#448: Refactor POSIX platforms and remove partial classes and unused …

…methods

We refactor the common methods and classes in the Linux and Mac platform implementations so they share a single common POSIX implementation instead, as much as is reasonably possible.

Scalar.Common/NativeMethods.cs

@@ -1,12 +1,82 @@
 using Microsoft.Win32.SafeHandles;
 using System;
+using System.ComponentModel;
 using System.IO;
 using System.Runtime.InteropServices;
+using System.Text;
 
 namespace Scalar.Common
 {
-    public static partial class NativeMethods
+    public static class NativeMethods
     {
+        public enum FileAttributes : uint
+        {
+            FILE_ATTRIBUTE_READONLY = 1,
+            FILE_ATTRIBUTE_HIDDEN = 2,
+            FILE_ATTRIBUTE_SYSTEM = 4,
+            FILE_ATTRIBUTE_DIRECTORY = 16,
+            FILE_ATTRIBUTE_ARCHIVE = 32,
+            FILE_ATTRIBUTE_DEVICE = 64,
+            FILE_ATTRIBUTE_NORMAL = 128,
+            FILE_ATTRIBUTE_TEMPORARY = 256,
+            FILE_ATTRIBUTE_SPARSEFILE = 512,
+            FILE_ATTRIBUTE_REPARSEPOINT = 1024,
+            FILE_ATTRIBUTE_COMPRESSED = 2048,
+            FILE_ATTRIBUTE_OFFLINE = 4096,
+            FILE_ATTRIBUTE_NOT_CONTENT_INDEXED = 8192,
+            FILE_ATTRIBUTE_ENCRYPTED = 16384,
+            FILE_FLAG_FIRST_PIPE_INSTANCE = 524288,
+            FILE_FLAG_OPEN_NO_RECALL = 1048576,
+            FILE_FLAG_OPEN_REPARSE_POINT = 2097152,
+            FILE_FLAG_POSIX_SEMANTICS = 16777216,
+            FILE_FLAG_BACKUP_SEMANTICS = 33554432,
+            FILE_FLAG_DELETE_ON_CLOSE = 67108864,
+            FILE_FLAG_SEQUENTIAL_SCAN = 134217728,
+            FILE_FLAG_RANDOM_ACCESS = 268435456,
+            FILE_FLAG_NO_BUFFERING = 536870912,
+            FILE_FLAG_OVERLAPPED = 1073741824,
+            FILE_FLAG_WRITE_THROUGH = 2147483648
+        }
+
+        public enum FileAccess : uint
+        {
+            FILE_READ_DATA = 1,
+            FILE_LIST_DIRECTORY = 1,
+            FILE_WRITE_DATA = 2,
+            FILE_ADD_FILE = 2,
+            FILE_APPEND_DATA = 4,
+            FILE_ADD_SUBDIRECTORY = 4,
+            FILE_CREATE_PIPE_INSTANCE = 4,
+            FILE_READ_EA = 8,
+            FILE_WRITE_EA = 16,
+            FILE_EXECUTE = 32,
+            FILE_TRAVERSE = 32,
+            FILE_DELETE_CHILD = 64,
+            FILE_READ_ATTRIBUTES = 128,
+            FILE_WRITE_ATTRIBUTES = 256,
+            SPECIFIC_RIGHTS_ALL = 65535,
+            DELETE = 65536,
+            READ_CONTROL = 131072,
+            STANDARD_RIGHTS_READ = 131072,
+            STANDARD_RIGHTS_WRITE = 131072,
+            STANDARD_RIGHTS_EXECUTE = 131072,
+            WRITE_DAC = 262144,
+            WRITE_OWNER = 524288,
+            STANDARD_RIGHTS_REQUIRED = 983040,
+            SYNCHRONIZE = 1048576,
+            FILE_GENERIC_READ = 1179785,
+            FILE_GENERIC_EXECUTE = 1179808,
+            FILE_GENERIC_WRITE = 1179926,
+            STANDARD_RIGHTS_ALL = 2031616,
+            FILE_ALL_ACCESS = 2032127,
+            ACCESS_SYSTEM_SECURITY = 16777216,
+            MAXIMUM_ALLOWED = 33554432,
+            GENERIC_ALL = 268435456,
+            GENERIC_EXECUTE = 536870912,
+            GENERIC_WRITE = 1073741824,
+            GENERIC_READ = 2147483648
+        }
+
         [Flags]
         public enum MoveFileFlags : uint
         {
@@ -49,6 +119,76 @@ public static void MoveFile(string existingFileName, string newFileName, MoveFil
             }
         }
 
+        public static string GetFinalPathName(string path)
+        {
+            // Using FILE_FLAG_BACKUP_SEMANTICS as it works with file as well as folder path
+            // According to MSDN, https://msdn.microsoft.com/en-us/library/windows/desktop/aa363858(v=vs.85).aspx,
+            // we must set this flag to obtain a handle to a directory
+            using (SafeFileHandle fileHandle = CreateFile(
+                path,
+                FileAccess.FILE_READ_ATTRIBUTES,
+                FileShare.ReadWrite,
+                IntPtr.Zero,
+                FileMode.Open,
+                FileAttributes.FILE_FLAG_BACKUP_SEMANTICS,
+                IntPtr.Zero))
+            {
+                if (fileHandle.IsInvalid)
+                {
+                    ThrowLastWin32Exception($"Invalid file handle for {path}");
+                }
+
+                int finalPathSize = GetFinalPathNameByHandle(fileHandle, null, 0, 0);
+                StringBuilder finalPath = new StringBuilder(finalPathSize + 1);
+
+                // GetFinalPathNameByHandle buffer size should not include a NULL termination character
+                finalPathSize = GetFinalPathNameByHandle(fileHandle, finalPath, finalPathSize, 0);
+                if (finalPathSize == 0)
+                {
+                    ThrowLastWin32Exception($"Failed to get final path size for {finalPath}");
+                }
+
+                string pathString = finalPath.ToString();
+
+                // The remarks section of GetFinalPathNameByHandle mentions the return being prefixed with "\\?\" or "\\?\UNC\"
+                // More information the prefixes is here http://msdn.microsoft.com/en-us/library/aa365247(v=VS.85).aspx
+                const string PathPrefix = @"\\?\";
+                const string UncPrefix = @"\\?\UNC\";
+                if (pathString.StartsWith(UncPrefix, StringComparison.Ordinal))
+                {
+                    pathString = @"\\" + pathString.Substring(UncPrefix.Length);
+                }
+                else if (pathString.StartsWith(PathPrefix, StringComparison.Ordinal))
+                {
+                    pathString = pathString.Substring(PathPrefix.Length);
+                }
+
+                return pathString;
+            }
+        }
+
+        public static void ThrowLastWin32Exception(string message)
+        {
+            throw new Win32Exception(Marshal.GetLastWin32Error(), message);
+        }
+
+        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
+        private static extern SafeFileHandle CreateFile(
+            [In] string lpFileName,
+            [MarshalAs(UnmanagedType.U4)] FileAccess dwDesiredAccess,
+            FileShare dwShareMode,
+            [In] IntPtr lpSecurityAttributes,
+            [MarshalAs(UnmanagedType.U4)]FileMode dwCreationDisposition,
+            [MarshalAs(UnmanagedType.U4)]FileAttributes dwFlagsAndAttributes,
+            [In] IntPtr hTemplateFile);
+
+        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
+        private static extern int GetFinalPathNameByHandle(
+            SafeFileHandle hFile,
+            [Out] StringBuilder lpszFilePath,
+            int cchFilePath,
+            int dwFlags);
+
         [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
         private static extern bool MoveFileEx(
             string existingFileName,