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87 lines
3.3 KiB
C#
87 lines
3.3 KiB
C#
// /***************************************************************************
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// Aaru Data Preservation Suite
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// ----------------------------------------------------------------------------
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//
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// Filename : Block.cs
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// Author(s) : Natalia Portillo <claunia@claunia.com>
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//
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// Component : Reiser4 filesystem plugin
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//
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// --[ License ] --------------------------------------------------------------
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//
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// This library is free software; you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 2.1 of the
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// License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, see <http://www.gnu.org/licenses/>.
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//
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// ----------------------------------------------------------------------------
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// Copyright © 2011-2026 Natalia Portillo
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// ****************************************************************************/
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using System;
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using Aaru.CommonTypes.Enums;
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using Aaru.Logging;
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namespace Aaru.Filesystems;
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public sealed partial class Reiser4
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{
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/// <summary>Reads a filesystem block by its block number</summary>
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/// <param name="blockNumber">Block number to read</param>
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/// <param name="data">The read block data</param>
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/// <returns>Error number indicating success or failure</returns>
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ErrorNumber ReadBlock(ulong blockNumber, out byte[] data)
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{
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data = null;
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if(_blockCache != null && _blockCache.TryGetValue(blockNumber, out data)) return ErrorNumber.NoError;
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uint sectorSize = _imagePlugin.Info.SectorSize;
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// Calculate byte offset of the block
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ulong byteOffset = blockNumber * _blockSize;
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// Calculate which sector contains this byte offset
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ulong sectorNumber = byteOffset / sectorSize + _partition.Start;
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var offsetInSector = (int)(byteOffset % sectorSize);
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// Calculate how many sectors we need to read to get the full block
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var sectorsToRead = (uint)((offsetInSector + _blockSize + sectorSize - 1) / sectorSize);
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ErrorNumber errno = _imagePlugin.ReadSectors(sectorNumber, false, sectorsToRead, out byte[] sectorData, out _);
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if(errno != ErrorNumber.NoError)
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{
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AaruLogging.Debug(MODULE_NAME, "Error reading block {0}: {1}", blockNumber, errno);
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return errno;
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}
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// Extract the block data from the sector data
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if(offsetInSector == 0 && sectorData.Length == _blockSize)
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data = sectorData;
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else
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{
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data = new byte[_blockSize];
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Array.Copy(sectorData,
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offsetInSector,
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data,
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0,
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(long)Math.Min(_blockSize, (ulong)(sectorData.Length - offsetInSector)));
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}
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// Cache the block (limit cache to avoid excessive memory use)
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if(_blockCache is { Count: < 4096 }) _blockCache[blockNumber] = data;
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return ErrorNumber.NoError;
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}
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} |