[XMLBEANS-604] Incorrect Assert in Saver.TextSaver

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Version 5.0.3
• Fix Version/s: Version 5.1.0
• Component/s: XmlObject
• Environment: Windows 10, JDK 1.8.0_311
• Assignee: Unassigned
• Reporter: Timon Hertli
• Created: 14/Apr/22 13:19
• Updated: 02/Jun/22 09:13
• Resolved: 02/Jun/22 09:13

Description

If the Buffer _buf in org.apache.xmlbeans.impl.store.Saver.TextSaver.write(Writer, int) is completely filled (this happens if the current charsAvailable is a large power of 2, in the example 2^14=16384), the _in index is set to 0 ( = 16384 % 16384) in emit(String). This causes the assertion

 

assert _free == _buf.length - _in;

to fail (with _free = 0, _buf.length = 16384, _in = 0). The behaviour of the code seems correct, but the assert does not account for the fact that _in can wrap around to 0.

 

The following code reproduces the problem (if assertions are enabled):

 

import org.apache.xmlbeans.XmlBeans;
import org.apache.xmlbeans.XmlObject;

import java.io.InputStream;

public class AssertionTest {
  public static void main(String[] args) throws Exception {
    System.getProperties().setProperty("line.separator", "\n");
    String xml = "<test>" + new String(new char[16339]).replace('\0', 'x') + "</test>";
    XmlObject object = XmlObject.Factory.parse(xml);
    try (InputStream is = object.newInputStream()) {
      is.read(new byte[8192], 0, 8192);
    }
  }
}

with the following stack trace:

 

 

Exception in thread "main" java.lang.AssertionError
    at org.apache.xmlbeans.impl.store.Saver$TextSaver.write(Saver.java:1708)
    at org.apache.xmlbeans.impl.store.Saver$InputStreamSaver.ensure(Saver.java:2344)
    at org.apache.xmlbeans.impl.store.Saver$InputStreamSaver.access$200(Saver.java:2230)
    at org.apache.xmlbeans.impl.store.Saver$InputStreamSaver$OutputStreamImpl.read(Saver.java:2389)
    at org.apache.xmlbeans.impl.store.Saver$InputStreamSaver.lambda$read$0(Saver.java:2328)
    at org.apache.xmlbeans.impl.store.Saver.syncWrap(Saver.java:2180)
    at org.apache.xmlbeans.impl.store.Saver.access$000(Saver.java:33)
    at org.apache.xmlbeans.impl.store.Saver$InputStreamSaver.read(Saver.java:2328)
    at AssertionTest.main(AssertionTest.java:12)