From 13ecb822e8da5668133b706474c25bc908ae370a Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Sat, 19 Apr 2014 08:41:51 -0400
Subject: [PATCH] libpq:  have PQconnectdbParams() and PQpingParams accept ""
 as default

Previously, these functions treated "" optin values as defaults in some
ways, but not in others, like when comparing to .pgpass.  Also, add
documentation to clarify that now "" and NULL use defaults, like
PQsetdbLogin() has always done.

BACKWARD INCOMPATIBILITY

Patch by Adrian Vondendriesch, docs by me

Report by Jeff Janes
---
 doc/src/sgml/libpq.sgml           | 12 ++++++------
 src/interfaces/libpq/fe-connect.c |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index be0d602508..1f0975ada6 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -131,15 +131,15 @@ PGconn *PQconnectdbParams(const char * const *keywords,
       <para>
        The passed arrays can be empty to use all default parameters, or can
        contain one or more parameter settings. They should be matched in length.
-       Processing will stop with the last non-<symbol>NULL</symbol> element
-       of the <literal>keywords</literal> array.
+       Processing will stop at the first <symbol>NULL</symbol> element
+       in the <literal>keywords</literal> array.
       </para>
 
       <para>
-       If  any  parameter is unspecified, then the corresponding
-       environment variable (see <xref linkend="libpq-envars">)
-       is checked. If the  environment  variable is not set either,
-       then the indicated built-in defaults are used.
+       If  any  parameter is NULL or an emptry string, the corresponding
+       environment variable (see <xref linkend="libpq-envars">) is checked.
+       If the  environment  variable is not set either, then the indicated
+       built-in defaults are used.
       </para>
 
       <para>
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 3909367be6..0791774af7 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -4357,7 +4357,7 @@ conninfo_array_parse(const char *const * keywords, const char *const * values,
 		const char *pname = keywords[i];
 		const char *pvalue = values[i];
 
-		if (pvalue != NULL)
+		if (pvalue != NULL && pvalue[0] != '\0')
 		{
 			/* Search for the param record */
 			for (option = options; option->keyword != NULL; option++)