public FileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize)
{
// This will perform validation on path
_fileName = Path.GetFullPath(path);
// make sure mode, access, and share are within range
if (mode < FileMode.CreateNew || mode > FileMode.Append ||
access < FileAccess.Read || access > FileAccess.ReadWrite ||
share < FileShare.None || share > FileShare.ReadWrite)
{
throw new ArgumentOutOfRangeException();
}
// Get wantsRead and wantsWrite from access, note that they cannot both be false
bool wantsRead = (access & FileAccess.Read) == FileAccess.Read;
bool wantsWrite = (access & FileAccess.Write) == FileAccess.Write;
// You can't open for readonly access (wantsWrite == false) when
// mode is CreateNew, Create, Truncate or Append (when it's not Open or OpenOrCreate)
if (mode != FileMode.Open && mode != FileMode.OpenOrCreate && !wantsWrite)
{
throw new ArgumentException();
}
// We need to register the share information prior to the actual file open call (the NativeFileStream ctor)
// so subsequent file operation on the same file will behave correctly
_fileRecord = FileSystemManager.AddToOpenList(_fileName, (int)access, (int)share);
try
{
uint attributes = NativeIO.GetAttributes(_fileName);
bool exists = (attributes != 0xFFFFFFFF);
bool isReadOnly = (exists) ? (((FileAttributes)attributes) & FileAttributes.ReadOnly) == FileAttributes.ReadOnly : false;
// If the path specified is an existing directory, fail
if (exists && ((((FileAttributes)attributes) & FileAttributes.Directory) == FileAttributes.Directory))
{
throw new IOException("", (int)IOException.IOExceptionErrorCode.UnauthorizedAccess);
}
// The seek limit is 0 (the beginning of the file) for all modes except Append
_seekLimit = 0;
switch (mode)
{
case FileMode.CreateNew: // if the file exists, IOException is thrown
if (exists)
{
throw new IOException("", (int)IOException.IOExceptionErrorCode.PathAlreadyExists);
}
_nativeFileStream = new NativeFileStream(_fileName, bufferSize);
break;
case FileMode.Create: // if the file exists, it should be overwritten
_nativeFileStream = new NativeFileStream(_fileName, bufferSize);
if (exists)
{
_nativeFileStream.SetLength(0);
}
break;
case FileMode.Open: // if the file does not exist, IOException/FileNotFound is thrown
if (!exists)
{
throw new IOException("", (int)IOException.IOExceptionErrorCode.FileNotFound);
}
_nativeFileStream = new NativeFileStream(_fileName, bufferSize);
break;
case FileMode.OpenOrCreate: // if the file does not exist, it is created
_nativeFileStream = new NativeFileStream(_fileName, bufferSize);
break;
case FileMode.Truncate: // the file would be overwritten. if the file does not exist, IOException/FileNotFound is thrown
if (!exists)
{
throw new IOException("", (int)IOException.IOExceptionErrorCode.FileNotFound);
}
_nativeFileStream = new NativeFileStream(_fileName, bufferSize);
_nativeFileStream.SetLength(0);
break;
case FileMode.Append: // Opens the file if it exists and seeks to the end of the file. Append can only be used in conjunction with FileAccess.Write
// Attempting to seek to a position before the end of the file will throw an IOException and any attempt to read fails and throws an NotSupportedException
if (access != FileAccess.Write)
{
throw new ArgumentException();
}
_nativeFileStream = new NativeFileStream(_fileName, bufferSize);
_seekLimit = _nativeFileStream.Seek(0, (uint)SeekOrigin.End);
break;
// We've already checked the mode value previously, so no need for default
//default:
// throw new ArgumentOutOfRangeException();
}
// Now that we have a valid NativeFileStream, we add it to the FileRecord, so it could gets clean up
// in case an eject or force format
_fileRecord.NativeFileStream = _nativeFileStream;
// Retrive the filesystem capabilities
_nativeFileStream.GetStreamProperties(out _canRead, out _canWrite, out _canSeek);
// If the file is readonly, regardless of the filesystem capability, we'll turn off write
if (isReadOnly)
{
_canWrite = false;
}
// Make sure the requests (wantsRead / wantsWrite) matches the filesystem capabilities (canRead / canWrite)
if ((wantsRead && !_canRead) || (wantsWrite && !_canWrite))
{
throw new IOException("", (int)IOException.IOExceptionErrorCode.UnauthorizedAccess);
}
// finally, adjust the _canRead / _canWrite to match the requests
if (!wantsWrite)
{
_canWrite = false;
}
else if (!wantsRead)
{
_canRead = false;
}
}
catch
{
// something went wrong, clean up and re-throw the exception
if (_nativeFileStream != null)
{
_nativeFileStream.Close();
}
FileSystemManager.RemoveFromOpenList(_fileRecord);
throw;
}
}