org.apache.commons.weaver.privilizer.InlineNestedPrivilegedCalls Maven / Gradle / Ivy

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Implements the Apache Commons Weaver SPI for the Privilizer module.
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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 org.apache.commons.weaver.privilizer;

import java.util.Map;

import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.commons.Method;
import org.objectweb.asm.tree.ClassNode;

/**
 * For any privileged method called from another privileged method (actually the internal implementation method copied
 * from the original method body) the call is replaced by a call to the target's internal implementation method, thus
 * avoiding nested privileged invocations when possible. Persists everything to a tree model until the parent is
 * complete; allowing us to use a tree model while yet building the high-level view as a stack of visitors.
 */
class InlineNestedPrivilegedCalls extends ClassNode {
    private final class VisitEnd extends ClassVisitor {
        private final class VisitMethod extends MethodVisitor {
            private final Method outer;

            private VisitMethod(final MethodVisitor orig, final Method outer) {
                super(Privilizer.ASM_VERSION, orig);
                this.outer = outer;
            }

            @Override
            public void visitMethodInsn(final int opcode, final String owner, final String name,
                final String desc, final boolean itf) {
                String useName = name;
                if (owner.equals(InlineNestedPrivilegedCalls.this.name)) {
                    final Method methd = new Method(name, desc);
                    if (privilegedMethods.containsKey(methd)) {
                        useName = privilegedMethods.get(methd);
                        privilizer.env.debug("Inlining call from %s to %s as %s", outer, methd,
                            useName);
                    }
                }
                super.visitMethodInsn(opcode, owner, useName, desc, itf);
            }
        }

        private VisitEnd() {
            super(Privilizer.ASM_VERSION, next);
        }

        @Override
        @SuppressWarnings("PMD.UseVarargs") //overridden method
        public MethodVisitor visitMethod(final int access, final String name, final String desc,
            final String signature, final String[] exceptions) {
            final Method outer = new Method(name, desc);
            final MethodVisitor orig = super.visitMethod(access, name, desc, signature, exceptions);
            if (!privilegedMethods.containsValue(name)) {
                return orig;
            }
            return new VisitMethod(orig, outer);
        }
    }

    /**
     * Owning {@link Privilizer}.
     */
    final Privilizer privilizer;

    /**
     * Map of original method to name of internal implementation method.
     */
    final Map privilegedMethods;

    /**
     * Next {@link ClassVisitor}.
     */
    final ClassVisitor next;

    /**
     * Create a new {@link InlineNestedPrivilegedCalls} object.
     * @param privilizer owner
     * @param privilegedMethods map of original method to name of internal implementation method
     * @param next visitor
     */
    InlineNestedPrivilegedCalls(final Privilizer privilizer, final Map privilegedMethods,
        final ClassVisitor next) {
        super(Privilizer.ASM_VERSION);
        this.privilizer = privilizer;
        this.privilegedMethods = privilegedMethods;
        this.next = next;
    }

    @Override
    public void visitEnd() {
        super.visitEnd();
        accept(new VisitEnd());
    }
}