Add files via upload

Islet Online Unpacker.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+    <RootNamespace>Islet_Online_Unpacker</RootNamespace>
+  </PropertyGroup>
+
+</Project>

Islet Online Unpacker.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.34407.143
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Islet Online Unpacker", "Islet Online Unpacker.csproj", "{4B9BADD3-EE27-4AC6-8D4E-E5CAA2D2FAA1}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{4B9BADD3-EE27-4AC6-8D4E-E5CAA2D2FAA1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4B9BADD3-EE27-4AC6-8D4E-E5CAA2D2FAA1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4B9BADD3-EE27-4AC6-8D4E-E5CAA2D2FAA1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4B9BADD3-EE27-4AC6-8D4E-E5CAA2D2FAA1}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {0969BADB-BDC0-4879-9427-A89BCF47474B}
+	EndGlobalSection
+EndGlobal

Program.cs

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+using System.IO;
+using System.IO.Compression;
+
+namespace Islet_Online_Unpacker
+{
+    static class Program
+    {
+        static void Main(string[] args)
+        {
+            using FileStream source = File.OpenRead(args[0]);
+            BinaryReader br = new(source);
+            Directory.CreateDirectory(Path.GetDirectoryName(source.Name) + "//" + Path.GetFileNameWithoutExtension(source.Name));
+            while (br.BaseStream.Position < br.BaseStream.Length)
+            {
+                int size = br.ReadInt32();
+                if (size == 0x100)
+                {
+                    br.BaseStream.Position -= 4;
+                    break;
+                };
+                br.BaseStream.Position += size;
+            }
+
+            System.Collections.Generic.List<SUBFILE> subfiles = new();
+            while (br.BaseStream.Position < br.BaseStream.Length - 0x28)
+            {
+                SUBFILE subfile = new()
+                {
+                    isCompressed = br.ReadInt32(),
+                    sizeUncompressed = br.ReadInt32(),
+                    sizeCompressed = br.ReadInt32(),
+                    offset = br.ReadInt32()
+                };
+                br.ReadBytes(20);
+                subfile.name = new(br.ReadChars(br.ReadInt16()));
+                subfiles.Add(subfile);
+            }
+            foreach (SUBFILE sub in subfiles)
+            {
+                br.BaseStream.Position = sub.offset;
+                int size = br.ReadInt32();
+                if ((sub.isCompressed == 0 && size != sub.sizeUncompressed) || (sub.isCompressed == 0x100 && size != sub.sizeCompressed))
+                    throw new System.Exception("Fuck.");
+
+                if (sub.name.Contains(@"\"))
+                    Directory.CreateDirectory(Path.GetDirectoryName(source.Name) + "//" + Path.GetDirectoryName(sub.name));
+
+                using FileStream FS = File.Create(Path.GetDirectoryName(source.Name) + "//" + sub.name);
+                BinaryWriter bw = new(FS);
+                if (sub.isCompressed == 0x100)
+                {
+                    MemoryStream ms = new();
+                    br.ReadInt16();
+                    using (var ds = new DeflateStream(new MemoryStream(br.ReadBytes(size)), CompressionMode.Decompress))
+                        ds.CopyTo(ms);
+                    br = new(ms);
+                    br.BaseStream.Position = 0;
+                    bw.Write(br.ReadBytes(sub.sizeUncompressed));
+                    br = new(source);
+                    continue;
+                }
+
+                bw.Write(br.ReadBytes(size));
+                bw.Close();
+            }
+        }
+        struct SUBFILE
+        {
+            public int isCompressed;
+            public int sizeUncompressed;
+            public int sizeCompressed;
+            public int offset;
+            public string name;
+        }
+    }
+}