desktop-edge-win/DesktopEdge/Native/NativeMethods.cs

/*
	Copyright NetFoundry Inc.

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	https://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
*/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace ZitiDesktopEdge.Native {

    public static class NativeMethods {
        private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);

        private const uint FILE_READ_EA = 0x0008;
        private const uint FILE_FLAG_BACKUP_SEMANTICS = 0x2000000;

        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern uint GetFinalPathNameByHandle(IntPtr hFile, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder lpszFilePath, uint cchFilePath, uint dwFlags);

        [DllImport("kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool CloseHandle(IntPtr hObject);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern IntPtr CreateFile(
                [MarshalAs(UnmanagedType.LPTStr)] string filename,
                [MarshalAs(UnmanagedType.U4)] uint access,
                [MarshalAs(UnmanagedType.U4)] FileShare share,
                IntPtr securityAttributes, // optional SECURITY_ATTRIBUTES struct or IntPtr.Zero
                [MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
                [MarshalAs(UnmanagedType.U4)] uint flagsAndAttributes,
                IntPtr templateFile);

        public static string GetFinalPathName(string path) {
            var h = CreateFile(path,
                FILE_READ_EA,
                FileShare.ReadWrite | FileShare.Delete,
                IntPtr.Zero,
                FileMode.Open,
                FILE_FLAG_BACKUP_SEMANTICS,
                IntPtr.Zero);
            if (h == INVALID_HANDLE_VALUE)
                throw new Win32Exception();

            try {
                var sb = new StringBuilder(1024);
                var res = GetFinalPathNameByHandle(h, sb, 1024, 0);
                if (res == 0)
                    throw new Win32Exception();

                return sb.ToString();
            } finally {
                CloseHandle(h);
            }
        }
    }
}