I'm trying to shrink my app size with the R8 compiler and the Proguard Rules. The problem is that the Safe Args extension uses reflection in NavArgsLazy.kt like so:
override val value: Args
get() {
var args = cached
if (args == null) {
val arguments = argumentProducer()
val method: Method = methodMap[navArgsClass]
?: navArgsClass.java.getMethod("fromBundle", *methodSignature).also { method ->
// Save a reference to the method
methodMap[navArgsClass] = method
}
#SuppressLint("BanUncheckedReflection") // needed for method.invoke
#Suppress("UNCHECKED_CAST")
args = method.invoke(null, arguments) as Args
cached = args
}
return args
}
And when I try to run the app I get an exception saying that the method fromBundle does not exist when the fragment that uses Safe Args is created.
I'm aware of the reflection problems with ProGuard but I cannot fix this, I'm unable to exclude the class that is giving me this error as I cannot access the generated file and excluding all the files that extends from NavArgs interface is not working either.
This issue has already fixed in Navigation Component version 2.4.0-alpha03
The detailed problem is described here: https://issuetracker.google.com/issues/190082521
Related
I want to use Frida to add a class method to the existing Objective C class on Mac OS. After I read the Frida docs, I tried the following code:
const NSString = ObjC.classes.NSString
function func (n) { console.log(n) }
var nativeCb = new NativeCallback(func, 'void', ['int'])
ObjC.api.class_addMethod(
NSString.handle,
ObjC.selector('onTest:'),
nativeCb,
ObjC.api.method_getTypeEncoding(nativeCb)
)
The above code looks straightforward. However, after the ObjC.api.class_addMethod() call, the attached App and the Frida REPL both froze, it looks that the pointers are not right.
I have tried many possible parameter values for a whole night but still can figure the problem out. What's wrong with my code?
Only two issues:
method_getTypeEncoding() can only be called on a Method, which the NativeCallback is not. You could pass it the handle of an existing Objective-C method that has the same signature as the one you're adding, or use Memory.allocUtf8String() to specify your own signature from scratch.
Objective-C methods, at the C ABI level, have two implicit arguments preceding the method's arguments. These are:
self: The class/instance the method is being invoked on.
_cmd: The selector.
Here's a complete example in TypeScript:
const { NSAutoreleasePool, NSString } = ObjC.classes;
const onTest = new NativeCallback(onTestImpl, "void", ["pointer", "pointer", "int"]);
function onTestImpl(selfHandle: NativePointer, cmd: NativePointer, n: number): void {
const self = new ObjC.Object(selfHandle);
console.log(`-[NSString onTestImpl]\n\tself="${self.toString()}"\n\tn=${n}`);
}
function register(): void {
ObjC.api.class_addMethod(
NSString,
ObjC.selector("onTest:"),
onTest,
Memory.allocUtf8String("v#:i"));
}
function test(): void {
const pool = NSAutoreleasePool.alloc().init();
try {
const s = NSString.stringWithUTF8String_(Memory.allocUtf8String("yo"));
s.onTest_(42);
} finally {
pool.release();
}
}
function exposeToRepl(): void {
const g = global as any;
g.register = register;
g.test = test;
}
exposeToRepl();
You can paste it into https://github.com/oleavr/frida-agent-example, and then with one terminal running npm run watch you can load it into a running app using the REPL: frida -n Telegram -l _agent.js. From the REPL you can then call register() to plug in the new method, and test() to take it for a spin.
I'm creating a costum Android Lint Inspection and I need to register the inspection, to be run. Where do I need to register it?
I've already tried to register the inspection which provides the inspection inside plugin.xml file.
The actual inspection:
class HardcodedDimensionsInspection : AndroidLintInspectionBase("Hardcoded dimensions", HardcodedDimensDetector.ISSUE) {
override fun getShortName(): String {
return "AndroidLintHardcodedDimension"
}
}
The entry in plugin.xml file
<extensions defaultExtensionNs="com.intellij">
<!-- Add your extensions here -->
<!-- <inspectionToolProvider implementation="JavaInspectionProvider"/>-->
<globalInspection shortName="AndroidLintHardcodedDimension" displayName="Hardcoded dimensions"
enabledByDefault="true" level="WARNING"
implementationClass="HardcodedDimensionsInspection"/>
</extensions>
The actual detector
class HardcodedDimensDetector : LayoutDetector() {
override fun getApplicableAttributes(): Collection<String>? {
return Arrays.asList(
// Layouts
ATTR_TEXT
)
}
override fun appliesTo(folderType: ResourceFolderType): Boolean {
return (folderType == ResourceFolderType.LAYOUT ||
folderType == ResourceFolderType.MENU ||
folderType == ResourceFolderType.XML)
}
override fun visitAttribute(context: XmlContext, attribute: Attr) {
val value = attribute.value
}
companion object {
/** The main issue discovered by this detector */
#JvmField
val ISSUE = Issue.create(
id = "HardcodedDimension",
briefDescription = "Hardcoded dimens",
explanation = """
Brief
""",
category = Category.I18N,
priority = 5,
severity = Severity.ERROR,
implementation = Implementation(
HardcodedDimensDetector::class.java,
Scope.RESOURCE_FILE_SCOPE
)
)
}
}
I've expected to hit the breakpoints in any of the functions for Detector but the code is never called. Seems like my detector is not registered. Can you please point me to the missing part, is there a class where I should register my Detector?
Thank you.
The link to the full project: https://github.com/magicbytes/Android-Lint-Inspection
I don't see anything obvious wrong from these snippets. Could you please post on our forum and link to the full sources of your plugin? Thanks. https://intellij-support.jetbrains.com/hc/en-us/community/topics/200366979-IntelliJ-IDEA-Open-API-and-Plugin-Development
I have a workaround for now, not sure it's the official way to do it. Android Lint has a registry with all the Issue classes (built-in), the class is called LintIdeIssueRegistry. When it runs the Android Lint, it's looking in this registry for Issue processors. Since the list is hardcoded, we need to inject ours in the list. I'm using the following code for that:
val registry = LintIdeIssueRegistry()
val issue = registry.getIssue(HardcodedDimensDetector.ISSUE.id)
if (issue == null) {
val list = registry.issues as MutableList<Issue>
list.add(HardcodedDimensDetector.ISSUE)
}
Hopefully in future we will have a method called addIssue inside the LintIdeIssueRegistry.
Is it possible to compile and instantiate Kotlin class at runtime? I'm talking about something like that but using Kotlin API: How do I programmatically compile and instantiate a Java class?
As example:
I'm getting full class definition as String:
val example = "package example\n" +
"\n" +
"fun main(args: Array<String>) {\n" +
" println(\"Hello World\")\n" +
"}\n"
And then inserting it into some class.kt and running it so I'm getting "Hello World" printed in console at runtime.
You might want to look at Kotlin Scripting, see https://github.com/andrewoma/kotlin-script
Alternatively, you'll need to write your own eval(kotlin-code-string-here) method which will dump the text inside blah.kt file for example, compile it using an external Kotlin compiler into blah.class then dynamically load those classes into the runtime using the Java Classloader doing something like this:
MainClass.class.classLoader.loadClass("com.mypackage.MyClass")
This might be very slow and unreliable.
Another no so great option is to make use of Rhino and run JavaScript inside your Kotlin code. So once again, you'll have an eval(kotlin-code-string-here) method which will dump the content to a blah.kt file, then you would use a Kotlin2JS compiler to compile it to JavaScript and directly execute the JavaScript inside Kotlin using Rhino which is not great either.
Another option is to make use of Kotlin Scripting or an external Kotlin compiler (in both cases, the Kotlin compiler will have to start up) and doing something like this will also allow you to execute dynamically, albeit, only on Unix systems.
Runtime.getRuntime().exec(""" "kotlin code here" > blah.kts | sh""")
I'm not aware of a clean solution for this, Kotlin was not designed to be run like like PHP / JavaScript / Python which just interprets text dynamically, it has to compile to bytecode first before it can do anything on the JVM; so in each scenario, you will need to compile that code first in one way or another, whether to bytecode or to javascript and in both cases load it into you application using the Java Classloader or Rhino.
Please check this solution for dependencies, jar resources, etc. Code below isn't enough for successful execution.
However, to compile dynamic class you can do the following:
val classLoader = Thread.currentThread().contextClassLoader
val engineManager = ScriptEngineManager(classLoader)
setIdeaIoUseFallback() // hack to have ability to do this from IntelliJ Idea context
val ktsEngine: ScriptEngine = engineManager.getEngineByExtension("kts")
ktsEngine.eval("object MyClass { val number = 123 } ")
println(ktsEngine.eval("MyClass.number"))
Please note: there is code injection possible here. Please be careful and use dedicated process or dedicated ClassLoader for this.
KotlinScript can be used to compile Kotlin source code (e.g. to generate a jar file that can then be loaded).
Here's a Java project which demonstrates this (code would be cleaner in Kotlin):
https://github.com/alexoooo/sample-kotlin-compile/blob/main/src/main/java/io/github/alexoooo/sample/compile/KotlinCompilerFacade.java
Note that the code you provide would be generated as a nested class (inside the script).
Here is a Kotlin version:
#KotlinScript
object KotlinDynamicCompiler {
//-----------------------------------------------------------------------------------------------------------------
const val scriptClassName = "__"
const val classNamePrefix = "${scriptClassName}$"
private val baseClassType: KotlinType = KotlinType(KotlinDynamicCompiler::class.java.kotlin)
private val contextClass: KClass<*> = ScriptCompilationConfiguration::class.java.kotlin
//-----------------------------------------------------------------------------------------------------------------
fun compile(
kotlinCode: String, outputJarFile: Path, classpathLocations: List<Path>, classLoader: ClassLoader
): String? {
Files.createDirectories(outputJarFile.parent)
val scriptCompilationConfiguration = createCompilationConfigurationFromTemplate(
baseClassType, defaultJvmScriptingHostConfiguration, contextClass
) {
jvm {
val classloaderClasspath: List<File> = classpathFromClassloader(classLoader, false)!!
val classpathFiles = classloaderClasspath + classpathLocations.map { it.toFile() }
updateClasspath(classpathFiles)
}
hostConfiguration(ScriptingHostConfiguration (defaultJvmScriptingHostConfiguration) {
jvm {
compilationCache(
CompiledScriptJarsCache { _, _ ->
outputJarFile.toFile()
}
)
}
})
}
val scriptCompilerProxy = ScriptJvmCompilerIsolated(defaultJvmScriptingHostConfiguration)
val result = scriptCompilerProxy.compile(
kotlinCode.toScriptSource(KotlinCode.scriptClassName), scriptCompilationConfiguration)
val errors = result.reports.filter { it.severity == ScriptDiagnostic.Severity.ERROR }
return when {
errors.isEmpty() -> null
else -> errors.joinToString(" | ")
}
}
}
I know an alternative of reflection which is using javassist, but using javassist is a little bit complex. And because of lambda or some other features in koltin, the javassist doesn't work well sometimes. So is there any other way to iterate all fields of a data class without using reflection.
There are two ways. The first is relatively easy, and is essentially what's mentioned in the comments: assuming you know how many fields there are, you can unpack it and throw that into a list, and iterate over those. Or alternatively use them directly:
data class Test(val x: String, val y: String) {
fun getData() : List<Any> = listOf(x, y)
}
data class Test(val x: String, val y: String)
...
val (x, y) = Test("x", "y")
// And optionally throw those in a list
Although iterating like this is a slight extra step, this is at least one way you can relatively easy unpack a data class.
If you don't know how many fields there are (or you don't want to refactor), you have two options:
The first is using reflection. But as you mentioned, you don't want this.
That leaves a second, somewhat more complicated preprocessing option: annotations. Note that this only works with data classes you control - beyond that, you're stuck with reflection or implementations from the library/framework coder.
Annotations can be used for several things. One of which is metadata, but also code generation. This is a somewhat complicated alternative, and requires an additional module in order to get compile order right. If it isn't compiled in the right order, you'll end up with unprocessed annotations, which kinda defeats the purpose.
I've also created a version you can use with Gradle, but that's at the end of the post and it's a shortcut to implementing it yourself.
Note that I have only tested this with a pure Kotlin project - I've personally had problems with annotations between Java and Kotlin (although that was with Lombok), so I do not guarantee this will work at compile time if called from Java. Also note that this is complex, but avoids runtime reflection.
Explanation
The main issue here is a certain memory concern. This will create a new list every time you call the method, which makes it very similar to the method used by enums.
Local testing over 10000 iterations also show a general consistency of ~200 milliseconds to execute my approach, versus roughly 600 for reflection. However, for one iteration, mine uses ~20 milliseconds, where as reflection uses between 400 and 500 milliseconds. On one run, reflection took 1500 (!) milliseconds, while my approach took 18 milliseconds.
See also Java Reflection: Why is it so slow?. This appears to affect Kotlin as well.
The memory impact of creating a new list every time it's called can be noticeable though, but it'll also be collected so it shouldn't be that big a problem.
For reference, the code used for benchmarking (this will make sense after the rest of the post):
#AutoUnpack data class ExampleDataClass(val x: String, val y: Int, var m: Boolean)
fun main(a: Array<String>) {
var mine = 0L
var reflect = 0L
// for(i in 0 until 10000) {
var start = System.currentTimeMillis()
val cls = ExampleDataClass("example", 42, false)
for (field in cls) {
println(field)
}
mine += System.currentTimeMillis() - start
start = System.currentTimeMillis()
for (prop in ExampleDataClass::class.memberProperties) {
println("${prop.name} = ${prop.get(cls)}")
}
reflect += System.currentTimeMillis() - start
// }
println(mine)
println(reflect)
}
Setting up from scratch
This bases itself around two modules: a consumer module, and a processor module. The processor HAS to be in a separate module. It needs to be compiled separately from the consumer for the annotations to work properly.
First of all, your consumer project needs the annotation processor:
apply plugin: 'kotlin-kapt'
Additionally, you need to add stub generation. It complains it's unused while compiling, but without it, the generator seems to break for me:
kapt {
generateStubs = true
}
Now that that's in order, create a new module for the unpacker. Add the Kotlin plugin if you didn't already. You do not need the annotation processor Gradle plugin in this project. That's only needed by the consumer. You do, however, need kotlinpoet:
implementation "com.squareup:kotlinpoet:1.2.0"
This is to simplify aspects of the code generation itself, which is the important part here.
Now, create the annotation:
#Retention(AnnotationRetention.SOURCE)
#Target(AnnotationTarget.CLASS)
annotation class AutoUnpack
This is pretty much all you need. The retention is set to source because it has no value at runtime, and it only targets compile time.
Next, there's the processor itself. This is somewhat complicated, so bear with me. For reference, this uses the javax.* packages for annotation processing. Android note: this might work assuming you can plug in a Java module on a compileOnly scope without getting the Android SDK restrictions. As I mentioned earlier, this is mainly for pure Kotlin; Android might work, but I haven't tested that.
Anyways, the generator:
Because I couldn't find a way to generate the method into the class without touching the rest (and because according to this, that isn't possible), I'm going with an extension function generation approach.
You'll need a class UnpackCodeGenerator : AbstractProcessor(). In there, you'll first need two lines of boilerplate:
override fun getSupportedAnnotationTypes(): MutableSet<String> = mutableSetOf(AutoUnpack::class.java.name)
override fun getSupportedSourceVersion(): SourceVersion = SourceVersion.latest()
Moving on, there's the processing. Override the process function:
override fun process(annotations: MutableSet<out TypeElement>, roundEnv: RoundEnvironment): Boolean {
// Find elements with the annotation
val annotatedElements = roundEnv.getElementsAnnotatedWith(AutoUnpack::class.java)
if(annotatedElements.isEmpty()) {
// Self-explanatory
return false;
}
// Iterate the elements
annotatedElements.forEach { element ->
// Grab the name and package
val name = element.simpleName.toString()
val pkg = processingEnv.elementUtils.getPackageOf(element).toString()
// Then generate the class
generateClass(name,
if (pkg == "unnamed package") "" else pkg, // This is a patch for an issue where classes in the root
// package return package as "unnamed package" rather than empty,
// which breaks syntax because "package unnamed package" isn't legal.
element)
}
// Return true for success
return true;
}
This just sets up some of the later framework. The real magic happens in the generateClass function:
private fun generateClass(className: String, pkg: String, element: Element){
val elements = element.enclosedElements
val classVariables = elements
.filter {
val name = if (it.simpleName.contains("\$delegate"))
it.simpleName.toString().substring(0, it.simpleName.indexOf("$"))
else it.simpleName.toString()
it.kind == ElementKind.FIELD // Find fields
&& Modifier.STATIC !in it.modifiers // that aren't static (thanks to sebaslogen for issue #1: https://github.com/LunarWatcher/KClassUnpacker/issues/1)
// Additionally, we have to ignore private fields. Extension functions can't access these, and accessing
// them is a bad idea anyway. Kotlin lets you expose get without exposing set. If you, by default, don't
// allow access to the getter, there's a high chance exposing it is a bad idea.
&& elements.any { getter -> getter.kind == ElementKind.METHOD // find methods
&& getter.simpleName.toString() ==
"get${name[0].toUpperCase().toString() + (if (name.length > 1) name.substring(1) else "")}" // that matches the getter name (by the standard convention)
&& Modifier.PUBLIC in getter.modifiers // that are marked public
}
} // Grab the variables
.map {
// Map the name now. Also supports later filtering
if (it.simpleName.endsWith("\$delegate")) {
// Support by lazy
it.simpleName.subSequence(0, it.simpleName.indexOf("$"))
} else it.simpleName
}
if (classVariables.isEmpty()) return; // Self-explanatory
val file = FileSpec.builder(pkg, className)
.addFunction(FunSpec.builder("iterator") // For automatic unpacking in a for loop
.receiver(element.asType().asTypeName().copy()) // Add it as an extension function of the class
.addStatement("return listOf(${classVariables.joinToString(", ")}).iterator()") // add the return statement. Create a list, push an iterator.
.addModifiers(KModifier.PUBLIC, KModifier.OPERATOR) // This needs to be public. Because it's an iterator, the function also needs the `operator` keyword
.build()
).build()
// Grab the generate directory.
val genDir = processingEnv.options["kapt.kotlin.generated"]!!
// Then write the file.
file.writeTo(File(genDir, "$pkg/${element.simpleName.replace("\\.kt".toRegex(), "")}Generated.kt"))
}
All of the relevant lines have comments explaining use, in case you're not familiar with what this does.
Finally, in order to get the processor to process, you need to register it. In the module for the generator, add a file called javax.annotation.processing.Processor under main/resources/META-INF/services. In there you write:
com.package.of.UnpackCodeGenerator
From here, you need to link it using compileOnly and kapt. If you added it as a module to your project, you can do:
kapt project(":ClassUnpacker")
compileOnly project(":ClassUnpacker")
Alternative source setup:
Like I mentioned earlier, I bundled this into a jar for convenience. It's under the same license as SO uses (CC-BY-SA 3.0), and it contains the exact same code as in the answer (although compiled into a single project).
If you want to use this one, just add the Jitpack repo:
repositories {
// Other repos here
maven { url 'https://jitpack.io' }
}
And hook it up with:
kapt 'com.github.LunarWatcher:KClassUnpacker:v1.0.1'
compileOnly "com.github.LunarWatcher:KClassUnpacker:v1.0.1"
Note that the version here may not be up to date: the up to date list of versions is available here. The code in the post still aims to reflect the repo, but versions aren't really important enough to edit every time.
Usage
Regardless of which way you ended up using to get the annotations, the usage is relatively easy:
#AutoUnpack data class ExampleDataClass(val x: String, val y: Int, var m: Boolean)
fun main(a: Array<String>) {
val cls = ExampleDataClass("example", 42, false)
for(field in cls) {
println(field)
}
}
This prints:
example
42
false
Now you have a reflection-less way of iterating fields.
Note that local testing has been done partially with IntelliJ, but IntelliJ doesn't seem to like me - I've had various failed builds where gradlew clean && gradlew build from a command line oddly works fine. I'm not sure whether this is a local problem, or if this is a general problem, but you might have some issues like this if you build from IntelliJ.
Also, you might get errors if the build fails. The IntelliJ linter builds on top of the build directory for some sources, so if the build fails and the file with the extension function isn't generated, that'll cause it to appear as an error. Building usually fixes this when I tested (with both modules and from Jitpack).
You'll also likely have to enable the annotation processor setting if you use Android Studio or IntelliJ.
here is another idea, that i came up with, but am not satisfied with...but it has some pros and cons:
pros:
adding/removing fields to/from the data class causes compiler errors at field-iteration sites
no boiler-plate code needed
cons:
won't work if default values are defined for arguments
declaration:
data class Memento(
val testType: TestTypeData,
val notes: String,
val examinationTime: MillisSinceEpoch?,
val administeredBy: String,
val signature: SignatureViewHolder.SignatureData,
val signerName: String,
val signerRole: SignerRole
) : Serializable
iterating through all fields (can use this directly at call sites, or apply the Visitor pattern, and use this in the accept method to call all the visit methods):
val iterateThroughAllMyFields: Memento = someValue
Memento(
testType = iterateThroughAllMyFields.testType.also { testType ->
// do something with testType
},
notes = iterateThroughAllMyFields.notes.also { notes ->
// do something with notes
},
examinationTime = iterateThroughAllMyFields.examinationTime.also { examinationTime ->
// do something with examinationTime
},
administeredBy = iterateThroughAllMyFields.administeredBy.also { administeredBy ->
// do something with administeredBy
},
signature = iterateThroughAllMyFields.signature.also { signature ->
// do something with signature
},
signerName = iterateThroughAllMyFields.signerName.also { signerName ->
// do something with signerName
},
signerRole = iterateThroughAllMyFields.signerRole.also { signerRole ->
// do something with signerRole
}
)
I'm trying to create a Java Binding Library for BugSense, but one of the methods has a parameter named "params" which is a reserved word in C#. I've tried to use the Metadata.xml file to rename it, but I can't figure out how to access the class, let alone the method or it's parameter.
Here is the problem code it's generating:
namespace Com.Bugsense.Trace {
[global::Android.Runtime.Register ("com/bugsense/trace/ActivityAsyncTask", DoNotGenerateAcw=true)]
internal partial class ActivityAsyncTaskInvoker : ActivityAsyncTask {
static IntPtr id_doInBackground_arrayLjava_lang_Object_;
[Register ("doInBackground", "([Ljava/lang/Object;)Ljava/lang/Object;", "GetDoInBackground_arrayLjava_lang_Object_Handler")]
protected override global::Java.Lang.Object DoInBackground (global::Java.Lang.Object[] params)
{
if (id_doInBackground_arrayLjava_lang_Object_ == IntPtr.Zero)
id_doInBackground_arrayLjava_lang_Object_ = JNIEnv.GetMethodID (class_ref, "doInBackground", "([Ljava/lang/Object;)Ljava/lang/Object;");
IntPtr native_params = JNIEnv.NewArray (params);
global::Java.Lang.Object __ret = Java.Lang.Object.GetObject<global::Java.Lang.Object> (JNIEnv.CallObjectMethod (Handle, id_doInBackground_arrayLjava_lang_Object_, new JValue (native_params)), JniHandleOwnership.TransferLocalRef);
if (params != null) {
JNIEnv.CopyArray (native_params, params);
JNIEnv.DeleteLocalRef (native_params);
}
return __ret;
}
}
}
Here is my mapping, which I feel should work, but just refuses to.
<attr path="/api/package[#name='com.bugsense.trace']/class[#name='ActivityAsyncTaskInvoker']/method[#name='doInBackground']/parameter[#name='params']" name="managedName">#params</attr>
I've tried everything I can think of. Please, HELP!
So, turns out it's just a bug in the current version of Mono for Android. If you update to the 4.2.4 build, which is in beta, everything compiles fine.