Horton

Re: making the backend's json parser work in frontend code

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Mahendra Singh Thalor <mahi6run@gmail.com>, Mark Dilger <mark.dilger@enterprisedb.com>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, David Steele <david@pgmasters.net>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2020-01-28T18:32:26Z
Lists: pgsql-hackers 
I wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> Is the example of CreateDestReceiver() sufficient to show that this is
>> not a problem in practice?

> Dunno.  I don't see any warnings about that in the buildfarm, but
> that's not a very large sample of non-gcc compilers.

BTW, now that I think about it, CreateDestReceiver is not up to project
standards anyway, in that it fails to provide reasonable behavior in
the case where what's passed is not a legal value of the enum.
What you'll get, if you're lucky, is a SIGABRT crash with no
indication of the cause --- or if you're not lucky, some very
hard-to-debug crash elsewhere as a result of the function returning
a garbage pointer.  So independently of whether the current coding
suppresses compiler warnings reliably, I think we ought to replace it
with elog()-and-return-NULL.  Admittedly, that's wasting a few bytes
on a case that should never happen ... but we haven't ever hesitated
to do that elsewhere, if it'd make the problem more diagnosable.

IOW, there's a good reason why there are exactly no other uses
of that coding pattern.

			regards, tom lane

Commits

  1. Add jsonapi.c to Mkvcbuild.pm's @pgcommonallfiles.

  2. Move jsonapi.c and jsonapi.h to src/common.

  3. Move some code from jsonapi.c to jsonfuncs.c.

  4. Adjust pg_parse_json() so that it does not directly ereport().

  5. Remove jsonapi.c's lex_accept().

  6. Split JSON lexer/parser from 'json' data type support.

  7. Rationalize code placement between wchar.c, encnames.c, and mbutils.c.

  8. Move wchar.c and encnames.c to src/common/.

  9. Update header comments for wchar.c and encnames.c.

  10. Make StringInfo available to frontend code.

  11. Use SASLprep to normalize passwords for SCRAM authentication.