// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Windows.Automation;
using Microsoft.Win32.SafeHandles;
using MS.Win32;
 
namespace MS.Internal.Automation
{
    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(NativeMethods.HWND hwnd) : base(true)
        {
            int processId;
 
            // Get process id...
            // GetWindowThreadProcessId does use SetLastError().  So a call to GetLastError() would be meanless.
            if (SafeNativeMethods.GetWindowThreadProcessId(hwnd, out processId) == 0)
            {
                throw new ElementNotAvailableException();
            }
 
            SetHandle(Misc.OpenProcess(UnsafeNativeMethods.PROCESS_QUERY_INFORMATION | UnsafeNativeMethods.PROCESS_VM_READ, false, processId, hwnd));
        }
 
        protected override bool ReleaseHandle()
        {
            return Misc.CloseHandle(handle);
        }
    }
}