Aaru/Aaru.Filesystems/LisaFS/Xattr.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Xattr.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Apple Lisa filesystem plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Methods to handle Apple Lisa extended attributes (label, tags, serial,
//     etc).
//
// --[ 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 © 2011-2022 Natalia Portillo
// ****************************************************************************/

namespace Aaru.Filesystems.LisaFS;

using System;
using System.Collections.Generic;
using System.Text;
using Aaru.CommonTypes.Enums;
using Aaru.Decoders;
using Aaru.Helpers;

public sealed partial class LisaFS
{
    /// <inheritdoc />
    public ErrorNumber ListXAttr(string path, out List<string> xattrs)
    {
        xattrs = null;
        ErrorNumber error = LookupFileId(path, out short fileId, out bool isDir);

        if(error != ErrorNumber.NoError)
            return error;

        return isDir ? ErrorNumber.InvalidArgument : ListXAttr(fileId, out xattrs);
    }

    /// <inheritdoc />
    public ErrorNumber GetXattr(string path, string xattr, ref byte[] buf)
    {
        ErrorNumber error = LookupFileId(path, out short fileId, out bool isDir);

        if(error != ErrorNumber.NoError)
            return error;

        return isDir ? ErrorNumber.InvalidArgument : GetXattr(fileId, xattr, out buf);
    }

    /// <summary>Lists special Apple Lisa filesystem features as extended attributes</summary>
    /// <returns>Error number.</returns>
    /// <param name="fileId">File identifier.</param>
    /// <param name="xattrs">Extended attributes.</param>
    ErrorNumber ListXAttr(short fileId, out List<string> xattrs)
    {
        xattrs = null;

        if(!_mounted)
            return ErrorNumber.AccessDenied;

        // System files
        if(fileId < 4)
        {
            if(!_debug ||
               fileId == 0)
                return ErrorNumber.InvalidArgument;

            xattrs = new List<string>();

            // Only MDDF contains an extended attributes
            if(fileId == FILEID_MDDF)
            {
                byte[] buf = Encoding.ASCII.GetBytes(_mddf.password);

                // If the MDDF contains a password, show it
                if(buf.Length > 0)
                    xattrs.Add("com.apple.lisa.password");
            }
        }
        else
        {
            // Search for the file
            ErrorNumber error = ReadExtentsFile(fileId, out ExtentFile file);

            if(error != ErrorNumber.NoError)
                return error;

            xattrs = new List<string>();

            // Password field is never emptied, check if valid
            if(file.password_valid > 0)
                xattrs.Add("com.apple.lisa.password");

            // Check for a valid copy-protection serial number
            if(file.serial > 0)
                xattrs.Add("com.apple.lisa.serial");

            // Check if the label contains something or is empty
            if(!ArrayHelpers.ArrayIsNullOrEmpty(file.LisaInfo))
                xattrs.Add("com.apple.lisa.label");
        }

        // On debug mode allow sector tags to be accessed as an xattr
        if(_debug)
            xattrs.Add("com.apple.lisa.tags");

        xattrs.Sort();

        return ErrorNumber.NoError;
    }

    /// <summary>Lists special Apple Lisa filesystem features as extended attributes</summary>
    /// <returns>Error number.</returns>
    /// <param name="fileId">File identifier.</param>
    /// <param name="xattr">Extended attribute name.</param>
    /// <param name="buf">Buffer where the extended attribute will be stored.</param>
    ErrorNumber GetXattr(short fileId, string xattr, out byte[] buf)
    {
        buf = null;

        if(!_mounted)
            return ErrorNumber.AccessDenied;

        // System files
        if(fileId < 4)
        {
            if(!_debug ||
               fileId == 0)
                return ErrorNumber.InvalidArgument;

            // Only MDDF contains an extended attributes
            if(fileId == FILEID_MDDF)
                if(xattr == "com.apple.lisa.password")
                {
                    buf = Encoding.ASCII.GetBytes(_mddf.password);

                    return ErrorNumber.NoError;
                }

            // But on debug mode even system files contain tags
            if(_debug && xattr == "com.apple.lisa.tags")
                return ReadSystemFile(fileId, out buf, true);

            return ErrorNumber.NoSuchExtendedAttribute;
        }

        // Search for the file
        ErrorNumber error = ReadExtentsFile(fileId, out ExtentFile file);

        if(error != ErrorNumber.NoError)
            return error;

        switch(xattr)
        {
            case "com.apple.lisa.password" when file.password_valid > 0:
                buf = new byte[8];
                Array.Copy(file.password, 0, buf, 0, 8);

                return ErrorNumber.NoError;
            case "com.apple.lisa.serial" when file.serial > 0:
                buf = Encoding.ASCII.GetBytes(file.serial.ToString());

                return ErrorNumber.NoError;
        }

        if(!ArrayHelpers.ArrayIsNullOrEmpty(file.LisaInfo) &&
           xattr == "com.apple.lisa.label")
        {
            buf = new byte[128];
            Array.Copy(file.LisaInfo, 0, buf, 0, 128);

            return ErrorNumber.NoError;
        }

        if(_debug && xattr == "com.apple.lisa.tags")
            return ReadFile(fileId, out buf, true);

        return ErrorNumber.NoSuchExtendedAttribute;
    }

    /// <summary>Decodes a sector tag. Not tested with 24-byte tags.</summary>
    /// <returns>Error number.</returns>
    /// <param name="tag">Sector tag.</param>
    /// <param name="decoded">Decoded sector tag.</param>
    static ErrorNumber DecodeTag(byte[] tag, out LisaTag.PriamTag decoded)
    {
        decoded = new LisaTag.PriamTag();
        LisaTag.PriamTag? pmTag = LisaTag.DecodeTag(tag);

        if(!pmTag.HasValue)
            return ErrorNumber.InvalidArgument;

        decoded = pmTag.Value;

        return ErrorNumber.NoError;
    }
}