Feat (Bungee): Use only unsafe field modifications (#2440)

bungee/build.gradle.kts

@@ -3,9 +3,3 @@ dependencies {
     implementation(projects.javaCompat)
     compileOnly(libs.bungee)
 }
-
-configure<JavaPluginConvention> {
-    // This is necessary to allow compilation for Java 8 while still including
-    // newer Java versions in the code.
-    disableAutoTargetJvm()
-}

bungee/src/main/java/us/myles/ViaVersion/bungee/platform/BungeeViaInjector.java

@@ -25,50 +25,23 @@ import it.unimi.dsi.fastutil.ints.IntSortedSet;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.platform.ViaInjector;
 import us.myles.ViaVersion.bungee.handlers.BungeeChannelInitializer;
-import us.myles.ViaVersion.compatibility.FieldModifierAccessor;
+import us.myles.ViaVersion.compatibility.ForcefulFieldModifier;
-import us.myles.ViaVersion.compatibility.JavaVersionIdentifier;
+import us.myles.ViaVersion.compatibility.unsafe.UnsafeBackedForcefulFieldModifier;
-import us.myles.ViaVersion.compatibility.jre16.Jre16FieldModifierAccessor;
-import us.myles.ViaVersion.compatibility.jre8.Jre8FieldModifierAccessor;
-import us.myles.ViaVersion.compatibility.jre9.Jre9FieldModifierAccessor;
 import us.myles.ViaVersion.util.ReflectionUtil;
 
 import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
 import java.util.List;
 
 public class BungeeViaInjector implements ViaInjector {
 
-    private final FieldModifierAccessor fieldModifierAccessor;
+    private final ForcefulFieldModifier forcefulFieldModifier;
 
     public BungeeViaInjector() {
-        FieldModifierAccessor fieldModifierAccessor = null;
         try {
-            if (JavaVersionIdentifier.IS_JAVA_16) {
+            this.forcefulFieldModifier = new UnsafeBackedForcefulFieldModifier();
-                fieldModifierAccessor = new Jre16FieldModifierAccessor();
-            } else if (JavaVersionIdentifier.IS_JAVA_9) {
-                fieldModifierAccessor = new Jre9FieldModifierAccessor();
-            }
-        } catch (final ReflectiveOperationException outer) {
-            try {
-                fieldModifierAccessor = new Jre8FieldModifierAccessor();
-                Via.getPlatform().getLogger().warning("Had to fall back to the Java 8 field modifier accessor.");
-                outer.printStackTrace();
-            } catch (final ReflectiveOperationException inner) {
-                inner.addSuppressed(outer);
-                throw new IllegalStateException("Cannot create a modifier accessor", inner);
-            }
-        }
-
-        try {
-          if (fieldModifierAccessor == null) {
-              fieldModifierAccessor = new Jre8FieldModifierAccessor();
-          }
         } catch (final ReflectiveOperationException ex) {
             throw new IllegalStateException("Cannot create a modifier accessor", ex);
         }
-
-        // Must be non-null by now.
-        this.fieldModifierAccessor = fieldModifierAccessor;
     }
 
     @Override
@@ -78,14 +51,9 @@ public class BungeeViaInjector implements ViaInjector {
             Field field = pipelineUtils.getDeclaredField("SERVER_CHILD");
             field.setAccessible(true);
 
-            // Remove the final modifier (unless removed by a fork)
-            int modifiers = field.getModifiers();
-            if (Modifier.isFinal(modifiers)) {
-                this.fieldModifierAccessor.setModifiers(field, modifiers & ~Modifier.FINAL);
-            }
-
             BungeeChannelInitializer newInit = new BungeeChannelInitializer((ChannelInitializer<Channel>) field.get(null));
-            field.set(null, newInit);
+
+            this.forcefulFieldModifier.setField(field, null, newInit);
         } catch (Exception e) {
             Via.getPlatform().getLogger().severe("Unable to inject ViaVersion, please post these details on our GitHub and ensure you're using a compatible server version.");
             throw e;

java-compat/build.gradle.kts

@@ -1,12 +1,4 @@
 dependencies {
     api(projects.javaCompat.javaCompatCommon)
-    api(projects.javaCompat.javaCompat8)
+    api(projects.javaCompat.javaCompatUnsafe)
-    api(projects.javaCompat.javaCompat9)
-    api(projects.javaCompat.javaCompat16)
-}
-
-configure<JavaPluginConvention> {
-    // This is necessary to allow compilation for Java 8 while still including
-    // newer Java versions in the code.
-    disableAutoTargetJvm()
 }

java-compat/java-compat-16/build.gradle.kts

@@ -1,7 +0,0 @@
-dependencies {
-    api(projects.javaCompat.javaCompatCommon)
-}
-
-// This is for Java 16, but the minimum required for this
-// is actually just Java 9!
-configureJavaTarget(9)

java-compat/java-compat-16/src/main/java/us/myles/ViaVersion/compatibility/jre16/Jre16FieldModifierAccessor.java

@@ -1,35 +0,0 @@
-package us.myles.ViaVersion.compatibility.jre16;
-
-import us.myles.ViaVersion.compatibility.FieldModifierAccessor;
-
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.VarHandle;
-import java.lang.reflect.Field;
-import java.util.Objects;
-
-@SuppressWarnings({
-        "java:S1191", // SonarLint/-Qube/-Cloud: We (sadly) need Unsafe for the Java 16 impl.
-        "java:S3011", // ^: We need to circumvent the access restrictions of fields.
-})
-public final class Jre16FieldModifierAccessor implements FieldModifierAccessor {
-    private final VarHandle modifiersHandle;
-
-    public Jre16FieldModifierAccessor() throws ReflectiveOperationException {
-        final Field theUnsafeField = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
-        theUnsafeField.setAccessible(true);
-        final sun.misc.Unsafe unsafe = (sun.misc.Unsafe) theUnsafeField.get(null);
-
-        final Field trustedLookup = MethodHandles.Lookup.class.getDeclaredField("IMPL_LOOKUP");
-        final MethodHandles.Lookup lookup = (MethodHandles.Lookup) unsafe.getObject(
-                unsafe.staticFieldBase(trustedLookup), unsafe.staticFieldOffset(trustedLookup));
-
-        this.modifiersHandle = lookup.findVarHandle(Field.class, "modifiers", int.class);
-    }
-
-    @Override
-    public void setModifiers(final Field field, final int modifiers) {
-        Objects.requireNonNull(field, "field must not be null");
-
-        this.modifiersHandle.set(field, modifiers);
-    }
-}

java-compat/java-compat-8/build.gradle.kts

@@ -1,5 +0,0 @@
-dependencies {
-    api(projects.javaCompat.javaCompatCommon)
-}
-
-configureJavaTarget(8)

java-compat/java-compat-8/src/main/java/us/myles/ViaVersion/compatibility/jre8/Jre8FieldModifierAccessor.java

@@ -1,23 +0,0 @@
-package us.myles.ViaVersion.compatibility.jre8;
-
-import us.myles.ViaVersion.compatibility.FieldModifierAccessor;
-
-import java.lang.reflect.Field;
-import java.util.Objects;
-
-@SuppressWarnings("java:S3011") // SonarLint/-Qube/-Cloud: we are intentionally bypassing the setter.
-public final class Jre8FieldModifierAccessor implements FieldModifierAccessor {
-    private final Field modifiersField;
-
-    public Jre8FieldModifierAccessor() throws ReflectiveOperationException {
-        this.modifiersField = Field.class.getDeclaredField("modifiers");
-        this.modifiersField.setAccessible(true);
-    }
-
-    @Override
-    public void setModifiers(final Field field, final int modifiers) throws ReflectiveOperationException {
-        Objects.requireNonNull(field, "field must not be null");
-
-        this.modifiersField.setInt(field, modifiers);
-    }
-}

java-compat/java-compat-9/build.gradle.kts

@@ -1,5 +0,0 @@
-dependencies {
-    api(projects.javaCompat.javaCompatCommon)
-}
-
-configureJavaTarget(9)

java-compat/java-compat-9/src/main/java/us/myles/ViaVersion/compatibility/jre9/Jre9FieldModifierAccessor.java

@@ -1,24 +0,0 @@
-package us.myles.ViaVersion.compatibility.jre9;
-
-import us.myles.ViaVersion.compatibility.FieldModifierAccessor;
-
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.VarHandle;
-import java.lang.reflect.Field;
-import java.util.Objects;
-
-public final class Jre9FieldModifierAccessor implements FieldModifierAccessor {
-    private final VarHandle modifiersHandle;
-
-    public Jre9FieldModifierAccessor() throws ReflectiveOperationException {
-        final MethodHandles.Lookup lookup = MethodHandles.privateLookupIn(Field.class, MethodHandles.lookup());
-        this.modifiersHandle = lookup.findVarHandle(Field.class, "modifiers", int.class);
-    }
-
-    @Override
-    public void setModifiers(final Field field, final int modifiers) {
-        Objects.requireNonNull(field, "field must not be null");
-
-        this.modifiersHandle.set(field, modifiers);
-    }
-}

java-compat/java-compat-common/src/main/java/us/myles/ViaVersion/compatibility/FieldModifierAccessor.java

@@ -1,26 +0,0 @@
-package us.myles.ViaVersion.compatibility;
-
-import java.lang.reflect.Field;
-
-/**
- * Exposes a way to access the modifiers of a {@link Field} mutably.
- * <p>
- * <i>Note:</i> This is <b>explicitly</b> an implementation detail. Do not rely on this within plugins and any
- * non-ViaVersion code.
- * </p>
- */
-public interface FieldModifierAccessor {
-    /**
-     * Sets the modifiers of a field.
-     * <p>
-     * <i>Note:</i> This does not set the accessibility of the field. If you need to read or mutate it, you must handle
-     * that yourself.
-     * </p>
-     *
-     * @param field     the field to set the modifiers of. Will throw if {@code null}.
-     * @param modifiers the modifiers to set on the given {@code field}.
-     * @throws ReflectiveOperationException if the reflective operation fails this method is implemented with fails.
-     */
-    void setModifiers(final Field field, final int modifiers)
-            throws ReflectiveOperationException;
-}

java-compat/java-compat-common/src/main/java/us/myles/ViaVersion/compatibility/ForcefulFieldModifier.java

@@ -0,0 +1,25 @@
+package us.myles.ViaVersion.compatibility;
+
+import java.lang.reflect.Field;
+
+/**
+ * Exposes a way to modify a {@link Field}, regardless of its limitations (given it is accessible by the caller).
+ * <p>
+ * <i>Note:</i> This is <b>explicitly</b> an implementation detail. Do not rely on this within plugins and any
+ * non-ViaVersion code.
+ * </p>
+ */
+public interface ForcefulFieldModifier {
+    /**
+     * Sets the field regardless of field finality.
+     * <p>
+     * <i>Note:</i> This does not set the accessibility of the field.
+     * </p>
+     *
+     * @param field the field to set the modifiers of. Will throw if {@code null}.
+     * @param holder the eye of the beholder. For static fields, use {@code null}.
+     * @param object the new value to set of the object.
+     */
+    void setField(final Field field, final Object holder, final Object object)
+        throws ReflectiveOperationException;
+}

java-compat/java-compat-common/src/main/java/us/myles/ViaVersion/compatibility/JavaVersionIdentifier.java

@@ -1,41 +0,0 @@
-package us.myles.ViaVersion.compatibility;
-
-import java.lang.reflect.Method;
-import java.util.Optional;
-import java.util.stream.Stream;
-
-public enum JavaVersionIdentifier {
-    ;
-
-    public static final boolean IS_JAVA_9;
-    public static final boolean IS_JAVA_16;
-
-    static {
-        // Optional<T>#stream()Stream<T> is marked `@since 9`.
-        IS_JAVA_9 = doesMethodExist(Optional.class, "stream");
-
-        // Stream<T>#toList()List<T> is marked `@since 16`.
-        IS_JAVA_16 = doesMethodExist(Stream.class, "toList");
-    }
-
-    /**
-     * Checks if the given name of a {@link Method} exists on the given {@link Class} without comparing parameters or
-     * other parts of the descriptor. The method must be public and declared on the given class.
-     * <p>
-     * <i>Note:</i> This should only check for stable methods that are expected to stay permanently.
-     * </p>
-     *
-     * @param clazz  the type to get the given {@code method} on.
-     * @param method the name to find.
-     * @return whether the given method exists.
-     */
-    private static boolean doesMethodExist(final Class<?> clazz, final String method) {
-        for (final Method reflect : clazz.getMethods()) {
-            if (reflect.getName().equals(method)) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-}

java-compat/java-compat-unsafe/build.gradle.kts

@@ -0,0 +1,3 @@
+dependencies {
+    api(project(":java-compat:java-compat-common"))
+}

java-compat/java-compat-unsafe/src/main/java/us/myles/ViaVersion/compatibility/unsafe/UnsafeBackedForcefulFieldModifier.java

@@ -0,0 +1,30 @@
+package us.myles.ViaVersion.compatibility.unsafe;
+
+import us.myles.ViaVersion.compatibility.ForcefulFieldModifier;
+
+import java.lang.reflect.Field;
+import java.util.Objects;
+
+@SuppressWarnings({
+        "java:S1191", // SonarLint/-Qube/-Cloud: We need Unsafe for the modifier implementation.
+        "java:S3011", // ^: We need to circumvent the access restrictions of fields.
+})
+public final class UnsafeBackedForcefulFieldModifier implements ForcefulFieldModifier {
+    private final sun.misc.Unsafe unsafe;
+
+    public UnsafeBackedForcefulFieldModifier() throws ReflectiveOperationException {
+        final Field theUnsafeField = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
+        theUnsafeField.setAccessible(true);
+        this.unsafe = (sun.misc.Unsafe) theUnsafeField.get(null);
+    }
+
+    @Override
+    public void setField(final Field field, final Object holder, final Object object) {
+        Objects.requireNonNull(field, "field must not be null");
+
+        final Object ufo = holder != null ? holder : this.unsafe.staticFieldBase(field);
+        final long offset = holder != null ? this.unsafe.objectFieldOffset(field) : this.unsafe.staticFieldOffset(field);
+
+        this.unsafe.putObject(ufo, offset, object);
+    }
+}

settings.gradle.kts

@@ -4,8 +4,7 @@ enableFeaturePreview("TYPESAFE_PROJECT_ACCESSORS")
 enableFeaturePreview("VERSION_CATALOGS")
 
 include("adventure")
-include("java-compat", "java-compat:java-compat-common", "java-compat:java-compat-8",
+include("java-compat", "java-compat:java-compat-common", "java-compat:java-compat-unsafe")
-    "java-compat:java-compat-9", "java-compat:java-compat-16")
 
 setupViaSubproject("api")
 setupViaSubproject("common")