How to determine if a user exists..

On Mon, 23 Apr 2001, Dominic J. Eidson wrote:

I am trying to add another authentication mechanism to PostgreSQL... And,
in doing that, I need to verify the existance of an user within PG. Short
of hacking together code from verify_password(), is there any way to check
if a user exists in postgresql? (The actuall password verification will be
taken care of elsewhere... I just need to check if the user exists.)

pg_user holds users

(passwords in pg_shadow)

HTH,
--
Joel Burton <jburton@scw.org>
Director of Information Systems, Support Center of Washington

On Mon, 23 Apr 2001, Joel Burton wrote:

pg_user holds users

(passwords in pg_shadow)

I doubt the -hackers people would let me add SPI_* stuff into libpq, just
to retrieve whether a user exists or not.. My first thought was to check
the existance of users against $PGDATA/pg_pwd... One question I'd have
there, is whether pg_pwd always exists (or, can be relied upon existing.)?

--
Dominic J. Eidson
"Baruk Khazad! Khazad ai-menu!" - Gimli
-------------------------------------------------------------------------------
http://www.the-infinite.org/ http://www.the-infinite.org/~dominic/

"Dominic J. Eidson" <sauron@the-infinite.org> writes:

I am trying to add another authentication mechanism to PostgreSQL... And,
in doing that, I need to verify the existance of an user within PG. Short
of hacking together code from verify_password(), is there any way to check
if a user exists in postgresql?

If you're trying to do this from the postmaster, I think the only way is
to look at $PGDATA/global/pg_pwd, which is a flat-file version of
pg_shadow.

You'd be well advised to study the existing verification mechanisms in
src/backend/libpq/.

regards, tom lane

On Mon, 23 Apr 2001, Tom Lane wrote:

If you're trying to do this from the postmaster, I think the only way is
to look at $PGDATA/global/pg_pwd, which is a flat-file version of
pg_shadow.

This is what I thought - thanks.

--
Dominic J. Eidson
"Baruk Khazad! Khazad ai-menu!" - Gimli
-------------------------------------------------------------------------------
http://www.the-infinite.org/ http://www.the-infinite.org/~dominic/

Dominic J. Eidson writes:

On Mon, 23 Apr 2001, Joel Burton wrote:

pg_user holds users

(passwords in pg_shadow)

I doubt the -hackers people would let me add SPI_* stuff into libpq, just
to retrieve whether a user exists or not..

You wouldn't have to do that. There are better ways to read system tables
in the backend. See FAQ_DEV.

My first thought was to check
the existance of users against $PGDATA/pg_pwd... One question I'd have
there, is whether pg_pwd always exists (or, can be relied upon existing.)?

No it doesn't and no you can't.

The best way to verify a user's existence in the context of a new
authentication method is to not do that at all. None of the other methods
do it, the existence of a user is checked when authentication has
completed and the backend starts.

--
Peter Eisentraut peter_e@gmx.net http://funkturm.homeip.net/~peter