C# Section.Extend方法代码示例

        public MemoryFileSystem(string fileName, MfsOpenMode mode, bool readOnly, MfsParameters createParams)
        {
            FileCreationDispositionWin32 cdWin32;

            if (readOnly && mode != MfsOpenMode.Open)
                throw new ArgumentException("Invalid mode for read only access.");

            switch (mode)
            {
                case MfsOpenMode.Open:
                    cdWin32 = FileCreationDispositionWin32.OpenExisting;
                    break;
                default:
                case MfsOpenMode.OpenIf:
                    cdWin32 = FileCreationDispositionWin32.OpenAlways;
                    break;
                case MfsOpenMode.OverwriteIf:
                    cdWin32 = FileCreationDispositionWin32.CreateAlways;
                    break;
            }

            using (FileHandle fhandle = FileHandle.CreateWin32(
                fileName,
                FileAccess.GenericRead | (!readOnly ? FileAccess.GenericWrite : 0),
                FileShareMode.Read,
                cdWin32
                ))
            {
                bool justCreated = false;

                _readOnly = readOnly;
                _protection = !readOnly ? MemoryProtection.ReadWrite : MemoryProtection.ReadOnly;

                if (fhandle.FileSize == 0)
                {
                    if (readOnly)
                    {
                        throw new MfsInvalidFileSystemException();
                    }
                    
                    // File is too small. Make it 1 byte large and we'll deal with it soon.
                    fhandle.SetEnd(1);
                }

                _section = new Section(fhandle, _protection);

                _blockSize = MfsBlockSizeBase; // fake block size to begin with; we'll fix it up later.

                if (fhandle.FileSize < _blockSize)
                {
                    if (readOnly)
                    {
                        throw new MfsInvalidFileSystemException();
                    }
                    
                    // We're creating a new file system. We need the correct block size now.
                    if (createParams != null)
                        this._blockSize = createParams.BlockSize;
                    else
                        this._blockSize = MfsDefaultBlockSize;

                    this._section.Extend(this._blockSize);

                    using (SectionView view = this._section.MapView(0, this._blockSize, this._protection))
                    {
                        this.InitializeFs((MfsFsHeader*)view.Memory, createParams);
                    }

                    justCreated = true;
                }

                _header = (MfsFsHeader*)this.ReferenceBlock(0);

                // Check the magic.
                if (_header->Magic != MfsMagic)
                    throw new MfsInvalidFileSystemException();

                // Set up the local constants.
                _blockSize = _header->BlockSize;
                _cellSize = _header->CellSize;

                // Backwards compatibility.
                if (_blockSize == 0)
                    _blockSize = MfsDefaultBlockSize;
                if (_cellSize == 0)
                    _cellSize = MfsDefaultCellSize;

                // Validate the parameters.
                this.ValidateFsParameters(_blockSize, _cellSize);

                _blockMask = _blockSize - 1;
                _cellCount = _blockSize / _cellSize;
                _dataCellDataMaxLength = _cellSize - MfsDataCell.DataOffset;

                // Remap block 0 with the correct block size.
                this.DereferenceBlock(0);

                // If we just created a new file system, fix the section size.
                if (justCreated)
                    _section.Extend(_blockSize);
//.........这里部分代码省略.........