[xml] xmlXPathNodeSetAddUnique:out of memory ?

[Jasmit Singh <jsingh boulder vni com>]

Hello,

I am currently working with 100KB xml file and using xpath to query the
file. the //* query works great but when I try to use
/ADDRESSBOOK/PERSON[5]/following::* the xmlxpathNodeSetAddUnique gives me an
out of memory error.  The xml file is just a repetition of the text below to
make it 100KB.

The entire tree is returned without a problem but when returning part of the
tree it runs out of memory.  Is this the correct behavior?

I did look at the xmlXPathNodeSetAddUnique function in the xpath.c file.  I
noticed that the cur->nodeMax was doubled every time and thus when realloc
is done it runs out of memory.  The value of cur->nodeNr reached 167772160
before it gave up.  In case of querying the entire tree (//*) the
cur->nodeNr value never goes above 10.

Thanks,
Jasmit Singh  
LibXml 2.4.23
Solaris 2.7



} else if (cur->nodeNr == cur->nodeMax) {
        xmlNodePtr *temp;
> >   cur->nodeMax *= 2;
         temp = (xmlNodePtr *) xmlRealloc(cur->nodeTab, cur->nodeMax *
                                      sizeof(xmlNodePtr));
        if (temp == NULL) {
            xmlGenericError(xmlGenericErrorContext,
                    "xmlXPathNodeSetAddUnique: out of memory\n");
            return;
        }
        cur->nodeTab = temp;
    }


Note: Just repeat the Person over and over again until 100 KB is reached.

<?xml version= '1.0'?>
<!DOCTYPE ADDRESSBOOK [
<!ELEMENT ADDRESSBOOK (PERSON)*>
<!ELEMENT PERSON (LASTNAME, FIRSTNAME, COMPANY, EMAIL, PHONE)>
<!ELEMENT LASTNAME (#PCDATA)>
<!ELEMENT FIRSTNAME (#PCDATA)>
<!ELEMENT COMPANY (#PCDATA)>
<!ELEMENT EMAIL (#PCDATA)>
<!ELEMENT PHONE (#PCDATA)>
<!ENTITY PHONENUMBER '540-552-7788'>
<!ATTLIST PERSON gender CDATA #IMPLIED>
]>
<ADDRESSBOOK>

  <!--new information-->
  <PERSON gender='male'>
    <LASTNAME>Idris</LASTNAME>
    <FIRSTNAME>Namul</FIRSTNAME>
    <COMPANY><![CDATA[<<The Bean Factory>>]]></COMPANY>
    <EMAIL>xml beanfactory com</EMAIL>
    <PHONE>&PHONENUMBER;</PHONE>
  </PERSON>