Aaru/Aaru.Filesystems/AppleMFS/Dir.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Dir.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Apple Macintosh File System plugin.
//
// --[ License ] --------------------------------------------------------------
//
//     This library is free software; you can redistribute it and/or modify
//     it under the terms of the GNU Lesser General Public License as
//     published by the Free Software Foundation; either version 2.1 of the
//     License, or (at your option) any later version.
//
//     This library is distributed in the hope that it will be useful, but
//     WITHOUT ANY WARRANTY; without even the implied warranty of
//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
//     Lesser General Public License for more details.
//
//     You should have received a copy of the GNU Lesser General Public
//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2025 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
using Aaru.Logging;

namespace Aaru.Filesystems;

// Information from Inside Macintosh Volume II
public sealed partial class AppleMFS
{
    bool FillDirectory()
    {
        _idToFilename = new Dictionary<uint, string>();
        _idToEntry    = new Dictionary<uint, FileEntry>();
        _filenameToId = new Dictionary<string, uint>();

        var offset = 0;

        while(offset + 51 < _directoryBlocks.Length)
        {
            var entry = new FileEntry
            {
                flFlags = (FileFlags)_directoryBlocks[offset + 0]
            };

            if(!entry.flFlags.HasFlag(FileFlags.Used)) break;

            entry.flTyp = _directoryBlocks[offset + 1];

            entry.flUsrWds = Marshal.ByteArrayToStructureBigEndian<AppleCommon.FInfo>(_directoryBlocks, offset + 2, 16);

            entry.flFlNum  = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 18);
            entry.flStBlk  = BigEndianBitConverter.ToUInt16(_directoryBlocks, offset + 22);
            entry.flLgLen  = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 24);
            entry.flPyLen  = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 28);
            entry.flRStBlk = BigEndianBitConverter.ToUInt16(_directoryBlocks, offset + 32);
            entry.flRLgLen = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 34);
            entry.flRPyLen = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 38);
            entry.flCrDat  = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 42);
            entry.flMdDat  = BigEndianBitConverter.ToUInt32(_directoryBlocks, offset + 46);
            entry.flNam    = new byte[_directoryBlocks[offset + 50] + 1];
            Array.Copy(_directoryBlocks, offset + 50, entry.flNam, 0, entry.flNam.Length);

            string lowerFilename = StringHandlers.PascalToString(entry.flNam, _encoding)
                                                 .ToLowerInvariant()
                                                 .Replace('/', ':');

            if(entry.flFlags.HasFlag(FileFlags.Used)     &&
               !_idToFilename.ContainsKey(entry.flFlNum) &&
               !_idToEntry.ContainsKey(entry.flFlNum)    &&
               !_filenameToId.ContainsKey(lowerFilename) &&
               entry.flFlNum > 0)
            {
                _idToEntry.Add(entry.flFlNum, entry);

                _idToFilename.Add(entry.flFlNum,
                                  StringHandlers.PascalToString(entry.flNam, _encoding).Replace('/', ':'));

                _filenameToId.Add(lowerFilename, entry.flFlNum);

                AaruLogging.Debug(MODULE_NAME, "entry.flFlags = {0}",  entry.flFlags);
                AaruLogging.Debug(MODULE_NAME, "entry.flTyp = {0}",    entry.flTyp);
                AaruLogging.Debug(MODULE_NAME, "entry.flFlNum = {0}",  entry.flFlNum);
                AaruLogging.Debug(MODULE_NAME, "entry.flStBlk = {0}",  entry.flStBlk);
                AaruLogging.Debug(MODULE_NAME, "entry.flLgLen = {0}",  entry.flLgLen);
                AaruLogging.Debug(MODULE_NAME, "entry.flPyLen = {0}",  entry.flPyLen);
                AaruLogging.Debug(MODULE_NAME, "entry.flRStBlk = {0}", entry.flRStBlk);
                AaruLogging.Debug(MODULE_NAME, "entry.flRLgLen = {0}", entry.flRLgLen);
                AaruLogging.Debug(MODULE_NAME, "entry.flRPyLen = {0}", entry.flRPyLen);

                AaruLogging.Debug(MODULE_NAME, "entry.flCrDat = {0}", DateHandlers.MacToDateTime(entry.flCrDat));

                AaruLogging.Debug(MODULE_NAME, "entry.flMdDat = {0}", DateHandlers.MacToDateTime(entry.flMdDat));

                AaruLogging.Debug(MODULE_NAME,
                                  "entry.flNam0 = {0}",
                                  StringHandlers.PascalToString(entry.flNam, _encoding));
            }

            offset += 50 + entry.flNam.Length;

            // "Entries are always an integral number of words"
            if(offset % 2 != 0) offset++;

            // TODO: "Entries don't cross logical block boundaries"
        }

        return true;
    }

#region IReadOnlyFilesystem Members

    /// <inheritdoc />
    public ErrorNumber OpenDir(string path, out IDirNode node)
    {
        node = null;

        if(!_mounted) return ErrorNumber.AccessDenied;

        if(!string.IsNullOrEmpty(path) && !string.Equals(path, "/", StringComparison.OrdinalIgnoreCase))
            return ErrorNumber.NotSupported;

        var contents = _idToFilename.Select(static kvp => kvp.Value).ToList();

        if(_debug)
        {
            contents.Add("$");
            contents.Add("$Bitmap");
            contents.Add("$MDB");

            if(_bootBlocks != null) contents.Add("$Boot");
        }

        contents.Sort();

        node = new AppleMfsDirNode
        {
            Path      = path,
            _position = 0,
            _contents = contents.ToArray()
        };

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber ReadDir(IDirNode node, out string filename)
    {
        filename = null;

        if(!_mounted) return ErrorNumber.AccessDenied;

        if(node is not AppleMfsDirNode mynode) return ErrorNumber.InvalidArgument;

        if(mynode._position < 0) return ErrorNumber.InvalidArgument;

        if(mynode._position >= mynode._contents.Length) return ErrorNumber.NoError;

        filename = mynode._contents[mynode._position++];

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber CloseDir(IDirNode node)
    {
        if(node is not AppleMfsDirNode mynode) return ErrorNumber.InvalidArgument;

        mynode._position = -1;
        mynode._contents = null;

        return ErrorNumber.NoError;
    }

#endregion
}