study-springframework-master.zip

// ASM: a very small and fast Java bytecode manipulation framework // Copyright (c) 2000-2011 INRIA, France Telecom // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions // are met: // 1. Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // 2. Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in the // documentation and/or other materials provided with the distribution. // 3. Neither the name of the copyright holders nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF // THE POSSIBILITY OF SUCH DAMAGE. package org.springframework.asm; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; /** * A parser to make a {@link ClassVisitor} visit a ClassFile structure, as defined in the Java * Virtual Machine Specification (JVMS). This class parses the ClassFile content and calls the * appropriate visit methods of a given {@link ClassVisitor} for each field, method and bytecode * instruction encountered. * * @author Eric Bruneton * @author Eugene Kuleshov * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html">JVMS 4</a> */ public class ClassReader { /** * A flag to skip the Code attributes. If this flag is set the Code attributes are neither parsed * nor visited. */ public static final int SKIP_CODE = 1; /** * A flag to skip the SourceFile, SourceDebugExtension, LocalVariableTable, LocalVariableTypeTable * and LineNumberTable attributes. If this flag is set these attributes are neither parsed nor * visited (i.e. {@link ClassVisitor#visitSource}, {@link MethodVisitor#visitLocalVariable} and * {@link MethodVisitor#visitLineNumber} are not called). */ public static final int SKIP_DEBUG = 2; /** * A flag to skip the StackMap and StackMapTable attributes. If this flag is set these attributes * are neither parsed nor visited (i.e. {@link MethodVisitor#visitFrame} is not called). This flag * is useful when the {@link ClassWriter#COMPUTE_FRAMES} option is used: it avoids visiting frames * that will be ignored and recomputed from scratch. */ public static final int SKIP_FRAMES = 4; /** * A flag to expand the stack map frames. By default stack map frames are visited in their * original format (i.e. "expanded" for classes whose version is less than V1_6, and "compressed" * for the other classes). If this flag is set, stack map frames are always visited in expanded * format (this option adds a decompression/compression step in ClassReader and ClassWriter which * degrades performance quite a lot). */ public static final int EXPAND_FRAMES = 8; /** * A flag to expand the ASM specific instructions into an equivalent sequence of standard bytecode * instructions. When resolving a forward jump it may happen that the signed 2 bytes offset * reserved for it is not sufficient to store the bytecode offset. In this case the jump * instruction is replaced with a temporary ASM specific instruction using an unsigned 2 bytes * offset (see {@link Label#resolve}). This internal flag is used to re-read classes containing * such instructions, in order to replace them with standard instructions. In addition, when this * flag is used, goto_w and jsr_w are <i>not</i> converted into goto and jsr, to make sure that * infinite loops where a goto_w is replaced with a goto in ClassReader and converted back to a * goto_w in ClassWriter cannot occur. */ static final int EXPAND_ASM_INSNS = 256; /** The size of the temporary byte array used to read class input streams chunk by chunk. */ private static final int INPUT_STREAM_DATA_CHUNK_SIZE = 4096; /** * A byte array containing the JVMS ClassFile structure to be parsed. <i>The content of this array * must not be modified. This field is intended for {@link Attribute} sub classes, and is normally * not needed by class visitors.</i> * * <p>NOTE: the ClassFile structure can start at any offset within this array, i.e. it does not * necessarily start at offset 0. Use {@link #getItem} and {@link #header} to get correct * ClassFile element offsets within this byte array. */ // DontCheck(MemberName): can't be renamed (for backward binary compatibility). public final byte[] b; /** The offset in bytes, in {@link #b}, of the ClassFile's access_flags field. */ public final int header; /** * The offset in bytes, in {@link #b}, of each cp_info entry of the ClassFile's constant_pool * array, <i>plus one</i>. In other words, the offset of constant pool entry i is given by * cpInfoOffsets[i] - 1, i.e. its cp_info's tag field is given by b[cpInfoOffsets[i] - 1]. */ private final int[] cpInfoOffsets; /** * The String objects corresponding to the CONSTANT_Utf8 constant pool items. This cache avoids * multiple parsing of a given CONSTANT_Utf8 constant pool item. */ private final String[] constantUtf8Values; /** * The ConstantDynamic objects corresponding to the CONSTANT_Dynamic constant pool items. This * cache avoids multiple parsing of a given CONSTANT_Dynamic constant pool item. */ private final ConstantDynamic[] constantDynamicValues; /** * The start offsets in {@link #b} of each element of the bootstrap_methods array (in the * BootstrapMethods attribute). * * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.23">JVMS * 4.7.23</a> */ private final int[] bootstrapMethodOffsets; /** * A conservative estimate of the maximum length of the strings contained in the constant pool of * the class. */ private final int maxStringLength; // ----------------------------------------------------------------------------------------------- // Constructors // ----------------------------------------------------------------------------------------------- /** * Constructs a new {@link ClassReader} object. * * @param classFile the JVMS ClassFile structure to be read. */ public ClassReader(final byte[] classFile) { this(classFile, 0, classFile.length); } /** * Constructs a new {@link ClassReader} object. * * @param classFileBuffer a byte array containing the JVMS ClassFile structure to be read. * @param classFileOffset the offset in byteBuffer of the first byte of the ClassFile to be read. * @param classFileLength the length in bytes of the ClassFile to be read. */ public ClassReader(final byte[] classFileBuffer, final int classFileOffset, final int classFileLength) { // NOPMD(UnusedFormalParameter) u