Aaru/Aaru.Filters/BZip2.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : BZip2.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Filters.
//
// --[ Description ] ----------------------------------------------------------
//
//     Allow to open files that are compressed using bzip2.
//
// --[ 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 © 2011-2020 Natalia Portillo
// ****************************************************************************/

using System;
using System.IO;
using Aaru.CommonTypes.Interfaces;
using SharpCompress.Compressors;
using SharpCompress.Compressors.BZip2;

namespace Aaru.Filters
{
    /// <summary>Decompress bz2 files while reading</summary>
    public class BZip2 : IFilter
    {
        string   basePath;
        DateTime creationTime;
        Stream   dataStream;
        long     decompressedSize;
        Stream   innerStream;
        DateTime lastWriteTime;
        bool     opened;

        public string Name   => "BZip2";
        public Guid   Id     => new Guid("FCCFB0C3-32EF-40D8-9714-2333F6AC72A9");
        public string Author => "Natalia Portillo";

        public void Close()
        {
            dataStream?.Close();
            dataStream = null;
            basePath   = null;
            opened     = false;
        }

        public string GetBasePath() => basePath;

        public Stream GetDataForkStream() => innerStream;

        public string GetPath() => basePath;

        public Stream GetResourceForkStream() => null;

        public bool HasResourceFork() => false;

        public bool Identify(byte[] buffer)
        {
            if(buffer[0] != 0x42 ||
               buffer[1] != 0x5A ||
               buffer[2] != 0x68 ||
               buffer[3] < 0x31  ||
               buffer[3] > 0x39)
                return false;

            if(buffer.Length <= 512)
                return true;

            return buffer[^512] != 0x6B || buffer[^511] != 0x6F || buffer[^510] != 0x6C || buffer[^509] != 0x79;
        }

        public bool Identify(Stream stream)
        {
            byte[] buffer = new byte[4];

            stream.Seek(0, SeekOrigin.Begin);
            stream.Read(buffer, 0, 4);
            stream.Seek(0, SeekOrigin.Begin);

            if(buffer[0] != 0x42 ||
               buffer[1] != 0x5A ||
               buffer[2] != 0x68 ||
               buffer[3] < 0x31  ||
               buffer[3] > 0x39)
                return false;

            if(stream.Length <= 512)
                return true;

            stream.Seek(-512, SeekOrigin.End);
            stream.Read(buffer, 0, 4);
            stream.Seek(0, SeekOrigin.Begin);

            // Check it is not an UDIF
            return buffer[0] != 0x6B || buffer[1] != 0x6F || buffer[2] != 0x6C || buffer[3] != 0x79;
        }

        public bool Identify(string path)
        {
            if(!File.Exists(path))
                return false;

            var    stream = new FileStream(path, FileMode.Open, FileAccess.Read);
            byte[] buffer = new byte[4];

            stream.Seek(0, SeekOrigin.Begin);
            stream.Read(buffer, 0, 4);
            stream.Seek(0, SeekOrigin.Begin);

            if(buffer[0] != 0x42 ||
               buffer[1] != 0x5A ||
               buffer[2] != 0x68 ||
               buffer[3] < 0x31  ||
               buffer[3] > 0x39)
                return false;

            if(stream.Length <= 512)
                return true;

            stream.Seek(-512, SeekOrigin.End);
            stream.Read(buffer, 0, 4);
            stream.Seek(0, SeekOrigin.Begin);

            // Check it is not an UDIF
            return buffer[0] != 0x6B || buffer[1] != 0x6F || buffer[2] != 0x6C || buffer[3] != 0x79;
        }

        public void Open(byte[] buffer)
        {
            dataStream       = new MemoryStream(buffer);
            basePath         = null;
            creationTime     = DateTime.UtcNow;
            lastWriteTime    = creationTime;
            innerStream      = new ForcedSeekStream<BZip2Stream>(dataStream, CompressionMode.Decompress, false);
            decompressedSize = innerStream.Length;
            opened           = true;
        }

        public void Open(Stream stream)
        {
            dataStream       = stream;
            basePath         = null;
            creationTime     = DateTime.UtcNow;
            lastWriteTime    = creationTime;
            innerStream      = new ForcedSeekStream<BZip2Stream>(dataStream, CompressionMode.Decompress, false);
            decompressedSize = innerStream.Length;
            opened           = true;
        }

        public void Open(string path)
        {
            dataStream = new FileStream(path, FileMode.Open, FileAccess.Read);
            basePath   = Path.GetFullPath(path);

            var fi = new FileInfo(path);
            creationTime     = fi.CreationTimeUtc;
            lastWriteTime    = fi.LastWriteTimeUtc;
            innerStream      = new ForcedSeekStream<BZip2Stream>(dataStream, CompressionMode.Decompress, false);
            decompressedSize = innerStream.Length;
            opened           = true;
        }

        public DateTime GetCreationTime() => creationTime;

        public long GetDataForkLength() => decompressedSize;

        public DateTime GetLastWriteTime() => lastWriteTime;

        public long GetLength() => decompressedSize;

        public long GetResourceForkLength() => 0;

        public string GetFilename()
        {
            if(basePath?.EndsWith(".bz2", StringComparison.InvariantCultureIgnoreCase) == true)
                return basePath.Substring(0, basePath.Length - 4);

            return basePath?.EndsWith(".bzip2", StringComparison.InvariantCultureIgnoreCase) == true
                       ? basePath.Substring(0, basePath.Length - 6) : basePath;
        }

        public string GetParentFolder() => Path.GetDirectoryName(basePath);

        public bool IsOpened() => opened;
    }
}