GARbro-mirror/ArcFormats/Eagls/ArcEAGLS.cs

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//! \file ArcEAGLS.cs
//! \date Fri May 15 02:52:04 2015
//! \brief EAGLS system resource archives.
//
// Copyright (C) 2015 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.Utility;
namespace GameRes.Formats.Eagls
{
[Export(typeof(ArchiveFormat))]
public class PakOpener : ArchiveFormat
{
public override string Tag { get { return "PAK/EAGLS"; } }
public override string Description { get { return "EAGLS engine resource archive"; } }
public override uint Signature { get { return 0; } }
public override bool IsHierarchic { get { return false; } }
public override bool CanCreate { get { return false; } }
public PakOpener ()
{
Extensions = new string[] { "pak" };
}
static readonly string IndexKey = "1qaz2wsx3edc4rfv5tgb6yhn7ujm8ik,9ol.0p;/-@:^[]";
static readonly string Key = "EAGLS_SYSTEM";
public override ArcFile TryOpen (ArcView file)
{
string idx_name = Path.ChangeExtension (file.Name, ".idx");
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if (!VFS.FileExists (idx_name))
return null;
var idx_entry = VFS.FindFile (idx_name);
if (idx_entry.Size > 0xfffff || idx_entry.Size < 10000)
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return null;
byte[] index;
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using (var idx = VFS.OpenView (idx_entry))
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index = DecryptIndex (idx);
int index_offset = 0;
int entry_size = index.Length / 10000;
bool long_offsets = 40 == entry_size;
int name_size = long_offsets ? 0x18 : 0x14;
long first_offset = LittleEndian.ToUInt32 (index, name_size);
var dir = new List<Entry>();
while (index_offset < index.Length)
{
if (0 == index[index_offset])
break;
var name = Binary.GetCString (index, index_offset, name_size);
index_offset += name_size;
var entry = FormatCatalog.Instance.Create<Entry> (name);
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if (name.EndsWith (".dat", StringComparison.InvariantCultureIgnoreCase))
entry.Type = "script";
if (long_offsets)
{
entry.Offset = LittleEndian.ToInt64 (index, index_offset) - first_offset;
entry.Size = LittleEndian.ToUInt32 (index, index_offset+8);
index_offset += 0x10;
}
else
{
entry.Offset = LittleEndian.ToUInt32 (index, index_offset) - first_offset;
entry.Size = LittleEndian.ToUInt32 (index, index_offset+4);
index_offset += 8;
}
if (!entry.CheckPlacement (file.MaxOffset))
return null;
dir.Add (entry);
}
if (0 == dir.Count)
return null;
return new ArcFile (file, this, dir);
}
public override Stream OpenEntry (ArcFile arc, Entry entry)
{
if (entry.Name.EndsWith (".gr", StringComparison.InvariantCultureIgnoreCase))
return DecryptGr (arc, entry);
if (entry.Name.EndsWith (".dat", StringComparison.InvariantCultureIgnoreCase))
return DecryptDat (arc, entry);
return arc.File.CreateStream (entry.Offset, entry.Size);
}
Stream DecryptGr (ArcFile arc, Entry entry)
{
var input = new byte[entry.Size];
arc.File.View.Read (entry.Offset, input, 0, entry.Size);
int seed = 0x75bd924 ^ input[input.Length-1];
int limit = Math.Min (input.Length-1, 0x174b);
for (int i = 0; i < limit; ++i)
{
seed = LRand (seed);
int index = (int)(seed * 4.656612875245797e-10 * 256);
input[i] ^= (byte)Key[index % Key.Length];
}
return new MemoryStream (input);
}
Stream DecryptDat (ArcFile arc, Entry entry)
{
byte[] input = new byte[entry.Size];
arc.File.View.Read (entry.Offset, input, 0, entry.Size);
int text_offset = 3600;
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int text_length = (int)(entry.Size - text_offset - 2);
int seed = (sbyte)input[input.Length-1];
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for (int i = 0; i < text_length; i += 2)
{
seed = seed * 0x343FD + 0x269EC3;
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int index = (int)(((uint)seed >> 16) & 0x7fff);
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input[text_offset + i] ^= (byte)Key[index % Key.Length];
}
return new MemoryStream (input);
}
byte[] DecryptIndex (ArcView idx)
{
int idx_size = (int)idx.MaxOffset-4;
byte[] output = new byte[idx_size];
using (var view = idx.CreateViewAccessor (0, (uint)idx.MaxOffset))
unsafe
{
uint seed = view.ReadUInt32 (idx_size);
byte* ptr = view.GetPointer (0);
try
{
for (int i = 0; i < idx_size; ++i)
{
seed = seed * 0x343FD + 0x269EC3;
int index = (int)(seed >> 16) & 0x7FFF;
output[i] = (byte)(ptr[i] ^ IndexKey[index % IndexKey.Length]);
}
return output;
}
finally
{
view.SafeMemoryMappedViewHandle.ReleasePointer();
}
}
}
int LRand (int seed)
{
const int A = 48271;
const int Q = 44488;
const int R = 3399;
const int M = 2147483647;
seed = A * (seed % Q) - R * (seed / Q);
if (seed < 0)
seed += M;
return seed;
}
}
}