feat: allocateInstance & invokeConstructor (#11)

README.md

@@ -8,6 +8,10 @@ from original Xposed and it should work with almost no modificiations.
 
 Additionally, XposedBridge contains these new methods:
 
+- `allocateInstance` - Allocates a class instance without calling any constructors
+   Can be used as a simpler alternative to `sun.misc.Unsafe#allocateInstance`
+- `invokeConstructor` - Invokes a constructor for an existing instance, most useful in conjunction
+   raw instance allocation.
 - `makeClassInheritable` - Makes a final class inheritable, see LSPlant doc for more info
 - `deoptimizeMethod` - Deoptimises method to solve inline issues, see LSPlant doc for more info
 - `disableProfileSaver` - Disables Android Profile Saver to try to prevent ahead of time compilation

core/src/androidTest/java/com/aliucord/hook/Dummy.java

@@ -0,0 +1,30 @@
+package com.aliucord.hook;
+
+public class Dummy {
+    public boolean initialized;
+
+    Object a;
+    int b;
+    Integer c;
+    String d;
+
+    public Dummy() {
+        initialized = true;
+    }
+
+    public Dummy(Object a, int b, Integer c, String d) {
+        this.a = a;
+        this.b = b;
+        this.c = c;
+        this.d = d;
+    }
+
+    public Dummy(Object... varargs) {}
+
+    public static class Dummy2 extends Dummy {
+        public Dummy2() {
+            super();
+            d = "dummy2";
+        }
+    }
+}

core/src/androidTest/java/com/aliucord/hook/UnitTest.java

@@ -2,6 +2,8 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 import android.os.Build;
@@ -116,6 +118,90 @@ public void shouldNotHookField() throws Throwable {
         XposedBridge.hookMethod(UnitTest.class.getDeclaredField("counter"), XC_MethodReplacement.DO_NOTHING);
     }
 
+    @Test
+    public void shouldAllocateInstance() {
+        var instance = XposedBridge.allocateInstance(Dummy.class);
+        assertNotNull("failed to alloc", instance);
+        assertFalse(instance.initialized);
+    }
+
+    @Test
+    public void shouldInvokeConstructor() throws Throwable {
+        var instance = XposedBridge.allocateInstance(Dummy.class);
+        assertFalse("constructor not supposed to be called", instance.initialized);
+
+        var success = XposedBridge.invokeConstructor(instance, Dummy.class.getDeclaredConstructor());
+        assertTrue("invokeConstructor failed", success);
+        assertTrue("constructor not called", instance.initialized);
+    }
+
+    @Test
+    public void shouldInvokeSuperConstructor() throws Throwable {
+        var instance = XposedBridge.allocateInstance(Dummy.Dummy2.class);
+        assertFalse("constructor not supposed to be called", instance.initialized);
+
+        var success = XposedBridge.invokeConstructor(instance, Dummy.class.getDeclaredConstructor());
+        assertTrue("invokeConstructor failed", success);
+        assertTrue("supertype ctor not called", instance.initialized);
+        assertNull("subtype ctor should not be called", instance.d);
+    }
+
+    @Test
+    public void shouldInvokeSubConstructor() throws Throwable {
+        var instance = XposedBridge.allocateInstance(Dummy.Dummy2.class);
+        assertFalse("constructor not supposed to be called", instance.initialized);
+
+        var success = XposedBridge.invokeConstructor(instance, Dummy.Dummy2.class.getDeclaredConstructor());
+        assertTrue("invokeConstructor failed", success);
+        assertTrue("supertype ctor not called", instance.initialized);
+        assertEquals("subtype ctor not called", "dummy2", instance.d);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldNotInvokeVarargsConstructor() throws Throwable {
+        XposedBridge.invokeConstructor(new Dummy(), Dummy.class.getDeclaredConstructor(Object[].class));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldFailInvokeConstructorWrongArgCount() throws Throwable {
+        XposedBridge.invokeConstructor(
+                new Dummy(),
+                Dummy.class.getDeclaredConstructor(),
+                "balls"
+        );
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldFailInvokeConstructorWrongArgs() throws Throwable {
+        var constructor = Dummy.class.getDeclaredConstructor(Object.class, int.class, Integer.class, String.class);
+        XposedBridge.invokeConstructor(
+                new Dummy(),
+                constructor,
+                "balls",
+                Integer.valueOf(1),
+                "ballsv2",
+                new Object()
+        );
+    }
+
+    @Test
+    public void shouldInvokeArgsConstructor() throws Throwable {
+        var a = new Object();
+        var b = 42;
+        var c = Integer.valueOf(420);
+        var d = "balls";
+
+        var instance = XposedBridge.allocateInstance(Dummy.class);
+        var constructor = Dummy.class.getDeclaredConstructor(Object.class, int.class, Integer.class, String.class);
+        var success = XposedBridge.invokeConstructor(instance, constructor, a, b, c, d);
+        assertTrue("invokeConstructor failed", success);
+        assertFalse("wrong constructor called", instance.initialized);
+        assertEquals("a does not match", a, instance.a);
+        assertEquals("b does not match", b, instance.b);
+        assertEquals("c does not match", c, instance.c);
+        assertEquals("d does not match", d, instance.d);
+    }
+
     @Test
     public void shouldDisableProfileSaver() {
         assertTrue(XposedBridge.disableProfileSaver());

core/src/main/cpp/CMakeLists.txt

@@ -8,7 +8,18 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 include_directories(xz/linux/lib/xz xz/linux/include/linux xz/userspace)
 
-add_library(aliuhook SHARED aliuhook.cpp elf_img.cpp profile_saver.cpp hidden_api.cpp xz/linux/lib/xz/xz_crc32.c xz/linux/lib/xz/xz_crc64.c xz/linux/lib/xz/xz_dec_bcj.c xz/linux/lib/xz/xz_dec_lzma2.c xz/linux/lib/xz/xz_dec_stream.c)
+add_library(aliuhook SHARED
+        aliuhook.cpp
+        elf_img.cpp
+        profile_saver.cpp
+        hidden_api.cpp
+        invoke_constructor.cpp
+        xz/linux/lib/xz/xz_crc32.c
+        xz/linux/lib/xz/xz_crc64.c
+        xz/linux/lib/xz/xz_dec_bcj.c
+        xz/linux/lib/xz/xz_dec_lzma2.c
+        xz/linux/lib/xz/xz_dec_stream.c
+)
 
 find_package(lsplant REQUIRED CONFIG)
 find_package(dobby REQUIRED CONFIG)

core/src/main/cpp/aliuhook.cpp

@@ -18,6 +18,7 @@
 #include <cstdlib>
 #include <cerrno>
 #include "aliuhook.h"
+#include "invoke_constructor.h"
 
 int AliuHook::android_version = -1;
 pine::ElfImg AliuHook::elf_img; // NOLINT(cert-err58-cpp)
@@ -110,6 +111,26 @@ Java_de_robv_android_xposed_XposedBridge_disableHiddenApiRestrictions(JNIEnv *en
     return disable_hidden_api(env);
 }
 
+extern "C"
+JNIEXPORT jobject JNICALL
+Java_de_robv_android_xposed_XposedBridge_allocateInstance0(JNIEnv *env, jclass, jclass clazz) {
+    return env->AllocObject(clazz);
+}
+
+extern "C"
+JNIEXPORT jboolean JNICALL
+Java_de_robv_android_xposed_XposedBridge_invokeConstructor0(JNIEnv *env, jclass, jobject instance, jobject constructor, jobjectArray args) {
+    jmethodID constructorMethodId = env->FromReflectedMethod(constructor);
+    if (!constructorMethodId) return JNI_FALSE;
+
+    if (!args) {
+        env->CallVoidMethod(instance, constructorMethodId);
+        return JNI_TRUE;
+    } else {
+        return InvokeConstructorWithArgs(env, instance, constructor, args);
+    }
+}
+
 JNIEXPORT jint JNICALL
 JNI_OnLoad(JavaVM *vm, void *) {
     JNIEnv *env;
@@ -154,5 +175,19 @@ JNI_OnLoad(JavaVM *vm, void *) {
 
     LOGI("lsplant init finished");
 
+    res = LoadInvokeConstructorCache(env);
+    if (!res) {
+        LOGE("invoke_constructor init failed");
+        return JNI_ERR;
+    }
+
     return JNI_VERSION_1_6;
 }
+
+JNIEXPORT void JNICALL
+JNI_OnUnload(JavaVM *vm, void *) {
+    JNIEnv *env;
+    vm->GetEnv((void **) &env, JNI_VERSION_1_1);
+
+    UnloadInvokeConstructorCache(env);
+}