poi/src/testcases/org/apache/poi/poifs/filesystem/TestFileMagic.java

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   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
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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   See the License for the specific language governing permissions and
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package org.apache.poi.poifs.filesystem;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNotSame;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Random;

import org.apache.poi.POIDataSamples;
import org.apache.poi.util.TempFile;
import org.junit.Test;

public class TestFileMagic {
    @Test
    public void testFileMagic() {
        assertEquals(FileMagic.XML, FileMagic.valueOf("XML"));
        assertEquals(FileMagic.XML, FileMagic.valueOf("<?xml".getBytes(StandardCharsets.UTF_8)));

        assertEquals(FileMagic.HTML, FileMagic.valueOf("HTML"));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("<!DOCTYP".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("<!DOCTYPE".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("<html".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("\n\r<html".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("\n<html".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("\r\n<html".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.HTML, FileMagic.valueOf("\r<html".getBytes(StandardCharsets.UTF_8)));

        assertEquals(FileMagic.JPEG, FileMagic.valueOf(new byte[]{ (byte)0xFF, (byte)0xD8, (byte)0xFF, (byte)0xDB }));
        assertEquals(FileMagic.JPEG, FileMagic.valueOf(new byte[]{ (byte)0xFF, (byte)0xD8, (byte)0xFF, (byte)0xE0, 'a', 'b', 'J', 'F', 'I', 'F', 0x00, 0x01 }));
        assertEquals(FileMagic.JPEG, FileMagic.valueOf(new byte[]{ (byte)0xFF, (byte)0xD8, (byte)0xFF, (byte)0xEE }));
        assertEquals(FileMagic.JPEG, FileMagic.valueOf(new byte[]{ (byte)0xFF, (byte)0xD8, (byte)0xFF, (byte)0xE1, 'd', 'c', 'E', 'x', 'i', 'f', 0x00, 0x00 }));

        assertEquals(FileMagic.UNKNOWN, FileMagic.valueOf("something".getBytes(StandardCharsets.UTF_8)));
        assertEquals(FileMagic.UNKNOWN, FileMagic.valueOf(new byte[0]));

        try {
            FileMagic.valueOf("some string");
            fail("Should catch exception here");
        } catch (IllegalArgumentException e) {
            // expected here
        }
    }

    @Test
    public void testFileMagicFile() throws IOException {
        assertEquals(FileMagic.OLE2, FileMagic.valueOf(POIDataSamples.getSpreadSheetInstance().getFile("SampleSS.xls")));
        assertEquals(FileMagic.OOXML, FileMagic.valueOf(POIDataSamples.getSpreadSheetInstance().getFile("SampleSS.xlsx")));
    }

    @Test
    public void testFileMagicStream() throws IOException {
        try (InputStream stream = new BufferedInputStream(new FileInputStream(POIDataSamples.getSpreadSheetInstance().getFile("SampleSS.xls")))) {
            assertEquals(FileMagic.OLE2, FileMagic.valueOf(stream));
        }
        try (InputStream stream = new BufferedInputStream(new FileInputStream(POIDataSamples.getSpreadSheetInstance().getFile("SampleSS.xlsx")))) {
            assertEquals(FileMagic.OOXML, FileMagic.valueOf(stream));
        }
    }

    @Test
    public void testPrepare() throws IOException {
        try (InputStream stream = new BufferedInputStream(new FileInputStream(POIDataSamples.getSpreadSheetInstance().getFile("SampleSS.xlsx")))) {
            assertSame(stream, FileMagic.prepareToCheckMagic(stream));
        }

        try (InputStream stream = new InputStream() {
            @Override
            public int read() {
                return 0;
            }
        }) {
            assertNotSame(stream, FileMagic.prepareToCheckMagic(stream));
        }
    }

    @Test
    public void testMatchingButTooLessData() {
        // this matches JPG, but is not long enough, previously this caused an Exception
        byte[] data = new byte[] { -1, -40, -1, -32, 0, 16, 74, 70 };

        assertEquals(FileMagic.UNKNOWN, FileMagic.valueOf(data));
    }

    @Test
    public void testShortFile() throws IOException {
        // having a file shorter than 8 bytes previously caused an exception
        fetchMagicFromData(new byte[] { -1, -40, -1, -32, 0 });
        fetchMagicFromData(new byte[] { -1, -40, -1, -32 });
        fetchMagicFromData(new byte[] { -1, -40, -1 });
        fetchMagicFromData(new byte[] { -1, -40 });
        fetchMagicFromData(new byte[] { -1 });
        fetchMagicFromData(new byte[0]);
    }

    private void fetchMagicFromData(byte[] data) throws IOException {
        File file = TempFile.createTempFile("TestFileMagic", ".bin");
        try {
            try (FileOutputStream fos = new FileOutputStream(file)) {
                fos.write(data);
            }

            assertEquals(FileMagic.UNKNOWN, FileMagic.valueOf(file));
        } finally {
            assertTrue(file.delete());
        }
    }

    @Test(expected = IOException.class)
    public void testMarkRequired() throws IOException {
        byte[] data = new byte[] { -1, -40, -1, -32, 0 };

        File file = TempFile.createTempFile("TestFileMagic", ".bin");
        try {
            try (FileOutputStream fos = new FileOutputStream(file)) {
                fos.write(data);
            }

            // a FileInputStream does not support "marking"
            try (FileInputStream str = new FileInputStream(file)) {
                assertFalse(str.markSupported());

                FileMagic.valueOf(str);
            }
        } finally {
            assertTrue(file.delete());
        }
    }

    @Test
    public void testPatterns() {
        // just try to trash the functionality with some byte-patterns
        for(int i = 0; i < 256;i++) {
            final byte[] data = new byte[12];
            for(int j = 0;j < 12; j++) {
                data[j] = (byte)i;

                assertEquals(FileMagic.UNKNOWN, FileMagic.valueOf(data));
            }
        }
    }

    @Test
    public void testRandomPatterns() {
        Random random = new Random();

        // just try to trash the functionality with some byte-patterns
        for(int i = 0; i < 1000;i++) {
            final byte[] data = new byte[12];
            random.nextBytes(data);

            // we cannot check for UNKNOWN as we might hit valid byte-patterns here as well
            try {
                assertNotNull(FileMagic.valueOf(data));
            } catch (Exception e) {
                throw new IllegalStateException("Failed with pattern " + Arrays.toString(data), e);
            }
        }
    }
}