From: Tom Lane <tgl@sss.pgh.pa.us>
To: Chapman Flack <chap@anastigmatix.net>
cc: Ryan Lambert <ryan@rustprooflabs.com>, pgsql-hackers@postgresql.org
Subject: Re: Fix XML handling with DOCTYPE
In-reply-to: <5C8E7FC0.8040401@anastigmatix.net>
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Comments: In-reply-to Chapman Flack <chap@anastigmatix.net>
	message dated "Sun, 17 Mar 2019 13:11:28 -0400"
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Date: Sun, 17 Mar 2019 13:16:31 -0400
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Chapman Flack <chap@anastigmatix.net> writes:
> What I was doing in the patch is the reverse: parsing with the expectation
> of CONTENT to see if a DTD gets tripped over. It isn't allowed for an
> element to precede a DTD, so that approach can be expected to fail fast
> if the other branch needs to be taken.

Ah, right.  I don't have any problem with trying the CONTENT approach
before the DOCUMENT approach rather than vice-versa.  What I was concerned
about was adding a lot of assumptions about exactly how libxml would
report the failure.  IMO a maximally-safe patch would just rearrange
things we're already doing without adding new things.

> But a quick pre-scan for the same thing would have the same property,
> without the libxml dependencies that bother you here. Watch this space.

Do we need a pre-scan at all?

			regards, tom lane