Bug->Req #79344 [Asn]: xmlwriter_write_attribute_ns: $prefix should be nullable

Edit report at https://bugs.php.net/bug.php?id=79344&edit=1 ID: 79344 Updated by: cmb@php.net Reported by: jtojnar at gmail dot com -Summary: XmlWriter::writeAttributeNS produces bad XML with null prefix +Summary: xmlwriter_write_attribute_ns: $prefix should be nullable Status: Assigned -Type: Bug +Type: Feature/Change Request Package: XML Writer Operating System: NixOS PHP Version: 7.4.3 Assigned To: cmb Block user comment: N Private report: N New Comment: Not strictly a bug; changing to feature request. Previous Comments: ------------------------------------------------------------------------ [2020-06-16 12:17:40] cmb@php.net The following pull request has been associated: Patch Name: FR #79344: xmlwriter_write_attribute_ns: $prefix should be nullable On GitHub: https://github.com/php/php-src/pull/5724 Patch: https://github.com/php/php-src/pull/5724.patch ------------------------------------------------------------------------ [2020-06-16 12:16:44] cmb@php.net Indeed, @nikic, my analysis was nonsense. The point is that the $prefix parameter is not nullable. ------------------------------------------------------------------------ [2020-03-05 08:30:57] nikic@php.net @cmb: Are you sure that's the reason? Looking at the implementation, $prefix is accepted as s, not s!, so we will cast NULL to "". ------------------------------------------------------------------------ [2020-03-05 08:05:48] cmb@php.net The difference between passing NULL and an empty string to XMLWriter::writeAttributeNS() is that either NULL or an empty string is passed to xmlTextWriterWriteAttributeNS() (which does the actual work). The documentation of that function[1] is unfortunately not clear about whether there is a difference or not. So we can only observe the current libxml2 behavior, and it seems there is no difference. So I don't think there is anything we could do (except for calling xmlTextWriterWriteAttribute() if both prefix and uri are NULL, but that would constitute a BC break), besides documenting the behavior. http://xmlsoft.org/html/libxml-xmlwriter.html#xmlTextWriterWriteAttributeNS ------------------------------------------------------------------------ [2020-03-04 16:38:53] jtojnar at gmail dot com Description: ------------ When passing a $prefix = null to XMLWriter::writeAttributeNs, it behaves as if empty string was passed, producing a non-well-formed XML document. Same issue happens with startAttributeNS method but it works fine for methods for creating elements. Test script: --------------- <?php $writer = new XMLWriter; $writer->openMemory(); $writer->setIndent(true); $writer->startElement('foo'); $writer->writeAttributeNS(null, 'test', null, 'test'); // $writer->startAttributeNS(null, 'test', null); // $writer->text('test'); // $writer->endAttribute(); $writer->endElement(); echo $writer->outputMemory(); Expected result: ---------------- <foo test="test"/> Actual result: -------------- <foo :test="test"/> ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79344&edit=1