From e468be7ff7d19645aeb77bef21a383960a47731e Mon Sep 17 00:00:00 2001
From: Jacob Champion <pchampion@vmware.com>
Date: Tue, 18 May 2021 15:01:29 -0700
Subject: [PATCH 6/7] Add a very simple authn_id extension

...for retrieving the authn_id from the server in tests.
---
 contrib/authn_id/Makefile          | 19 +++++++++++++++++++
 contrib/authn_id/authn_id--1.0.sql |  8 ++++++++
 contrib/authn_id/authn_id.c        | 28 ++++++++++++++++++++++++++++
 contrib/authn_id/authn_id.control  |  5 +++++
 4 files changed, 60 insertions(+)
 create mode 100644 contrib/authn_id/Makefile
 create mode 100644 contrib/authn_id/authn_id--1.0.sql
 create mode 100644 contrib/authn_id/authn_id.c
 create mode 100644 contrib/authn_id/authn_id.control

diff --git a/contrib/authn_id/Makefile b/contrib/authn_id/Makefile
new file mode 100644
index 0000000000..46026358e0
--- /dev/null
+++ b/contrib/authn_id/Makefile
@@ -0,0 +1,19 @@
+# contrib/authn_id/Makefile
+
+MODULE_big = authn_id
+OBJS = authn_id.o
+
+EXTENSION = authn_id
+DATA = authn_id--1.0.sql
+PGFILEDESC = "authn_id - information about the authenticated user"
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/authn_id
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/contrib/authn_id/authn_id--1.0.sql b/contrib/authn_id/authn_id--1.0.sql
new file mode 100644
index 0000000000..af2a4d3991
--- /dev/null
+++ b/contrib/authn_id/authn_id--1.0.sql
@@ -0,0 +1,8 @@
+/* contrib/authn_id/authn_id--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION authn_id" to load this file. \quit
+
+CREATE FUNCTION authn_id() RETURNS text
+AS 'MODULE_PATHNAME', 'authn_id'
+LANGUAGE C IMMUTABLE;
diff --git a/contrib/authn_id/authn_id.c b/contrib/authn_id/authn_id.c
new file mode 100644
index 0000000000..0fecac36a8
--- /dev/null
+++ b/contrib/authn_id/authn_id.c
@@ -0,0 +1,28 @@
+/*
+ * Extension to expose the current user's authn_id.
+ *
+ * contrib/authn_id/authn_id.c
+ */
+
+#include "postgres.h"
+
+#include "fmgr.h"
+#include "libpq/libpq-be.h"
+#include "miscadmin.h"
+#include "utils/builtins.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(authn_id);
+
+/*
+ * Returns the current user's authenticated identity.
+ */
+Datum
+authn_id(PG_FUNCTION_ARGS)
+{
+	if (!MyProcPort->authn_id)
+		PG_RETURN_NULL();
+
+	PG_RETURN_TEXT_P(cstring_to_text(MyProcPort->authn_id));
+}
diff --git a/contrib/authn_id/authn_id.control b/contrib/authn_id/authn_id.control
new file mode 100644
index 0000000000..e0f9e06bed
--- /dev/null
+++ b/contrib/authn_id/authn_id.control
@@ -0,0 +1,5 @@
+# authn_id extension
+comment = 'current user identity'
+default_version = '1.0'
+module_pathname = '$libdir/authn_id'
+relocatable = true
-- 
2.25.1