On Fri, Jan  9, 2015 at 06:42:19PM -0500, Tom Lane wrote:
> Christoph Berg <c...@df7cb.de> writes:
> > libpq wants the user home directory to find .pgpass and
> > .pg_service.conf files, but apparently the behavior to require the
> > existence of the passwd file (or nss equivalent) is new in 9.4.
> 
> There is demonstrably no direct reference to /etc/passwd in the PG code.
> It's possible that we've added some new expectation that $HOME can be
> identified, but a quick look through the code shows no such checks that
> don't look like they've been there for some time.
> 
> Are the complainants doing anything that would result in SSL certificate
> checking?  More generally, it'd be useful to see an exact example of
> what are the connection parameters and environment that result in a
> failure.

I see similar error strings, but nothing that ends with a question mark:
"out of memory?".  However, I wonder if the crux of the problem is that
they are running in a chroot environment where the user id can't be
looked up.

Looking at libpq's pg_fe_getauthname(), I see that if it can't get the
OS user name of the effective user, it assumes it failed and returns
NULL:

            /*
             * We document PQconndefaults() to return NULL for a memory 
allocation
             * failure.  We don't have an API to return a user name lookup 
failure, so
             * we just assume it always succeeds.
             */
        #ifdef WIN32
            if (GetUserName(username, &namesize))
                name = username;
        #else
            if (pqGetpwuid(geteuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pw) == 
0)
                name = pw->pw_name;
        #endif
        
            authn = name ? strdup(name) : NULL;

and conninfo_add_defaults() assumes a pg_fe_getauthname() failure is a
memory allocation failure:

        option->val = pg_fe_getauthname();
        if (!option->val)
        {
                if (errorMessage)
                        printfPQExpBuffer(errorMessage,
                                                          libpq_gettext("out of 
memory\n"));
                return false;

It was my 9.4 commit that changed this:

        commit a4c8f14364c27508233f8a31ac4b10a4c90235a9
        Author: Bruce Momjian <br...@momjian.us>
        Date:   Thu Mar 20 11:48:31 2014 -0400
        
            libpq:  pass a memory allocation failure error up to 
PQconndefaults()
        
            Previously user name memory allocation failures were ignored and the
            default user name set to NULL.

I am thinking we have to now assume that user name lookups can fail for
other reasons.  I am unclear how this worked in the past though.

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

  + Everyone has their own god. +


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