Sudo In Java Process

Question

I am working on a Terminal application that allows people to execute bash commands from a Swing GUI. I run into the following problem when trying to execute a command with sudo:

sudo cd /Users/{myname}/Desktop

sudo: no tty present and no askpass program specified

Here's my code:

package me.nrubin29.jterminal;

import javax.swing.*;
import javax.swing.filechooser.FileSystemView;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.*;
import java.util.ArrayList;

public class JTerminal extends JFrame {

    private JTextPane area = new JTextPane();
    private JTextField input = new JTextField("Input");

    private SimpleAttributeSet inputSAS = new SimpleAttributeSet(), output = new SimpleAttributeSet(), error = new SimpleAttributeSet();

    private File workingFolder = FileSystemView.getFileSystemView().getDefaultDirectory();

    public JTerminal() throws IOException {
        super("JTerminal");

        getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));

        StyleConstants.setForeground(inputSAS, Color.GREEN);
        StyleConstants.setBackground(inputSAS, Color.BLACK);

        StyleConstants.setForeground(output, Color.WHITE);
        StyleConstants.setBackground(output, Color.BLACK);

        StyleConstants.setForeground(error, Color.RED);
        StyleConstants.setBackground(error, Color.BLACK);

        input.addKeyListener(new KeyListener() {
            public void keyPressed(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    try {
                        String command = input.getText();
                        if (command.equals("")) return;

                        setTitle("JTerminal (" + command.split(" ")[0] + ")");

                        input.setText("");
                        input.setEditable(false);

                        write(inputSAS, command);

                        Process bash = new ProcessBuilder("bash").directory(workingFolder).start();

                        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(bash.getOutputStream());
                        outputStreamWriter.write(command);
                        outputStreamWriter.close();

                        int code = bash.waitFor();

                        writeStream(bash.getErrorStream(), error);
                        writeStream(bash.getInputStream(), output);

                        input.setEditable(true);
                        setTitle("JTerminal");

                        if (code == 0 && command.split(" ").length > 1) workingFolder = new File(command.split(" ")[1]);

                    } catch (Exception ex) { error(ex); }
                }
            }

            public void keyTyped(KeyEvent e) {}
            public void keyReleased(KeyEvent e) {}
        });

        area.setBackground(Color.black);
        area.setCaretColor(Color.green);
        area.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 14));
        area.setEditable(false);

        JScrollPane pane = new JScrollPane(area);
        pane.setBorder(BorderFactory.createLineBorder(Color.GREEN));
        pane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
        pane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        pane.setPreferredSize(new Dimension(640, 460));

        input.setBackground(Color.black);
        input.setForeground(Color.green);
        input.setCaretColor(Color.green);
        input.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 14));
        input.setBorder(BorderFactory.createLineBorder(Color.GREEN));

        add(pane);
        add(input);

        Dimension DIM = new Dimension(640, 480);
        setPreferredSize(DIM);
        setSize(DIM);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setResizable(true);
        pack();
        setVisible(true);

        input.requestFocus();
    }

    public static void main(String[] args) throws IOException {
        new JTerminal();
    }

    private void write(SimpleAttributeSet attributeSet, String... lines) {
        try {
            if (lines.length == 0) return;
            for (String line : lines) {
                area.getStyledDocument().insertString(area.getStyledDocument().getLength(), line + "\n", attributeSet);
            }
            area.getStyledDocument().insertString(area.getStyledDocument().getLength(), "\n", attributeSet);
        }
        catch (Exception e) { error(e); }
    }

    private void error(Exception e) {
        write(error, "An error has occured: " + e.getLocalizedMessage());
        e.printStackTrace(); //TODO: temp.
    }

    private void writeStream(InputStream s, SimpleAttributeSet color) {
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(s));

            ArrayList<String> strs = new ArrayList<String>();

            while(reader.ready()) strs.add(reader.readLine());

            if (strs.size() > 0) write(color, strs.toArray(new String[strs.size()]));
        }
        catch (Exception e) { error(e); }
    }
}

Answer 1

I writed simple api: package me.barwnikk.library.linuxcommandroot;

import java.awt.BorderLayout;
import java.io.IOException;
import java.io.InputStream;

import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;

public class LinuxCommand {
    static InputStream is;
    static byte[] buff = new byte[8192];
    static int n;
    public static String getPasswdForRoot() throws IOException {
        Process p = Runtime.getRuntime().exec(new String[]{"sh","-c","sudo -S id"});
        is = p.getErrorStream();
        n = is.read(buff, 0, 8192);
        String text = new String(buff,0,n);
        if(text.contains("root"))return null; //not set password
        JPanel panel = new JPanel(new BorderLayout());
        JLabel lab = new JLabel(text);
        panel.add(lab,BorderLayout.NORTH);
        JPasswordField password = new JPasswordField();
        panel.add(password,BorderLayout.SOUTH);
        JOptionPane.showMessageDialog(null, panel);
        byte[] passwd = (new String(password.getPassword())+"\r\n").getBytes();
        p.getOutputStream().write(passwd);
        p.getOutputStream().flush();
        n = is.read(buff, 0, 8192);
        if(n==-1) return new String(password.getPassword());
        text = new String(buff,0,n);
        while(true) {
            lab.setText(text);
            JOptionPane.showMessageDialog(null, panel);
            p = Runtime.getRuntime().exec(new String[]{"sh","-c","sudo -S id"});
            is = p.getErrorStream();
            n = is.read(buff, 0, 8192);
            passwd = (new String(password.getPassword())+"\n").getBytes();
            p.getOutputStream().write(passwd);
            p.getOutputStream().flush();
            n = is.read(buff, 0, 8192);
            if(n==-1) return new String(password.getPassword());
            text = new String(buff,0,n);
        }
    }
    public static Process runFromRoot(String command, String password) throws IOException {
        byte[] passwd = (password+"\n").getBytes(); //for OutputStream better is byte[]
        Process p = Runtime.getRuntime().exec(new String[]{"sh","-c","sudo -S "+command});
        p.getOutputStream().write(passwd);
        p.getOutputStream().flush();
        return p;
    }
}

It's a mini api to get root password (user must write correct). Sample of usage:

public static void main(String[] args) throws IOException, InterruptedException {
    String password = LinuxCommand.getPasswdForRoot();
    System.out.println("stdout of 'id':");
    Process p = LinuxCommand.runFromRoot("id",password);
    System.out.print(streamToString(p.getInputStream()));
    System.out.println("stdout of 'fdisk -l':");
    p = LinuxCommand.runFromRoot("fdisk -l",password);
    System.out.print(streamToString(p.getInputStream()));
}

Method streamToString:

public static String streamToString(InputStream stream) {
    String read = "";
    try {
        while((n=stream.read(buff, 0, 8192))!=-1) {
            read+=new String(buff,0,n);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return read;
}

Sample return in my test (in polish):

stdout of 'id':
uid=0(root) gid=0(root) grupy=0(root)
stdout of 'fdisk -l':

Disk /dev/sda: 640.1 GB, 640135028736 bytes
głowic: 255, sektorów/ścieżkę: 63, cylindrów: 77825, w sumie sektorów: 1250263728
Jednostka = sektorów, czyli 1 * 512 = 512 bajtów
Rozmiar sektora (logiczny/fizyczny) w bajtach: 512 / 4096
Rozmiar we/wy (minimalny/optymalny) w bajtach: 4096 / 4096
Identyfikator dysku: 0xc56b9eef

Urządzenie Rozruch   Początek      Koniec   Bloków   ID  System
/dev/sda1            2048    37064703    18531328   27  Hidden NTFS WinRE
/dev/sda2   *    37064704    37269503      102400    7  HPFS/NTFS/exFAT
/dev/sda3        37269504   456711884   209721190+   7  HPFS/NTFS/exFAT
/dev/sda4       456711946  1250258624   396773339+   f  W95 Rozsz. (LBA)
Partycja 4 nie zaczyna się na granicy bloku fizycznego.
/dev/sda5       456711948   810350729   176819391    7  HPFS/NTFS/exFAT
Partycja 5 nie zaczyna się na granicy bloku fizycznego.
/dev/sda6       810350793   862802954    26226081    7  HPFS/NTFS/exFAT
Partycja 6 nie zaczyna się na granicy bloku fizycznego.
/dev/sda7       862803018  1020078408    78637695+  83  Linux
Partycja 7 nie zaczyna się na granicy bloku fizycznego.
/dev/sda8      1020079368  1229791814   104856223+   7  HPFS/NTFS/exFAT
/dev/sda9      1229791878  1250258624    10233373+   7  HPFS/NTFS/exFAT
Partycja 9 nie zaczyna się na granicy bloku fizycznego.

This api create and write to Process password. So, you can run command with permission sudo.

P.S. I test your program. And there are one bug: you must add terminate - I must destroy and run. Write in console "ping google.com" - program doesn't response. You must create new thread.

Answer 2

Since this is a Swing application, there is indeed no terminal (tty) present, even if you're using JTerminal (which looks like a terminal but doesn't actually take over your tty). You will instead need to set up an askpass program (as the error message says), which will prompt the user for a password.

To set up an askpass program, you can either set the SUDO_ASKPASS environment variable, or else set it up in sudoers using Path askpass .... See the manual page for more details.

Alternatively, if your password isn't very secret and you don't mind seeing it echoed on screen, run sudo with the -S option.