/*

 * Copyright (c) 2003, 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.

 *

 * 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.

 */

/* @test

 * @bug 4806007

 * @summary Checks for vague exceptions from writeUTF/readUTF

 * @key randomness

 */

import java.io.*;

import java.util.*;

public class ReadUTF {

    private static Random generator = new Random();

    private static final int TEST_ITERATIONS = 1000;

    private static final int A_NUMBER_NEAR_65535 = 60000;

    private static final int MAX_CORRUPTIONS_PER_CYCLE = 3;

    public static final void main(String[] args) throws Exception {

        for (int i=0; i<TEST_ITERATIONS; i++) {

            try {

                writeAndReadAString();

            } catch (UTFDataFormatException utfdfe) {

                if (utfdfe.getMessage() == null)

                    throw new RuntimeException("vague exception thrown");

            } catch (EOFException eofe) {

                // These are rare and beyond the scope of the test

            }

        }

    }

    private static void writeAndReadAString() throws Exception {

        // Write out a string whose UTF-8 encoding is quite possibly

        // longer than 65535 bytes

        int length = generator.nextInt(A_NUMBER_NEAR_65535) + 1;

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        StringBuffer testBuffer = new StringBuffer();

        for (int i=0; i<length; i++)

            testBuffer.append((char)generator.nextInt());

        String testString = testBuffer.toString();

        DataOutputStream dos = new DataOutputStream(baos);

        dos.writeUTF(testString);

        // Corrupt the data to produce malformed characters

        byte[] testBytes = baos.toByteArray();

        int dataLength = testBytes.length;

        int corruptions = generator.nextInt(MAX_CORRUPTIONS_PER_CYCLE);

        for (int i=0; i<corruptions; i++) {

            int index = generator.nextInt(dataLength);

            testBytes[index] = (byte)generator.nextInt();

        }

        // Pay special attention to mangling the end to produce

        // partial characters at end

        testBytes[dataLength-1] = (byte)generator.nextInt();

        testBytes[dataLength-2] = (byte)generator.nextInt();

        // Attempt to decode the bytes back into a String

        ByteArrayInputStream bais = new ByteArrayInputStream(testBytes);

        DataInputStream dis = new DataInputStream(bais);

        dis.readUTF();

    }

}