Re: [xslt] calling EXSLT function str:replace() without transform context raises memory error in 1.1.27

On 28/09/2012 15:33, Stefan Behnel wrote:

a side effect of this commit:

is that the str:replace() function is no longer usable without a transform
context. I take it from the bug report that it is not supposed to be used
from plain XPath but only from XSLT according to the EXSLT specification.

However, the previous implementation used to work in XPath and is still
registered on an xmlXPathContext by the exsltStrXpathCtxtRegister()
function. When called from plain XPath, it results in a memory error in
line 526 (exsltStrReturnString()) of strings.c because xsltCreateRVT()
returns NULL as an error indicator due to a NULL transform context being
passed in, which was the return value from xsltXPathGetTransformContext() a
bit further up (and the code doesn't validate that).

I see two ways to deal with this. Either fix the error handling in
exsltStrReturnString() and deliberately break backwards compatibility by
removing the function from exsltStrXpathCtxtRegister(), or rewrite the new
function in a way that makes it work in both contexts, i.e. from both XSLT
and plain XPath. I have no idea if the latter is possible, but it would
certainly be the "friendlier" solution.

One of the problems of the old str:replace implementation was that it returned a string whereas it should return a node set. From what I understand, the nodes in the node set have to be added to a RVT, so they will be garbage collected later. I don't see a way to do that without a transform context.

The str:tokenize and str:split function do the same thing btw, although it seems that they don't raise an error, but simply return an empty node set when used without a transform context.


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