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commit bcec4b0af865024db4c6d5877fad9d5cdacdbefc Author: Gary Gregory <[email protected]> AuthorDate: Mon Jan 12 17:54:49 2026 -0500 org.apache.bcel.classfile.Synthetic now requires its the attribute_length item be zero. See https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.8 --- src/changes/changes.xml | 1 + .../java/org/apache/bcel/classfile/Synthetic.java | 81 +++++++++------------- .../org/apache/bcel/classfile/SyntheticTest.java | 38 ++++++++++ 3 files changed, 71 insertions(+), 49 deletions(-) diff --git a/src/changes/changes.xml b/src/changes/changes.xml index 5f9759f2..2f7bb72d 100644 --- a/src/changes/changes.xml +++ b/src/changes/changes.xml @@ -76,6 +76,7 @@ The <action> type attribute can be add,update,fix,remove. <action type="fix" dev="ggregory" due-to="Gary Gregory">ClassDumper.dump() should not call the input stream it didn't open; fixes IOException when calling DumpClass.main(ClassDumper.java:351).</action> <action type="fix" dev="ggregory" due-to="Gary Gregory">org.apache.bcel.classfile.ConstantPool.ConstantPool(Constant[]) now uses varagrs: ConstantPool(Constant...).</action> <action type="fix" dev="ggregory" due-to="Gary Gregory">org.apache.bcel.classfile.Deprecated now requires its the attribute_length item be zero. See https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.15.</action> + <action type="fix" dev="ggregory" due-to="Gary Gregory">org.apache.bcel.classfile.Synthetic now requires its the attribute_length item be zero. See https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.8.</action> <!-- ADD --> <action type="add" dev="ggregory" due-to="Gary Gregory">Add Const.MAJOR_26.</action> <action type="add" dev="ggregory" due-to="Gary Gregory">Add Const.MINOR_26.</action> diff --git a/src/main/java/org/apache/bcel/classfile/Synthetic.java b/src/main/java/org/apache/bcel/classfile/Synthetic.java index a1f6493a..b21546c1 100644 --- a/src/main/java/org/apache/bcel/classfile/Synthetic.java +++ b/src/main/java/org/apache/bcel/classfile/Synthetic.java @@ -16,59 +16,61 @@ * specific language governing permissions and limitations * under the License. */ + package org.apache.bcel.classfile; import java.io.DataInput; -import java.io.DataOutputStream; import java.io.IOException; import org.apache.bcel.Const; import org.apache.bcel.util.Args; +import org.apache.commons.lang3.ArrayUtils; /** - * This class is derived from <em>Attribute</em> and declares this class as 'synthetic', that is, it needs special - * handling. The JVM specification states "A class member that does not appear in the source code must be marked using a - * Synthetic attribute." It may appear in the ClassFile attribute table, a field_info table or a method_info table. This - * class is intended to be instantiated from the <em>Attribute.readAttribute()</em> method. + * This class is derived from <em>Attribute</em> and declares this class as 'synthetic', that is, it needs special handling. The JVM specification states "A + * class member that does not appear in the source code must be marked using a Synthetic attribute." It may appear in the ClassFile attribute table, a + * field_info table or a method_info table. This class is intended to be instantiated from the <em>Attribute.readAttribute()</em> method. + * + * <pre> + * + * Synthetic_attribute { + * u2 attribute_name_index; + * u4 attribute_length; + * } + * </pre> * * @see Attribute + * @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.8";>JVM Specification: The Synthetic Attribute</a> */ public final class Synthetic extends Attribute { - private byte[] bytes; - /** - * @param nameIndex Index in constant pool to CONSTANT_Utf8, which should represent the string "Synthetic". - * @param length Content length in bytes - should be zero. - * @param bytes Attribute contents + * @param nameIndex Index in constant pool to CONSTANT_Utf8, which should represent the string "Synthetic". + * @param length JVM Specification: "The value of the attribute_length item must be zero." + * @param bytes Attribute contents. * @param constantPool The constant pool this attribute is associated with. + * @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.8";>JVM Specification: The Synthetic Attribute</a> */ public Synthetic(final int nameIndex, final int length, final byte[] bytes, final ConstantPool constantPool) { super(Const.ATTR_SYNTHETIC, nameIndex, Args.require0(length, "Synthetic attribute length"), constantPool); - this.bytes = bytes; } /** * Constructs object from input stream. * - * @param nameIndex Index in constant pool to CONSTANT_Utf8 - * @param length Content length in bytes - * @param input Input stream + * @param nameIndex Index in constant pool to CONSTANT_Utf8. + * @param length JVM Specification: "The value of the attribute_length item must be zero." + * @param input Input stream. * @param constantPool Array of constants * @throws IOException if an I/O error occurs. + * @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.8";>JVM Specification: The Synthetic Attribute</a> */ Synthetic(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException { this(nameIndex, length, (byte[]) null, constantPool); - if (length > 0) { - bytes = new byte[length]; - input.readFully(bytes); - println("Synthetic attribute with length > 0"); - } } /** - * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a - * physical copy. + * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a physical copy. * * @param c Source to copy. */ @@ -77,10 +79,10 @@ public final class Synthetic extends Attribute { } /** - * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. - * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects. + * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e., the hierarchy of methods, fields, + * attributes, etc. spawns a tree of objects. * - * @param v Visitor object + * @param v Visitor object. */ @Override public void accept(final Visitor v) { @@ -88,44 +90,29 @@ public final class Synthetic extends Attribute { } /** - * @return deep copy of this attribute + * @return deep copy of this attribute. */ @Override public Attribute copy(final ConstantPool constantPool) { final Synthetic c = (Synthetic) clone(); - if (bytes != null) { - c.bytes = bytes.clone(); - } c.setConstantPool(constantPool); return c; } - /** - * Dumps source file attribute to file stream in binary format. - * - * @param file Output file stream - * @throws IOException if an I/O error occurs. - */ - @Override - public void dump(final DataOutputStream file) throws IOException { - super.dump(file); - if (super.getLength() > 0) { - file.write(bytes, 0, super.getLength()); - } - } - /** * @return data bytes. */ public byte[] getBytes() { - return bytes; + return ArrayUtils.EMPTY_BYTE_ARRAY; } /** * @param bytes */ public void setBytes(final byte[] bytes) { - this.bytes = bytes; + if (bytes != null) { + Args.require0(bytes.length, "Deprecated attribute length"); + } } /** @@ -133,10 +120,6 @@ public final class Synthetic extends Attribute { */ @Override public String toString() { - final StringBuilder buf = new StringBuilder("Synthetic"); - if (super.getLength() > 0) { - buf.append(" ").append(Utility.toHexString(bytes)); - } - return buf.toString(); + return "Synthetic"; } } diff --git a/src/test/java/org/apache/bcel/classfile/SyntheticTest.java b/src/test/java/org/apache/bcel/classfile/SyntheticTest.java new file mode 100644 index 00000000..2d15786a --- /dev/null +++ b/src/test/java/org/apache/bcel/classfile/SyntheticTest.java @@ -0,0 +1,38 @@ +/* + * 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 + * + * https://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.bcel.classfile; + +import static org.junit.jupiter.api.Assertions.assertThrows; + +import java.io.DataInput; + +import org.junit.jupiter.api.Test; + +/** + * Tests {@link Synthetic}. + */ +public class SyntheticTest { + + @Test + public void testAttributeLength() { + assertThrows(ClassFormatException.class, () -> new Synthetic(1, 0, (byte[]) null, new ConstantPool())); + assertThrows(ClassFormatException.class, () -> new Synthetic(1, 0, (DataInput) null, new ConstantPool())); + } +}
