// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Security;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Windows.Automation;
using Microsoft.Win32.SafeHandles;
using MS.Win32;
 
namespace MS.Internal.AutomationProxies
{
    internal sealed class SafeProcessHandle : SafeHandleZeroOrMinusOneIsInvalid
    {
        // This constructor is used by the P/Invoke marshaling layer
        // to allocate a SafeHandle instance.  P/Invoke then does the
        // appropriate method call, storing the handle in this class.
        private SafeProcessHandle() : base(true) {}
 
        internal SafeProcessHandle(IntPtr hwnd) : base(true)
        {
            uint processId;
 
            if (hwnd == IntPtr.Zero)
            {
                processId = (uint)Environment.ProcessId;
            }
            else
            {
                // Get process id...
                Misc.GetWindowThreadProcessId(hwnd, out processId);
            }
 
            // handle might be used to query for Wow64 information (_QUERY_), or to do cross-process allocs (VM_*)
            SetHandle(Misc.OpenProcess(NativeMethods.PROCESS_QUERY_INFORMATION | NativeMethods.PROCESS_VM_OPERATION | NativeMethods.PROCESS_VM_READ | NativeMethods.PROCESS_VM_WRITE, false, processId, hwnd));
        }
 
        // Uncomment this if & only if we need a constructor 
        // that takes a handle from external code
        //internal SafeProcessHandle(IntPtr preexistingHandle, bool ownsHandle) : base(ownsHandle)
        //{
        //    SetHandle(preexistingHandle);
        //}
 
        protected override bool ReleaseHandle()
        {
            return Misc.CloseHandle(handle);
        }
    }
}