add_commandline.ps1xml

<?xml version="1.0" encoding="utf-8" ?>
<Types>
  <Type>
    <Name>System.Diagnostics.Process</Name>
    <Members>
      <ScriptProperty>
        <Name>CommandLine</Name>
        <GetScriptBlock>
$src = @"
using Microsoft.Win32.SafeHandles;
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;

public class CommandLine
{
    const int ProcessCommandLineInformation = 60;

    [StructLayout(LayoutKind.Sequential)]
    class CommandLineString
    {
        public ushort Length;
        public ushort MaximumLength;
        public IntPtr Buffer;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32*1024)]
        public byte[] Data;

        public CommandLineString()
        {
            Data = new byte[32 * 1024];
            MaximumLength = (ushort) Data.Length;
        }

        public override string ToString()
        {
            return Encoding.Unicode.GetString(Data, 0, Length);
        }
    }

    [DllImport("ntdll.dll")]
    static extern int NtQueryInformationProcess(
        SafeProcessHandle ProcessHandle,
        int ProcessInformationClass,
        [In, Out] CommandLineString ProcessInformation,
        int ProcessInformationLength,
        out int ReturnLength
    );

    const int QueryLimitedInformation = 0x1000;

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern SafeProcessHandle OpenProcess(
        int dwDesiredAccess,
        bool bInheritHandle,
        int dwProcessId
    );


    public static string Get(Process process)
    {
        using (var handle = OpenProcess(QueryLimitedInformation, false, process.Id))
        {
            if (handle.IsInvalid)
            {
                return string.Empty;
            }

            int return_length;
            CommandLineString str = new CommandLineString();
            int status = NtQueryInformationProcess(handle, ProcessCommandLineInformation, str, Marshal.SizeOf(str), out return_length);
            if (status == 0)
            {
                return str.ToString();
            }
            return string.Empty;
        }
    }
}
"@

Add-Type -TypeDefinition $src | Out-Null
[CommandLine]::Get($this)
        </GetScriptBlock>
      </ScriptProperty>
    </Members>
  </Type>
</Types>