Subject: Re: Fix XML handling with DOCTYPE
To: Tom Lane <tgl@sss.pgh.pa.us>
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Cc: Ryan Lambert <ryan@rustprooflabs.com>, pgsql-hackers@postgresql.org
From: Chapman Flack <chap@anastigmatix.net>
Message-ID: <5C96AAD4.1090006@anastigmatix.net>
Date: Sat, 23 Mar 2019 17:53:24 -0400
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On 03/23/19 16:59, Tom Lane wrote:
> Unicode-code-point numbers.  I removed that, made some other changes to
> bring the patch more in line with PG coding style, and pushed it.

Thanks! It looks good. I'm content with the extra PI checking being gone.

The magic Unicode-code-point numbers come straight from the XML standard;
I couldn't make that stuff up. :)

> > You're not really validating that the input
> is something that libxml would accept, unless its processing of XML PIs
> is far stupider than I would expect it to be.

Out of curiosity, what further processing would you expect libxml to do?

XML parsers are supposed to be transparent PI-preservers, except in the
rare case of seeing a PI that actually means something to the embedding
application, which isn't going to be the case for a database simply
implementing an XML data type.

The standard literally requires that the target must be a NAME, and
can't match [Xx][Mm][Ll], and if there's whitespace and anything after
that, there can't be an embedded ?> ... and that's it.

Regards,
-Chap