bug#20339: sxml simple: sxml->xml mishandles namespaces?

[tomas@tuxteam.de]

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Hi,

I posted more details on guile-devel. Perhaps this was the wrong list?

When transforming SXML to XML, namespaces don't seem to be handled
properly:


  #!/usr/bin/guile -s
  !#
  (use-modules (sxml simple))
  
  ;; An XML with two namespaces (one default)
  (define the-svg "<svg xmlns='http://www.w3.org/2000/svg'
       xmlns:xlink='http://www.w3.org/1999/xlink'>
    <rect x='5' y='5' width='20' height='20'
          stroke-width='2' stroke='purple' fill='yellow'
          id='rect1' />
    <rect x='30' y='5' width='20' height='20'
          ry='5' rx='8' stroke-width='2' stroke='purple' fill='blue'
          xlink:href='#rect1' />
  </svg>")
  
  ;; Note how SXML handles QNames (just concatenating NS and
  ;; local-name with a colon):
  (define the-sxml
    (with-input-from-string the-svg xml->sxml))
  (format #t "~A\n" the-sxml)
  
  ;; If we try to serialize this: kaboom!
  (sxml->xml the-sxml)

The parsing into SXML goes well, the (format ...) outputs what
I'd expect. But the (sxml->xml ...) dies with:

  ERROR: In procedure scm-error:
  ERROR: Invalid QName: more than one colon http://www.w3.org/2000/svg:svg

The problem is that SXML used the concatenated (full) namespace with the
name as tag (and attribute) names for namespaced items. When serializing
to XML it should try to find abbreviations for those namespaces and issue
the corresponding namespace declarations.

Instead, sxml->xml tries to split the (namespace:name) combination
at the first colon and to check the name -- and fails miserably at
(namespace:name) combinations à la "http://www.w3.org/1999/xlink:href"
(procedure check-name). Since there are two colons, the name part
has now a colon.

There are more details at:

http://lists.gnu.org/archive/html/guile-devel/2015-04/msg00000.html

with a first attempt at a patch against guile (GNU Guile) 2.0.5-deb+1-3.
I'm more than willing to beat the patch into shape, but will possibly
need some guidance. Perhaps I'd need to sign papers with the FSF, which
I'd gladly do.

Regards
- -- tomás
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