.net - Suspend Process in C#

Question

How do I suspend a whole process (like the Process Explorer does when I click Suspend) in C#.

I'm starting the Process with Process.Start, and on a certain event, I want to suspend the process to be able to do some investigation on a "snapshot" of it.

Answer 1

Here's my suggestion:

 [Flags]
    public enum ThreadAccess : int
    {
      TERMINATE = (0x0001),
      SUSPEND_RESUME = (0x0002),
      GET_CONTEXT = (0x0008),
      SET_CONTEXT = (0x0010),
      SET_INFORMATION = (0x0020),
      QUERY_INFORMATION = (0x0040),
      SET_THREAD_TOKEN = (0x0080),
      IMPERSONATE = (0x0100),
      DIRECT_IMPERSONATION = (0x0200)
    }

    [DllImport("kernel32.dll")]
    static extern IntPtr OpenThread(ThreadAccess dwDesiredAccess, bool bInheritHandle, uint dwThreadId);
    [DllImport("kernel32.dll")]
    static extern uint SuspendThread(IntPtr hThread);
    [DllImport("kernel32.dll")]
    static extern int ResumeThread(IntPtr hThread);
    [DllImport("kernel32", CharSet = CharSet.Auto,SetLastError = true)]
    static extern bool CloseHandle(IntPtr handle);


private static void SuspendProcess(int pid)
{
  var process = Process.GetProcessById(pid); // throws exception if process does not exist

  foreach (ProcessThread pT in process.Threads)
  {
    IntPtr pOpenThread = OpenThread(ThreadAccess.SUSPEND_RESUME, false, (uint)pT.Id);

    if (pOpenThread == IntPtr.Zero)
    {
      continue;
    }

    SuspendThread(pOpenThread);

    CloseHandle(pOpenThread);
  }
}

public static void ResumeProcess(int pid)
{
  var process = Process.GetProcessById(pid);

  if (process.ProcessName == string.Empty)
    return;

  foreach (ProcessThread pT in process.Threads)
  {
    IntPtr pOpenThread = OpenThread(ThreadAccess.SUSPEND_RESUME, false, (uint)pT.Id);

    if (pOpenThread == IntPtr.Zero)
    {
      continue;
    }

    var suspendCount = 0;
    do
    {
      suspendCount = ResumeThread(pOpenThread);
    } while (suspendCount > 0);

    CloseHandle(pOpenThread);
  }
}