ArrayIndexOfOufBounds in TargetImportHandler$BufferedStringValue.append()

[Ingomar Otter <in...@valtech.de>]

I've encountered an ArrayIndexOutOfBounds in 2.2.10 when using Session.importXML of larger documents.
It appears that buffer size calculation is wrong. That error should be exist also in trunk and 2.4.0.

The problem seems to occur when the string to append exceeds the existing buffer by more than BUFFER_INCREMENT characters as 
the buffer is only incremented by BUFFER_INCREMENT chars no matter how big the string to append really is.

Afaik, the length of the destination buffer needs to be at least bufferPos (existing content) + length (as passed in).

In my example is saw 15854 (bufferPos) and 16384 (length param to append()) requiring at least 15854+ 16384=32238 bytes.
In that case the existing buffer was 16384 and the new buffer is 16384+BUFFER_INCREMENT=16384+8192 = 24576.
32238 > 24576 => ArrayIndexOutOfBounds exception.

Fix: I think the resizing of the buffer should observe the length.
Today: new size = old size + BUFFER_INCREMENT
New: new size =  bufferPos + length  
and if one would like to avoid future copies on small appends even  
new size = bufferPos + length + BUFFER_INCREMENT

So instead of
char[] newBuffer = new char[buffer.length + BUFFER_INCREMENT];
I changed it  to
char[] newBuffer = new char[ bufferPos +length + BUFFER_INCREMENT];

This is line 326 of  
jackrabbit-jcr2spi: org/apache/jackrabbit/jcr2spi/xml/TargetImportHandler.java

I've created a bug for this as
https://issues.apache.org/jira/browse/JCR-3235

If BuffferedStringValue wouldn't be inner, I would even create a test case for this ;-)
 

For completeness this is the stack trace:
java.lang.ArrayIndexOutOfBoundsException: null
at java.lang.System.arraycopy(Native Method) ~[na:1.7.0_04-ea]
at org.apache.jackrabbit.jcr2spi.xml.TargetImportHandler$BufferedStringValue.append(TargetImportHandler.java:330) ~[jackrabbit-jcr2spi-2.2.10.jar:na]
at org.apache.jackrabbit.jcr2spi.xml.SysViewImportHandler.characters(SysViewImportHandler.java:204) ~[jackrabbit-jcr2spi-2.2.10.jar:na]
at org.apache.jackrabbit.jcr2spi.xml.ImportHandler.characters(ImportHandler.java:262) ~[jackrabbit-jcr2spi-2.2.10.jar:na]
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.characters(AbstractSAXParser.java:543) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:441) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:835) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:764) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:123) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1210) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:568) ~[na:1.7.0_04-ea]
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.parse(SAXParserImpl.java:302) ~[na:1.7.0_04-ea]
at org.apache.jackrabbit.jcr2spi.SessionImpl.importXML(SessionImpl.java:400) ~[jackrabbit-jcr2spi-2.2.10.jar:na]

--I