Aaru/Aaru.Filesystems/ISO9660/PathTable.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : PathTable.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : ISO9660 filesystem 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
// In the loving memory of Facunda "Tata" Suárez Domínguez, R.I.P. 2019/07/24
// ****************************************************************************/

using System.Collections.Generic;
using Aaru.Helpers;

namespace Aaru.Filesystems;

public sealed partial class ISO9660
{
    PathTableEntryInternal[] DecodePathTable(byte[] data)
    {
        if(data is null || data.Length == 0) return null;

        List<PathTableEntryInternal> table = [];

        var off = 0;

        PathTableEntry entry =
            Marshal.ByteArrayToStructureBigEndian<PathTableEntry>(data, off, Marshal.SizeOf<PathTableEntry>());

        if(entry.name_len                         != 1                                ||
           entry.parent_dirno                     != 1                                ||
           data.Length                            <= Marshal.SizeOf<PathTableEntry>() ||
           data[Marshal.SizeOf<PathTableEntry>()] != 0x00)
            return null;

        while(off < data.Length)
        {
            entry = Marshal.ByteArrayToStructureBigEndian<PathTableEntry>(data, off, Marshal.SizeOf<PathTableEntry>());

            if(entry.name_len == 0) break;

            off += Marshal.SizeOf<PathTableEntry>();

            string name = _encoding.GetString(data, off, entry.name_len);

            table.Add(new PathTableEntryInternal
            {
                Extent      = entry.start_lbn,
                Name        = name,
                Parent      = entry.parent_dirno,
                XattrLength = entry.xattr_len
            });

            off += entry.name_len;

            if(entry.name_len % 2 != 0) off++;
        }

        return table.ToArray();
    }

    PathTableEntryInternal[] DecodeHighSierraPathTable(byte[] data)
    {
        if(data is null) return null;

        List<PathTableEntryInternal> table = [];

        var off = 0;

        while(off < data.Length)
        {
            HighSierraPathTableEntry entry =
                Marshal.ByteArrayToStructureBigEndian<HighSierraPathTableEntry>(data,
                                                                                    off,
                                                                                    Marshal
                                                                                       .SizeOf<
                                                                                            HighSierraPathTableEntry>());

            if(entry.name_len == 0) break;

            off += Marshal.SizeOf<HighSierraPathTableEntry>();

            string name = _encoding.GetString(data, off, entry.name_len);

            table.Add(new PathTableEntryInternal
            {
                Extent      = entry.start_lbn,
                Name        = name,
                Parent      = entry.parent_dirno,
                XattrLength = entry.xattr_len
            });

            off += entry.name_len;

            if(entry.name_len % 2 != 0) off++;
        }

        return table.ToArray();
    }
}