make child process terminate automatically when the current process terminates

ProcessJob.cs

using System;
using System.Runtime.InteropServices;

using static PInvoke.Kernel32;

// usage: new Job().AddProcess(new SafeObjectHandle(win32childProcessHandle, ownsHandle: false);
// might need to keep Job instance alive

public class Job : IDisposable
{
    readonly SafeObjectHandle handle;

    public Job() {
        this.handle = CreateJobObject(IntPtr.Zero, null);

        var info = new JOBOBJECT_BASIC_LIMIT_INFORMATION {
            LimitFlags = JOB_OBJECT_LIMIT_FLAGS.JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE,
        };

        var extendedInfo = new JOBOBJECT_EXTENDED_LIMIT_INFORMATION {BasicLimitInformation = info};

        int length = Marshal.SizeOf(typeof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION));
        IntPtr extendedInfoPtr = Marshal.AllocHGlobal(length);
        Marshal.StructureToPtr(extendedInfo, extendedInfoPtr, false);

        if (!SetInformationJobObject(this.handle, JOBOBJECTINFOCLASS.JobObjectExtendedLimitInformation, extendedInfoPtr, (uint)length))
            throw new System.ComponentModel.Win32Exception();
    }

    public bool AddProcess(SafeObjectHandle processHandle) {
        return AssignProcessToJobObject(this.handle, processHandle);
    }

    #region IDisposable Members

    public void Dispose() {
        this.Dispose(true);
        GC.SuppressFinalize(this);
    }


    private void Dispose(bool disposing) => this.Close();

    public void Close() => this.handle.Close();

    #endregion
}