Dynamic data in dyld cache loaded

Author: p-x9

Sources/MachOKit/DyldCacheLoaded.swift

@@ -392,4 +392,14 @@ extension DyldCacheLoaded {
             .advanced(by: numericCast(header.swiftOptsOffset))
             .autoBoundPointee()
     }
+
+    public var dynamicData: DyldCacheDynamicData? {
+        guard mainCacheHeader.dynamicDataOffset > 0,
+              mainCacheHeader.hasProperty(\.dynamicDataMaxSize) else {
+            return nil
+        }
+        return ptr
+            .advanced(by: numericCast(header.dynamicDataOffset))
+            .autoBoundPointee()
+    }
 }

Sources/MachOKit/Model/DyldCache/DyldCacheDynamicData.swift

@@ -0,0 +1,39 @@
+//
+//  DyldCacheDynamicData.swift
+//  MachOKit
+//
+//  Created by p-x9 on 2025/02/28
+//  
+//
+
+import Foundation
+
+public struct DyldCacheDynamicData: LayoutWrapper {
+    public typealias Layout = dyld_cache_dynamic_data_header
+
+    public var layout: Layout
+}
+
+extension DyldCacheDynamicData {
+    public var magic: String {
+        .init(tuple: layout.magic)
+    }
+}
+
+#if canImport(Darwin)
+extension DyldCacheDynamicData {
+    public var path: String {
+        let path: UnsafeMutablePointer<CChar> = .allocate(capacity: Int(MAXPATHLEN))
+        var fsid: UInt64 = numericCast(layout.fsId)
+        return withUnsafeMutablePointer(to: &fsid) { fsid in
+            fsgetpath(
+                path,
+                Int(MAXPATHLEN),
+                UnsafeMutableRawPointer(fsid).assumingMemoryBound(to: fsid_t.self),
+                layout.fsObjId
+            )
+            return String(cString: path)
+        }
+    }
+}
+#endif

Tests/MachOKitTests/DyldCacheLoadedPrintTests.swift

@@ -318,6 +318,14 @@ final class DyldCacheLoadedPrintTests: XCTestCase {
         print("Metadata Conformance Hash Table Cache Offset:", swiftOptimization.metadataConformanceHashTableCacheOffset)
         print("Foreign Type Conformance Hash Table Cache Offset:", swiftOptimization.foreignTypeConformanceHashTableCacheOffset)
     }
+
+    func testDynamicData() throws {
+        guard let dynamicData = cache.dynamicData else { return }
+        print("Magic:", dynamicData.magic)
+        print("fsId:", dynamicData.fsId)
+        print("fsObjId:", dynamicData.fsObjId)
+        print("path:", dynamicData.path)
+    }
 }
 
 #endif