WPF - how to determine how the app was launched

Question

I've never used a WPF project before. We're trying to determine, if in the

    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);
    }

Can we determine if the application was started by the user clicking on the Icon or if the application was started by a Task? I'm not sure where to start looking?

Any insight would be helpful, thank you.

Answer 1

I would have the task pass in a command line parameter to tell you the app was started by the task

https://www.wpf-tutorial.com/wpf-application/command-line-parameters/

Answer 2

A way is to get the parent PID, with NtQueryInformationProcess then QueryFullProcessImageName to get the parent name

I tested on Windows 10, I get :

From Explorer : c:\windows\explorer.exe
From Task Scheduler : c:\windows\system32\svchost.exe

(must be executed with maximum authorizations with Task Scheduler, otherwise OpenProcess returns ACCESS_DENIED )

int nStatus = STATUS_SUCCESS;
PROCESS_BASIC_INFORMATION pbi = new PROCESS_BASIC_INFORMATION();
nStatus = NtQueryInformationProcess(GetCurrentProcess(), PROCESSINFOCLASS.ProcessBasicInformation, pbi, (int)Marshal.SizeOf(pbi), null);
if (nStatus == 0)
{
    IntPtr hProcessForName = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, true, (uint)pbi.InheritedFromUniqueProcessId);
    if (hProcessForName != IntPtr.Zero)
    {
        uint nSize = 260;
        StringBuilder sProcessImageName = new StringBuilder((int)nSize);
        QueryFullProcessImageName(hProcessForName, 0, sProcessImageName, ref nSize);
        string sName = sProcessImageName.ToString();
        CloseHandle(hProcessForName);
        MessageBox.Show(sName, "Information");
    }
    else
    {
        int nError = Marshal.GetLastWin32Error();
        // ...
    }
}

Declarations (using System.Runtime.InteropServices;):

public const int STATUS_SUCCESS = 0x0;

[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern IntPtr GetCurrentProcess();

public const int SYNCHRONIZE = 0x100000;
public const int STANDARD_RIGHTS_REQUIRED = 0xF0000;

public const int PROCESS_VM_READ = (0x10);
public const int PROCESS_VM_WRITE = (0x20);
public const int PROCESS_DUP_HANDLE = (0x40);
public const int PROCESS_CREATE_PROCESS = (0x80);
public const int PROCESS_SET_QUOTA = (0x100);
public const int PROCESS_SET_INFORMATION = (0x200);
public const int PROCESS_QUERY_INFORMATION = (0x400);
public const int PROCESS_SUSPEND_RESUME = (0x800);
public const int PROCESS_QUERY_LIMITED_INFORMATION = (0x1000);
public const int PROCESS_SET_LIMITED_INFORMATION = (0x2000);
public const long PROCESS_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED | SYNCHRONIZE | 0xFFFF);

[DllImport("Kernel32.dll", SetLastError = true)]
public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, uint dwProcessId);

[DllImport("Kernel32.dll", SetLastError = true)]
public static extern bool CloseHandle(IntPtr hObject);

[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern bool QueryFullProcessImageName(IntPtr hProcess, int dwFlags, StringBuilder lpExeName, ref uint lpdwSize);

[DllImport("NtDll.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern int NtQueryInformationProcess(IntPtr ProcessHandle, PROCESSINFOCLASS ProcessInformationClass, PROCESS_BASIC_INFORMATION info, int ProcessInformationLength, int[] ReturnLength);

public enum PROCESSINFOCLASS
{
    ProcessBasicInformation,
    ProcessQuotaLimits,
    ProcessIoCounters,
    ProcessVmCounters,
    ProcessTimes,
    ProcessBasePriority,
    ProcessRaisePriority,
    ProcessDebugPort,
    ProcessExceptionPort,
    ProcessAccessToken,
    ProcessLdtInformation,
    ProcessLdtSize,
    ProcessDefaultHardErrorMode,
    ProcessIoPortHandlers,          // Note: this is kernel mode only
    ProcessPooledUsageAndLimits,
    ProcessWorkingSetWatch,
    ProcessUserModeIOPL,
    ProcessEnableAlignmentFaultFixup,
    ProcessPriorityClass,
    ProcessWx86Information,
    ProcessHandleCount,
    ProcessAffinityMask,
    ProcessPriorityBoost,
    ProcessDeviceMap,
    ProcessSessionInformation,
    ProcessForegroundInformation,
    ProcessWow64Information,
    ProcessImageFileName,
    ProcessLUIDDeviceMapsEnabled,
    ProcessBreakOnTermination,
    ProcessDebugObjectHandle,
    ProcessDebugFlags,
    ProcessHandleTracing,
    ProcessUnusedSpare1,
    ProcessExecuteFlags,
    ProcessResourceManagement,
    ProcessCookie,
    ProcessImageInformation,
    MaxProcessInfoClass             // MaxProcessInfoClass should always be the last enum
}

[StructLayout(LayoutKind.Sequential)]
public class PROCESS_BASIC_INFORMATION
{
    public int ExitStatus = 0;
    public IntPtr PebBaseAddress = (IntPtr)0;
    public IntPtr AffinityMask = (IntPtr)0;
    public int BasePriority = 0;
    public IntPtr UniqueProcessId = (IntPtr)0;
    public IntPtr InheritedFromUniqueProcessId = (IntPtr)0;
}