GARbro-mirror/ArcFormats/Actgs/ArcCG.cs

//! \file       ArcCG.cs
//! \date       2018 Jan 09
//! \brief      ACTGS engine encrypted archive.
//
// Copyright (C) 2018 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//

using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.Linq;

namespace GameRes.Formats.Actgs
{
    [Export(typeof(ArchiveFormat))]
    public class CgOpener : DatOpener
    {
        public override string         Tag { get { return "CG/ACTGS"; } }
        public override string Description { get { return "ACTGS engine resource archive"; } }
        public override uint     Signature { get { return 0; } }
        public override bool  IsHierarchic { get { return false; } }
        public override bool      CanWrite { get { return false; } }

        public override ArcFile TryOpen (ArcView file)
        {
            var key = FindKey (file);
            if (null == key)
                return null;
            uint signature_key = key.ToUInt32 (0);
            int count = (int)(file.View.ReadUInt32 (0) ^ signature_key);
            if (!IsSaneCount (count))
                return null;
            uint index_size = 32 * (uint)count;
            using (var enc = file.CreateStream (0x10, index_size))
            using (var input = new ByteStringEncryptedStream (enc, key))
            using (var index = new BinaryStream (input, file.Name))
            {
                var reader = new IndexReader (file.MaxOffset);
                var dir = reader.Read (index, count);
                if (null == dir)
                    return null;
                return new ActressArchive (file, this, dir, key);
            }
        }

        byte[] FindKey (ArcView file)
        {
            var pattern = file.View.ReadBytes (4, 8);
            return Array.Find (KnownKeys, k => KeySequence (k).Skip (4).Take (8).SequenceEqual (pattern));
        }

        internal static IEnumerable<byte> KeySequence (byte[] key)
        {
            for (;;)
            {
                for (int i = 0; i < key.Length; ++i)
                    yield return key[i];
            }
        }
    }
}