FOP-2811: PDF larger than 100k pages can have wrong content stream

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1841574 13f79535-47bb-0310-9956-ffa450edef68

fop-core/src/main/java/org/apache/fop/pdf/PDFStream.java

 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
-import java.util.Arrays;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 
 /**
  * Class representing a PDF stream.
         return len;
     }
 
-    public int streamHashCode() throws IOException {
+    public String streamHashCode() throws IOException {
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         outputRawStreamData(bos);
-        return Arrays.hashCode(bos.toByteArray());
+        try {
+            MessageDigest md = MessageDigest.getInstance("MD5");
+            byte[] thedigest = md.digest(bos.toByteArray());
+            StringBuilder hex = new StringBuilder();
+            for (byte b : thedigest) {
+                hex.append(String.format("%02x", b));
+            }
+            return hex.toString();
+        } catch (NoSuchAlgorithmException e) {
+            throw new IOException(e);
+        }
     }
 }

fop-core/src/main/java/org/apache/fop/render/pdf/PDFDocumentHandler.java

             = new PDFDocumentNavigationHandler(this);
 
     private Map<Integer, PDFArray> pageNumbers = new HashMap<Integer, PDFArray>();
-    private Map<Integer, PDFReference> contents = new HashMap<Integer, PDFReference>();
+    private Map<String, PDFReference> contents = new HashMap<String, PDFReference>();
 
     /**
      * Default constructor.
 
     private void setUpContents() throws IOException {
         PDFStream stream = generator.getStream();
-        int hash = stream.streamHashCode();
+        String hash = stream.streamHashCode();
         if (!contents.containsKey(hash)) {
             pdfDoc.registerObject(stream);
             PDFReference ref = new PDFReference(stream);

fop-core/src/test/java/org/apache/fop/pdf/PDFStreamTestCase.java

         stream.write("\nendstream".getBytes("US-ASCII"));
         return stream.toByteArray();
     }
+
+    @Test
+    public void testHash() throws IOException {
+        assertFalse(getStreamHash(65025).equals(getStreamHash(127076)));
+    }
+
+    private String getStreamHash(int i) throws IOException {
+        PDFStream stream = new PDFStream();
+        String txt = "1 0 0 -1 0 790.866 cm\n"
+                + "q\n"
+                + "0 g\n"
+                + "BT\n"
+                + "/F1 12 Tf\n"
+                + "1 0 0 -1 0 10.26599979 Tm [(" + i + ")] TJ\n"
+                + "ET\n";
+        String img = "q\n"
+                + "126.734001 0 0 -38.244999 0 54.294998 cm\n"
+                + "/Im2 Do\n"
+                + "Q\n";
+        if (i % 2 == 0) {
+            stream.add(txt + img + "Q\n");
+        } else {
+            stream.add(txt + "Q\n");
+        }
+        return stream.streamHashCode();
+    }
 }