Inno Setup run/execute code as another user

Question

Much as it is possible to use ExecAsOriginalUser to run something using the starting/logged in user's credentials, is there a command or way to run a particular piece of code as a specific user?

To explain further, I am writing the computer name into a log on a file share at the end of installation. This works perfectly as long as not installing using a local Administrator account which does not have a matching local Administrator account on the server. Therefore, what I need to do is have the particular bit of code that writes to the log execute as a specific user account, which I have the credentials for, that I know exists on the server.

The code I am using is as follows:

{ Auto audit the computer name }
procedure AutoAudit();
var
  strComputerName: TArrayOfString;
  strAutoAuditFile: String;
begin
  strAutoAuditFile := '\\' + ClientConnectionPage.Values[0] + '\Audit\Client Audit.txt';
  SetArrayLength(strComputerName, 1);
  strComputerName[0] :=
    ExpandConstant('{computername} ') + GetDateTimeString('dd/mm/yyyy hh:mm', '/', ':');
  SaveStringsToFile(strAutoAuditFile, strComputerName, True);
end;

So, what I need is a way of executing the SaveStringsToFile function as another user.

I have thought of a rather messy way to do this, which would involve testing for an available drive letter, mapping a drive using the account credentials, writing to the file and then disconnecting the drive. However, I am hoping there is a more elegant way to do this?

Answer 1

You have to use the LogonUser WinAPI function to run a piece of code as a different account.

It's likely possible to run this from an Inno Setup code, but I haven't found an example.

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Alternatively, you can develop a separate tiny application that impersonates the other user and embed the application into your installer.

In C#/VB.NET, you can use the Impersonator class (which uses the LogonUser internally):

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        using (new Impersonator("username", "domain", "password"))
        {
            string strAutoAuditFile = @"\\" + args[0] + @"\Audit\Client Audit.txt";
            string strComputerName =
                Environment.MachineName + " " + DateTime.Now.ToString("dd/mm/yyyy hh:mm");
            File.WriteAllText(strAutoAuditFile, strComputerName);
        }
    }
}

Run the application from Inno Setup like:

[Files]
Source: "getcompname.exe"; Flags: dontcopy

[Code]
...

var
  ResultCode: Integer;
begin
  ...
  ExtractTemporaryFile('getcompname.exe');
  ExecAsOriginalUser(
    ExpandConstant('{tmp}') + '\getcompname.exe ',
    ClientConnectionPage.Values[0],
    '', SW_HIDE, ewWaitUntilTerminated, ResultCode);
  ...
end;

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If you are not experienced with a console application development, note that the "tiny" application can be even a batch file with use of the runas command (which does not allow specifying password automatically) or the PsExec (which does).