mirror of
https://github.com/aaru-dps/Aaru.git
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250 lines
8.6 KiB
C#
250 lines
8.6 KiB
C#
// /***************************************************************************
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// Aaru Data Preservation Suite
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// ----------------------------------------------------------------------------
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//
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// Filename : Mount.cs
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// Author(s) : Natalia Portillo <claunia@claunia.com>
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//
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// Component : Cram file system 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.Text;
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using Aaru.CommonTypes.AaruMetadata;
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using Aaru.CommonTypes.Enums;
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using Aaru.CommonTypes.Interfaces;
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using Aaru.Helpers;
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using Aaru.Logging;
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using Partition = Aaru.CommonTypes.Partition;
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namespace Aaru.Filesystems;
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/// <inheritdoc />
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public sealed partial class Cram
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{
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/// <inheritdoc />
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public ErrorNumber Mount(IMediaImage imagePlugin, Partition partition, Encoding encoding,
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Dictionary<string, string> options, string @namespace)
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{
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AaruLogging.Debug(MODULE_NAME, "Mounting CramFS volume");
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_imagePlugin = imagePlugin;
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_partition = partition;
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_encoding = encoding ?? Encoding.GetEncoding("iso-8859-15");
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_rootDirectoryCache = new Dictionary<string, DirectoryEntryInfo>(StringComparer.Ordinal);
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// Read and validate the superblock
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ErrorNumber errno = ReadSuperBlock();
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if(errno != ErrorNumber.NoError)
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{
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AaruLogging.Debug(MODULE_NAME, "Error reading superblock: {0}", errno);
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return errno;
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}
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AaruLogging.Debug(MODULE_NAME, "Superblock read successfully");
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// Check for unsupported flags
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var flags = (CramFlags)_superBlock.flags;
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if(((uint)flags & ~(uint)CramSupportedFlags.All) != 0)
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{
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AaruLogging.Debug(MODULE_NAME, "Unsupported flags: 0x{0:X8}", _superBlock.flags);
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return ErrorNumber.NotSupported;
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}
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// Validate root inode is a directory
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if(!IsDirectory(GetInodeMode(_superBlock.root)))
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{
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AaruLogging.Debug(MODULE_NAME, "Root is not a directory, mode: 0x{0:X4}", GetInodeMode(_superBlock.root));
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return ErrorNumber.InvalidArgument;
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}
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// Load root directory
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errno = LoadRootDirectory();
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if(errno != ErrorNumber.NoError)
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{
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AaruLogging.Debug(MODULE_NAME, "Error loading root directory: {0}", errno);
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return errno;
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}
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AaruLogging.Debug(MODULE_NAME, "Root directory loaded with {0} entries", _rootDirectoryCache.Count);
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// Build metadata
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string volumeName = StringHandlers.CToString(_superBlock.name, _encoding);
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Metadata = new FileSystem
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{
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Type = FS_TYPE,
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VolumeName = volumeName,
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ClusterSize = 4096, // CramFS uses 4K pages
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Clusters = _superBlock.fsid.blocks,
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Files = _superBlock.fsid.files,
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FreeClusters = 0 // CramFS is read-only, no free space
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};
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_mounted = true;
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AaruLogging.Debug(MODULE_NAME, "Volume mounted successfully");
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return ErrorNumber.NoError;
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}
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/// <inheritdoc />
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public ErrorNumber Unmount()
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{
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if(!_mounted) return ErrorNumber.AccessDenied;
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AaruLogging.Debug(MODULE_NAME, "Unmounting volume");
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_rootDirectoryCache?.Clear();
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_mounted = false;
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_imagePlugin = null;
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_partition = default(Partition);
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_superBlock = default(SuperBlock);
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_encoding = null;
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_baseOffset = 0;
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Metadata = null;
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AaruLogging.Debug(MODULE_NAME, "Volume unmounted");
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return ErrorNumber.NoError;
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}
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/// <summary>Reads and validates the CramFS superblock</summary>
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/// <returns>Error number indicating success or failure</returns>
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ErrorNumber ReadSuperBlock()
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{
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AaruLogging.Debug(MODULE_NAME, "Reading superblock...");
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// Read the first sector
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ErrorNumber errno = _imagePlugin.ReadSector(_partition.Start, false, out byte[] sector, out _);
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if(errno != ErrorNumber.NoError)
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{
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AaruLogging.Debug(MODULE_NAME, "Error reading first sector: {0}", errno);
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return errno;
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}
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// Check magic at offset 0
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var magic = BitConverter.ToUInt32(sector, 0);
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_baseOffset = 0;
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if(magic == CRAM_MAGIC)
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{
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_superBlock = Marshal.ByteArrayToStructureLittleEndian<SuperBlock>(sector);
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_littleEndian = true;
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}
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else if(magic == CRAM_CIGAM)
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{
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_superBlock = Marshal.ByteArrayToStructureBigEndian<SuperBlock>(sector);
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_littleEndian = false;
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}
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else
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{
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// Check at 512 byte offset (some cramfs images have the superblock shifted)
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if(sector.Length >= 512 + 4)
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{
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magic = BitConverter.ToUInt32(sector, 512);
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if(magic == CRAM_MAGIC)
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{
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var sbData = new byte[sector.Length - 512];
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Array.Copy(sector, 512, sbData, 0, sbData.Length);
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_superBlock = Marshal.ByteArrayToStructureLittleEndian<SuperBlock>(sbData);
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_littleEndian = true;
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_baseOffset = 512;
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}
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else if(magic == CRAM_CIGAM)
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{
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var sbData = new byte[sector.Length - 512];
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Array.Copy(sector, 512, sbData, 0, sbData.Length);
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_superBlock = Marshal.ByteArrayToStructureBigEndian<SuperBlock>(sbData);
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_littleEndian = false;
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_baseOffset = 512;
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}
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else
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{
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AaruLogging.Debug(MODULE_NAME, "Invalid magic: 0x{0:X8}", magic);
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return ErrorNumber.InvalidArgument;
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}
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}
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else
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{
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AaruLogging.Debug(MODULE_NAME, "Invalid magic: 0x{0:X8}", magic);
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return ErrorNumber.InvalidArgument;
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}
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}
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AaruLogging.Debug(MODULE_NAME,
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"Magic: 0x{0:X8}, little-endian: {1}, base offset: {2}",
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_superBlock.magic,
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_littleEndian,
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_baseOffset);
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// Validate signature
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string signature = Encoding.ASCII.GetString(_superBlock.signature);
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if(!signature.StartsWith(CRAMFS_SIGNATURE, StringComparison.Ordinal))
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{
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AaruLogging.Debug(MODULE_NAME, "Invalid signature: {0}", signature);
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return ErrorNumber.InvalidArgument;
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}
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AaruLogging.Debug(MODULE_NAME, "Filesystem size: {0} bytes", _superBlock.size);
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AaruLogging.Debug(MODULE_NAME, "Flags: 0x{0:X8}", _superBlock.flags);
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AaruLogging.Debug(MODULE_NAME, "Files: {0}, Blocks: {1}", _superBlock.fsid.files, _superBlock.fsid.blocks);
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return ErrorNumber.NoError;
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}
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/// <summary>Loads and caches the root directory contents</summary>
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/// <returns>Error number indicating success or failure</returns>
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ErrorNumber LoadRootDirectory()
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{
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// Root directory offset is in the root inode
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uint rootOffset = GetInodeOffset(_superBlock.root) << 2;
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uint rootSize = GetInodeSize(_superBlock.root);
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AaruLogging.Debug(MODULE_NAME, "Root directory offset: {0}, size: {1}", rootOffset, rootSize);
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if(rootOffset == 0)
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{
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// Empty filesystem
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AaruLogging.Debug(MODULE_NAME, "Empty filesystem (root offset is 0)");
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return ErrorNumber.NoError;
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}
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return ReadDirectoryContents(rootOffset, rootSize, _rootDirectoryCache);
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}
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} |