How to determine whether a System.Diagnostics.Process is 32 or 64 bit?

Question

I tried:

process.MainModule.FileName.Contains("x86")

But it threw an exception for a x64 process:

Win32Exception: Only a part of the ReadProcessMemory ou WriteProcessMemory request finished

Answer 1

You need to call IsWow64Process via P/Invoke:

[DllImport( "kernel32.dll", SetLastError = true, CallingConvention = CallingConvention.Winapi )]
[return: MarshalAs( UnmanagedType.Bool )]
public static extern bool IsWow64Process( [In] IntPtr processHandle, [Out, MarshalAs( UnmanagedType.Bool )] out bool wow64Process );

Here's a helper to make it a bit easier to call:

public static bool Is64BitProcess( this Process process )
{
    if ( !Environment.Is64BitOperatingSystem )
        return false;

    bool isWow64Process;
    if ( !IsWow64Process( process.Handle, out isWow64Process ) )
        throw new Win32Exception( Marshal.GetLastWin32Error() );

    return !isWow64Process;
}