IL2CPP: Change metadata and binary to derive from BinaryObjectStream

Il2CppInspector.Common/FileFormatStreams/APKReader.cs

@@ -0,0 +1,73 @@
+/*
+    Copyright 2020 Katy Coe - http://www.djkaty.com - https://github.com/djkaty
+
+    All rights reserved.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.Compression;
+using System.Linq;
+
+namespace Il2CppInspector
+{
+    // This is a wrapper for multiple binary files of different architectures within a single APK
+    internal class APKReader : FileFormatStream<APKReader>
+    {
+        private ZipArchive zip;
+        private ZipArchiveEntry[] binaryFiles;
+
+        public override string DefaultFilename => "Package.apk";
+
+        protected override bool Init() {
+
+            // Check if it's a zip file first because ZipFile.OpenRead is extremely slow if it isn't
+            // 0x04034B50 = magic file header
+            // 0x02014B50 = central directory file header (will appear if we merged a split APK in memory)
+            var magic = ReadUInt32();
+            if (magic != 0x04034B50 && magic != 0x02014B50)
+                return false;
+
+            try {
+                zip = new ZipArchive(this);
+
+                // Get list of binary files
+                binaryFiles = zip.Entries.Where(f => f.FullName.StartsWith("lib/") && f.Name == "libil2cpp.so").ToArray();
+
+                // This package doesn't contain an IL2CPP binary
+                if (!binaryFiles.Any())
+                    return false;
+            }
+
+            // Not an archive
+            catch (InvalidDataException) {
+                return false;
+            }
+
+            NumImages = (uint) binaryFiles.Count();
+            return true;
+        }
+
+        public override IFileFormatStream this[uint index] {
+            get {
+                Console.WriteLine($"Extracting binary from {binaryFiles[index].FullName}");
+                IFileFormatStream loaded = null;
+
+                // ZipArchiveEntry does not support seeking so we have to close and re-open for each possible load format
+                var binary = binaryFiles[index].Open();
+                loaded = ElfReader32.Load(binary, LoadOptions, OnStatusUpdate);
+                binary.Close();
+
+                if (loaded != null)
+                    return loaded;
+
+                binary = binaryFiles[index].Open();
+                loaded = ElfReader64.Load(binary, LoadOptions, OnStatusUpdate);
+                binary.Close();
+
+                return loaded;
+            }
+        }
+    }
+}