Dynamic Invocation

InterposeKit.xcodeproj/project.pbxproj

@@ -17,9 +17,13 @@
 		781095B4248D6DFD008A943C /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 781095B2248D6DFD008A943C /* LaunchScreen.storyboard */; };
 		781095F5248E7C91008A943C /* InterposeKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 78863EC62464B2F900BA3762 /* InterposeKit.framework */; };
 		781095F6248E7C91008A943C /* InterposeKit.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 78863EC62464B2F900BA3762 /* InterposeKit.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		781EB556249BEF54002545B4 /* ObjCInvocation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 781EB555249BEF54002545B4 /* ObjCInvocation.swift */; };
+		781EB558249BF0D1002545B4 /* DynamicHook.swift in Sources */ = {isa = PBXBuildFile; fileRef = 781EB557249BF0D1002545B4 /* DynamicHook.swift */; };
+		781EB55A249BFA58002545B4 /* DynamicHookTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 781EB559249BFA58002545B4 /* DynamicHookTests.swift */; };
 		78A2F265249635B100F5AC5F /* KVOTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 78A2F264249635B100F5AC5F /* KVOTests.swift */; };
 		78A2F26724964AF200F5AC5F /* InterposeKitTestCase.swift in Sources */ = {isa = PBXBuildFile; fileRef = 78A2F26624964AF200F5AC5F /* InterposeKitTestCase.swift */; };
 		78A2F26E2496B54B00F5AC5F /* InterposeError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 78A2F26D2496B54B00F5AC5F /* InterposeError.swift */; };
+		78AB64B5249EAED3002394CD /* InterposeRuntime.swift in Sources */ = {isa = PBXBuildFile; fileRef = 78AB64B4249EAED3002394CD /* InterposeRuntime.swift */; };
 		78C39D7C2482CC7D00B46395 /* InterposeKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 78863EC62464B2F900BA3762 /* InterposeKit.framework */; };
 		78C39D8F2483164500B46395 /* InterposeKit.h in Headers */ = {isa = PBXBuildFile; fileRef = 78C39D8E2483164500B46395 /* InterposeKit.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		78C39D912483165600B46395 /* InterposeKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = 78C39D902483165600B46395 /* InterposeKit.swift */; };
@@ -78,11 +82,15 @@
 		781095B3248D6DFD008A943C /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
 		781095B5248D6DFD008A943C /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		781095B9248D6E0A008A943C /* InterposeTestHost.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.plist.entitlements; path = InterposeTestHost.entitlements; sourceTree = "<group>"; };
+		781EB555249BEF54002545B4 /* ObjCInvocation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = ObjCInvocation.swift; path = Sources/InterposeKit/ObjCInvocation.swift; sourceTree = SOURCE_ROOT; };
+		781EB557249BF0D1002545B4 /* DynamicHook.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = DynamicHook.swift; path = Sources/InterposeKit/DynamicHook.swift; sourceTree = SOURCE_ROOT; };
+		781EB559249BFA58002545B4 /* DynamicHookTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = DynamicHookTests.swift; path = Tests/InterposeKitTests/DynamicHookTests.swift; sourceTree = SOURCE_ROOT; };
 		78863EC62464B2F900BA3762 /* InterposeKit.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = InterposeKit.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		78863ECA2464B2F900BA3762 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist; name = Info.plist; path = InterposeKit.xcodeproj/Info.plist; sourceTree = "<group>"; };
 		78A2F264249635B100F5AC5F /* KVOTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = KVOTests.swift; path = Tests/InterposeKitTests/KVOTests.swift; sourceTree = SOURCE_ROOT; };
 		78A2F26624964AF200F5AC5F /* InterposeKitTestCase.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = InterposeKitTestCase.swift; path = Tests/InterposeKitTests/InterposeKitTestCase.swift; sourceTree = SOURCE_ROOT; };
 		78A2F26D2496B54B00F5AC5F /* InterposeError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = InterposeError.swift; path = Sources/InterposeKit/InterposeError.swift; sourceTree = SOURCE_ROOT; };
+		78AB64B4249EAED3002394CD /* InterposeRuntime.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = InterposeRuntime.swift; path = Sources/InterposeKit/InterposeRuntime.swift; sourceTree = SOURCE_ROOT; };
 		78C39D772482CC7D00B46395 /* InterposeKitTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = InterposeKitTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		78C39D7B2482CC7D00B46395 /* Info-Tests.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist; name = "Info-Tests.plist"; path = "InterposeKit.xcodeproj/Info-Tests.plist"; sourceTree = "<group>"; };
 		78C39D8E2483164500B46395 /* InterposeKit.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = InterposeKit.h; path = Sources/InterposeKit/InterposeKit.h; sourceTree = SOURCE_ROOT; };
@@ -184,10 +192,13 @@
 				78EDB8DC248BAA5600D2F6C1 /* AnyHook.swift */,
 				7810959D248D43DC008A943C /* ClassHook.swift */,
 				78EDB8FE248D0A9900D2F6C1 /* ObjectHook.swift */,
-				78EDB902248D42CD00D2F6C1 /* LinuxCompileSupport.swift */,
+				781EB557249BF0D1002545B4 /* DynamicHook.swift */,
 				7810959F248D50C1008A943C /* Watcher.swift */,
 				78E20D9724981B2A0021552C /* InterposeSubclass.swift */,
 				780FC9F9249822C900DA5A14 /* HookFinder.swift */,
+				781EB555249BEF54002545B4 /* ObjCInvocation.swift */,
+				78EDB902248D42CD00D2F6C1 /* LinuxCompileSupport.swift */,
+				78AB64B4249EAED3002394CD /* InterposeRuntime.swift */,
 			);
 			path = InterposeKit;
 			sourceTree = "<group>";
@@ -208,6 +219,7 @@
 				78EDB8D4248B9BB500D2F6C1 /* TestClass.swift */,
 				78C39D922483169300B46395 /* InterposeKitTests.swift */,
 				78EDB8D6248B9C1200D2F6C1 /* ObjectInterposeTests.swift */,
+				781EB559249BFA58002545B4 /* DynamicHookTests.swift */,
 				78C5A4A72494D75100EE9756 /* MultipleInterposing.swift */,
 				78A2F264249635B100F5AC5F /* KVOTests.swift */,
 				78A2F26624964AF200F5AC5F /* InterposeKitTestCase.swift */,
@@ -405,7 +417,10 @@
 				78C39D912483165600B46395 /* InterposeKit.swift in Sources */,
 				78EDB8FF248D0A9900D2F6C1 /* ObjectHook.swift in Sources */,
 				78EDB903248D42CD00D2F6C1 /* LinuxCompileSupport.swift in Sources */,
+				781EB556249BEF54002545B4 /* ObjCInvocation.swift in Sources */,
 				78E20D9824981B2A0021552C /* InterposeSubclass.swift in Sources */,
+				781EB558249BF0D1002545B4 /* DynamicHook.swift in Sources */,
+				78AB64B5249EAED3002394CD /* InterposeRuntime.swift in Sources */,
 				78EDB8DD248BAA5600D2F6C1 /* AnyHook.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -418,6 +433,7 @@
 				78C5A4A82494D75100EE9756 /* MultipleInterposing.swift in Sources */,
 				78EDB8DA248BA9B300D2F6C1 /* TestClass.swift in Sources */,
 				78EDB8DB248BA9BB00D2F6C1 /* ObjectInterposeTests.swift in Sources */,
+				781EB55A249BFA58002545B4 /* DynamicHookTests.swift in Sources */,
 				78A2F26724964AF200F5AC5F /* InterposeKitTestCase.swift in Sources */,
 				78A2F265249635B100F5AC5F /* KVOTests.swift in Sources */,
 			);

Sources/InterposeKit/AnyHook.swift

@@ -37,6 +37,11 @@ public class AnyHook {
         try validate()
     }
 
+    /// Helper to get class wrapper
+    var klass: InterposeClass {
+        InterposeClass(`class`)
+    }
+
     func replaceImplementation() throws {
         preconditionFailure("Not implemented")
     }

Sources/InterposeKit/ClassHook.swift

@@ -14,15 +14,17 @@ extension Interpose {
 
         override func replaceImplementation() throws {
             let method = try validate()
-            origIMP = class_replaceMethod(`class`, selector, replacementIMP, method_getTypeEncoding(method))
-            guard origIMP != nil else { throw InterposeError.nonExistingImplementation(`class`, selector) }
+
+            origIMP = try klass.replace(method: method, imp: replacementIMP)
             Interpose.log("Swizzled -[\(`class`).\(selector)] IMP: \(origIMP!) -> \(replacementIMP!)")
         }
 
         override func resetImplementation() throws {
             let method = try validate(expectedState: .interposed)
             precondition(origIMP != nil)
-            let previousIMP = class_replaceMethod(`class`, selector, origIMP!, method_getTypeEncoding(method))
+
+
+            let previousIMP = try klass.replace(method: method, imp: origIMP!)
             guard previousIMP == replacementIMP else {
                 throw InterposeError.unexpectedImplementation(`class`, selector, previousIMP)
             }

Sources/InterposeKit/DynamicHook.swift

@@ -0,0 +1,132 @@
+import Foundation
+
+extension Interpose {
+
+    public enum AspectStrategy {
+        case before  /// Called before the original implementation.
+        case instead /// Called insted of the original implementation.
+        case after   /// Called after the original implementation.
+    }
+
+    /// Hook that uses `NSInvocation `to not require specific signatures
+    /// The call is converted into an invocation via `_objc_msgForward`.
+    final public class DynamicHook: AnyHook {
+
+        /// The object that is being hooked.
+        public let object: AnyObject
+
+        /// The position of this hook.
+        public let strategy: AspectStrategy
+
+        /// The stored action to be called
+        public let action: (AnyObject) -> Void
+
+        /// Subclass that we create on the fly
+        var subclass: InterposeSubclass!
+
+        // Logic switch to use super builder
+        let makesSuperIMP: Bool
+
+        public init(object: AnyObject,
+                    selector: Selector,
+                    strategy: AspectStrategy = .before,
+                    makeSuper: Bool = true,
+                    implementation: @escaping (AnyObject) -> Void) throws {
+            if makeSuper && !InterposeSubclass.supportsSuperTrampolines {
+                throw InterposeError.superTrampolineNotAvailable
+            }
+
+            self.object = object
+            self.strategy = strategy
+            self.action = implementation
+            self.makesSuperIMP = makeSuper
+            try super.init(class: type(of: object), selector: selector)
+        }
+
+        private lazy var forwardIMP: IMP = {
+            resolve(symbol: "_objc_msgForward")
+        }()
+
+        // stret is needed for x86-64 struct returns but not for ARM64
+        private lazy var forwardStretIMP: IMP = {
+            resolve(symbol: "_objc_msgForward_stret")
+        }()
+
+        override func replaceImplementation() throws {
+            let method = try validate()
+
+            // Check if there's an existing subclass we can reuse.
+            // Create one at runtime if there is none.
+            let subclass = try InterposeSubclass(object: object)
+            try subclass.prepareDynamicInvocation()
+            self.subclass = subclass
+
+            // If there is no existing implementation, add one.
+            if !subclass.implementsExact(selector: selector) {
+                // Add super trampoline, then swizzle
+                subclass.addSuperTrampoline(selector: selector)
+                let superCallingMethod = subclass.instanceMethod(selector)!
+
+                // add a prefixed copy of the method
+                let aspectSelector = InterposeSubclass.aspectPrefixed(selector)
+                let origImp = superCallingMethod.implementation
+
+                try subclass.add(selector: aspectSelector, imp: origImp, encoding: method.typeEncoding)
+
+                Interpose.log("maked -[\(`class`).\(aspectSelector)]: \(origImp)")
+            }
+
+            // append hook as copy
+            let newContainer = DynamicHookContainer()
+            var hooks = subclass.hookContainer?.hooks ?? []
+            hooks.append(self)
+            newContainer.hooks = hooks
+            subclass.hookContainer = newContainer
+
+            try subclass.replace(method: method, imp: self.forwardIMP)
+            Interpose.log("Added dynamic -[\(`class`).\(selector)]")
+        }
+
+        override func resetImplementation() throws {
+            let method = try validate(expectedState: .interposed)
+
+            // Get the super-implementation via the prefixed method...
+            let aspectSelector = InterposeSubclass.aspectPrefixed(selector)
+
+            let superIMP = try subclass.methodImplementation(aspectSelector)
+
+            // ... and replace the original
+            // The subclassed method can't be removed, but will be unused.
+            let origIMP = try subclass.replace(method: method, imp: superIMP)
+
+            // If the IMP does not match our expectations, throw!
+            // TODO: guard for dynamic + static hook mix!
+            guard origIMP == forwardIMP else {
+                throw InterposeError.unexpectedImplementation(subclass.class, selector, origIMP)
+            }
+
+            Interpose.log("Removed dynamic -[\(`class`).\(selector)]")
+        }
+    }
+
+    /// Store all hooks
+    class DynamicHookContainer {
+        var hooks: [DynamicHook] = []
+
+        var before: [DynamicHook] {
+            hooks.filter { $0.strategy == .before }
+        }
+        var instead: [DynamicHook] {
+            hooks.filter { $0.strategy == .instead }
+        }
+        var after: [DynamicHook] {
+            hooks.filter { $0.strategy == .after }
+        }
+    }
+}
+
+extension Collection where Iterator.Element == Interpose.DynamicHook {
+    func executeAll(_ bSelf: AnyObject) {
+        forEach { $0.action(bSelf) }
+    }
+}

Sources/InterposeKit/HookFinder.swift

@@ -2,8 +2,9 @@ import Foundation
 
 extension Interpose {
 
-    private struct AssociatedKeys {
+    struct AssociatedKeys {
         static var hookForBlock: UInt8 = 0
+        static var hookContainer: UInt8 = 0
     }
 
     private class WeakObjectContainer<T: AnyObject>: NSObject {
@@ -17,6 +18,12 @@ extension Interpose {
         }
     }
 
+    /// Helper to resolve an implementation
+    static func resolve(symbol: String) -> IMP {
+        let imp = dlsym(dlopen(nil, RTLD_LAZY), symbol)
+        return unsafeBitCast(imp, to: IMP.self)
+    }
+
     static func storeHook<HookType: AnyHook>(hook: HookType, to block: AnyObject) {
         // Weakly store reference to hook inside the block of the IMP.
         objc_setAssociatedObject(block, &AssociatedKeys.hookForBlock,

Sources/InterposeKit/InterposeError.swift

@@ -34,6 +34,9 @@
     /// Can't revert or apply if already done so.
     case invalidState(expectedState: AnyHook.State)
 
+    /// SuperBuilder is not in the runtime but required for this configuration.
+    case superTrampolineNotAvailable
+
     /// Unable to remove hook.
     case resetUnsupported(_ reason: String)
 
@@ -51,22 +54,34 @@
         switch self {
         case .methodNotFound(let klass, let selector):
             return "Method not found: -[\(klass) \(selector)]"
+
         case .nonExistingImplementation(let klass, let selector):
             return "Implementation not found: -[\(klass) \(selector)]"
+
         case .unexpectedImplementation(let klass, let selector, let IMP):
             return "Unexpected Implementation in -[\(klass) \(selector)]: \(String(describing: IMP))"
+
         case .failedToAllocateClassPair(let klass, let subclassName):
             return "Failed to allocate class pair: \(klass), \(subclassName)"
+
         case .unableToAddMethod(let klass, let selector):
             return "Unable to add method: -[\(klass) \(selector)]"
+
         case .keyValueObservationDetected(let obj):
             return "Unable to hook object that uses Key Value Observing: \(obj)"
+
         case .objectPosingAsDifferentClass(let obj, let actualClass):
             return "Unable to hook \(type(of: obj)) posing as \(NSStringFromClass(actualClass))/"
+
         case .invalidState(let expectedState):
             return "Invalid State. Expected: \(expectedState)"
+
         case .resetUnsupported(let reason):
             return "Reset Unsupported: \(reason)"
+
+        case .superTrampolineNotAvailable:
+            return "SuperBuilder is required but not available at runtime."
+
         case .unknownError(let reason):
             return reason
         }

Sources/InterposeKit/InterposeKit.swift

@@ -15,13 +15,22 @@
         }
     }
 
+    /// Hook an `@objc dynamic` instance method via selector  on the current object or class..
+    @discardableResult public func hook (
+        _ selector: Selector,
+        strategy: Interpose.AspectStrategy = .before,
+        _ implementation: @escaping (AnyObject) -> Void) throws -> AnyHook {
+        try Interpose.DynamicHook(object: self, selector: selector,
+            strategy: strategy, implementation: implementation).apply()
+    }
+
     /// Hook an `@objc dynamic` instance method via selector  on the current object or class..
     @discardableResult public class func hook<MethodSignature, HookSignature> (
         _ selector: Selector,
         methodSignature: MethodSignature.Type = MethodSignature.self,
         hookSignature: HookSignature.Type = HookSignature.self,
         _ implementation: (TypedHook<MethodSignature, HookSignature>) -> HookSignature?) throws -> AnyHook {
-        return try Interpose.ClassHook(class: self as AnyClass,
+        try Interpose.ClassHook(class: self as AnyClass,
                                        selector: selector, implementation: implementation).apply()
     }
 }
@@ -51,7 +60,7 @@
     }
 
     // This is based on observation, there is no documented way
-    private func isKVORuntimeGeneratedClass(_ klass: AnyClass) -> Bool {
+    private func isKVORuntimemakedClass(_ klass: AnyClass) -> Bool {
         NSStringFromClass(klass).hasPrefix("NSKVO")
     }
 
@@ -73,7 +82,7 @@
         self.class = type(of: object)
 
         if let actualClass = checkObjectPosingAsDifferentClass(object) {
-            if isKVORuntimeGeneratedClass(actualClass) {
+            if isKVORuntimemakedClass(actualClass) {
                 throw InterposeError.keyValueObservationDetected(object)
             } else {
                 throw InterposeError.objectPosingAsDifferentClass(object, actualClass: actualClass)
@@ -97,8 +106,8 @@
         hookSignature: HookSignature.Type = HookSignature.self,
         _ implementation: (TypedHook<MethodSignature, HookSignature>) -> HookSignature?)
         throws -> TypedHook<MethodSignature, HookSignature> {
-        try hook(NSSelectorFromString(selName),
-            methodSignature: methodSignature, hookSignature: hookSignature, implementation)
+            try hook(NSSelectorFromString(selName),
+                     methodSignature: methodSignature, hookSignature: hookSignature, implementation)
     }
 
     /// Hook an `@objc dynamic` instance method via selector  on the current class.