GARbro-mirror/ArcFormats/DxLib/ArcMED.cs

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//! \file ArcMED.cs
//! \date Mon May 30 12:35:24 2016
//! \brief DxLib resource archive.
//
// Copyright (C) 2016 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.IO;
using GameRes.Formats.Strings;
using GameRes.Utility;
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namespace GameRes.Formats.DxLib
{
public interface IScriptEncryption
{
int StartOffset { get; }
bool IsEncrypted (byte[] data);
void Decrypt (byte[] data, int offset, int length);
}
[Serializable]
public class FudegakiEncryption : IScriptEncryption
{
readonly byte[] Key;
public FudegakiEncryption (string keyword)
{
Key = Encodings.cp932.GetBytes (keyword);
}
public int StartOffset { get { return 0x10; } }
public bool IsEncrypted (byte[] data)
{
return LittleEndian.ToInt32 (data, 0) + 0x10 == data.Length && Key.Length > 0;
}
public void Decrypt (byte[] data, int offset, int length)
{
for (int i = 0; i < length; ++i)
{
data[offset+i] += Key[(offset+i) % Key.Length];
}
}
}
[Serializable]
public class MedOptions : ResourceOptions
{
public IScriptEncryption Encryption;
}
[Serializable]
public class ScrMedScheme : ResourceScheme
{
public Dictionary<string, IScriptEncryption> KnownSchemes;
}
internal class ScrMedArchive : ArcFile
{
public readonly IScriptEncryption Encryption;
public ScrMedArchive (ArcView arc, ArchiveFormat impl, ICollection<Entry> dir, IScriptEncryption enc)
: base (arc, impl, dir)
{
Encryption = enc;
}
}
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[Export(typeof(ArchiveFormat))]
public class MedOpener : ArchiveFormat
{
public override string Tag { get { return "MED"; } }
public override string Description { get { return "DxLib engine resource archive"; } }
public override uint Signature { get { return 0; } }
public override bool IsHierarchic { get { return false; } }
public override bool CanWrite { get { return false; } }
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static readonly ResourceInstance<ImageFormat> PrsFormat = new ResourceInstance<ImageFormat> ("PRS");
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static ScrMedScheme DefaultScheme = new ScrMedScheme {
KnownSchemes = new Dictionary<string, IScriptEncryption>()
};
public static Dictionary<string, IScriptEncryption> KnownSchemes { get { return DefaultScheme.KnownSchemes; } }
public override ResourceScheme Scheme
{
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get { return DefaultScheme; }
set { DefaultScheme = (ScrMedScheme)value; }
}
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public override ArcFile TryOpen (ArcView file)
{
if (!file.View.AsciiEqual (0, "MD"))
return null;
uint entry_length = file.View.ReadUInt16 (4);
int count = file.View.ReadUInt16 (6);
if (entry_length <= 8 || !IsSaneCount (count))
return null;
uint name_length = entry_length - 8;
uint index_offset = 0x10;
var dir = new List<Entry> (count);
for (int i = 0; i < count; ++i)
{
var name = file.View.ReadString (index_offset, name_length);
index_offset += name_length;
uint offset = file.View.ReadUInt32 (index_offset+4);
var entry = new AutoEntry (name, () => {
uint signature = file.View.ReadUInt32 (offset);
if (0x4259 == (signature & 0xFFFF)) // 'YB'
return PrsFormat.Value;
return AutoEntry.DetectFileType (signature);
});
entry.Size = file.View.ReadUInt32 (index_offset);
entry.Offset = offset;
if (!entry.CheckPlacement (file.MaxOffset))
return null;
dir.Add (entry);
index_offset += 8;
}
var base_name = Path.GetFileNameWithoutExtension (file.Name);
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if (base_name.EndsWith ("_scr", StringComparison.OrdinalIgnoreCase)
&& KnownSchemes.Count > 0)
{
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var encryption = QueryEncryption (file.Name);
if (encryption != null)
return new ScrMedArchive (file, this, dir, encryption);
}
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return new ArcFile (file, this, dir);
}
public override Stream OpenEntry (ArcFile arc, Entry entry)
{
var scr_arc = arc as ScrMedArchive;
if (null == scr_arc || entry.Size <= scr_arc.Encryption.StartOffset)
return base.OpenEntry (arc, entry);
var data = arc.File.View.ReadBytes (entry.Offset, entry.Size);
if (scr_arc.Encryption.IsEncrypted (data))
{
var offset = scr_arc.Encryption.StartOffset;
scr_arc.Encryption.Decrypt (data, offset, data.Length-offset);
}
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return new BinMemoryStream (data, entry.Name);
}
public override ResourceOptions GetDefaultOptions ()
{
return new MedOptions {
Encryption = GetEncryption (Properties.Settings.Default.MEDScriptScheme),
};
}
public override object GetAccessWidget ()
{
return new GUI.WidgetSCR();
}
public static IScriptEncryption GetEncryption (string scheme)
{
IScriptEncryption enc;
if (string.IsNullOrEmpty (scheme) || !KnownSchemes.TryGetValue (scheme, out enc))
return null;
return enc;
}
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IScriptEncryption QueryEncryption (string arc_name)
{
var title = FormatCatalog.Instance.LookupGame (arc_name);
if (!string.IsNullOrEmpty (title) && KnownSchemes.ContainsKey (title))
return KnownSchemes[title];
var options = Query<MedOptions> (arcStrings.ArcEncryptedNotice);
return options.Encryption;
}
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}
}