Get process session, station, and desktop

Get-ProcessSessionStationAndDesktop.ps1

Add-Type -TypeDefinition @'
using System;
using System.Runtime.InteropServices;

namespace ProcessInfo
{
    public class NativeMethods
    {
        [DllImport("User32.dll", SetLastError = true)]
        public static extern bool CloseDesktop(
            IntPtr hDesktop);

        [DllImport("Kernel32.dll")]
        public static extern UInt32 GetCurrentThreadId();

        [DllImport("User32.dll", SetLastError = true)]
        public static extern IntPtr GetProcessWindowStation();

        [DllImport("User32.dll", SetLastError = true)]
        public static extern IntPtr GetThreadDesktop(
            UInt32 dwThreadId);

        [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern bool GetUserObjectInformationW(
            IntPtr hObject,
            int nIndex,
            IntPtr pvInfo,
            UInt32 nLength,
            ref UInt32 lpnLengthNeeded);
    }
}
'@

Function Get-UserObjectName {
    [CmdletBinding()]
    Param([IntPtr]$Handle)

    $ptr_length = 0
    [ProcessInfo.NativeMethods]::GetUserObjectInformationW($Handle, 2, [IntPtr]::Zero, $ptr_length,
        [Ref]$ptr_length) > $null

    $name_ptr = [System.Runtime.InteropServices.Marshal]::AllocHGlobal($ptr_length)
    try {
        $res = [ProcessInfo.NativeMethods]::GetUserObjectInformationW($Handle, 2, $name_ptr, $ptr_length,
            [Ref]$ptr_length)

        if (-not $res) {
            $err_code = [System.Runtime.InteropServices.Marshal]::GetLastWin32Error()
            $exp = New-Object -TypeName System.ComponentModel.Win32Exception -ArgumentList $err_code
            Write-Error -Message ("Failed to get object name: {0} (Win32 ErrorCode {1} - 0x{1:X8})" -f $exp.Message, $err_code)
            return
        }

        [System.Runtime.InteropServices.Marshal]::PtrToStringUni($name_ptr)
    } finally {
        [System.Runtime.InteropServices.Marshal]::FreeHGlobal($name_ptr)
    }
}

Function Get-ProcessSessionStationAndDesktop {
    [CmdletBinding()]
    Param ()

    $station_ptr = [ProcessInfo.NativeMethods]::GetProcessWindowStation()
    $station_name = Get-UserObjectName -Handle $station_ptr

    $desktop_ptr = [ProcessInfo.NativeMethods]::GetThreadDesktop([ProcessInfo.NativeMethods]::GetCurrentThreadId())
    try {
        $desktop_name = Get-UserObjectName -Handle $desktop_ptr
    } finally {
        [ProcessInfo.NativeMethods]::CloseDesktop($desktop_ptr) > $null
    }

    [PSCustomObject]@{
        Session = ([System.Diagnostics.Process]::GetCurrentProcess()).SessionId
        Station = $station_name
        Desktop = $desktop_name
    }
}