[xslt] Obscure bug?

[Gary Benson <gary inauspicious org>]

Hi all,

I originally posted this to xml-bindings but got no response so I'm
reposting it here.  I think I found a very obscure bug in which
extension functions are not recognised within {} XPath syntax if the
stylesheet was imported into another stylesheet via xsl:import.  The
attached file broken-ext2func.py exercises the bug on my system:

| $ ./broken-ext2func.py 
| xmlXPathCompOpEval: function foo bound to undefined prefix foo
| Unexpected root property content, extension function failed

The file broken-ext2func-workaround.py contains the workaround that I am
currently using:

| $ ./broken-ext2func-workaround.py 
| OK

Can anyone else verify that they are seeing this?

Cheers,
Gary

[ gary@inauspicious.org ][ GnuPG 85A8F78B ][ http://inauspicious.org/ ]
#!/usr/bin/python -u
import sys
import string
import libxml2
import libxslt

# Memory debug specific
libxml2.debugMemory(1)

nodeName = None

def f(ctx, str):
    global nodeName

    #
    # Small check to verify the context is correcly accessed
    #
    try:
        pctxt = libxslt.xpathParserContext(_obj=ctx)
        ctxt = pctxt.context()
        tctxt = ctxt.transformContext()
        nodeName = tctxt.insertNode().name
    except:
        pass

    return string.upper(str)

libxslt.registerExtModuleFunction("foo", "http://example.com/foo";, f)

open("tmp.xsl", "w").write("""
<xsl:stylesheet version='1.0'
  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
  xmlns:foo='http://example.com/foo'
  xsl:exclude-result-prefixes='foo'>

  <xsl:param name='bar'>failure</xsl:param>
  <xsl:template match='/'>
    <article baz='{foo:foo($bar)}'>
      <xsl:value-of select='foo:foo($bar)'/>
    </article>
  </xsl:template>
</xsl:stylesheet>
""")
styledoc = libxml2.parseDoc("""
<xsl:stylesheet version='1.0'
  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>
  <xsl:import href='tmp.xsl'/>
</xsl:stylesheet>
""")  
    
style = libxslt.parseStylesheetDoc(styledoc)
doc = libxml2.parseDoc("<doc/>")
result = style.applyStylesheet(doc, { "bar": "'success'" })
style.freeStylesheet()
doc.freeDoc()

root = result.children
if root.name != "article":
    print "Unexpected root node name"
    sys.exit(1)
if root.content != "SUCCESS":
    print "Unexpected root node content, extension function failed"
    sys.exit(1)
if root.prop("baz") != "SUCCESS":
    print "Unexpected root property content, extension function failed"
    sys.exit(1)
if nodeName != 'article':
    print "The function callback failed to access its context"
    sys.exit(1)

result.freeDoc()

# Memory debug specific
libxslt.cleanup()
if libxml2.debugMemory(1) == 0:
    print "OK"
else:
    print "Memory leak %d bytes" % (libxml2.debugMemory(1))
    libxml2.dumpMemory()
#!/usr/bin/python -u
import sys
import string
import libxml2
import libxslt

# Memory debug specific
libxml2.debugMemory(1)

nodeName = None

def f(ctx, str):
    global nodeName

    #
    # Small check to verify the context is correcly accessed
    #
    try:
        pctxt = libxslt.xpathParserContext(_obj=ctx)
        ctxt = pctxt.context()
        tctxt = ctxt.transformContext()
        nodeName = tctxt.insertNode().name
    except:
        pass

    return string.upper(str)

libxslt.registerExtModuleFunction("foo", "http://example.com/foo";, f)

open("tmp.xsl", "w").write("""
<xsl:stylesheet version='1.0'
  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
  xmlns:foo='http://example.com/foo'
  xsl:exclude-result-prefixes='foo'>

  <xsl:param name='bar'>failure</xsl:param>
  <xsl:template match='/'>
    <article>
      <xsl:attribute name='baz'>
        <xsl:value-of select='foo:foo($bar)'/>
      </xsl:attribute>
      <xsl:value-of select='foo:foo($bar)'/>
    </article>
  </xsl:template>
</xsl:stylesheet>
""")
styledoc = libxml2.parseDoc("""
<xsl:stylesheet version='1.0'
  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>
  <xsl:import href='tmp.xsl'/>
</xsl:stylesheet>
""")  
    
style = libxslt.parseStylesheetDoc(styledoc)
doc = libxml2.parseDoc("<doc/>")
result = style.applyStylesheet(doc, { "bar": "'success'" })
style.freeStylesheet()
doc.freeDoc()

root = result.children
if root.name != "article":
    print "Unexpected root node name"
    sys.exit(1)
if root.content != "SUCCESS":
    print "Unexpected root node content, extension function failed"
    sys.exit(1)
if root.prop("baz") != "SUCCESS":
    print "Unexpected root property content, extension function failed"
    sys.exit(1)
if nodeName != 'article':
    print "The function callback failed to access its context"
    sys.exit(1)

result.freeDoc()

# Memory debug specific
libxslt.cleanup()
if libxml2.debugMemory(1) == 0:
    print "OK"
else:
    print "Memory leak %d bytes" % (libxml2.debugMemory(1))
    libxml2.dumpMemory()