From 4b82c6d940643b752ce70356c2523f014cf1bff9 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 18 Apr 1999 02:57:22 +0000
Subject: [PATCH] Allow CREATE FUNCTION xyz AS '' LANGUAGE 'internal' to work
 the way it used to (ie, assume xyz is the name of the builtin function to
 call).  Complain if an unknown builtin function name is referenced.

---
 src/backend/catalog/pg_proc.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/backend/catalog/pg_proc.c b/src/backend/catalog/pg_proc.c
index 71cb21822e..90c41f57ee 100644
--- a/src/backend/catalog/pg_proc.c
+++ b/src/backend/catalog/pg_proc.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/pg_proc.c,v 1.26 1999/02/21 03:48:32 scrappy Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/pg_proc.c,v 1.27 1999/04/18 02:57:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -26,6 +26,7 @@
 #include "parser/parse_node.h"
 #include "tcop/tcopprot.h"
 #include "utils/builtins.h"
+#include "utils/fmgrtab.h"
 #include "utils/lsyscache.h"
 #include "utils/sets.h"
 #include "utils/syscache.h"
@@ -37,7 +38,7 @@
 #endif
 
 /* ----------------------------------------------------------------
- *		ProcedureDefine
+ *		ProcedureCreate
  * ----------------------------------------------------------------
  */
 Oid
@@ -94,7 +95,7 @@ ProcedureCreate(char *procedureName,
 		if (strcmp(strVal(t), "opaque") == 0)
 		{
 			if (strcmp(languageName, "sql") == 0)
-				elog(ERROR, "ProcedureDefine: sql functions cannot take type \"opaque\"");
+				elog(ERROR, "ProcedureCreate: sql functions cannot take type \"opaque\"");
 			toid = 0;
 		}
 		else
@@ -220,6 +221,32 @@ ProcedureCreate(char *procedureName,
 		pg_checkretval(typeObjectId, querytree_list);
 	}
 
+	/*
+	 * If this is an internal procedure, check that the given internal
+	 * function name (the 'prosrc' value) is a known builtin function.
+	 *
+	 * NOTE: in Postgres versions before 6.5, the SQL name of the created
+	 * function could not be different from the internal name, and 'prosrc'
+	 * wasn't used.  So there is code out there that does CREATE FUNCTION
+	 * xyz AS '' LANGUAGE 'internal'.  To preserve some modicum of
+	 * backwards compatibility, accept an empty 'prosrc' value as meaning
+	 * the supplied SQL function name.
+	 */
+
+	if (strcmp(languageName, "internal") == 0)
+	{
+		if (strlen(prosrc) == 0)
+			prosrc = procedureName;
+		if (fmgr_lookupByName(prosrc) == (func_ptr) NULL)
+			elog(ERROR,
+				 "ProcedureCreate: there is no builtin function named \"%s\"",
+				 prosrc);
+	}
+
+	/*
+	 * All seems OK; prepare the tuple to be inserted into pg_proc.
+	 */
+
 	for (i = 0; i < Natts_pg_proc; ++i)
 	{
 		nulls[i] = ' ';
-- 
2.24.1