gistfile1.txt

using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;
using System;
using System.Diagnostics.Contracts;
using System.Runtime.InteropServices;
using System.Security;
namespace System.IO
{
	/// <summary>Provides static methods for the creation, copying, deletion, moving, and opening of files, and aids in the creation of <see cref="T:System.IO.FileStream" /> objects.</summary>
	/// <filterpriority>1</filterpriority>
	[ComVisible(true)]
	internal static class File
	{
		private const int GetFileExInfoStandard = 0;
		private const int ERROR_INVALID_PARAMETER = 87;
		private const int ERROR_ACCESS_DENIED = 5;
		[SecurityCritical]
		internal static bool UnsafeExists(string path)
		{
			return File.InternalExistsHelper(path, false);
		}
		[SecurityCritical]
		private static bool InternalExistsHelper(string path, bool checkHost)
		{
			try
			{
				bool result;
				if (path == null)
				{
					result = false;
					return result;
				}
				if (path.Length == 0)
				{
					result = false;
					return result;
				}
				path = Path.GetFullPathInternal(path);
				Contract.Assert(path != null, "File.Exists: GetFullPathInternal returned null");
				if (path.Length > 0 && Path.IsDirectorySeparator(path[path.Length - 1]))
				{
					result = false;
					return result;
				}
				if (checkHost)
				{
					FileSecurityState fileSecurityState = new FileSecurityState(FileSecurityStateAccess.Read, string.Empty, path);
					fileSecurityState.EnsureState();
				}
				result = File.InternalExists(path);
				return result;
			}
			catch (ArgumentException)
			{
			}
			catch (NotSupportedException)
			{
			}
			catch (SecurityException)
			{
			}
			catch (IOException)
			{
			}
			catch (UnauthorizedAccessException)
			{
			}
			return false;
		}
		[SecurityCritical]
		internal static bool InternalExists(string path)
		{
			Win32Native.WIN32_FILE_ATTRIBUTE_DATA wIN32_FILE_ATTRIBUTE_DATA = default(Win32Native.WIN32_FILE_ATTRIBUTE_DATA);
			return File.FillAttributeInfo(path, ref wIN32_FILE_ATTRIBUTE_DATA, false, true) == 0 && wIN32_FILE_ATTRIBUTE_DATA.fileAttributes != -1 && (wIN32_FILE_ATTRIBUTE_DATA.fileAttributes & 16) == 0;
		}
		[SecurityCritical]
		internal static int FillAttributeInfo(string path, ref Win32Native.WIN32_FILE_ATTRIBUTE_DATA data, bool tryagain, bool returnErrorOnNotFound)
		{
			int num = 0;
			if (tryagain)
			{
				Win32Native.WIN32_FIND_DATA wIN32_FIND_DATA = new Win32Native.WIN32_FIND_DATA();
				string fileName = path.TrimEnd(new char[]
				{
					Path.DirectorySeparatorChar,
					Path.AltDirectorySeparatorChar
				});
				int errorMode = Win32Native.SetErrorMode(1);
				try
				{
					bool flag = false;
					SafeFindHandle safeFindHandle = Win32Native.FindFirstFile(fileName, wIN32_FIND_DATA);
					try
					{
						if (safeFindHandle.IsInvalid)
						{
							flag = true;
							num = Marshal.GetLastWin32Error();
							if ((num == 2 || num == 3 || num == 21) && !returnErrorOnNotFound)
							{
								num = 0;
								data.fileAttributes = -1;
							}
							return num;
						}
					}
					finally
					{
						try
						{
							safeFindHandle.Close();
						}
						catch
						{
							if (!flag)
							{
								Contract.Assert(false, "File::FillAttributeInfo - FindClose failed!");
								__Error.WinIOError();
							}
						}
					}
				}
				finally
				{
					Win32Native.SetErrorMode(errorMode);
				}
				data.PopulateFrom(wIN32_FIND_DATA);
				return num;
			}
			bool flag2 = false;
			int errorMode2 = Win32Native.SetErrorMode(1);
			try
			{
				flag2 = Win32Native.GetFileAttributesEx(path, 0, ref data);
			}
			finally
			{
				Win32Native.SetErrorMode(errorMode2);
			}
			if (!flag2)
			{
				num = Marshal.GetLastWin32Error();
				if (num != 2 && num != 3 && num != 21)
				{
					return File.FillAttributeInfo(path, ref data, true, returnErrorOnNotFound);
				}
				if (!returnErrorOnNotFound)
				{
					num = 0;
					data.fileAttributes = -1;
				}
			}
			return num;
		}
	}
}