Elevating a ProcessBuilder process via UAC?

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:
", Arrays.toString(command));
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
        try {
            int exitValue = process.waitFor();
            System.out.println("

Exit 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?

prunge · Accepted Answer

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 + ")");
        }
    }
}

Elevating a ProcessBuilder process via UAC?

Answers (2)

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