiest would be to write the file to some place where u have access using standard java api's and then move it to the new location using the su binary.

Upvotes: 1

Related Questions