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java/org/apache/tomcat/util/bcel/classfile/Utility.java

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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.tomcat.util.bcel.classfile;
+
+import java.io.DataInput;
+import java.io.EOFException;
+import java.io.IOException;
+
+import org.apache.tomcat.util.bcel.Const;
+
+/**
+ * Utility functions that do not really belong to any class in particular.
+ */
+final class Utility {
+
+    private Utility() {
+        // Hide default constructor
+    }
+
+    /**
+     * Shorten long class name <em>str</em>, i.e., chop off the <em>prefix</em>,
+     * if the
+     * class name starts with this string and the flag <em>chopit</em> is true.
+     * Slashes <em>/</em> are converted to dots <em>.</em>.
+     *
+     * @param str The long class name
+     * @return Compacted class name
+     */
+    static String compactClassName(final String str) {
+        return str.replace('/', '.'); // Is `/' on all systems, even DOS
+    }
+
+    static String getClassName(final ConstantPool constant_pool, final int index) {
+        Constant c = constant_pool.getConstant(index, Const.CONSTANT_Class);
+        int i = ((ConstantClass) c).getNameIndex();
+
+        // Finally get the string from the constant pool
+        c = constant_pool.getConstant(i, Const.CONSTANT_Utf8);
+        String name = ((ConstantUtf8) c).getBytes();
+
+        return compactClassName(name);
+    }
+
+    static void skipFully(final DataInput file, final int length) throws IOException {
+        int total = file.skipBytes(length);
+        if (total != length) {
+            throw new EOFException();
+        }
+    }
+
+    static void swallowFieldOrMethod(final DataInput file)
+            throws IOException {
+        // file.readUnsignedShort(); // Unused access flags
+        // file.readUnsignedShort(); // name index
+        // file.readUnsignedShort(); // signature index
+        skipFully(file, 6);
+
+        int attributes_count = file.readUnsignedShort();
+        for (int i = 0; i < attributes_count; i++) {
+            swallowAttribute(file);
+        }
+    }
+
+    static void swallowAttribute(final DataInput file)
+            throws IOException {
+        //file.readUnsignedShort();   // Unused name index
+        skipFully(file, 2);
+        // Length of data in bytes
+        int length = file.readInt();
+        skipFully(file, length);
+    }
+}