1 files changed, 121 insertions, 0 deletions
diff --git a/src/android/com/android/jarjar/StripAnnotationsJarTransformer.java b/src/android/com/android/jarjar/StripAnnotationsJarTransformer.java
new file mode 100644
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+++ b/src/android/com/android/jarjar/StripAnnotationsJarTransformer.java
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.jarjar;
+
+import com.tonicsystems.jarjar.util.JarTransformer;
+
+import org.objectweb.asm.AnnotationVisitor;
+import org.objectweb.asm.ClassVisitor;
+import org.objectweb.asm.FieldVisitor;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Opcodes;
+
+import java.util.List;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+
+/**
+ * A transformer that strips annotations from all classes based on custom rules.
+ */
+public final class StripAnnotationsJarTransformer extends JarTransformer {
+
+    private static int ASM_VERSION = Opcodes.ASM9;
+
+    private final List<String> stripAnnotationList;
+
+    public StripAnnotationsJarTransformer(List<StripAnnotation> stripAnnotationList) {
+        this.stripAnnotationList = getAnnotationList(stripAnnotationList);
+    }
+
+    private static List<String> getAnnotationList(List<StripAnnotation> stripAnnotationList) {
+        return stripAnnotationList.stream().map(el -> getClassName(el)).collect(Collectors.toList());
+    }
+
+    private static String getClassName(StripAnnotation element) {
+        return "L" + element.getPattern().replace('.', '/') + ";";
+    }
+
+    @Override
+    protected ClassVisitor transform(ClassVisitor classVisitor) {
+        return new AnnotationRemover(classVisitor);
+    }
+
+    private class AnnotationRemover extends ClassVisitor {
+
+        AnnotationRemover(ClassVisitor cv) {
+            super(ASM_VERSION, cv);
+        }
+
+        @Override
+        public AnnotationVisitor visitAnnotation(String descriptor, boolean visible) {
+            return visitAnnotationCommon(descriptor,
+                    () -> super.visitAnnotation(descriptor, visible));
+        }
+
+        @Override
+        public FieldVisitor visitField(int access, String name, String descriptor, String signature,
+                Object value) {
+            FieldVisitor superVisitor =
+                    super.visitField(access, name, descriptor, signature, value);
+            return new FieldVisitor(ASM_VERSION, superVisitor) {
+                @Override
+                public AnnotationVisitor visitAnnotation(String descriptor, boolean visible) {
+                    return visitAnnotationCommon(descriptor,
+                            () -> super.visitAnnotation(descriptor, visible));
+
+                }
+            };
+        }
+
+        @Override
+        public MethodVisitor visitMethod(int access, String name, String descriptor,
+                String signature, String[] exceptions) {
+            MethodVisitor superVisitor =
+                    super.visitMethod(access, name, descriptor, signature, exceptions);
+            return new MethodVisitor(ASM_VERSION, superVisitor) {
+                @Override
+                public AnnotationVisitor visitAnnotation(String descriptor, boolean visible) {
+                    return visitAnnotationCommon(descriptor,
+                            () -> super.visitAnnotation(descriptor, visible));
+                }
+
+                @Override
+                public AnnotationVisitor visitParameterAnnotation(int parameter,
+                        String descriptor, boolean visible) {
+                    return visitAnnotationCommon(descriptor,
+                            () -> super.visitParameterAnnotation(parameter, descriptor, visible));
+                }
+            };
+        }
+
+        /**
+         * Create an {@link AnnotationVisitor} that removes any annotations from {@link
+         * #stripAnnotationList}.
+         */
+        private AnnotationVisitor visitAnnotationCommon(String annotation,
+                Supplier<AnnotationVisitor> defaultVisitorSupplier) {
+            if (stripAnnotationList.contains(annotation)) {
+                return null;
+            }
+            // Only get() the default AnnotationVisitor if the annotation is to be included.
+            // Invoking super.visitAnnotation(descriptor, visible) causes the annotation to be
+            // included in the output even if the resulting AnnotationVisitor is not returned or
+            // used.
+            return defaultVisitorSupplier.get();
+        }
+    }
+}