From d28720afd08d1998a7784f09e6cfd5ed9bec2dc9 Mon Sep 17 00:00:00 2001
From: Dominik Stadler <centic@apache.org>
Date: Sun, 25 Nov 2018 21:56:43 +0000
Subject: [PATCH] Add test for FileMagic JavaDoc warning fixes Remove some IDE
 warnings Reformat code of sample application

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1847437 13f79535-47bb-0310-9956-ffa450edef68
---
 .../apache/poi/stress/XSSFFileHandler.java    |  9 +--
 .../org/apache/poi/hpsf/VariantSupport.java   |  2 +-
 .../poi/hpsf/wellknown/PropertyIDMap.java     |  7 +-
 .../poi/hssf/model/InternalWorkbook.java      |  2 +
 .../poi/hssf/record/RecordInputStream.java    | 16 ++--
 .../org/apache/poi/hssf/record/SSTRecord.java |  8 +-
 .../poi/hssf/record/SharedFormulaRecord.java  |  6 +-
 .../hssf/record/SharedValueRecordBase.java    | 12 +--
 .../poi/util/RecordFormatException.java       |  4 +-
 .../extractor/CommandLineTextExtractor.java   | 66 +++++++--------
 .../poi/openxml4j/opc/internal/ZipHelper.java |  2 -
 .../poi/ooxml/TestPOIXMLProperties.java       |  5 +-
 .../extractor/TestXDGFVisioExtractor.java     |  2 +-
 .../apache/poi/xssf/XSSFTestDataSamples.java  | 51 +++++-------
 .../poi/poifs/filesystem/TestFileMagic.java   | 80 +++++++++++++++++++
 15 files changed, 174 insertions(+), 98 deletions(-)
 create mode 100644 src/testcases/org/apache/poi/poifs/filesystem/TestFileMagic.java

diff --git a/src/integrationtest/org/apache/poi/stress/XSSFFileHandler.java b/src/integrationtest/org/apache/poi/stress/XSSFFileHandler.java
index 5c47d9af7e..48a30a2569 100644
--- a/src/integrationtest/org/apache/poi/stress/XSSFFileHandler.java
+++ b/src/integrationtest/org/apache/poi/stress/XSSFFileHandler.java
@@ -35,7 +35,6 @@ import java.util.Iterator;
 import java.util.Locale;
 import java.util.Set;
 
-import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.transform.TransformerException;
 
 import org.apache.poi.EncryptedDocumentException;
@@ -148,7 +147,7 @@ public class XSSFFileHandler extends SpreadsheetHandler {
     }
     
     private void exportToXML(XSSFWorkbook wb) throws SAXException,
-            ParserConfigurationException, TransformerException {
+            TransformerException {
         for (XSSFMap map : wb.getCustomXMLMappings()) {
             XSSFExportToXml exporter = new XSSFExportToXml(map);
 
@@ -165,7 +164,6 @@ public class XSSFFileHandler extends SpreadsheetHandler {
         // zip-bomb
         EXPECTED_ADDITIONAL_FAILURES.add("spreadsheet/54764.xlsx");
         EXPECTED_ADDITIONAL_FAILURES.add("spreadsheet/54764-2.xlsx");
-        EXPECTED_ADDITIONAL_FAILURES.add("spreadsheet/54764.xlsx");
         EXPECTED_ADDITIONAL_FAILURES.add("spreadsheet/poc-xmlbomb.xlsx");
         EXPECTED_ADDITIONAL_FAILURES.add("spreadsheet/poc-xmlbomb-empty.xlsx");
         // strict OOXML
@@ -185,18 +183,19 @@ public class XSSFFileHandler extends SpreadsheetHandler {
     public void handleAdditional(File file) throws Exception {
         // redirect stdout as the examples often write lots of text
         PrintStream oldOut = System.out;
+        String testFile = file.getParentFile().getName() + "/" + file.getName();
         try {
             System.setOut(new NullPrintStream());
             FromHowTo.main(new String[]{file.getAbsolutePath()});
             XLSX2CSV.main(new String[]{file.getAbsolutePath()});
 
             assertFalse("Expected Extraction to fail for file " + file + " and handler " + this + ", but did not fail!",
-                    EXPECTED_ADDITIONAL_FAILURES.contains(file.getParentFile().getName() + "/" + file.getName()));
+                    EXPECTED_ADDITIONAL_FAILURES.contains(testFile));
 
         } catch (OLE2NotOfficeXmlFileException e) {
             // we have some files that are not actually OOXML and thus cannot be tested here
         } catch (IllegalArgumentException | InvalidFormatException | POIXMLException | IOException e) {
-            if(!EXPECTED_ADDITIONAL_FAILURES.contains(file.getParentFile().getName() + "/" + file.getName())) {
+            if(!EXPECTED_ADDITIONAL_FAILURES.contains(testFile)) {
                 throw e;
             }
         } finally {
diff --git a/src/java/org/apache/poi/hpsf/VariantSupport.java b/src/java/org/apache/poi/hpsf/VariantSupport.java
index e60679027d..0e8dc08c6e 100644
--- a/src/java/org/apache/poi/hpsf/VariantSupport.java
+++ b/src/java/org/apache/poi/hpsf/VariantSupport.java
@@ -36,7 +36,7 @@ import org.apache.poi.util.POILogger;
  * Supports reading and writing of variant data.<p>
  *
  * <strong>FIXME (3):</strong> Reading and writing should be made more
- * uniform than it is now. The following items should be resolved:<p>
+ * uniform than it is now. The following items should be resolved:
  *
  * <ul>
  *
diff --git a/src/java/org/apache/poi/hpsf/wellknown/PropertyIDMap.java b/src/java/org/apache/poi/hpsf/wellknown/PropertyIDMap.java
index 130408e7b5..c01ded7fe8 100644
--- a/src/java/org/apache/poi/hpsf/wellknown/PropertyIDMap.java
+++ b/src/java/org/apache/poi/hpsf/wellknown/PropertyIDMap.java
@@ -33,8 +33,11 @@ import org.apache.poi.hpsf.SummaryInformation;
  * The methods {@link #getSummaryInformationProperties} and {@link
  * #getDocumentSummaryInformationProperties} return singleton {@link
  * PropertyIDMap}s. An application that wants to extend these maps
- * should treat them as unmodifiable, copy them and modifiy the
+ * should treat them as unmodifiable, copy them and modify the
  * copies.
+ *
+ * Trying to modify the map directly will cause exceptions
+ * {@link UnsupportedOperationException} to be thrown.
  */
 public class PropertyIDMap implements Map<Long,String> {
 
@@ -490,11 +493,13 @@ public class PropertyIDMap implements Map<Long,String> {
 
     @Override
     public String put(Long key, String value) {
+        //noinspection ConstantConditions
         return idMap.put(key, value);
     }
 
     @Override
     public String remove(Object key) {
+        //noinspection ConstantConditions
         return idMap.remove(key);
     }
 
diff --git a/src/java/org/apache/poi/hssf/model/InternalWorkbook.java b/src/java/org/apache/poi/hssf/model/InternalWorkbook.java
index 46d8678229..4ff370125c 100644
--- a/src/java/org/apache/poi/hssf/model/InternalWorkbook.java
+++ b/src/java/org/apache/poi/hssf/model/InternalWorkbook.java
@@ -2276,6 +2276,8 @@ public final class InternalWorkbook {
 
     /**
      * Only for internal calls - code based on this is not supported ...
+     *
+     * @return The list of records.
      */
     @Internal
     public WorkbookRecordList getWorkbookRecordList() {
diff --git a/src/java/org/apache/poi/hssf/record/RecordInputStream.java b/src/java/org/apache/poi/hssf/record/RecordInputStream.java
index 4f5f589032..8347655a81 100644
--- a/src/java/org/apache/poi/hssf/record/RecordInputStream.java
+++ b/src/java/org/apache/poi/hssf/record/RecordInputStream.java
@@ -33,8 +33,9 @@ import org.apache.poi.util.LittleEndianInputStream;
 import org.apache.poi.util.RecordFormatException;
 
 /**
- * Title:  Record Input Stream<P>
- * Description:  Wraps a stream and provides helper methods for the construction of records.<P>
+ * Title:  Record Input Stream
+ *
+ * Description:  Wraps a stream and provides helper methods for the construction of records.
  */
 public final class RecordInputStream implements LittleEndianInput {
 
@@ -194,11 +195,11 @@ public final class RecordInputStream implements LittleEndianInput {
 	private int readNextSid() {
 		int nAvailable  = _bhi.available();
 		if (nAvailable < EOFRecord.ENCODED_SIZE) {
-			if (nAvailable > 0) {
+			/*if (nAvailable > 0) {
 				// some scrap left over?
 				// ex45582-22397.xls has one extra byte after the last record
 				// Excel reads that file OK
-			}
+			}*/
 			return INVALID_SID_VALUE;
 		}
 		int result = _bhi.readRecordSID();
@@ -305,14 +306,13 @@ public final class RecordInputStream implements LittleEndianInput {
 	@Override
     public double readDouble() {
 		long valueLongBits = readLong();
-		double result = Double.longBitsToDouble(valueLongBits);
-		if (Double.isNaN(result)) {
+		/*if (Double.isNaN(result)) {
             // YK: Excel doesn't write NaN but instead converts the cell type into {@link CellType#ERROR}.
             // HSSF prior to version 3.7 had a bug: it could write Double.NaN but could not read such a file back.
             // This behavior was fixed in POI-3.7.
             //throw new RuntimeException("Did not expect to read NaN"); // (Because Excel typically doesn't write NaN)
-		}
-		return result;
+		}*/
+		return Double.longBitsToDouble(valueLongBits);
 	}
 	
 	public void readPlain(byte[] buf, int off, int len) {
diff --git a/src/java/org/apache/poi/hssf/record/SSTRecord.java b/src/java/org/apache/poi/hssf/record/SSTRecord.java
index 20d99319d6..1de2fe4fc2 100644
--- a/src/java/org/apache/poi/hssf/record/SSTRecord.java
+++ b/src/java/org/apache/poi/hssf/record/SSTRecord.java
@@ -161,7 +161,7 @@ public final class SSTRecord extends ContinuableRecord {
      * <P>
      * The data consists of sets of string data. This string data is
      * arranged as follows:
-     * <P>
+     * </P><P>
      * <pre>
      * short  string_length;   // length of string data
      * byte   string_flag;     // flag specifying special string
@@ -176,9 +176,9 @@ public final class SSTRecord extends ContinuableRecord {
      * byte[] extension;       // optional extension (length of array
      *                         // is extend_length)
      * </pre>
-     * <P>
+     * </P><P>
      * The string_flag is bit mapped as follows:
-     * <P>
+     * </P><P>
      * <TABLE summary="string_flag mapping">
      *   <TR>
      *      <TH>Bit number</TH>
@@ -232,7 +232,7 @@ public final class SSTRecord extends ContinuableRecord {
      * associated data. The UnicodeString class can handle the byte[]
      * vs short[] nature of the actual string data
      *
-     * @param in the RecordInputstream to read the record from
+     * @param in the RecordInputStream to read the record from
      */
     public SSTRecord(RecordInputStream in) {
         // this method is ALWAYS called after construction -- using
diff --git a/src/java/org/apache/poi/hssf/record/SharedFormulaRecord.java b/src/java/org/apache/poi/hssf/record/SharedFormulaRecord.java
index 770f740a09..328402db80 100644
--- a/src/java/org/apache/poi/hssf/record/SharedFormulaRecord.java
+++ b/src/java/org/apache/poi/hssf/record/SharedFormulaRecord.java
@@ -77,7 +77,7 @@ public final class SharedFormulaRecord extends SharedValueRecordBase {
 
     public String toString()
     {
-        StringBuffer buffer = new StringBuffer();
+        StringBuilder buffer = new StringBuilder();
 
         buffer.append("[SHARED FORMULA (").append(HexDump.intToHex(sid)).append("]\n");
         buffer.append("    .range      = ").append(getRange()).append("\n");
@@ -99,6 +99,10 @@ public final class SharedFormulaRecord extends SharedValueRecordBase {
     }
 
     /**
+     * Convert formula into an array of {@link Ptg} tokens.
+     *
+     * @param formula The record to break into tokens, cannot be null
+     *
      * @return the equivalent {@link Ptg} array that the formula would have, were it not shared.
      */
     public Ptg[] getFormulaTokens(FormulaRecord formula) {
diff --git a/src/java/org/apache/poi/hssf/record/SharedValueRecordBase.java b/src/java/org/apache/poi/hssf/record/SharedValueRecordBase.java
index a5035303a3..51fe091808 100644
--- a/src/java/org/apache/poi/hssf/record/SharedValueRecordBase.java
+++ b/src/java/org/apache/poi/hssf/record/SharedValueRecordBase.java
@@ -42,6 +42,8 @@ public abstract class SharedValueRecordBase extends StandardRecord {
 
 	/**
 	 * reads only the range (1 {@link CellRangeAddress8Bit}) from the stream
+	 *
+	 * @param in The interface for reading the record data.
 	 */
 	public SharedValueRecordBase(LittleEndianInput in) {
 		_range = new CellRangeAddress8Bit(in);
@@ -99,14 +101,12 @@ public abstract class SharedValueRecordBase extends StandardRecord {
 			&& r.getLastColumn() >= colIx;
 	}
 	/**
-	 * @return {@code true} if (rowIx, colIx) describes the first cell in this shared value
-	 * object's range
-	 * 
 	 * @param rowIx the row index
 	 * @param colIx the column index
-	 * 
-	 * @return {@code true} if its the first cell in this shared value object range
-	 * 
+	 *
+	 * @return {@code true} if (rowIx, colIx) describes the first cell in this shared value
+	 * object's range
+	 *
 	 * @see #getRange()
 	 */
 	public final boolean isFirstCell(int rowIx, int colIx) {
diff --git a/src/java/org/apache/poi/util/RecordFormatException.java b/src/java/org/apache/poi/util/RecordFormatException.java
index 2bc4ba3bcb..65bea581ee 100644
--- a/src/java/org/apache/poi/util/RecordFormatException.java
+++ b/src/java/org/apache/poi/util/RecordFormatException.java
@@ -45,8 +45,8 @@ public class RecordFormatException
      * be thrown.  If assertTrue is <code>false</code>, this will throw this
      * exception with the message.
      *
-     * @param assertTrue
-     * @param message
+     * @param assertTrue If false, the exception is thrown, if true, no action is performed
+     * @param message The message to include in the thrown exception
      */
     public static void check(boolean assertTrue, String message) {
         if (! assertTrue) {
diff --git a/src/ooxml/java/org/apache/poi/ooxml/extractor/CommandLineTextExtractor.java b/src/ooxml/java/org/apache/poi/ooxml/extractor/CommandLineTextExtractor.java
index 999abd46ee..c3d429b3c7 100644
--- a/src/ooxml/java/org/apache/poi/ooxml/extractor/CommandLineTextExtractor.java
+++ b/src/ooxml/java/org/apache/poi/ooxml/extractor/CommandLineTextExtractor.java
@@ -22,41 +22,37 @@ import org.apache.poi.extractor.POITextExtractor;
 
 /**
  * A command line wrapper around {@link ExtractorFactory}, useful
- *  for when debugging.
+ * for when debugging.
  */
 public class CommandLineTextExtractor {
-   public static final String DIVIDER = "=======================";
-   
-   public static void main(String[] args) throws Exception {
-      if(args.length < 1) {
-         System.err.println("Use:");
-         System.err.println("   CommandLineTextExtractor <filename> [filename] [filename]");
-         System.exit(1);
-      }
-
-       for (String arg : args) {
-           System.out.println(DIVIDER);
-
-           File f = new File(arg);
-           System.out.println(f);
-
-           POITextExtractor extractor =
-                   ExtractorFactory.createExtractor(f);
-           try {
-               POITextExtractor metadataExtractor =
-                       extractor.getMetadataTextExtractor();
-
-               System.out.println("   " + DIVIDER);
-               String metaData = metadataExtractor.getText();
-               System.out.println(metaData);
-               System.out.println("   " + DIVIDER);
-               String text = extractor.getText();
-               System.out.println(text);
-               System.out.println(DIVIDER);
-               System.out.println("Had " + metaData.length() + " characters of metadata and " + text.length() + " characters of text");
-           } finally {
-               extractor.close();
-           }
-       }
-   }
+    public static final String DIVIDER = "=======================";
+
+    public static void main(String[] args) throws Exception {
+        if (args.length < 1) {
+            System.err.println("Use:");
+            System.err.println("   CommandLineTextExtractor <filename> [filename] [filename]");
+            System.exit(1);
+        }
+
+        for (String arg : args) {
+            System.out.println(DIVIDER);
+
+            File f = new File(arg);
+            System.out.println(f);
+
+            try (POITextExtractor extractor = ExtractorFactory.createExtractor(f)) {
+                POITextExtractor metadataExtractor =
+                        extractor.getMetadataTextExtractor();
+
+                System.out.println("   " + DIVIDER);
+                String metaData = metadataExtractor.getText();
+                System.out.println(metaData);
+                System.out.println("   " + DIVIDER);
+                String text = extractor.getText();
+                System.out.println(text);
+                System.out.println(DIVIDER);
+                System.out.println("Had " + metaData.length() + " characters of metadata and " + text.length() + " characters of text");
+            }
+        }
+    }
 }
diff --git a/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ZipHelper.java b/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ZipHelper.java
index 094e89c6d7..0169909c9b 100644
--- a/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ZipHelper.java
+++ b/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ZipHelper.java
@@ -154,8 +154,6 @@ public final class ZipHelper {
                 "The supplied data appears to be a raw XML file. " +
                 "Formats such as Office 2003 XML are not supported");
         default:
-        case OOXML:
-        case UNKNOWN:
             // Don't check for a Zip header, as to maintain backwards
             //  compatibility we need to let them seek over junk at the
             //  start before beginning processing.
diff --git a/src/ooxml/testcases/org/apache/poi/ooxml/TestPOIXMLProperties.java b/src/ooxml/testcases/org/apache/poi/ooxml/TestPOIXMLProperties.java
index d91b8191eb..1ad2a633f9 100644
--- a/src/ooxml/testcases/org/apache/poi/ooxml/TestPOIXMLProperties.java
+++ b/src/ooxml/testcases/org/apache/poi/ooxml/TestPOIXMLProperties.java
@@ -19,6 +19,7 @@ package org.apache.poi.ooxml;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNotSame;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -89,7 +90,7 @@ public final class TestPOIXMLProperties {
         XSSFWorkbook newWorkbook =
                 XSSFTestDataSamples.writeOutAndReadBack(workbook);
         workbook.close();
-        assertTrue(workbook != newWorkbook);
+        assertNotSame(workbook, newWorkbook);
 
 
         POIXMLProperties newProps = newWorkbook.getProperties();
@@ -158,7 +159,7 @@ public final class TestPOIXMLProperties {
         p = ctProps.getPropertyArray(3);
         assertEquals("{D5CDD505-2E9C-101B-9397-08002B2CF9AE}", p.getFmtid());
         assertEquals("test-4", p.getName());
-        assertEquals(true, p.getBool());
+        assertTrue(p.getBool());
         assertEquals(5, p.getPid());
         
         wb2.close();
diff --git a/src/ooxml/testcases/org/apache/poi/xdgf/extractor/TestXDGFVisioExtractor.java b/src/ooxml/testcases/org/apache/poi/xdgf/extractor/TestXDGFVisioExtractor.java
index 6a3369ed90..c261e2c91b 100644
--- a/src/ooxml/testcases/org/apache/poi/xdgf/extractor/TestXDGFVisioExtractor.java
+++ b/src/ooxml/testcases/org/apache/poi/xdgf/extractor/TestXDGFVisioExtractor.java
@@ -42,7 +42,7 @@ public class TestXDGFVisioExtractor {
     }
     
     @After
-    public void closeResoures() throws IOException {
+    public void closeResources() throws IOException {
         if(xml != null) {
             xml.close();
         }
diff --git a/src/ooxml/testcases/org/apache/poi/xssf/XSSFTestDataSamples.java b/src/ooxml/testcases/org/apache/poi/xssf/XSSFTestDataSamples.java
index 0f03af7453..b981b9994e 100644
--- a/src/ooxml/testcases/org/apache/poi/xssf/XSSFTestDataSamples.java
+++ b/src/ooxml/testcases/org/apache/poi/xssf/XSSFTestDataSamples.java
@@ -70,7 +70,7 @@ public class XSSFTestDataSamples {
      * @param wb the workbook to write
      * @param testName a fragment of the filename
      * @return the location where the workbook was saved
-     * @throws IOException
+     * @throws IOException If writing the file fails
      */
     public static <R extends Workbook> File writeOut(R wb, String testName) throws IOException {
         final File file = getOutputFile(testName);
@@ -104,7 +104,9 @@ public class XSSFTestDataSamples {
             file = TempFile.createTempFile(testName, ".xlsx");
         }
         if (file.exists()) {
-            file.delete();
+            if(!file.delete()) {
+                throw new IOException("Could not delete file " + file);
+            }
         }
         return file;
     }
@@ -114,7 +116,7 @@ public class XSSFTestDataSamples {
      *
      * @param wb the workbook to write
      * @return the memory buffer
-     * @throws IOException
+     * @throws IOException If writing the file fails
      */
     public static <R extends Workbook> ByteArrayOutputStream writeOut(R wb) throws IOException {
         ByteArrayOutputStream out = new ByteArrayOutputStream(8192);
@@ -137,7 +139,7 @@ public class XSSFTestDataSamples {
      * to avoid creating a temporary file. However, this may complicate the calling
      * code to avoid having the workbook, BAOS, and BAIS open at the same time.
      *
-     * @param wb
+     * @param wb The workbook to write out, it is closed after the call.
      * @param testName file name to be used to write to a file. This file will be cleaned up by a call to readBack(String)
      * @return workbook location
      * @throws RuntimeException if {@link #TEST_OUTPUT_DIR} System property is not set
@@ -161,18 +163,13 @@ public class XSSFTestDataSamples {
      *
      * @param wb the workbook to write
      * @return the memory buffer
-     * @throws IOException
+     * @throws RuntimeException If writing the file fails
      */
-    public static <R extends Workbook> ByteArrayOutputStream writeOutAndClose(R wb) {
-        try {
-            ByteArrayOutputStream out = writeOut(wb);
-            // Do not close the workbook if there was a problem writing the workbook
-            wb.close();
-            return out;
-        }
-        catch (final IOException e) {
-            throw new RuntimeException(e);
-        }
+    public static <R extends Workbook> ByteArrayOutputStream writeOutAndClose(R wb) throws IOException {
+        ByteArrayOutputStream out = writeOut(wb);
+        // Do not close the workbook if there was a problem writing the workbook
+        wb.close();
+        return out;
     }
 
     /**
@@ -183,12 +180,14 @@ public class XSSFTestDataSamples {
      *
      * @param file the workbook file to read and delete
      * @return the read back workbook
-     * @throws IOException
+     * @throws IOException If reading or deleting the file fails
      */
     public static XSSFWorkbook readBackAndDelete(File file) throws IOException {
         XSSFWorkbook wb = readBack(file);
         // do not delete the file if there's an error--might be helpful for debugging
-        file.delete();
+        if(!file.delete()) {
+            throw new IOException("Could not delete file " + file + " after reading");
+        }
         return wb;
     }
 
@@ -198,16 +197,12 @@ public class XSSFTestDataSamples {
      *
      * @param file the workbook file to read
      * @return the read back workbook
-     * @throws IOException
+     * @throws IOException If reading the file fails
      */
     public static XSSFWorkbook readBack(File file) throws IOException {
-        InputStream in = new FileInputStream(file);
-        try {
+        try (InputStream in = new FileInputStream(file)) {
             return new XSSFWorkbook(in);
         }
-        finally {
-            in.close();
-        }
     }
 
     /**
@@ -216,17 +211,13 @@ public class XSSFTestDataSamples {
      *
      * @param out the output stream to read back from
      * @return the read back workbook
-     * @throws IOException
+     * @throws IOException If reading the file fails
      */
     public static XSSFWorkbook readBack(ByteArrayOutputStream out) throws IOException {
-        InputStream is = new ByteArrayInputStream(out.toByteArray());
-        out.close();
-        try {
+        try (InputStream is = new ByteArrayInputStream(out.toByteArray())) {
+            out.close();
             return new XSSFWorkbook(is);
         }
-        finally {
-            is.close();
-        }
     }
 
     /**
diff --git a/src/testcases/org/apache/poi/poifs/filesystem/TestFileMagic.java b/src/testcases/org/apache/poi/poifs/filesystem/TestFileMagic.java
new file mode 100644
index 0000000000..6587547b95
--- /dev/null
+++ b/src/testcases/org/apache/poi/poifs/filesystem/TestFileMagic.java
@@ -0,0 +1,80 @@
+/* ====================================================================
+   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.poi.poifs.filesystem;
+
+import org.apache.poi.POIDataSamples;
+import org.junit.Test;
+
+import java.io.BufferedInputStream;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import static org.junit.Assert.*;
+
+public class TestFileMagic {
+    @Test
+    public void testFileMagic() {
+        assertEquals(FileMagic.XML, FileMagic.valueOf("XML"));
+        assertEquals(FileMagic.XML, FileMagic.valueOf("<?xml".getBytes()));
+
+        assertEquals(FileMagic.HTML, FileMagic.valueOf("HTML"));
+        assertEquals(FileMagic.HTML, FileMagic.valueOf("<!DOCTYP".getBytes()));
+        assertEquals(FileMagic.HTML, FileMagic.valueOf("<!DOCTYPE".getBytes()));
+        assertEquals(FileMagic.HTML, FileMagic.valueOf("<html".getBytes()));
+
+        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));
+        }
+    }
+}
-- 
2.39.5