Add initial AccessWidener

2026-06-11 12:22:44 +02:00
parent e176b3bca8
commit 786257ad0e
15 changed files with 979 additions and 6 deletions
@@ -0,0 +1,63 @@
+/*
+ *   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.*;
+
+import java.util.List;
+import java.util.Set;
+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 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 internalName} is targeted.
+     *
+     * @return patched bytes, or {@code null} if no changes were needed
+     */
+    public byte[] patch(String internalName, byte[] classBytes) {
+        if (!targets.contains(internalName)) return null;
+
+        ClassReader cr = new ClassReader(classBytes);
+        // COMPUTE_FRAMES would require the full classpath; we only touch flags so 0 is fine
+        ClassWriter cw = new ClassWriter(cr, 0);
+        cr.accept(new ClassTransformer(cw, internalName, entries), 0);
+        return cw.toByteArray();
+    }
+}
+