From 8d193a63cdc43f5dd38a43c4ed2b33735d313382 Mon Sep 17 00:00:00 2001
From: Rudolf Kolbe <rkolbe96@gmail.com>
Date: Mon, 27 Dec 2021 08:59:18 +0100
Subject: [PATCH] Zip (including APK) Loading (#902)

* load ZipFile

makes it possible to directly load apk files

* use LoadFile for recursive zip opening

* set System.IO.Compression version

* keep identical format in AssetStudio.csproj

* try/catch the loading of each zip entry

* remove extra new line in FileReader.cs

* apply requested changes
---
 AssetStudio/AssetStudio.csproj |  1 +
 AssetStudio/AssetsManager.cs   | 46 ++++++++++++++++++++++++++++++++++
 AssetStudio/FileReader.cs      | 13 ++++++----
 AssetStudio/FileType.cs        |  3 ++-
 4 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/AssetStudio/AssetStudio.csproj b/AssetStudio/AssetStudio.csproj
index e821b3c..850a85a 100644
--- a/AssetStudio/AssetStudio.csproj
+++ b/AssetStudio/AssetStudio.csproj
@@ -14,6 +14,7 @@
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net472' ">
     <PackageReference Include="System.Memory" Version="4.5.4" />
+    <PackageReference Include="System.IO.Compression" Version="4.0.0" />
     <PackageReference Include="K4os.Compression.LZ4" Version="1.1.11" />
   </ItemGroup>
 
diff --git a/AssetStudio/AssetsManager.cs b/AssetStudio/AssetsManager.cs
index 8c69d89..818e35e 100644
--- a/AssetStudio/AssetsManager.cs
+++ b/AssetStudio/AssetsManager.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.IO.Compression;
 using System.Linq;
 using System.Text;
 using static AssetStudio.ImportHelper;
@@ -84,6 +85,9 @@ namespace AssetStudio
                 case FileType.BrotliFile:
                     LoadFile(DecompressBrotli(reader));
                     break;
+                case FileType.ZipFile:
+                    LoadZipFile(reader);
+                    break;
             }
         }
 
@@ -234,6 +238,48 @@ namespace AssetStudio
             }
         }
 
+        private void LoadZipFile(FileReader reader)
+        {
+            Logger.Info("Loading " + reader.FileName);
+            try
+            {
+                using (ZipArchive archive = new ZipArchive(reader.BaseStream, ZipArchiveMode.Read))
+                {
+                    foreach (ZipArchiveEntry entry in archive.Entries)
+                    {
+                        try
+                        {
+                            string dummyPath = Path.Combine(Path.GetDirectoryName(reader.FullPath), reader.FileName, entry.FullName);
+                            // create a new stream
+                            // - to store the deflated stream in
+                            // - to keep the data for later extraction
+                            Stream streamReader = new MemoryStream();
+                            using (Stream entryStream = entry.Open())
+                            {
+                                entryStream.CopyTo(streamReader);
+                            }
+                            streamReader.Position = 0;
+
+                            FileReader entryReader = new FileReader(dummyPath, streamReader);
+                            LoadFile(entryReader);
+                        }
+                        catch (Exception e)
+                        {
+                            Logger.Error($"Error while reading zip entry {entry.FullName}", e);
+                        }
+                    }
+                }
+            }
+            catch (Exception e)
+            {
+                Logger.Error($"Error while reading zip file {reader.FileName}", e);
+            }
+            finally
+            {
+                reader.Dispose();
+            }
+        }
+
         public void CheckStrippedVersion(SerializedFile assetsFile)
         {
             if (assetsFile.IsVersionStripped && string.IsNullOrEmpty(SpecifyUnityVersion))
diff --git a/AssetStudio/FileReader.cs b/AssetStudio/FileReader.cs
index 59ea66f..61426b4 100644
--- a/AssetStudio/FileReader.cs
+++ b/AssetStudio/FileReader.cs
@@ -11,6 +11,8 @@ namespace AssetStudio
 
         private static readonly byte[] gzipMagic = { 0x1f, 0x8b };
         private static readonly byte[] brotliMagic = { 0x62, 0x72, 0x6F, 0x74, 0x6C, 0x69 };
+        private static readonly byte[] zipMagic = { 0x50, 0x4B, 0x03, 0x04 };
+        private static readonly byte[] zipSpannedMagic = { 0x50, 0x4B, 0x07, 0x08 };
 
         public FileReader(string path) : this(path, File.Open(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)) { }
 
@@ -36,7 +38,7 @@ namespace AssetStudio
                     return FileType.WebFile;
                 default:
                     {
-                        var magic = ReadBytes(2);
+                        byte[] magic = ReadBytes(2);
                         Position = 0;
                         if (gzipMagic.SequenceEqual(magic))
                         {
@@ -53,10 +55,11 @@ namespace AssetStudio
                         {
                             return FileType.AssetsFile;
                         }
-                        else
-                        {
-                            return FileType.ResourceFile;
-                        }
+                        magic = ReadBytes(4);
+                        Position = 0;
+                        if (zipMagic.SequenceEqual(magic) || zipSpannedMagic.SequenceEqual(magic))
+                            return FileType.ZipFile;
+                        return FileType.ResourceFile;
                     }
             }
         }
diff --git a/AssetStudio/FileType.cs b/AssetStudio/FileType.cs
index 04fb30d..f803e97 100644
--- a/AssetStudio/FileType.cs
+++ b/AssetStudio/FileType.cs
@@ -13,6 +13,7 @@ namespace AssetStudio
         WebFile,
         ResourceFile,
         GZipFile,
-        BrotliFile
+        BrotliFile,
+        ZipFile
     }
 }