Re: BUG #9204: truncate_identifier may be called unnecessarily on escaped quoted identifiers

From: Joshua Yanovski <pythonesque(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #9204: truncate_identifier may be called unnecessarily on escaped quoted identifiers
Date: 2014-02-13 18:15:12
Message-ID: CABz-M-G25NEfT3kZMUwkgVcTiCjJqYBHUvKSNjFOO8OJJysUiQ@mail.gmail.com
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There is one other thing I noticed in that area of the code--namely, if
NAMEDATALEN is low enough, an identifier can be truncated down to an empty
identifier, since the check for empty identifier length is done before the
call to truncate_identifier. But I doubt this will ever be a problem in
practice and there may be other compensatory checks elsewhere.

On Thu, Feb 13, 2014 at 9:44 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> pythonesque(at)gmail(dot)com writes:
> > As in description. This follows from how these are scanned in scan.l:
>
> > ident = litbuf_udeescape('\\', yyscanner);
> > if (yyextra->literallen >= NAMEDATALEN)
> > truncate_identifier(ident, yyextra->literallen, true);
>
> Yeah, that's a bug --- yyextra->literallen is not the thing to use here.
> It's just luck that truncate_identifier doesn't fail entirely, since
> we're violating its API contract. Will fix, thanks for reporting it.
>
> regards, tom lane
>

--
Josh

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