jdk/src/java.base/share/classes/java/lang/classfile/ClassReader.java
2025-01-15 02:04:01 +00:00

234 lines
8.4 KiB
Java

/*
* Copyright (c) 2022, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang.classfile;
import java.lang.classfile.constantpool.ClassEntry;
import java.lang.classfile.constantpool.ConstantPool;
import java.lang.classfile.constantpool.ConstantPoolException;
import java.lang.classfile.constantpool.PoolEntry;
import java.lang.classfile.constantpool.Utf8Entry;
import java.util.Optional;
import java.util.function.Function;
import jdk.internal.classfile.impl.ClassReaderImpl;
/**
* Advanced {@code class} file reading support for {@link AttributeMapper}s.
* Supports reading arbitrary offsets within a {@code class} file and reading
* data of various numeric types (e.g., {@code u2}, {@code u4}) in addition to
* constant pool access.
* <p>
* All numeric values in the {@code class} file format are {@linkplain
* java.nio.ByteOrder#BIG_ENDIAN big endian}.
* <p>
* Unless otherwise specified, all out-of-bounds access result in an {@link
* IllegalArgumentException} to indicate the {@code class} file data is
* malformed. Since the {@code class} file data is arbitrary, users should
* sanity-check the structural integrity of the data before attempting to
* interpret the potentially malformed data.
*
* @see AttributeMapper#readAttribute(AttributedElement, ClassReader, int)
* @since 24
*/
public sealed interface ClassReader extends ConstantPool
permits ClassReaderImpl {
// Processing context
/**
* {@return the table of custom attribute mappers} This is derived from
* the processing option {@link ClassFile.AttributeMapperOption}.
*/
Function<Utf8Entry, AttributeMapper<?>> customAttributes();
// Class context
/**
* {@return the access flags for the class, as a bit mask}
*
* @see ClassModel#flags()
*/
int flags();
/**
* {@return the constant pool entry describing the name of class}
*
* @see ClassModel#thisClass()
*/
ClassEntry thisClassEntry();
/**
* {@return the constant pool entry describing the name of the superclass, if any}
*
* @see ClassModel#superclass()
*/
Optional<ClassEntry> superclassEntry();
/** {@return the length of the {@code class} file, in number of bytes} */
int classfileLength();
// Constant pool
/**
* {@return the constant pool entry whose index is given at the specified
* offset within the {@code class} file}
*
* @apiNote
* If only a particular type of entry is expected, use {@link #readEntry(
* int, Class) readEntry(int, Class)}.
*
* @param offset the offset of the index within the {@code class} file
* @throws ConstantPoolException if the index is out of range of the
* constant pool size, or zero
*/
PoolEntry readEntry(int offset);
/**
* {@return the constant pool entry of a given type whose index is given
* at the specified offset within the {@code class} file}
* @param <T> the entry type
* @param offset the offset of the index within the {@code class} file
* @param cls the entry type
* @throws ConstantPoolException if the index is out of range of the
* constant pool size, or zero, or the entry is not of the given type
*/
<T extends PoolEntry> T readEntry(int offset, Class<T> cls);
/**
* {@return the constant pool entry whose index is given at the specified
* offset within the {@code class} file, or {@code null} if the index at the
* specified offset is zero}
*
* @apiNote
* If only a particular type of entry is expected, use {@link #readEntryOrNull(
* int, Class) readEntryOrNull(int, Class)}.
*
* @param offset the offset of the index within the {@code class} file
* @throws ConstantPoolException if the index is out of range of the
* constant pool size
*/
PoolEntry readEntryOrNull(int offset);
/**
* {@return the constant pool entry of a given type whose index is given
* at the specified offset within the {@code class} file, or {@code null} if
* the index at the specified offset is zero}
*
* @param <T> the entry type
* @param offset the offset of the index within the {@code class} file
* @param cls the entry type
* @throws ConstantPoolException if the index is out of range of the
* constant pool size, or zero, or the entry is not of the given type
*/
<T extends PoolEntry> T readEntryOrNull(int offset, Class<T> cls);
/**
* {@return the unsigned byte at the specified offset within the {@code
* class} file} Reads a byte and zero-extends it to an {@code int}.
*
* @param offset the offset within the {@code class} file
*/
int readU1(int offset);
/**
* {@return the unsigned short at the specified offset within the {@code
* class} file} Reads a 2-byte value and zero-extends it to an {@code int}.
*
* @param offset the offset within the {@code class} file
*/
int readU2(int offset);
/**
* {@return the signed byte at the specified offset within the {@code class}
* file} Reads a byte and sign-extends it to an {@code int}.
*
* @param offset the offset within the {@code class} file
*/
int readS1(int offset);
/**
* {@return the signed byte at the specified offset within the {@code class}
* file} Reads a 2-byte value and sign-extends it to an {@code int}.
*
* @param offset the offset within the {@code class} file
*/
int readS2(int offset);
/**
* {@return the signed int at the specified offset within the {@code class}
* file} Reads 4 bytes of value.
*
* @param offset the offset within the {@code class} file
*/
int readInt(int offset);
/**
* {@return the signed long at the specified offset within the {@code class}
* file} Reads 8 bytes of value.
*
* @param offset the offset within the {@code class} file
*/
long readLong(int offset);
/**
* {@return the float value at the specified offset within the {@code class}
* file} Reads 4 bytes of value.
* <p>
* In the conversions, all NaN values of the {@code float} may or may not be
* collapsed into a single {@linkplain Float#NaN "canonical" NaN value}.
*
* @param offset the offset within the {@code class} file
*/
float readFloat(int offset);
/**
* {@return the double value at the specified offset within the {@code
* class} file} Reads 8 bytes of value.
* <p>
* In the conversions, all NaN values of the {@code double} may or may not
* be collapsed into a single {@linkplain Double#NaN "canonical" NaN value}.
*
* @param offset the offset within the {@code class} file
*/
double readDouble(int offset);
/**
* {@return a copy of the bytes at the specified range in the {@code class}
* file}
*
* @param offset the offset within the {@code class} file
* @param len the length of the range
*/
byte[] readBytes(int offset, int len);
/**
* Copy a range of bytes from the {@code class} file to a {@link BufWriter}.
*
* @param buf the {@linkplain BufWriter}
* @param offset the offset within the {@code class} file
* @param len the length of the range
*/
void copyBytesTo(BufWriter buf, int offset, int len);
}