[Dovecot] auth-req-handler.c adds spurious tab

[Chris Laif]

If the auth backend (postgresql in my case) returns extra fields, and
all of these extra_fields begin with 'userdb_', the auth_callback
functions adds an unwanted extra tab at the end of the response:

auth(default): client out: OK^I8^Iuser=foo at bar^I

This extra tab at the end confuses exim's dovecot-auth handler (the
exim-dovecot auth handler does not correctly count the number of
returned fields then (side note: the code on exim's side should
probably be cleaned up as well)).

A quick fix is attached below.

Chris

--- src/auth/auth-request-handler.c.orig        2006-11-03
13:10:35.000000000 +0100
+++ src/auth/auth-request-handler.c     2006-11-03 13:08:32.000000000 +0100
@@ -139,6 +139,10 @@
                        str_append(str, fields[src]);
                }
        }
+
+       if (str_len(str) == 0)
+               return NULL;
+
        return str_c(str);
 }