> looks like error in xmlXPathCompiledEval function, that produce little bit > broken result for XML_DOCUMENT_NODE type. I hadn't this problem with > libxml2 2.7.6 64bit, but I seen this issue on same version on 32bit. > > Currently I had not fresh 32 bit system to check it. > > I found a workaround - in this case copy (and release xmlNode) is not > necessary. > > please, apply attached patch.
Wow :-( At this point I'm wondering if this should be put in back branches as well ... I mean, distill part of commit 251cf2e27bec that doesn't affect the behavior of text nodes, and put it on all branches together with your fix?
The problem is just for case result: XML_DOCUMENT_TYPE, target XML. For this case the previously used transformation doesn't work.
Is not problem to detect this situation. The content field has -1 instead 0.
Originally there was inverted logic, so xmlCopyNode and xmlFreeNode was not used for XML_DOCUMENT_TYPE, and then we didn't hit this bug.
Another thought: should we refuse to work on known-broken libxml2 versions? Seems like this bug could affect other parts of code too -- I see that xmlXPathCompiledEval() is called in file places (including two in contrib/xml2).
Third thought: an alternative might be to create a wrapper for xmlXPathCompiledEval that detects NULL content and fills in a pointer that xmlFreeNode can free.