use same metareg scanner for < v27 and > v27, implement TryMapVATR in PEReader for performance

Il2CppInspector.Common/FileFormatStreams/PEReader.cs

@@ -197,7 +197,27 @@ namespace Il2CppInspector
 
             return exports.Values;
         }
-         
+
+        public override bool TryMapVATR(ulong uiAddr, out uint fileOffset)
+        {
+            if (uiAddr == 0)
+            {
+                fileOffset = 0;
+                return true;
+            }
+
+            var section = sections.FirstOrDefault(x => uiAddr - pe.ImageBase >= x.VirtualAddress &&
+                                              uiAddr - pe.ImageBase < x.VirtualAddress + x.SizeOfRawData);
+            if (section == null)
+            {
+                fileOffset = 0;
+                return false;
+            }
+
+            fileOffset = (uint)(uiAddr - section.VirtualAddress - pe.ImageBase + section.PointerToRawData);
+            return true;
+        }
+
         public override uint MapVATR(ulong uiAddr) {
             if (uiAddr == 0)
                 return 0;

Il2CppInspector.Common/IL2CPP/ImageScan.cs

@@ -277,21 +277,12 @@ namespace Il2CppInspector
 
             vas = FindAllMappedWords(imageBytes, typesLength).Select(a => a - mrSize + ptrSize * 4);
 
-            // >= 19 && < 27
+            // >= 19
-            if (Image.Version < MetadataVersions.V270)
+            // Luke: Previously, a check comparing MetadataUsagesCount was used here, 
-                foreach (var va in vas)
+            // but I know of at least one binary where this will break detection.
-                {
+            // Testing showed that we can just use the same heuristic used for v27+
-                    var mr = Image.ReadMappedVersionedObject<Il2CppMetadataRegistration>(va);
+            // on older versions as well, so we'll just use it for all cases.
-                    if (mr.MetadataUsagesCount == (ulong) metadata.MetadataUsageLists.Length)
+            if (Image.Version >= MetadataVersions.V190)
-                        metadataRegistration = va;
-                }
-
-            // plagiarism. noun - https://www.lexico.com/en/definition/plagiarism
-            //   the practice of taking someone else's work or ideas and passing them off as one's own.
-            // Synonyms: copying, piracy, theft, strealing, infringement of copyright
-
-            // >= 27
-            else
             {
                 foreach (var va in vas)
                 {
@@ -304,6 +295,7 @@ namespace Il2CppInspector
                     }
                 }
             }
+
             if (metadataRegistration == 0)
                 return (0, 0);