jdk/test/java/io/FileInputStream/NegativeAvailable.java
author dxu
Fri, 17 May 2013 12:04:18 -0700
changeset 17691 13931cd9405f
parent 16716 6d3f9ce0d776
permissions -rw-r--r--
8011136: FileInputStream.available and skip inconsistencies Summary: Correct the behavior of available() and update related java specs for available() and skip() in InputStream and FileInputStream classes. Reviewed-by: alanb
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/*
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 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 */
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/*
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 * @test
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 * @bug 8010837 8011136
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 * @summary Test if available returns correct value when skipping beyond
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 *          the end of a file.
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 * @author Dan Xu
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 */
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import java.io.BufferedWriter;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.IOException;
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import java.nio.charset.Charset;
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import java.nio.file.Files;
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import java.nio.file.Path;
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public class NegativeAvailable {
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    public static void main(String[] args) throws IOException {
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        final int SIZE = 10;
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        final int SKIP = 5;
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        final int NEGATIVE_SKIP = -5;
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        // Create a temporary file with size of 10 bytes.
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        Path tmp = Files.createTempFile(null, null);
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        try (BufferedWriter writer =
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            Files.newBufferedWriter(tmp, Charset.defaultCharset())) {
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            for (int i = 0; i < SIZE; i++) {
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                writer.write('1');
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            }
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        }
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        File tempFile = tmp.toFile();
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        try (FileInputStream fis = new FileInputStream(tempFile)) {
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            if (tempFile.length() != SIZE) {
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                throw new RuntimeException("unexpected file size = "
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                                           + tempFile.length());
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            }
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            long space = skipBytes(fis, SKIP, SIZE);
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            space = skipBytes(fis, NEGATIVE_SKIP, space);
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            space = skipBytes(fis, SKIP, space);
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            space = skipBytes(fis, SKIP, space);
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            space = skipBytes(fis, SKIP, space);
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            space = skipBytes(fis, NEGATIVE_SKIP, space);
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            space = skipBytes(fis, NEGATIVE_SKIP, space);
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        }
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        Files.deleteIfExists(tmp);
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    }
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    /**
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     *  Skip toSkip number of bytes and return the remaining bytes of the file.
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     */
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    private static long skipBytes(FileInputStream fis, int toSkip, long space)
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            throws IOException {
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        long skip = fis.skip(toSkip);
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        if (skip != toSkip) {
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            throw new RuntimeException("skip() returns " + skip
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                                       + " but expected " + toSkip);
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        }
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        long newSpace = space - toSkip;
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        long remaining = newSpace > 0 ? newSpace : 0;
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        int avail = fis.available();
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        if (avail != remaining) {
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            throw new RuntimeException("available() returns " + avail
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                                       + " but expected " + remaining);
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        }
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        System.out.println("Skipped " + skip + " bytes "
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                           + " available() returns " + avail);
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        return newSpace;
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    }
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}