Horton

Re: Fix XML handling with DOCTYPE

Chapman Flack <chap@anastigmatix.net>

View thread View on postgr.es
From: Chapman Flack <chap@anastigmatix.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Ryan Lambert <ryan@rustprooflabs.com>, pgsql-hackers@postgresql.org
Date: 2019-03-17T22:31:00Z
Lists: pgsql-hackers

Attachments

On 03/17/19 15:06, Tom Lane wrote:
> The error message issue is indeed a concern, but I don't see why it's
> complicated if you agree that
> 
>> If the query asked for CONTENT, any error result should be one you could get
>> when parsing as CONTENT.
> 
> That just requires us to save the first error message and be sure to issue
> that one not the DOCUMENT one, no?

I confess I haven't looked hard yet at how to do that. The way errors come
out of libxml is more involved than "here's a message", so there's a choice
of (a) try to copy off that struct in a way that's sure to survive
re-executing the parser, and then use the copy, or (b) generate a message
right away from the structured information and save that, and I guess b
might not be too bad; a might not be too bad, or it might, and slide right
back into the kind of libxml-behavior-assumptions you're wanting to avoid.

Meanwhile, here is a patch on the lines I proposed earlier, with a
pre-check. Any performance hit that it could entail (which I'd really
expect to be de minimis, though I haven't benchmarked) ought to be
compensated by the strlen I changed to strnlen in parse_xml_decl (as
there's really no need to run off and count the whole rest of the input
just to know if 1, 2, 3, or 4 bytes are available to decode a UTF-8 char).

... and, yes, I know that could be an independent patch, and then the
performance effect here should be measured from there. But it was near
what I was doing anyway, so I included it here.

Attaching both still-outstanding patches (this one and docfix) so the
CF app doesn't lose one.

Regards,
-Chap

Commits

  1. Improve documentation about our XML functionality

  2. Improve documentation about our XML functionality.

  3. Doc: clarify that REASSIGN OWNED doesn't handle default privileges.

  4. Suppress Append and MergeAppend plan nodes that have a single child.

  5. Accept XML documents when xmloption = content, as required by SQL:2006+.

  6. Ensure xmloption = content while restoring pg_dump output.