Greg Young

internal FileStream(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, bool useAsync, string msgPath, bool bFromProxy)
{
      IntPtr ptr1;
      this._fileName = msgPath;
      if (path == null)
      {
            throw new ArgumentNullException("path", Environment.GetResourceString("ArgumentNull_Path"));
      }
      if (path.Length == 0)
      {
            throw new ArgumentException(Environment.GetResourceString("Argument_EmptyPath"));
      }
      if ((((mode < FileMode.CreateNew) || (mode > FileMode.Append)) || ((access < FileAccess.Read) || (access > FileAccess.ReadWrite))) || ((share < FileShare.None) || (share > FileShare.ReadWrite)))
      {
            string text1 = "mode";
            if ((access < FileAccess.Read) || (access > FileAccess.ReadWrite))
            {
                  text1 = "access";
            }
            if ((share < FileShare.None) || (share > FileShare.ReadWrite))
            {
                  text1 = "share";
            }
            throw new ArgumentOutOfRangeException(text1, Environment.GetResourceString("ArgumentOutOfRange_Enum"));
      }
      if (bufferSize <= 0)
      {
            throw new ArgumentOutOfRangeException("bufferSize", Environment.GetResourceString("ArgumentOutOfRange_NeedPosNum"));
      }
      int num1 = (access == FileAccess.Read) ? -2147483648 : ((access == FileAccess.Write) ? 0x40000000 : -1073741824);
      string text2 = Path.GetFullPathInternal(path);
      this._fileName = text2;
      if (text2.StartsWith(@"\\.\"))
      {
            throw new ArgumentException(Environment.GetResourceString("Arg_DevicesNotSupported"));
      }
      FileIOPermissionAccess access1 = FileIOPermissionAccess.NoAccess;
      if ((access & FileAccess.Read) != ((FileAccess) 0))
      {
            if (mode == FileMode.Append)
            {
                  throw new ArgumentException(Environment.GetResourceString("Argument_InvalidAppendMode"));
            }
            access1 |= FileIOPermissionAccess.Read;
      }
      if ((access & FileAccess.Write) != ((FileAccess) 0))
      {
            if (mode == FileMode.Append)
            {
                  access1 |= FileIOPermissionAccess.Append;
            }
            else
            {
                  access1 |= FileIOPermissionAccess.Write;
            }
      }
      else if (((mode == FileMode.Truncate) || (mode == FileMode.CreateNew)) || ((mode == FileMode.Create) || (mode == FileMode.Append)))
      {
            throw new ArgumentException(string.Format(Environment.GetResourceString("Argument_InvalidFileMode&AccessCombo"), mode, access));
      }
      string[] textArray1 = new string[] { text2 } ;
      new FileIOPermission(access1, textArray1, false, false).Demand();
      bool flag1 = mode == FileMode.Append;
      if (mode == FileMode.Append)
      {
            mode = FileMode.OpenOrCreate;
      }
      Win32Native.SECURITY_ATTRIBUTES security_attributes1 = null;
      if ((share & FileShare.Inheritable) != FileShare.None)
      {
            security_attributes1 = new Win32Native.SECURITY_ATTRIBUTES();
            security_attributes1.nLength = Marshal.SizeOf(security_attributes1);
            security_attributes1.bInheritHandle = 1;
            share &= ((FileShare) (-17));
      }
      if (FileStream._canUseAsync && useAsync)
      {
            ptr1 = Win32Native.UnsafeCreateFile(text2, num1, share, security_attributes1, mode, 0x40000000, Win32Native.NULL);
            this._isAsync = true;
      }
      else
      {
            ptr1 = Win32Native.UnsafeCreateFile(text2, num1, share, security_attributes1, mode, 0x80, Win32Native.NULL);
            this._isAsync = false;
      }
      if (ptr1 != Win32Native.INVALID_HANDLE_VALUE)
      {
            this._handleProtector = new FileStream.__FileStreamHandleProtector(ptr1, true);
      }
      else
      {
            int num2 = Marshal.GetLastWin32Error();
            if ((num2 == 3) && text2.Equals(Directory.InternalGetDirectoryRoot(text2)))
            {
                  num2 = 5;
            }
            bool flag2 = false;
            if (!bFromProxy)
            {
                  try
                  {
                        textArray1 = new string[] { this._fileName } ;
                        new FileIOPermission(FileIOPermissionAccess.PathDiscovery, textArray1, false, false).Demand();
                        flag2 = true;
                  }
                  catch (SecurityException)
                  {
                  }
            }
            if (flag2)
            {
                  __Error.WinIOError(num2, this._fileName);
            }
            else
            {
                  __Error.WinIOError(num2, msgPath);
            }
      }
      int num3 = Win32Native.GetFileType(ptr1);
      if (num3 != 1)
      {
            this._handleProtector.Close();
            throw new NotSupportedException(Environment.GetResourceString("NotSupported_FileStreamOnNonFiles"));
      }
      if (this._isAsync)
      {
            bool flag3 = false;
            new SecurityPermission(SecurityPermissionFlag.UnmanagedCode).Assert();
            try
            {
                  flag3 = ThreadPool.BindHandle(ptr1);
            }
            finally
            {
                  CodeAccessPermission.RevertAssert();
            }
            if (!flag3)
            {
                  throw new IOException(Environment.GetResourceString("IO.IO_BindHandleFailed"));
            }
      }
      this._canRead = (access & FileAccess.Read) != ((FileAccess) 0);
      this._canWrite = (access & FileAccess.Write) != ((FileAccess) 0);
      this._canSeek = true;
      this._isPipe = false;
      this._pos = 0;
      this._bufferSize = bufferSize;
      this._readPos = 0;
      this._readLen = 0;
      this._writePos = 0;
      if (flag1)
      {
            this._appendStart = this.SeekCore((long) 0, SeekOrigin.End);
      }
      else
      {
            this._appendStart = -1;
      }
}