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Bug 924785

Summary: xmllint considers schema content model not determinist, although it is deterministic
Product: Red Hat Enterprise Linux 5 Reporter: Colin Guthrie <colin>
Component: libxml2Assignee: Daniel Veillard <veillard>
Status: CLOSED DUPLICATE QA Contact: qe-baseos-tools-bugs
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 5.9CC: joey.cai, ohudlick, slukasik, tcarter
Target Milestone: rc   
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Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2013-06-04 13:14:09 UTC Type: Bug
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Colin Guthrie 2013-03-22 13:51:27 UTC 
Followup to recent libxml2 update:
http://rhn.redhat.com/errata/RHBA-2013-0591.html

and likely a result of the following bugfix:
https://bugzilla.redhat.com/show_bug.cgi?id=915350


Something in the update seems to trigger a new bug related to schema validation:

https://bugzilla.gnome.org/show_bug.cgi?id=670865

and it's fix:

https://git.gnome.org/browse/libxml2/commit/?id=c70d185a2a3d09b0762560d4f93205da5d43396c

Certainly after updating to this version, I saw errors very similar to the ones reported above. The problems went away when I downgraded again.

Please can someone look at issuing another update for this?
Comment 1 Colin Guthrie 2013-03-22 15:03:57 UTC 
Just for clarity (this info is on the gnome bug)

Test case:

Create a schema with the following content:
  <?xml version="1.0" encoding="UTF-8"?>
  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="rules">
      <xs:complexType>
        <xs:sequence>
          <xs:element name="rule" minOccurs="0" maxOccurs="unbounded"/>
          <xs:sequence minOccurs="0" maxOccurs="1">
            <xs:element name="specialRule" minOccurs="1" maxOccurs="1"/>
            <xs:element name="rule" minOccurs="0" maxOccurs="unbounded"/>
          </xs:sequence>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
  </xs:schema>


Validate it with: xmllint --schema foo.xsd


It will print out usage info, but ignore that, just look at the errors above the usage which will state:

$ xmllint --schema foo.xsd 
foo.xsd:4: element complexType: Schemas parser error : local complex type: The content model is not determinist.
WXS schema foo.xsd failed to compile



However further testing would suggest it's not actually a regression with the above commit *in this particular test case*, but does fail on others!!

I will attempt to get a valid test case to you that highlights the before/after problems better...
Comment 2 Colin Guthrie 2013-03-22 15:11:42 UTC 
OK, the following schema appears to show a difference for me before and after the update:


<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           targetNamespace="http://foobar.org/wibble"
           elementFormDefault="qualified">

  <xs:element name="foo">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="bar" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="wibble" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
      </xs:choice>
      <xs:attribute name="version" type="xs:string" use="required"/>
    </xs:complexType>
  </xs:element>

</xs:schema>


Before:
$ xmllint --schema test.xsd  2>&1 | head -n 4
Usage : xmllint [options] XMLfiles ...
	Parse the XML files and output the result of the parsing
	--version : display the version of the XML library used
	--debug : dump a debug tree of the in-memory document

After:
$ xmllint --schema test.xsd  2>&1 | head -n 4
test.xsd:6: element complexType: Schemas parser error : local complex type: The content model is not determinist.
WXS schema test.xsd failed to compile
Usage : xmllint [options] XMLfiles ...
	Parse the XML files and output the result of the parsing
Comment 3 Travers Carter 2013-04-10 02:11:29 UTC 
I suspect that this is the same as Bug #922450.
Comment 4 Daniel Veillard 2013-06-04 13:14:09 UTC 
This is indeed the same bug, applying the 2 patches indicated in Bug #922450
fixes the problem:

thinkpad:~/XML -> ./xmllint --schema 924785.xsd --noout foo.xml
foo.xml validates
thinkpad:~/XML -> cat 924785.xsd
<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           targetNamespace="http://foobar.org/wibble"
           elementFormDefault="qualified">

  <xs:element name="foo">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="bar" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="wibble" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
      </xs:choice>
      <xs:attribute name="version" type="xs:string" use="required"/>
    </xs:complexType>
  </xs:element>

</xs:schema>
thinkpad:~/XML -> cat foo.xml
<foo xmlns="http://foobar.org/wibble" version="1"/>
thinkpad:~/XML -> 


Daniel

*** This bug has been marked as a duplicate of bug 922450 ***
Comment 5 Joe Cai 2013-07-24 07:28:03 UTC 
What is going on with this one? I tried to find more information of Bug #922450, but it told me I am not authorized to access it.
Comment 6 Daniel Veillard 2013-07-25 02:34:45 UTC 
An update fixing it will be pushed soon.

Daniel