Throw exception if PdfReader instance is attempted to be reused between PdfDocument instances

ITXT-CR-938

Author: yulian-gaponenko

kernel/src/main/java/com/itextpdf/kernel/PdfException.java

@@ -233,6 +233,7 @@ public class PdfException extends RuntimeException {
     public static final String PdfFormXobjectHasInvalidBbox = "PdfFormXObject has invalid BBox.";
     public static final String PdfObjectStreamReachMaxSize = "PdfObjectStream reach max size.";
     public static final String PdfPagesTreeCouldBeGeneratedOnlyOnce = "PdfPages tree could be generated only once.";
+    public static final String PdfReaderHasBeenAlreadyUtilized = "Given PdfReader instance has already been utilized. The PdfReader cannot be reused, please create a new instance.";
     public static final String PdfStartxrefIsNotFollowedByANumber = "PDF startxref is not followed by a number.";
     public static final String PdfStartxrefNotFound = "PDF startxref not found.";
     public static final String PdfIndirectObjectBelongsToOtherPdfDocument = "Pdf indirect object belongs to other PDF document. Copy object to current pdf document.";

kernel/src/main/java/com/itextpdf/kernel/pdf/PdfDocument.java

@@ -1811,6 +1811,9 @@ protected void open(PdfVersion newPdfVersion) {
         try {
             EventCounterHandler.getInstance().onEvent(CoreEvent.PROCESS, properties.metaInfo, getClass());
             if (reader != null) {
+                if (reader.pdfDocument != null) {
+                    throw new PdfException(PdfException.PdfReaderHasBeenAlreadyUtilized);
+                }
                 reader.pdfDocument = this;
                 reader.readPdf();
                 for (ICounter counter : getCounters()) {

kernel/src/test/java/com/itextpdf/kernel/pdf/PdfReaderTest.java

@@ -54,8 +54,10 @@ This file is part of the iText (R) project.
 import org.junit.Assert;
 import org.junit.BeforeClass;
 import org.junit.Ignore;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
+import org.junit.rules.ExpectedException;
 
 import java.io.IOException;
 import com.itextpdf.io.util.MessageFormatUtil;
@@ -74,6 +76,9 @@ public class PdfReaderTest extends ExtendedITextTest {
     static final String creator = "iText 6";
     static final String title = "Empty iText 6 Document";
 
+    @Rule
+    public ExpectedException junitExpectedException = ExpectedException.none();
+
     @BeforeClass
     public static void beforeClass() {
         createDestinationFolder(destinationFolder);
@@ -1587,6 +1592,18 @@ public void wrongStructureFlushingTest() throws IOException {
         pdfDoc.close();
     }
 
+    @Test
+    public void readerReuseTest() throws IOException {
+        junitExpectedException.expect(PdfException.class);
+        junitExpectedException.expectMessage(PdfException.PdfReaderHasBeenAlreadyUtilized);
+
+        String filename = sourceFolder + "hello.pdf";
+
+        PdfReader reader = new PdfReader(filename);
+        PdfDocument pdfDoc1 = new PdfDocument(reader);
+        PdfDocument pdfDoc2 = new PdfDocument(reader);
+    }
+
     private boolean objectTypeEqualTo(PdfObject object, PdfName type) {
         PdfName objectType = ((PdfDictionary) object).getAsName(PdfName.Type);
         return type.equals(objectType);