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Aaru/Aaru.Filesystems/CPM/Dir.cs

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// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename : Dir.cs
// Author(s) : Natalia Portillo <claunia@claunia.com>
//
// Component : CP/M filesystem plugin.
//
// --[ Description ] ----------------------------------------------------------
//
// Methods to show the CP/M filesystem directory.
//
// --[ 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 © 2011-2023 Natalia Portillo
// ****************************************************************************/
using System;
using System.Collections.Generic;
using System.Text;
using Aaru.CommonTypes.Enums;
using Aaru.Helpers;
namespace Aaru.Filesystems;
public sealed partial class CPM
{
/// <inheritdoc />
public ErrorNumber ReadDir(string path, out List<string> contents)
{
contents = null;
if(!_mounted)
return ErrorNumber.AccessDenied;
if(!string.IsNullOrEmpty(path) &&
string.Compare(path, "/", StringComparison.OrdinalIgnoreCase) != 0)
return ErrorNumber.NotSupported;
contents = new List<string>(_dirList);
return ErrorNumber.NoError;
}
/// <summary>
/// Checks that the given directory blocks follow the CP/M filesystem directory specification Corrupted
/// directories will fail. FAT directories will false positive if all files start with 0x05, and do not use full
/// extensions, for example: "σAFILE.GZ" (using code page 437)
/// </summary>
/// <returns>False if the directory does not follow the directory specification</returns>
/// <param name="directory">Directory blocks.</param>
bool CheckDir(byte[] directory)
{
try
{
if(directory == null)
return false;
int fileCount = 0;
for(int off = 0; off < directory.Length; off += 32)
{
DirectoryEntry entry = Marshal.ByteArrayToStructureLittleEndian<DirectoryEntry>(directory, off, 32);
if((entry.statusUser & 0x7F) < 0x20)
{
for(int f = 0; f < 8; f++)
if(entry.filename[f] < 0x20 &&
entry.filename[f] != 0x00)
return false;
for(int e = 0; e < 3; e++)
if(entry.extension[e] < 0x20 &&
entry.extension[e] != 0x00)
return false;
if(!ArrayHelpers.ArrayIsNullOrWhiteSpace(entry.filename))
fileCount++;
}
else
switch(entry.statusUser)
{
case 0x20:
{
for(int f = 0; f < 8; f++)
if(entry.filename[f] < 0x20 &&
entry.filename[f] != 0x00)
return false;
for(int e = 0; e < 3; e++)
if(entry.extension[e] < 0x20 &&
entry.extension[e] != 0x00)
return false;
_label = Encoding.ASCII.GetString(directory, off + 1, 11).Trim();
_labelCreationDate = new byte[4];
_labelUpdateDate = new byte[4];
Array.Copy(directory, off + 24, _labelCreationDate, 0, 4);
Array.Copy(directory, off + 28, _labelUpdateDate, 0, 4);
break;
}
case 0x21 when directory[off + 1] == 0x00:
_thirdPartyTimestamps = true;
break;
case 0x21:
_standardTimestamps |= directory[off + 21] == 0x00 && directory[off + 31] == 0x00;
break;
}
}
return fileCount > 0;
}
catch
{
return false;
}
}
}