119 lines
4.4 KiB
C#
119 lines
4.4 KiB
C#
// Copyright (C) 2026, The Duplicati Team
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// https://duplicati.com, hello@duplicati.com
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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using System;
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using System.IO;
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using System.Threading;
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using System.Threading.Tasks;
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using Duplicati.Library.Utility;
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using Duplicati.Proprietary.DiskImage.Disk;
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namespace Duplicati.Proprietary.DiskImage.Partition;
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/// <summary>
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/// A stream that buffers reads from a partition.
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/// Uses ArrayPool to avoid LOH allocations for large buffers.
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/// </summary>
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internal class PartitionReadStream : Stream
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{
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private readonly IRawDisk _disk;
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/// <summary>
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/// Starting offset of the partition on the disk.
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/// </summary>
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private readonly long _startOffset;
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private readonly long _length;
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private long _position;
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private bool _disposed = false;
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public PartitionReadStream(IRawDisk disk, long startOffset, long length)
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{
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_disk = disk;
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_startOffset = startOffset;
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_length = length;
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_position = 0;
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}
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public override bool CanRead => true;
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public override bool CanSeek => true;
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public override bool CanWrite => false;
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public override long Length => _length;
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public override long Position
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{
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get => _position;
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set
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{
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if (value < 0 || value > _length)
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throw new System.ArgumentOutOfRangeException(nameof(value));
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_position = value;
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}
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}
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public override void Flush() { }
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public override int Read(byte[] buffer, int offset, int count)
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=> ReadAsync(buffer, offset, count, CancellationToken.None).Await();
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public async override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken token)
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{
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if (_disposed)
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throw new ObjectDisposedException(nameof(PartitionReadStream));
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if (buffer == null)
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throw new ArgumentNullException(nameof(buffer));
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if (offset < 0 || offset > buffer.Length)
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throw new ArgumentOutOfRangeException(nameof(offset));
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if (count < 0 || offset + count > buffer.Length)
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throw new ArgumentOutOfRangeException(nameof(count));
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if (_position >= _length)
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return 0; // EOF
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var bytesToRead = Math.Min(count, _length - _position);
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if (bytesToRead > 0)
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{
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return await _disk.ReadBytesAsync(_startOffset + _position, buffer.AsMemory(offset, (int)bytesToRead), token).ConfigureAwait(false);
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}
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return 0;
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}
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public override long Seek(long offset, SeekOrigin origin)
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{
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var newPosition = origin switch
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{
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SeekOrigin.Begin => offset,
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SeekOrigin.Current => _position + offset,
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SeekOrigin.End => _length + offset,
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_ => throw new System.ArgumentOutOfRangeException(nameof(origin))
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};
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if (newPosition < 0 || newPosition > _length)
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throw new IOException("Cannot seek beyond partition size.");
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_position = newPosition;
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return _position;
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}
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public override void SetLength(long value)
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=> throw new NotSupportedException("SetLength is not supported on PartitionReadStream.");
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public override void Write(byte[] buffer, int offset, int count)
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=> throw new NotSupportedException("Write is not supported on PartitionReadStream.");
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protected override void Dispose(bool disposing)
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{
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if (!_disposed)
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_disposed = true;
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base.Dispose(disposing);
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}
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}
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