Add custom agent to work around FabricMC/fabric-loader#817

Author: embeddedt

.gitignore

@@ -5,6 +5,7 @@ media
 classes/
 .architectury-transformer/
 fabric/fabricloader.log
+fabric/test_run
 
 # Changelog
 CHANGELOG.md

build.gradle

@@ -93,7 +93,7 @@ allprojects {
     }
 }
 
-subprojects {
+configure(subprojects.findAll {it.name == "common" || it.name == "forge" || it.name == "fabric"}) {
     apply plugin: "dev.architectury.loom"
 
     loom {

fabric/build.gradle

@@ -22,6 +22,10 @@ configurations {
 
     include.extendsFrom modIncludeImplementation
     modImplementation.extendsFrom modIncludeImplementation
+
+    testAgent {
+        canBeConsumed = false
+    }
 }
 
 dependencies {
@@ -51,10 +55,22 @@ dependencies {
     testImplementation("org.assertj:assertj-core:3.19.0")
     testImplementation("com.google.guava:guava-testlib:21.0")
     testImplementation("org.mockito:mockito-junit-jupiter:5.3.1")
+
+    testAgent(project("path": ":test_agent", "configuration": "agentJar"))
 }
 
 test {
     useJUnitPlatform()
+    def runDir = file('test_run')
+    doFirst() {
+        runDir.mkdir()
+    }
+    workingDir = runDir
+
+    // inject our custom agent to fix #817
+    FileCollection agentFile = configurations.getByName("testAgent")
+    jvmArgs "-javaagent:${agentFile.singleFile.absolutePath}"
+    dependsOn(agentFile)
 }
 
 processResources {

settings.gradle

@@ -7,6 +7,7 @@ pluginManagement {
     }
 }
 
+include("test_agent")
 include("common")
 include("fabric")
 include("forge")

test_agent/build.gradle

@@ -0,0 +1,86 @@
+plugins {
+    //id 'com.github.johnrengelman.shadow' version '7.1.2'
+    id 'java'
+}
+
+group 'org.embeddedt'
+archivesBaseName = 'modernfix-test-agent'
+version '1.0'
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+repositories {
+    mavenCentral()
+    mavenLocal()
+    maven {
+        name = 'forge'
+        url = 'https://maven.minecraftforge.net/'
+    }
+}
+
+/*
+
+shadowJar {
+    relocate 'net.bytebuddy.agent', 'org.embeddedt.modernfix.testing.shadow.bytebuddyagent'
+    relocate 'org.objectweb.asm', 'org.embeddedt.modernfix.testing.shadow.asm'
+}
+
+
+
+shadowJar {
+    project.configurations.implementation.canBeResolved = true
+    configurations = [project.configurations.implementation]
+}
+ */
+dependencies {
+    compileOnly "net.fabricmc:fabric-loader:${rootProject.fabric_loader_version}"
+    implementation "org.ow2.asm:asm-tree:9.1"
+    implementation "org.ow2.asm:asm-commons:9.1"
+    implementation "org.ow2.asm:asm-util:9.1"
+
+    //implementation('net.bytebuddy:byte-buddy-agent:1.12.22')
+}
+
+tasks.withType(JavaCompile) {
+    // ensure that the encoding is set to UTF-8, no matter what the system default is
+    // this fixes some edge cases with special characters not displaying correctly
+    // see http://yodaconditions.net/blog/fix-for-java-file-encoding-problems-with-gradle.html
+    // If Javadoc is generated, this must be specified in that task too.
+    options.encoding = "UTF-8"
+}
+
+jar {
+    manifest {
+        attributes(
+                "Premain-Class": "org.embeddedt.modernfix.testing.Agent",
+                "Can-Redefine-Classes": false,
+                "Can-Set-Native-Method-Prefix": false
+        )
+    }
+}
+/*
+
+shadowJar {
+    archiveBaseName.set('modernfix-test-agent')
+    archiveClassifier.set('')
+    archiveVersion.set('v1')
+}
+
+ */
+
+configurations {
+    agentJar {
+        canBeConsumed = true
+        canBeResolved = false
+    }
+}
+
+artifacts {
+    agentJar(jar)
+}
+/*
+project.tasks.shadowJar.dependsOn build
+defaultTasks 'shadowJar'
+
+ */

test_agent/src/main/java/org/embeddedt/modernfix/testing/Agent.java

@@ -0,0 +1,61 @@
+package org.embeddedt.modernfix.testing;
+
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.lang.instrument.Instrumentation;
+import java.security.ProtectionDomain;
+import java.util.ListIterator;
+
+public class Agent {
+    /**
+     * Simple agent that transforms Fabric Loader to never mark game JARs as system libraries.
+     *
+     * Ugly, but usable workaround for <a href="https://github.com/FabricMC/fabric-loader/issues/817">issue #817</a>
+     * on the Loader bug tracker.
+     */
+    public static void premain(String args, Instrumentation instrumentation) {
+        instrumentation.addTransformer(new ClassFileTransformer() {
+            @Override
+            public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
+                if(className.equals("net/fabricmc/loader/impl/game/LibClassifier")) {
+                    ClassNode node = new ClassNode();
+                    ClassReader reader = new ClassReader(classfileBuffer);
+                    reader.accept(node, 0);
+                    for(MethodNode m : node.methods) {
+                        if(m.name.equals("<init>")) {
+                            ListIterator<AbstractInsnNode> iter = m.instructions.iterator();
+                            int addMatches = 0;
+                            while(iter.hasNext()) {
+                                AbstractInsnNode n = iter.next();
+                                if(n instanceof MethodInsnNode) {
+                                    MethodInsnNode invokeNode = (MethodInsnNode)n;
+                                    if(invokeNode.name.equals("add") && invokeNode.owner.equals("java/util/Set") && invokeNode.desc.equals("(Ljava/lang/Object;)Z")) {
+                                        addMatches++;
+                                        if(addMatches == 2) {
+                                            iter.set(new MethodInsnNode(Opcodes.INVOKESTATIC, "org/embeddedt/modernfix/testing/AgentHooks", "addLibraryWithCheck", "(Ljava/util/Set;Ljava/lang/Object;)Z", false));
+                                            break;
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
+                    node.accept(writer);
+                    byte[] finalArray = writer.toByteArray();
+                    //dumpDebugClass(className, finalArray);
+                    return finalArray;
+                }
+                return classfileBuffer;
+            }
+        });
+    }
+}

test_agent/src/main/java/org/embeddedt/modernfix/testing/AgentHooks.java

@@ -0,0 +1,17 @@
+package org.embeddedt.modernfix.testing;
+
+import java.nio.file.Path;
+import java.util.Set;
+
+@SuppressWarnings("unused")
+public class AgentHooks {
+    @SuppressWarnings({"unchecked", "rawtypes" })
+    public static boolean addLibraryWithCheck(Set pathSet, Object path) {
+        boolean shouldAdd;
+        if(path instanceof Path) {
+            shouldAdd = !((Path)path).toString().contains("minecraft-merged");
+        } else
+            shouldAdd = true;
+        return shouldAdd && pathSet.add(path);
+    }
+}