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Code modifiers and test extension

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This commit is contained in:
jglrxavpok 2020-08-21 01:32:59 +02:00
parent 164719090a
commit 223af361d8
11 changed files with 278 additions and 47 deletions
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4
build.gradle
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@ -111,6 +111,10 @@ dependencies {
api 'org.projectlombok:lombok:1.18.12'
annotationProcessor 'org.projectlombok:lombok:1.18.12'
// Code modification
api "org.ow2.asm:asm:6.2.1"
api "org.ow2.asm:asm-tree:6.2.1"
// Path finding
api 'com.github.MadMartian:hydrazine-path-finding:1.3.1'

1
src/main/java/fr/themode/demo/Main.java
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@ -36,6 +36,7 @@ public class Main {
commandManager.register(new ShutdownCommand());
commandManager.register(new TeleportCommand());
StorageManager storageManager = MinecraftServer.getStorageManager();
storageManager.defineDefaultStorageSystem(FileStorageSystem::new);

11
src/main/java/fr/themode/demo/MainWrapper.java
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@ -1,11 +0,0 @@
package fr.themode.demo;
import net.minestom.server.Bootstrap;
public class MainWrapper {
public static void main(String[] args) {
Bootstrap.bootstrap("fr.themode.demo.Main", args);
}
}

6
src/main/java/net/minestom/server/Bootstrap.java
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@ -13,6 +13,12 @@ public class Bootstrap {
public static void bootstrap(String mainClassFullName, String[] args) {
try {
ClassLoader classLoader = new MinestomOverwriteClassLoader(Bootstrap.class.getClassLoader());
// ensure extensions are loaded when starting the server
Class<?> serverClass = classLoader.loadClass("net.minestom.server.MinecraftServer");
Method init = serverClass.getMethod("init");
init.invoke(null);
Class<?> mainClass = classLoader.loadClass(mainClassFullName);
Method main = mainClass.getDeclaredMethod("main", String[].class);
main.invoke(null, new Object[] { args });

79
src/main/java/net/minestom/server/extensions/ExtensionManager.java
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@ -1,18 +1,13 @@
package net.minestom.server.extensions;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.*;
import lombok.extern.slf4j.Slf4j;
import net.minestom.server.extras.selfmodification.MinestomOverwriteClassLoader;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
@ -24,9 +19,11 @@ import java.util.zip.ZipFile;
@Slf4j
public class ExtensionManager {
private final Map<URL, URLClassLoader> extensionLoaders = new HashMap<>();
private final Map<String, URLClassLoader> extensionLoaders = new HashMap<>();
private final Map<String, Extension> extensions = new HashMap<>();
private final File extensionFolder = new File("extensions");
private final static String INDEV_CLASSES_FOLDER = "minestom.extension.indevfolder.classes";
private final static String INDEV_RESOURCES_FOLDER = "minestom.extension.indevfolder.resources";
public ExtensionManager() {
}
@ -42,27 +39,38 @@ public class ExtensionManager {
List<DiscoveredExtension> discoveredExtensions = discoverExtensions();
setupCodeModifiers(discoveredExtensions);
for (DiscoveredExtension extension : discoveredExtensions) {
for (DiscoveredExtension discoveredExtension : discoveredExtensions) {
URLClassLoader loader;
File file = extension.jarFile;
URL[] urls = new URL[discoveredExtension.files.length];
try {
URL url = file.toURI().toURL();
loader = loadJar(url);
extensionLoaders.put(url, loader);
for (int i = 0; i < urls.length; i++) {
urls[i] = discoveredExtension.files[i].toURI().toURL();
}
loader = newClassLoader(urls);
} catch (MalformedURLException e) {
log.error(String.format("Failed to get URL for file %s.", file.getPath()));
log.error("Failed to get URL.", e);
return;
}
InputStream extensionInputStream = loader.getResourceAsStream("extension.json");
if (extensionInputStream == null) {
log.error(String.format("Failed to find extension.json in the file '%s'.", file.getPath()));
StringBuilder urlsString = new StringBuilder();
for (int i = 0; i < urls.length; i++) {
URL url = urls[i];
if(i != 0) {
urlsString.append(" ; ");
}
urlsString.append("'").append(url.toString()).append("'");
}
log.error(String.format("Failed to find extension.json in the urls '%s'.", urlsString));
return;
}
JsonObject extensionDescription = JsonParser.parseReader(new InputStreamReader(extensionInputStream)).getAsJsonObject();
String mainClass = extensionDescription.get("entrypoint").getAsString();
String extensionName = extensionDescription.get("name").getAsString();
extensionLoaders.put(extensionName, loader);
if (extensions.containsKey(extensionName.toLowerCase())) {
log.error(String.format("An extension called '%s' has already been registered.", extensionName));
return;
@ -150,7 +158,22 @@ public class ExtensionManager {
InputStreamReader reader = new InputStreamReader(f.getInputStream(f.getEntry("extension.json")))) {
DiscoveredExtension extension = new DiscoveredExtension();
extension.jarFile = file;
extension.files = new File[]{file};
extension.description = gson.fromJson(reader, JsonObject.class);
extensions.add(extension);
} catch (IOException e) {
e.printStackTrace();
}
}
// this allows developers to have their extension discovered while working on it, without having to build a jar and put in the extension folder
if(System.getProperty(INDEV_CLASSES_FOLDER) != null && System.getProperty(INDEV_RESOURCES_FOLDER) != null) {
log.info("Found indev folders for extension. Adding to list of discovered extensions.");
String extensionClasses = System.getProperty(INDEV_CLASSES_FOLDER);
String extensionResources = System.getProperty(INDEV_RESOURCES_FOLDER);
try(InputStreamReader reader = new InputStreamReader(new FileInputStream(new File(extensionResources, "extension.json")))) {
DiscoveredExtension extension = new DiscoveredExtension();
extension.files = new File[] { new File(extensionClasses), new File(extensionResources) };
extension.description = gson.fromJson(reader, JsonObject.class);
extensions.add(extension);
} catch (IOException e) {
@ -163,11 +186,11 @@ public class ExtensionManager {
/**
* Loads a URL into the classpath.
*
* @param url {@link URL} (usually a JAR) that should be loaded.
* @param urls {@link URL} (usually a JAR) that should be loaded.
*/
@NotNull
public URLClassLoader loadJar(@NotNull URL url) {
return URLClassLoader.newInstance(new URL[]{url}, ExtensionManager.class.getClassLoader());
public URLClassLoader newClassLoader(@NotNull URL[] urls) {
return URLClassLoader.newInstance(urls, ExtensionManager.class.getClassLoader());
}
@NotNull
@ -186,7 +209,7 @@ public class ExtensionManager {
}
@NotNull
public Map<URL, URLClassLoader> getExtensionLoaders() {
public Map<String, URLClassLoader> getExtensionLoaders() {
return new HashMap<>(extensionLoaders);
}
@ -196,28 +219,30 @@ public class ExtensionManager {
private void setupCodeModifiers(List<DiscoveredExtension> extensions) {
ClassLoader cl = getClass().getClassLoader();
if(!(cl instanceof MinestomOverwriteClassLoader)) {
log.warning("Current class loader is not a MinestomOverwriteClassLoader, but "+cl+". This disables code modifiers (Mixin support is therefore disabled)");
log.warn("Current class loader is not a MinestomOverwriteClassLoader, but "+cl+". This disables code modifiers (Mixin support is therefore disabled)");
return;
}
MinestomOverwriteClassLoader modifiableClassLoader = (MinestomOverwriteClassLoader)cl;
log.info("Start loading code modifiers...");
for(DiscoveredExtension extension : extensions) {
try {
if(extension.description.has("codeModifier")) {
String codeModifierClass = extension.description.get("codeModifier").getAsString();
modifiableClassLoader.loadModifier(extension.jarFile, codeModifierClass);
if(extension.description.has("codeModifiers")) {
JsonArray codeModifierClasses = extension.description.getAsJsonArray("codeModifiers");
for(JsonElement elem : codeModifierClasses) {
modifiableClassLoader.loadModifier(extension.files, elem.getAsString());
}
}
// TODO: special support for mixins
} catch (Exception e) {
e.printStackTrace();
log.error("Failed to load code modifier for extension "+extension.jarFile, e);
log.error("Failed to load code modifier for extension in files: "+Arrays.toString(extension.files), e);
}
}
log.info("Done loading code modifiers.");
}
private class DiscoveredExtension {
private File jarFile;
private File[] files;
private JsonObject description;
}
}

22
src/main/java/net/minestom/server/extras/selfmodification/CodeModifier.java Normal file
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@ -0,0 +1,22 @@
package net.minestom.server.extras.selfmodification;
import org.objectweb.asm.tree.ClassNode;
/**
* Will be called by {@link MinestomOverwriteClassLoader} to transform classes at load-time
*/
public abstract class CodeModifier {
/**
* Must return true iif the class node has been modified
* @param source
* @return
*/
public abstract boolean transform(ClassNode source);
/**
* Beginning of the class names to transform.
* 'null' is allowed to transform any class, but not recommended
* @return
*/
public abstract String getNamespace();
}

130
src/main/java/net/minestom/server/extras/selfmodification/MinestomOverwriteClassLoader.java
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@ -1,15 +1,61 @@
package net.minestom.server.extras.selfmodification;
import lombok.extern.slf4j.Slf4j;
import org.jetbrains.annotations.NotNull;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.tree.ClassNode;
import java.io.File;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
// TODO: register code modifiers
@Slf4j
public class MinestomOverwriteClassLoader extends URLClassLoader {
/**
* Classes that cannot be loaded/modified by this classloader.
* Will go through parent class loader
*/
private static final Set<String> protectedClasses = Set.of(
"net.minestom.server.extras.selfmodification.CodeModifier",
"net.minestom.server.extras.selfmodification.MinestomOverwriteClassLoader"
);
private final URLClassLoader asmClassLoader;
// TODO: replace by tree to optimize lookup times. We can use the fact that package names are split with '.' to allow for fast lookup
// TODO: eg. Node("java", Node("lang"), Node("io")). Loading "java.nio.Channel" would apply modifiers from "java", but not "java.io" or "java.lang".
// TODO: that's an example, please don't modify standard library classes. And this classloader should not let you do it because it first asks the platform classloader
// TODO: priorities?
private List<CodeModifier> modifiers = new LinkedList<>();
private final Method findParentLoadedClass;
private final Class<?> loadedCodeModifier;
public MinestomOverwriteClassLoader(ClassLoader parent) {
super("Minestom ClassLoader", loadURLs(), parent);
try {
findParentLoadedClass = ClassLoader.class.getDeclaredMethod("findLoadedClass", String.class);
findParentLoadedClass.setAccessible(true);
} catch (NoSuchMethodException e) {
e.printStackTrace();
throw new Error("Failed to access ClassLoader#findLoadedClass", e);
}
try {
loadedCodeModifier = loadClass("net.minestom.server.extras.selfmodification.CodeModifier");
} catch (ClassNotFoundException e) {
e.printStackTrace();
throw new Error("Failed to access CodeModifier class.");
}
asmClassLoader = newChild(new URL[0]);
}
private static URL[] loadURLs() {
@ -48,17 +94,27 @@ public class MinestomOverwriteClassLoader extends URLClassLoader {
try {
Class<?> systemClass = ClassLoader.getPlatformClassLoader().loadClass(name);
log.trace("System class: "+systemClass);
return systemClass;
} catch (ClassNotFoundException e) {
try {
// check if parent already loaded the class
Class<?> loadedByParent = (Class<?>) findParentLoadedClass.invoke(getParent(), name);
if(loadedByParent != null) {
log.trace("Already found in parent: "+loadedByParent);
return super.loadClass(name, resolve);
}
if(isProtected(name)) {
log.trace("Protected: "+name);
return super.loadClass(name, resolve);
}
String path = name.replace(".", "/") + ".class";
byte[] bytes = getResourceAsStream(path).readAllBytes();
Class<?> defined = defineClass(name, bytes, 0, bytes.length);
if(resolve) {
resolveClass(defined);
}
return defined;
} catch (Exception ioException) {
return transformAndLoad(name, bytes, resolve);
} catch (Exception ex) {
log.trace("Fail to load class, resorting to parent loader: "+name, ex);
// fail to load class, let parent load
// this forbids code modification, but at least it will load
return super.loadClass(name, resolve);
@ -66,7 +122,63 @@ public class MinestomOverwriteClassLoader extends URLClassLoader {
}
}
public void loadModifier(File originFile, String codeModifierClass) {
throw new UnsupportedOperationException("TODO");
private boolean isProtected(String name) {
return protectedClasses.contains(name);
}
private Class<?> transformAndLoad(String name, byte[] bytes, boolean resolve) throws ClassNotFoundException {
ClassReader reader = new ClassReader(bytes);
ClassNode node = new ClassNode();
reader.accept(node, 0);
boolean modified = false;
synchronized (modifiers) {
for(CodeModifier modifier : modifiers) {
boolean shouldModify = modifier.getNamespace() == null || name.startsWith(modifier.getNamespace());
if(shouldModify) {
modified |= modifier.transform(node);
}
}
}
if(modified) {
ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_FRAMES) {
@Override
protected ClassLoader getClassLoader() {
return asmClassLoader;
}
};
node.accept(writer);
bytes = writer.toByteArray();
}
Class<?> defined = defineClass(name, bytes, 0, bytes.length);
log.trace("Loaded with code modifiers: "+name);
if(resolve) {
resolveClass(defined);
}
return defined;
}
@NotNull
public URLClassLoader newChild(@NotNull URL[] urls) {
return URLClassLoader.newInstance(urls, this);
}
public void loadModifier(File[] originFiles, String codeModifierClass) {
URL[] urls = new URL[originFiles.length];
try {
for (int i = 0; i < originFiles.length; i++) {
urls[i] = originFiles[i].toURI().toURL();
}
URLClassLoader loader = newChild(urls);
Class<?> modifierClass = loader.loadClass(codeModifierClass);
if(CodeModifier.class.isAssignableFrom(modifierClass)) {
CodeModifier modifier = (CodeModifier) modifierClass.getDeclaredConstructor().newInstance();
synchronized (modifiers) {
log.warn("Added Code modifier: "+modifier);
modifiers.add(modifier);
}
}
} catch (MalformedURLException | ClassNotFoundException | InvocationTargetException | InstantiationException | IllegalAccessException | NoSuchMethodException e) {
e.printStackTrace();
}
}
}

15
src/test/java/testextension/TestExtension.java Normal file
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@ -0,0 +1,15 @@
package testextension;
import net.minestom.server.extensions.Extension;
public class TestExtension extends Extension {
@Override
public void initialize() {
System.out.println("Hello from extension!");
}
@Override
public void terminate() {
}
}

13
src/test/java/testextension/TestExtensionLauncher.java Normal file
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@ -0,0 +1,13 @@
package testextension;
import net.minestom.server.Bootstrap;
// To launch with VM arguments:
// -Dminestom.extension.indevfolder.classes=build/classes/java/test/ -Dminestom.extension.indevfolder.resources=build/resources/test/
public class TestExtensionLauncher {
public static void main(String[] args) {
Bootstrap.bootstrap("fr.themode.demo.MainDemo", args);
}
}

37
src/test/java/testextension/TestModifier.java Normal file
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@ -0,0 +1,37 @@
package testextension;
import net.minestom.server.extras.selfmodification.CodeModifier;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.*;
import java.util.List;
public class TestModifier extends CodeModifier implements Opcodes {
@Override
public boolean transform(ClassNode source) {
if(source.name.equals("net/minestom/server/instance/InstanceContainer")) {
System.out.println("Modifying code source of "+source.name);
MethodNode constructor = findConstructor(source.methods);
constructor.instructions.insert(constructor.instructions.getFirst(), buildInjectionCode());
return true;
}
return false;
}
private InsnList buildInjectionCode() {
InsnList list = new InsnList();
list.add(new FieldInsnNode(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"));
list.add(new LdcInsnNode("Hello from modified code!!"));
list.add(new MethodInsnNode(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false));
return list;
}
private MethodNode findConstructor(List<MethodNode> methods) {
return methods.stream().filter(m -> m.name.equals("<init>")).findFirst().orElseThrow();
}
@Override
public String getNamespace() {
return "net.minestom.server";
}
}

7
src/test/resources/extension.json Normal file
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@ -0,0 +1,7 @@
{
"entrypoint": "testextension.TestExtension",
"name": "Test extension",
"codeModifiers": [
"testextension.TestModifier"
]
}