Win32File.cs

// Modified version of Balaji Lakshmanan's Win32File.
// Original here: http://www.codeproject.com/KB/files/LongFileNames.aspx

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.IO;


namespace System.IO
{
	class Win32File
	{
		
		// Error
		const int ERROR_ALREADY_EXISTS = 183;
		// seek location
		const uint FILE_BEGIN = 0x0;
		const uint FILE_CURRENT = 0x1;
		const uint FILE_END = 0x2;


		// access
		const uint GENERIC_READ = 0x80000000;
		const uint GENERIC_WRITE = 0x40000000;
		const uint GENERIC_EXECUTE = 0x20000000;
		const uint GENERIC_ALL = 0x10000000;

		const uint FILE_APPEND_DATA = 0x00000004;

		// attribute
		const uint FILE_ATTRIBUTE_NORMAL = 0x80;
		const uint FILE_ATTRIBUTE_DIRECTORY = 0x00000010;
		const uint INVALID_FILE_ATTRIBUTES = 0xFFFFFFFF;

		// share
		const uint FILE_SHARE_DELETE = 0x00000004;
		const uint FILE_SHARE_READ = 0x00000001;
		const uint FILE_SHARE_WRITE = 0x00000002;

		//mode
		const uint CREATE_NEW = 1;
		const uint CREATE_ALWAYS = 2;
		const uint OPEN_EXISTING = 3;
		const uint OPEN_ALWAYS = 4;
		const uint TRUNCATE_EXISTING = 5;

		[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		static extern SafeFileHandle CreateFileW(string lpFileName, uint dwDesiredAccess,
											  uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition,
											  uint dwFlagsAndAttributes, IntPtr hTemplateFile);

		[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		static extern uint SetFilePointer(SafeFileHandle hFile, long lDistanceToMove, IntPtr lpDistanceToMoveHigh, uint dwMoveMethod);

		[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		static extern uint GetFileAttributesW(string lpFileName);

		[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		static extern uint MoveFileW(string lpExistingFileName, string lpNewFileName);

		// uint GetMode( FileMode mode )
		// Converts the filemode constant to win32 constant
		#region GetMode
		private static uint GetMode(FileMode mode)
		{
			uint umode = 0;
			switch (mode)
			{
				case FileMode.CreateNew:
					umode = CREATE_NEW;
					break;
				case FileMode.Create:
					umode = CREATE_ALWAYS;
					break;
				case FileMode.Append:
					umode = OPEN_ALWAYS;
					break;
				case FileMode.Open:
					umode = OPEN_EXISTING;
					break;
				case FileMode.OpenOrCreate:
					umode = OPEN_ALWAYS;
					break;
				case FileMode.Truncate:
					umode = TRUNCATE_EXISTING;
					break;
			}
			return umode;
		}
		#endregion


		// uint GetAccess(FileAccess access)
		// Converts the FileAccess constant to win32 constant
		#region GetAccess
		private static uint GetAccess(FileAccess access)
		{
			uint uaccess = 0;
			switch (access)
			{
				case FileAccess.Read:
					uaccess = GENERIC_READ;
					break;
				case FileAccess.ReadWrite:
					uaccess = GENERIC_READ | GENERIC_WRITE;
					break;
				case FileAccess.Write:
					uaccess = GENERIC_WRITE;
					break;
			}
			return uaccess;
		}
		#endregion

		// uint GetShare(FileShare share)
		// Converts the FileShare constant to win32 constant
		#region GetShare
		private static uint GetShare(FileShare share)
		{
			uint ushare = 0;
			switch (share)
			{
				case FileShare.Read:
					ushare = FILE_SHARE_READ;
					break;
				case FileShare.ReadWrite:
					ushare = FILE_SHARE_READ | FILE_SHARE_WRITE;
					break;
				case FileShare.Write:
					ushare = FILE_SHARE_WRITE;
					break;
				case FileShare.Delete:
					ushare = FILE_SHARE_DELETE;
					break;
				case FileShare.None:
					ushare = 0;
					break;

			}
			return ushare;
		}
		#endregion

		public static string LongFileName(string filepath)
		{
			// If file path is disk file path then prepend it with \\?\
			// if file path is UNC prepend it with \\?\UNC\ and remove \\ prefix in unc path.
			if (filepath.StartsWith(@"\\"))
				return @"\\?\UNC\" + filepath.Substring(2, filepath.Length - 2);
			else
				return @"\\?\" + filepath;
		}

		public static FileStream Open(string filepath, FileMode mode)
		{
			//opened in the specified mode and path, with read/write access and not shared
			FileStream fs = null;
			uint umode = GetMode(mode);
			uint uaccess = GENERIC_READ | GENERIC_WRITE;
			uint ushare = 0;	//not shared
			if (mode == FileMode.Append)
				uaccess = FILE_APPEND_DATA;
			SafeFileHandle sh = CreateFileW(LongFileName(filepath), uaccess, ushare, IntPtr.Zero, umode, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);
			int iError = Marshal.GetLastWin32Error();
			if (/*(iError > 0 && !(mode == FileMode.Append && iError == ERROR_ALREADY_EXISTS)) || */sh.IsInvalid)
			{
				throw new Exception("Error opening file Win32 Error:" + iError);
			}
			else
			{
				fs = new FileStream(sh, FileAccess.ReadWrite);
			}

			// if opened in append mode
			if (mode == FileMode.Append)
			{
				if (!sh.IsInvalid)
				{
					SetFilePointer(sh, 0, IntPtr.Zero, FILE_END);
				}
			}

			return fs;
		}

		public static FileStream Open(string filepath, FileMode mode, FileAccess access)
		{
			//opened in the specified mode and access and not shared
			FileStream fs = null;
			uint umode = GetMode(mode);
			uint uaccess = GetAccess(access);
			uint ushare = 0;//not shared
			if (mode == FileMode.Append)
				uaccess = FILE_APPEND_DATA;
			SafeFileHandle sh = CreateFileW(LongFileName(filepath), uaccess, ushare, IntPtr.Zero, umode, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);
			int iError = Marshal.GetLastWin32Error();
			if ((iError > 0 && !(mode == FileMode.Append && iError != ERROR_ALREADY_EXISTS)) || sh.IsInvalid)
			{
				throw new Exception("Error opening file Win32 Error:" + iError);
			}
			else
			{
				fs = new FileStream(sh, access);
			}
			// if opened in append mode
			if (mode == FileMode.Append)
			{
				if (!sh.IsInvalid)
				{
					SetFilePointer(sh, 0, IntPtr.Zero, FILE_END);
				}
			}
			return fs;

		}

		public static FileStream Open(string filepath, FileMode mode, FileAccess access, FileShare share)
		{
			//opened in the specified mode , access and  share
			FileStream fs = null;
			uint umode = GetMode(mode);
			uint uaccess = GetAccess(access);
			uint ushare = GetShare(share);
			if (mode == FileMode.Append)
				uaccess = FILE_APPEND_DATA;
			SafeFileHandle sh = CreateFileW(LongFileName(filepath), uaccess, ushare, IntPtr.Zero, umode, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);
			int iError = Marshal.GetLastWin32Error();
			if ((iError > 0 && !(mode == FileMode.Append && iError != ERROR_ALREADY_EXISTS)) || sh.IsInvalid)
			{
				throw new Exception("Error opening file Win32 Error:" + iError);
			}
			else
			{
				fs = new FileStream(sh, access);
			}
			// if opened in append mode
			if (mode == FileMode.Append)
			{
				if (!sh.IsInvalid)
				{
					SetFilePointer(sh, 0, IntPtr.Zero, FILE_END);
				}
			}
			return fs;
		}

		public static FileStream OpenRead(string filepath)
		{
			// Open readonly file mode open(String, FileMode.Open, FileAccess.Read, FileShare.Read)
			return Open(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);
		}

		public static FileStream OpenWrite(string filepath)
		{
			//open writable open(String, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None).
			return Open(filepath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None);
		}

		public static bool Exists(string filepath)
		{
			uint attribs = GetFileAttributesW(LongFileName(filepath));
			return (attribs != INVALID_FILE_ATTRIBUTES) && ((attribs & FILE_ATTRIBUTE_DIRECTORY) == 0);
		}

		public static void Move(string oldName, string newName)
		{
			MoveFileW(LongFileName(oldName), LongFileName(newName));
		}
	}

	class Win32Directory
	{
		// file attributes
		const uint FILE_ATTRIBUTE_DIRECTORY = 0x00000010;
		const uint INVALID_FILE_ATTRIBUTES = 0xFFFFFFFF;

		[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		static extern bool CreateDirectoryW(string lpPathName, IntPtr lpSecurityAttributes);

		[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		static extern uint GetFileAttributesW(string lpFileName);

		public static void CreateDirectory(string path)
		{
			if (path[path.Length-1]!='\\')
				path += '\\';
			for (int i=0; i<path.Length; i++)
				if (path[i]=='\\')
				{
					string target = @"\\?\" + path.Substring(0, i);
					CreateDirectoryW(target, IntPtr.Zero);
				}
		}

		public static bool Exists(string filepath)
		{
			uint attribs = GetFileAttributesW(Win32File.LongFileName(filepath));
			return (attribs != INVALID_FILE_ATTRIBUTES) && ((attribs & FILE_ATTRIBUTE_DIRECTORY) != 0);
		}
	}
}