Question

I’m trying to run an external executable, but apparently it needs elevation. The code is this, modified from an example of using ProcessBuilder (hence the array with one argument) :

    public static void main(String[] args) throws IOException {
        File demo = new File("C:\\xyzwsdemo");
        if(!demo.exists()) demo.mkdirs();
        String[] command = {"C:\\fakepath\\bsdiff4.3-win32\\bspatch.exe"};
        ProcessBuilder pb = new ProcessBuilder( command );
        Process process = pb.start();
        InputStream is = process.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        String line;
        System.out.printf("Output of running %s is:\n", Arrays.toString(command));
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
        try {
            int exitValue = process.waitFor();
            System.out.println("\n\nExit Value is " + exitValue);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

It returns this when run:

Exception in thread "main" java.io.IOException: Cannot run program "C:\Users\Gilliane\Downloads\bsdiff4.3-win32\bspatch.exe": CreateProcess error=740, The requested operation requires elevation

I’ve done some browsing around, and know that in C#, you can request elevation by doing this, (as seen from this thread):

startInfo.Verb = "runas";

However, I don’t see anything like that with ProcessBuilder. Another method would be to have the Elevation Tools installed on the target system, and to invoke the “elevate” prompt with ProcessBuilder. However, I would rather not force the people who use my program to also install those elevation tools.

Is there another way?

Answer 1

This can’t be done with ProcessBuilder, you will need to call Windows API.

I’ve used JNA to achieve this with code similar to the following:

Shell32X.java:

import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.WString;
import com.sun.jna.platform.win32.Shell32;
import com.sun.jna.platform.win32.WinDef.HINSTANCE;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinNT.HANDLE;
import com.sun.jna.platform.win32.WinReg.HKEY;
import com.sun.jna.win32.W32APIOptions;

public interface Shell32X extends Shell32
{
    Shell32X INSTANCE = (Shell32X)Native.loadLibrary("shell32", Shell32X.class, W32APIOptions.UNICODE_OPTIONS);

    int SW_HIDE = 0;
    int SW_MAXIMIZE = 3;
    int SW_MINIMIZE = 6;
    int SW_RESTORE = 9;
    int SW_SHOW = 5;
    int SW_SHOWDEFAULT = 10;
    int SW_SHOWMAXIMIZED = 3;
    int SW_SHOWMINIMIZED = 2;
    int SW_SHOWMINNOACTIVE = 7;
    int SW_SHOWNA = 8;
    int SW_SHOWNOACTIVATE = 4;
    int SW_SHOWNORMAL = 1;

    /** File not found. */
    int SE_ERR_FNF = 2;

    /** Path not found. */
    int SE_ERR_PNF = 3;

    /** Access denied. */
    int SE_ERR_ACCESSDENIED = 5;

    /** Out of memory. */
    int SE_ERR_OOM = 8;

    /** DLL not found. */
    int SE_ERR_DLLNOTFOUND = 32;

    /** Cannot share an open file. */
    int SE_ERR_SHARE = 26;



    int SEE_MASK_NOCLOSEPROCESS = 0x00000040;


    int ShellExecute(int i, String lpVerb, String lpFile, String lpParameters, String lpDirectory, int nShow);
    boolean ShellExecuteEx(SHELLEXECUTEINFO lpExecInfo);



    public static class SHELLEXECUTEINFO extends Structure
    {
        /*
  DWORD     cbSize;
  ULONG     fMask;
  HWND      hwnd;
  LPCTSTR   lpVerb;
  LPCTSTR   lpFile;
  LPCTSTR   lpParameters;
  LPCTSTR   lpDirectory;
  int       nShow;
  HINSTANCE hInstApp;
  LPVOID    lpIDList;
  LPCTSTR   lpClass;
  HKEY      hkeyClass;
  DWORD     dwHotKey;
  union {
    HANDLE hIcon;
    HANDLE hMonitor;
  } DUMMYUNIONNAME;
  HANDLE    hProcess;
         */

        public int cbSize = size();
        public int fMask;
        public HWND hwnd;
        public WString lpVerb;
        public WString lpFile;
        public WString lpParameters;
        public WString lpDirectory;
        public int nShow;
        public HINSTANCE hInstApp;
        public Pointer lpIDList;
        public WString lpClass;
        public HKEY hKeyClass;
        public int dwHotKey;

        /*
         * Actually:
         * union {
         *  HANDLE hIcon;
         *  HANDLE hMonitor;
         * } DUMMYUNIONNAME;
         */
        public HANDLE hMonitor;
        public HANDLE hProcess;

        protected List getFieldOrder() {
            return Arrays.asList(new String[] {
                "cbSize", "fMask", "hwnd", "lpVerb", "lpFile", "lpParameters",
                "lpDirectory", "nShow", "hInstApp", "lpIDList", "lpClass",
                "hKeyClass", "dwHotKey", "hMonitor", "hProcess",
            });
        }
    }

}

Elevator.java:

package test;

import test.Shell32X.SHELLEXECUTEINFO;

import com.sun.jna.WString;
import com.sun.jna.platform.win32.Kernel32;
import com.sun.jna.platform.win32.Kernel32Util;

public class Elevator
{
    public static void main(String... args)
    {
        executeAsAdministrator("c:\\windows\\system32\\notepad.exe", "");
    }

    public static void executeAsAdministrator(String command, String args)
    {
        Shell32X.SHELLEXECUTEINFO execInfo = new Shell32X.SHELLEXECUTEINFO();
        execInfo.lpFile = new WString(command);
        if (args != null)
            execInfo.lpParameters = new WString(args);
        execInfo.nShow = Shell32X.SW_SHOWDEFAULT;
        execInfo.fMask = Shell32X.SEE_MASK_NOCLOSEPROCESS;
        execInfo.lpVerb = new WString("runas");
        boolean result = Shell32X.INSTANCE.ShellExecuteEx(execInfo);

        if (!result)
        {
            int lastError = Kernel32.INSTANCE.GetLastError();
            String errorMessage = Kernel32Util.formatMessageFromLastErrorCode(lastError);
            throw new RuntimeException("Error performing elevation: " + lastError + ": " + errorMessage + " (apperror=" + execInfo.hInstApp + ")");
        }
    }
}