Warning about invalid .pgpass passwords

Bruce Momjian wrote:
> Tom Lane wrote:
> > Alvaro Herrera <alvherre@commandprompt.com> writes:
> > > It had to do with me having a bogus password in .pgpass (so psql was
> > > first trying empty password, then the one in .pgpass, and both failing).
> > > Pilot error.  However, I'd say that we ought to give a notice if the
> > > password in .pgpass fails.
> >
> > Can we do something like
> >     ERROR: password authentication failed (using password from .pgpass)
> > ie, just tack on a comment to the error message?
>
> I looked into that but found it difficult to implement because only
> libpq knows about pgpass, while the message is printed by psql.

I just got confused for +10 minutes by an incorrect .pgpass password, so
I found new interest in improving this reported behavior.  ;-)

The attached patch reports the fact that .pgpass was used if the libpq
connection fails:

    $ psql -h localhost test
    psql: FATAL:  password authentication failed for user "postgres"
    (password retrieved from .pgpass)

I am not sure if I like the parentheses or not.  Ideally I would report
this only for password failures but that information is not passed back
from the server except as an error string.

I am thinking this could be in 9.0.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  PG East:  http://www.enterprisedb.com/community/nav-pg-east-2010.do
Index: src/interfaces/libpq/fe-connect.c
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v
retrieving revision 1.389
diff -c -c -r1.389 fe-connect.c
*** src/interfaces/libpq/fe-connect.c    3 Mar 2010 20:31:09 -0000    1.389
--- src/interfaces/libpq/fe-connect.c    10 Mar 2010 02:37:20 -0000
***************
*** 652,657 ****
--- 652,659 ----
                                          conn->dbName, conn->pguser);
          if (conn->pgpass == NULL)
              conn->pgpass = strdup(DefaultPassword);
+         else
+             conn->used_dot_pgpass = true;
      }

      /*
***************
*** 1144,1149 ****
--- 1146,1161 ----
              default:
                  /* Just in case we failed to set it in PQconnectPoll */
                  conn->status = CONNECTION_BAD;
+
+                 /*
+                  *    If the connection failed, we should mention that
+                  *    we got the password from .pgpass in case that
+                  *    password is wrong.
+                  */
+                 if (conn->used_dot_pgpass && conn->password_needed)
+                     appendPQExpBufferStr(&conn->errorMessage,
+                         libpq_gettext("(password retrieved from .pgpass)\n"));
+
                  return 0;
          }

***************
*** 2191,2196 ****
--- 2203,2209 ----
      conn->verbosity = PQERRORS_DEFAULT;
      conn->sock = -1;
      conn->password_needed = false;
+     conn->used_dot_pgpass = false;
  #ifdef USE_SSL
      conn->allow_ssl_try = true;
      conn->wait_ssl_try = false;
Index: src/interfaces/libpq/libpq-int.h
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/libpq/libpq-int.h,v
retrieving revision 1.149
diff -c -c -r1.149 libpq-int.h
*** src/interfaces/libpq/libpq-int.h    26 Feb 2010 02:01:33 -0000    1.149
--- src/interfaces/libpq/libpq-int.h    10 Mar 2010 02:37:20 -0000
***************
*** 343,348 ****
--- 343,349 ----
      ProtocolVersion pversion;    /* FE/BE protocol version in use */
      int            sversion;        /* server version, e.g. 70401 for 7.4.1 */
      bool        password_needed;    /* true if server demanded a password */
+     bool        used_dot_pgpass;    /* true if used .pgpass */
      bool        sigpipe_so;        /* have we masked SIGPIPE via SO_NOSIGPIPE? */
      bool        sigpipe_flag;    /* can we mask SIGPIPE via MSG_NOSIGNAL? */