mirror of
https://github.com/aaru-dps/Aaru.git
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Natalia Portillo
2adc7349a6
Had to fully reverse engineer the changes from SFS\0 because https://aminet.net/package/disk/misc/SFS includes the binaries but not the sources for SFS\2 effectively violating the GPL.
366 lines
14 KiB
C#
366 lines
14 KiB
C#
// /***************************************************************************
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// Aaru Data Preservation Suite
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// ----------------------------------------------------------------------------
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//
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// Filename : Object.cs
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// Author(s) : Natalia Portillo <claunia@claunia.com>
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//
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// Component : SmartFileSystem 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 System.Collections.Generic;
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using System.Linq;
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using Aaru.CommonTypes.Enums;
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using Aaru.Helpers;
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using Aaru.Logging;
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namespace Aaru.Filesystems;
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/// <inheritdoc />
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/// <summary>Implements the Smart File System</summary>
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public sealed partial class SFS
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{
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/// <summary>Reads an object's name from object data</summary>
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/// <param name="objectContainerData">The object container block data</param>
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/// <param name="objectOffset">Offset to the object within the container</param>
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/// <returns>The object name</returns>
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string ReadObjectName(byte[] objectContainerData, int objectOffset)
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{
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// Object structure: skip header fields to reach the name
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// SFS\0: ownerUid(2) + ownerGid(2) + objectNode(4) + protection(4) +
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// dataOrHashtable(4) + sizeOrFirstDirBlock(4) + dateModified(4) + bits(1) = 25 bytes
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// SFS\2: Same + sizeh(2) = 27 bytes
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// The name immediately follows the fixed part of the object
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int nameOffset = objectOffset + _objectSize;
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// Read null-terminated string
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var nameBytes = new List<byte>();
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for(int i = nameOffset; i < objectContainerData.Length && objectContainerData[i] != 0; i++)
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nameBytes.Add(objectContainerData[i]);
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return _encoding.GetString(nameBytes.ToArray());
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}
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/// <summary>Finds an object node's block address</summary>
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/// <param name="nodeNumber">The node number to find</param>
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/// <param name="blockAddress">The block address of the object container</param>
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/// <returns>Error code indicating success or failure</returns>
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ErrorNumber FindObjectNode(uint nodeNumber, out uint blockAddress)
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{
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blockAddress = 0;
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uint nodeIndex = _objectNodeRoot;
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// shifts_block32 = shifts_block - BLCKFACCURACY (5)
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// shifts_block = log2(block_size)
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int shiftsBlock32 = _blockShift - 5;
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if(shiftsBlock32 < 0) shiftsBlock32 = 0;
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while(true)
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{
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ErrorNumber errno = ReadBlock(nodeIndex, out byte[] nodeData);
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if(errno != ErrorNumber.NoError) return errno;
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// Validate node container
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var id = BigEndianBitConverter.ToUInt32(nodeData, 0);
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if(id != NODECONTAINER_ID)
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{
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AaruLogging.Debug(MODULE_NAME, "Invalid node container ID: 0x{0:X8}", id);
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return ErrorNumber.InvalidArgument;
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}
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// NodeContainer: header(12) + nodeNumber(4) + nodes(4)
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var nodeContainerNodeNumber = BigEndianBitConverter.ToUInt32(nodeData, 12);
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var nodesPerContainer = BigEndianBitConverter.ToUInt32(nodeData, 16);
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if(nodesPerContainer == 1)
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{
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// This is a leaf node container - find the actual node
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// ObjectNode: data(4) + next(4) + hash16(2) = 10 bytes
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const int objectNodeSize = 10;
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uint nodeOffset = (nodeNumber - nodeContainerNodeNumber) * objectNodeSize;
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int dataOffset = 20 + (int)nodeOffset; // After header
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if(dataOffset + 4 > nodeData.Length)
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{
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AaruLogging.Debug(MODULE_NAME, "Node offset out of bounds");
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return ErrorNumber.InvalidArgument;
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}
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blockAddress = BigEndianBitConverter.ToUInt32(nodeData, dataOffset);
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return ErrorNumber.NoError;
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}
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// Index node - descend to the appropriate child
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uint containerEntry = (nodeNumber - nodeContainerNodeNumber) / nodesPerContainer;
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int entryOffset = 20 + (int)containerEntry * 4;
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if(entryOffset + 4 > nodeData.Length)
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{
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AaruLogging.Debug(MODULE_NAME, "Container entry offset out of bounds");
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return ErrorNumber.InvalidArgument;
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}
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var entryValue = BigEndianBitConverter.ToUInt32(nodeData, entryOffset);
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// Extract block number from the entry (stored shifted)
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nodeIndex = entryValue >> shiftsBlock32;
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}
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}
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/// <summary>Finds an object in an object container</summary>
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/// <param name="containerData">The container data</param>
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/// <param name="objectNode">The object node number to find</param>
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/// <param name="objectOffset">The offset to the object in the container</param>
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/// <returns>Error code indicating success or failure</returns>
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ErrorNumber FindObjectInContainer(byte[] containerData, uint objectNode, out int objectOffset)
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{
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// Start after the ObjectContainer header: header(12) + parent(4) + next(4) + previous(4) = 24 bytes
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objectOffset = 24;
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int endOffset = (int)_blockSize - _objectSize - 2;
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while(objectOffset < endOffset)
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{
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// Check if there's a valid object (name[0] != 0)
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int nameOffset = objectOffset + _objectSize;
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if(nameOffset >= containerData.Length || containerData[nameOffset] == 0) break;
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// Read object node number
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var nodeNum = BigEndianBitConverter.ToUInt32(containerData, objectOffset + 4);
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if(nodeNum == objectNode) return ErrorNumber.NoError;
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// Move to next object
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objectOffset = GetNextObjectOffset(containerData, objectOffset);
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if(objectOffset < 0) break;
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}
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return ErrorNumber.NoData;
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}
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/// <summary>Gets the offset to the next object in a container</summary>
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/// <param name="containerData">The container data</param>
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/// <param name="currentOffset">Current object offset</param>
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/// <returns>Offset to next object, or -1 if none</returns>
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int GetNextObjectOffset(byte[] containerData, int currentOffset)
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{
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// Skip to name field
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int nameOffset = currentOffset + _objectSize;
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if(nameOffset >= containerData.Length) return -1;
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// Skip name (null-terminated)
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while(nameOffset < containerData.Length && containerData[nameOffset] != 0) nameOffset++;
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nameOffset++; // Skip null terminator
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// Skip comment (null-terminated)
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while(nameOffset < containerData.Length && containerData[nameOffset] != 0) nameOffset++;
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nameOffset++; // Skip null terminator
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// Align to word boundary
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if((nameOffset & 1) != 0) nameOffset++;
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return nameOffset;
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}
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/// <summary>Parses objects in a container and adds them to the directory cache</summary>
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/// <param name="containerData">The container data</param>
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void ParseObjectContainer(byte[] containerData)
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{
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// Start after the ObjectContainer header: header(12) + parent(4) + next(4) + previous(4) = 24 bytes
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var offset = 24;
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int endOffset = (int)_blockSize - _objectSize - 2;
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while(offset < endOffset && offset < containerData.Length - _objectSize)
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{
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// Check if there's a valid object (name[0] != 0)
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int nameOffset = offset + _objectSize;
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if(nameOffset >= containerData.Length || containerData[nameOffset] == 0) break;
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// Read object node number
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var objectNode = BigEndianBitConverter.ToUInt32(containerData, offset + 4);
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// Read name
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string name = ReadObjectName(containerData, offset);
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if(!string.IsNullOrEmpty(name) && !_rootDirectoryCache.ContainsKey(name))
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{
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_rootDirectoryCache[name] = objectNode;
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AaruLogging.Debug(MODULE_NAME, "Found entry: {0} -> node {1}", name, objectNode);
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}
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// Move to next object
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offset = GetNextObjectOffset(containerData, offset);
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if(offset < 0) break;
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}
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}
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/// <summary>Parses objects in a container and adds them to a dictionary</summary>
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/// <param name="containerData">The container data</param>
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/// <param name="entries">Dictionary to add entries to</param>
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void ParseObjectContainerToDict(byte[] containerData, Dictionary<string, uint> entries)
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{
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// Start after the ObjectContainer header: header(12) + parent(4) + next(4) + previous(4) = 24 bytes
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var offset = 24;
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int endOffset = (int)_blockSize - _objectSize - 2;
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while(offset < endOffset && offset < containerData.Length - _objectSize)
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{
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// Check if there's a valid object (name[0] != 0)
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int nameOffset = offset + _objectSize;
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if(nameOffset >= containerData.Length || containerData[nameOffset] == 0) break;
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// Read object node number
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var objectNode = BigEndianBitConverter.ToUInt32(containerData, offset + 4);
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// Read name
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string name = ReadObjectName(containerData, offset);
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if(!string.IsNullOrEmpty(name) && !entries.ContainsKey(name)) entries[name] = objectNode;
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// Move to next object
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offset = GetNextObjectOffset(containerData, offset);
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if(offset < 0) break;
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}
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}
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/// <summary>Gets the object node number for a given path</summary>
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/// <param name="path">The path to resolve</param>
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/// <param name="objectNode">Output object node number</param>
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/// <returns>Error code indicating success or failure</returns>
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ErrorNumber GetObjectNodeForPath(string path, out uint objectNode)
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{
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objectNode = 0;
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// Root directory
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if(path == "/" || string.Equals(path, "/", StringComparison.OrdinalIgnoreCase))
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{
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objectNode = ROOTNODE;
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return ErrorNumber.NoError;
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}
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// Remove leading slash and split path
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string pathWithoutLeadingSlash = path.StartsWith("/", StringComparison.Ordinal) ? path[1..] : path;
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string[] pathComponents = pathWithoutLeadingSlash.Split('/', StringSplitOptions.RemoveEmptyEntries);
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if(pathComponents.Length == 0) return ErrorNumber.InvalidArgument;
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// Start traversal from root directory cache
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Dictionary<string, uint> currentDirectory = _rootDirectoryCache;
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// Traverse all path components
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for(var i = 0; i < pathComponents.Length; i++)
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{
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string component = pathComponents[i];
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// Find the component in current directory (handle case sensitivity)
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string foundKey =
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currentDirectory.Keys.FirstOrDefault(key => string.Equals(key,
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component,
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_caseSensitive
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? StringComparison.Ordinal
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: StringComparison.OrdinalIgnoreCase));
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if(foundKey == null) return ErrorNumber.NoSuchFile;
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objectNode = currentDirectory[foundKey];
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// If this is the last component, we found our target
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if(i == pathComponents.Length - 1) return ErrorNumber.NoError;
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// Not the last component - read directory contents for next iteration
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ErrorNumber errno = ReadDirectoryContents(objectNode, out Dictionary<string, uint> childEntries);
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if(errno != ErrorNumber.NoError) return errno;
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currentDirectory = childEntries;
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}
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return ErrorNumber.NoError;
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}
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/// <summary>Reads the comment for an object given its node number</summary>
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/// <param name="objectNode">The object node number</param>
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/// <param name="comment">Output comment string</param>
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/// <returns>Error code indicating success or failure</returns>
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ErrorNumber ReadObjectComment(uint objectNode, out string comment)
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{
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comment = null;
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// Find the object container for this node
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ErrorNumber errno = FindObjectNode(objectNode, out uint objectBlock);
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if(errno != ErrorNumber.NoError) return errno;
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errno = ReadBlock(objectBlock, out byte[] objectData);
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if(errno != ErrorNumber.NoError) return errno;
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// Find the object in the container
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errno = FindObjectInContainer(objectData, objectNode, out int objectOffset);
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if(errno != ErrorNumber.NoError) return errno;
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// Object structure: fixed fields + name (null-terminated) + comment (null-terminated)
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// SFS\0: 25 bytes, SFS\2: 27 bytes
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// Skip to name field
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int nameOffset = objectOffset + _objectSize;
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if(nameOffset >= objectData.Length) return ErrorNumber.InvalidArgument;
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// Skip the name (null-terminated string)
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int commentOffset = nameOffset;
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while(commentOffset < objectData.Length && objectData[commentOffset] != 0) commentOffset++;
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commentOffset++; // Skip null terminator
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if(commentOffset >= objectData.Length) return ErrorNumber.NoError; // No comment
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// Read the comment (null-terminated string)
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var commentBytes = new List<byte>();
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while(commentOffset < objectData.Length && objectData[commentOffset] != 0)
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commentBytes.Add(objectData[commentOffset++]);
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if(commentBytes.Count > 0) comment = _encoding.GetString(commentBytes.ToArray());
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return ErrorNumber.NoError;
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}
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} |