Files
KekWar/AccessWidener/src/main/java/de/steamwar/ClassPatcher.java
T

72 lines
2.4 KiB
Java

/*
* This file is a part of the SteamWar software.
*
* Copyright (C) 2026 SteamWar.de-Serverteam
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package de.steamwar;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import java.util.List;
import java.util.Set;
import java.util.logging.Logger;
import java.util.stream.Collectors;
/**
* Uses ASM to patch class bytecode according to a list of access widener entries.
*
* Returns {@code null} if the class is not targeted by any entry (no-op signal
* to the caller so it can skip the write).
*/
public class ClassPatcher {
private static final Logger LOG = Logger.getLogger("ClassPatcher");
private final List<AccessWidenerEntry> entries;
/** Pre-computed set of targeted internal names for fast filtering. */
private final Set<String> targets;
public ClassPatcher(List<AccessWidenerEntry> entries) {
this.entries = entries;
this.targets = entries.stream()
.map(AccessWidenerEntry::target)
.collect(Collectors.toSet());
}
/**
* Patches {@code classBytes} if {@code className} is targeted.
*
* @return patched bytes, or {@code null} if no changes were needed
*/
public byte[] patch(String className, byte[] classBytes) {
if (!targets.contains(className)) return null;
try {
ClassReader cr = new ClassReader(classBytes);
ClassWriter cw = new ClassWriter(cr, 0);
cr.accept(new ClassTransformer(cw, className, entries), ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
return cw.toByteArray();
} catch (Exception e) {
LOG.warning("[AccessWidener] Failed to transform " + className + ": " + e.getMessage());
return null;
}
}
}