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- using DiskAccessLibrary.Mod.BlockDifferencingDiskImage;
- using System;
- using System.IO;
- using System.Security.Authentication;
- using System.Text;
- namespace DiskAccessLibrary
- {
- public class BlockDifferencingDiskImage : DiskImage
- {
- private const int SectorSize = 512;
- private BddInfo BddInfo { get; }
- public bool IsNoBaseImage => null == _basedFileStream;
- public int NumberOfBlocks => BddInfo.NumberOfBlocks;
- public int BlockSize => BddInfo.BlockSize;
- public IReadOnlyIndexer<int, bool> IsBlockAllocated { get; }
- private bool _isExclusiveLock;
- private FileStream _basedFileStream;
- private FileStream _snapshotFileStream;
- public BlockDifferencingDiskImage(string diskImagePath, bool isReadOnly) : base(diskImagePath, isReadOnly)
- {
- BddInfo = new BddInfo(diskImagePath);
- IsBlockAllocated = new IReadOnlyIndexer<int, bool>(i => BddInfo.Allocated[i]);
- }
- public void OpenForRead()
- {
- _snapshotFileStream = File.Open(Path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
- }
- public void CloseForRead()
- {
- _snapshotFileStream?.Close();
- }
- public void ReadBlock(byte[] buffer, int offset, int count, int blockIndex, int blockOffset)
- {
- if (false == BddInfo.Allocated[blockIndex])
- {
- if (null == _basedFileStream) return;
- _basedFileStream.Position = (long)blockIndex * BddInfo.BlockSize + blockOffset;
- while (count > 0)
- {
- var read = _basedFileStream.Read(buffer, offset, count);
- offset += read;
- count -= read;
- }
- }
- else
- {
- _snapshotFileStream.Position = BddInfo.Offset[blockIndex] + blockOffset;
- while (count > 0)
- {
- var read = _snapshotFileStream.Read(buffer, offset, count);
- offset += read;
- count -= read;
- }
- }
- }
- private void WriteBlock(byte[] buffer, int offset, int count, int blockIndex, int blockOffset)
- {
- if (false == BddInfo.Allocated[blockIndex])
- {
- //COW:allocate block
- _snapshotFileStream.Position = _snapshotFileStream.Length;
- BddInfo.Offset[blockIndex] = _snapshotFileStream.Position;
- //copy leading block from based image
- if (blockOffset > 0)
- {
- var readCount = blockOffset;
- var bufLeading = new byte[readCount];
- if (null != _basedFileStream)
- {
- _basedFileStream.Position = (long)blockIndex * BddInfo.BlockSize;
- var readOffset = 0;
- while (readCount > 0)
- {
- var read = _basedFileStream.Read(bufLeading, readOffset, readCount);
- readOffset += read;
- readCount -= read;
- }
- }
- _snapshotFileStream.Position = BddInfo.Offset[blockIndex];
- _snapshotFileStream.Write(bufLeading, 0, bufLeading.Length);
- }
- //write to snapshot directly
- _snapshotFileStream.Position = BddInfo.Offset[blockIndex] + blockOffset;
- _snapshotFileStream.Write(buffer, offset, count);
- //copy suffix block from based image
- if (blockOffset + count < BddInfo.BlockSize)
- {
- var suffixOffset = blockOffset + count;
- var readCount = BddInfo.BlockSize - suffixOffset;
- var bufSuffix = new byte[readCount];
- if (null != _basedFileStream)
- {
- _basedFileStream.Position = (long)blockIndex * BddInfo.BlockSize + suffixOffset;
- var readOffset = 0;
- while (readCount > 0)
- {
- var read = _basedFileStream.Read(bufSuffix, readOffset, readCount);
- readOffset += read;
- readCount -= read;
- }
- }
- _snapshotFileStream.Position = BddInfo.Offset[blockIndex] + suffixOffset;
- _snapshotFileStream.Write(bufSuffix, 0, bufSuffix.Length);
- }
- BddInfo.Allocated[blockIndex] = true;
- _snapshotFileStream.Position = BddInfo.EntryTableOffset + BddInfo.BlockIndexEntrySize * blockIndex;
- var bufEntry = BitConverter.GetBytes(BddInfo.Entries[blockIndex]);
- _snapshotFileStream.Write(bufEntry, 0, bufEntry.Length);
- }
- else
- {
- _snapshotFileStream.Position = BddInfo.Offset[blockIndex] + blockOffset;
- _snapshotFileStream.Write(buffer, offset, count);
- }
- }
- public override byte[] ReadSectors(long sectorIndex, int sectorCount)
- {
- var rawOffset = sectorIndex * SectorSize;
- var rawSize = sectorCount * SectorSize;
- var buffer = new byte[rawSize];
- for (var i = 0; i < rawSize;)
- {
- var blockIndex = (int)(rawOffset / BddInfo.BlockSize);
- var blockOffset = (int)(rawOffset % BddInfo.BlockSize);
- var bytesToRead = BddInfo.BlockSize - blockOffset;
- if (i + bytesToRead > rawSize)
- {
- bytesToRead = rawSize - i;
- }
- ReadBlock(buffer, i, bytesToRead, blockIndex, blockOffset);
- i += bytesToRead;
- rawOffset += bytesToRead;
- }
- return buffer;
- }
- public override void WriteSectors(long sectorIndex, byte[] data)
- {
- if (IsReadOnly) throw new AuthenticationException("Read only");
- var rawOffset = sectorIndex * SectorSize;
- for (var i = 0; i < data.Length;)
- {
- var blockIndex = (int)(rawOffset / BddInfo.BlockSize);
- var blockOffset = (int)(rawOffset % BddInfo.BlockSize);
- var bytesToWrite = BddInfo.BlockSize - blockOffset;
- if (i + bytesToWrite > data.Length)
- {
- bytesToWrite = data.Length - i;
- }
- WriteBlock(data, i, bytesToWrite, blockIndex, blockOffset);
- i += bytesToWrite;
- rawOffset += bytesToWrite;
- }
- }
- public override bool ExclusiveLock()
- {
- if (_isExclusiveLock) return true;
- _basedFileStream?.Close();
- _snapshotFileStream?.Close();
- if (null != BddInfo.BasedImagePath) _basedFileStream = new FileStream(BddInfo.BasedImagePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
- _snapshotFileStream = IsReadOnly
- ? File.Open(Path, FileMode.Open, FileAccess.Read, FileShare.Read)
- : File.Open(Path, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
- _isExclusiveLock = true;
- return true;
- }
- public void Clean()
- {
- if (IsReadOnly) return;
- for (var blockIndex = 0; blockIndex < BddInfo.NumberOfBlocks; blockIndex++)
- {
- BddInfo.Allocated[blockIndex] = false;
- }
- for (var blockIndex = 0; blockIndex < BddInfo.NumberOfBlocks; blockIndex++)
- {
- _snapshotFileStream.Position = BddInfo.EntryTableOffset + BddInfo.BlockIndexEntrySize * blockIndex;
- var bufEntry = BitConverter.GetBytes(BddInfo.Entries[blockIndex]);
- _snapshotFileStream.Write(bufEntry, 0, bufEntry.Length);
- }
- _snapshotFileStream.SetLength(BddInfo.EntryTableOffset + BddInfo.NumberOfBlocks * BddInfo.BlockIndexEntrySize);
- }
- public override bool ReleaseLock()
- {
- _basedFileStream?.Close();
- _snapshotFileStream?.Close();
- _isExclusiveLock = false;
- return true;
- }
- public static BlockDifferencingDiskImage Create(string snapshot, long size, int blockSize)
- {
- var numberOfBlocks = (int)Math.DivRem(size, blockSize, out var rem);
- if (rem != 0) throw new ArgumentException("Size no align to blockSize");
- using var stream = File.Create(snapshot);
- using var writer = new BinaryWriter(stream);
- writer.Write((ushort)0);
- writer.Write(blockSize);
- writer.Write(numberOfBlocks);
- writer.Flush();
- stream.SetLength(stream.Length + numberOfBlocks * BddInfo.BlockIndexEntrySize);
- writer.Close();
- stream.Close();
- //return instance
- return new BlockDifferencingDiskImage(snapshot);
- }
- public static BlockDifferencingDiskImage Create(string based, string snapshot, int blockSize)
- {
- var fileInfo = new FileInfo(based);
- if (fileInfo.Length % blockSize != 0) throw new ArgumentException("Block size no mul to base image size", nameof(blockSize));
- using var stream = File.Create(snapshot);
- using var writer = new BinaryWriter(stream);
- //create bdd struct
- var bufBasedPath = Encoding.UTF8.GetBytes(System.IO.Path.GetFullPath(based));
- var numberOfBlocks = (int)(fileInfo.Length / blockSize);
- writer.Write((ushort)bufBasedPath.Length);
- writer.Write(bufBasedPath);
- writer.Write(blockSize);
- writer.Write(numberOfBlocks);
- writer.Flush();
- stream.SetLength(stream.Length + numberOfBlocks * BddInfo.BlockIndexEntrySize);
- writer.Close();
- stream.Close();
- //return instance
- return new BlockDifferencingDiskImage(snapshot);
- }
- public override long Size => BddInfo.Length;
- public override int BytesPerSector => SectorSize;
- ////////////////////////////////////////////////////////////////////////////////////
- public BlockDifferencingDiskImage(string diskImagePath) : this(diskImagePath, false)
- {
- }
- public override bool ExclusiveLock(bool useOverlappedIO)
- {
- throw new System.NotImplementedException();
- }
- public override void Extend(long numberOfAdditionalBytes)
- {
- throw new System.NotImplementedException();
- }
- }
- }
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