src/backend/commands/extprotocolcmds.c - hawq - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 /*-------------------------------------------------------------------------
  *
  * extprotocolcmds.c
  *
  *	  Routines for external protocol-manipulation commands
  *
  * Portions Copyright (c) 2011, Greenplum/EMC.
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"

 #include "access/heapam.h"
 #include "access/genam.h"
 #include "catalog/catquery.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_extprotocol.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/extprotocolcmds.h"
 #include "miscadmin.h"
 #include "parser/parse_func.h"
 #include "parser/parse_type.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 #include "utils/fmgroids.h"

 #include "cdb/cdbvars.h"
 #include "cdb/cdbdisp.h"
 #include "cdb/dispatcher.h"


 /*
  *	DefineExtprotocol
  */
 void
 DefineExtProtocol(List *name, List *parameters, Oid newOid, bool trusted)
 {
 	char	   *protName;
 	List	   *readfuncName = NIL;
 	List	   *writefuncName = NIL;
 	List	   *validatorfuncName = NIL;
 	ListCell   *pl;
 	Oid			protOid;

 	protName = strVal(linitial(name));

 	foreach(pl, parameters)
 	{
 		DefElem    *defel = (DefElem *) lfirst(pl);

 		if (pg_strcasecmp(defel->defname, "readfunc") == 0)
 			readfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "writefunc") == 0)
 			writefuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "validatorfunc") == 0)
 			validatorfuncName = defGetQualifiedName(defel);
 		else if (gp_upgrade_mode && pg_strcasecmp(defel->defname, "oid") == 0) /* OID */
 		{
 			int64 oid = defGetInt64(defel);
 			Assert(oid < FirstBootstrapObjectId);
 			newOid = (Oid)oid;
 		}
 		else
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("protocol attribute \"%s\" not recognized",
 							defel->defname)));
 	}

 	/*
 	 * make sure we have our required definitions
 	 */
 	if (readfuncName == NULL && writefuncName == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
 				 errmsg("protocol must be specify at least a readfunc or a writefunc")));


 	/*
 	 * Most of the argument-checking is done inside of ExtProtocolCreate
 	 */
 	protOid = ExtProtocolCreateWithOid(protName,			/* protocol name */
 									   readfuncName,		/* read function name */
 									   writefuncName,		/* write function name */
 									   validatorfuncName, 	/* validator function name */
 									   newOid,
 									   trusted);

 	if (Gp_role == GP_ROLE_DISPATCH)
 	{
 		DefineStmt * stmt = makeNode(DefineStmt);
 		stmt->kind = OBJECT_EXTPROTOCOL;
 		stmt->oldstyle = false;
 		stmt->defnames = name;
 		stmt->args = NIL;
 		stmt->definition = parameters;
 		stmt->newOid = protOid;
 		stmt->shadowOid = 0;
 		stmt->ordered = false;
 		stmt->trusted = trusted;
 		dispatch_statement_node((Node *) stmt, NULL, NULL, NULL);
 	}
 }


 /*
  * RemoveExtProtocol
  *		Deletes an external protocol.
  */
 void
 RemoveExtProtocol(List *names, DropBehavior behavior, bool missing_ok)
 {
 	char	   *protocolName;
 	Oid			protocolOid = InvalidOid;
 	ObjectAddress object;

 	/*
 	 * General DROP (object) syntax allows fully qualified names, but
 	 * protocols are global objects that do not live in schemas, so
 	 * it is a syntax error if a fully qualified name was given.
 	 */
 	if (list_length(names) != 1)
 		ereport(ERROR,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("protocol name may not be qualified")));
 	protocolName = strVal(linitial(names));

 	/* find protocol Oid. error inline if doesn't exist */
 	protocolOid = LookupExtProtocolOid(protocolName, missing_ok);

 	if (!OidIsValid(protocolOid))
 	{
 		if (!missing_ok)
 		{
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_OBJECT),
 					 errmsg("protocol \"%s\" does not exist",
 							protocolName)));
 		}
 		else
 		{
 			if (Gp_role != GP_ROLE_EXECUTE)
 				ereport(NOTICE,
 						(errcode(ERRCODE_UNDEFINED_OBJECT),
 						 errmsg("protocol \"%s\" does not exist, skipping",
 								protocolName)));
 		}

 		return;
 	}

 	/* Permission check: must own protocol */
 	if (!pg_extprotocol_ownercheck(protocolOid, GetUserId()))
 		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_EXTPROTOCOL, protocolName);

 	/*
 	 * Do the deletion
 	 */
 	object.classId = ExtprotocolRelationId;
 	object.objectId = protocolOid;
 	object.objectSubId = 0;

 	performDeletion(&object, behavior);

 }

 /*
  * Drop PROTOCOL by OID. This is the guts of deletion.
  * This is called to clean up dependencies.
  */
 void
 RemoveExtProtocolById(Oid protOid)
 {
 	ExtProtocolDeleteByOid(protOid);
 }

 /*
  * Change external protocol owner
  */
 void
 AlterExtProtocolOwner(const char *name, Oid newOwnerId)
 {
 	HeapTuple	tup;
 	Relation	rel;
 	Oid			ptcId;
 	Oid			ownerId;
 	AclResult	aclresult;
 	bool		isNull;
 	bool		isTrusted;
 	Datum		ownerDatum;
 	Datum		trustedDatum;
 	cqContext	cqc;
 	cqContext  *pcqCtx;

 	/*
 	 * Check the pg_extprotocol relation to be certain the protocol
 	 * is there.
 	 */
 	rel = heap_open(ExtprotocolRelationId, RowExclusiveLock);

 	pcqCtx = caql_addrel(cqclr(&cqc), rel);

 	tup = caql_getfirst(
 			pcqCtx,
 			cql("SELECT * FROM pg_extprotocol "
 				" WHERE ptcname = :1 "
 				" FOR UPDATE ",
 				CStringGetDatum(name)));

 	if (!HeapTupleIsValid(tup))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("protocol \"%s\" does not exist",
 						name)));

 	ptcId = HeapTupleGetOid(tup);

 	ownerDatum = caql_getattr(pcqCtx,
 							  Anum_pg_extprotocol_ptcowner,
 							  &isNull);

 	if(isNull)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("internal error: protocol \"%s\"  has no owner defined",
 						 name)));

 	ownerId = DatumGetObjectId(ownerDatum);

 	trustedDatum = caql_getattr(pcqCtx,
 								Anum_pg_extprotocol_ptctrusted,
 								&isNull);

 	if(isNull)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("internal error: protocol \"%s\" has no trust attribute defined",
 						 name)));

 	isTrusted = DatumGetBool(trustedDatum);

 	if (ownerId != newOwnerId)
 	{
 		Acl		   *newAcl;
 		Datum		values[Natts_pg_extprotocol];
 		bool		nulls[Natts_pg_extprotocol];
 		bool		replaces[Natts_pg_extprotocol];
 		HeapTuple	newtuple;
 		Datum		aclDatum;

 		/* Superusers can always do it */
 		if (!superuser())
 		{
 			/* Must be owner */
 			if (!pg_extprotocol_ownercheck(ptcId, GetUserId()))
 				aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_EXTPROTOCOL,
 							   name);

 			/* Must be able to become new owner */
 			check_is_member_of_role(GetUserId(), newOwnerId);

 			/* New owner must have USAGE privilege on protocol */
 			aclresult = pg_extprotocol_aclcheck(ptcId, newOwnerId, ACL_USAGE);

 			if (aclresult != ACLCHECK_OK)
 				aclcheck_error(aclresult, ACL_KIND_EXTPROTOCOL, name);
 		}

 		/* MPP-14592: untrusted? don't allow ALTER OWNER to non-super user */
 		if(!isTrusted && !superuser_arg(newOwnerId))
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 					 errmsg("untrusted protocol \"%s\" can't be owned by non superuser",
 							 name)));


 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, false, sizeof(nulls));
 		MemSet(replaces, false, sizeof(replaces));

 		replaces[Anum_pg_extprotocol_ptcowner - 1] = true;
 		values[Anum_pg_extprotocol_ptcowner - 1] = ObjectIdGetDatum(newOwnerId);

 		aclDatum = caql_getattr(pcqCtx,
 								Anum_pg_extprotocol_ptcacl,
 								&isNull);

 		if (!isNull)
 		{
 			newAcl = aclnewowner(DatumGetAclP(aclDatum),
 								 ownerId, newOwnerId);
 			replaces[Anum_pg_extprotocol_ptcacl - 1] = true;
 			values[Anum_pg_extprotocol_ptcacl - 1] = PointerGetDatum(newAcl);
 		}

 		newtuple = caql_modify_current(pcqCtx, values,
 									   nulls, replaces);

 		caql_update_current(pcqCtx, newtuple);
 		/* and Update indexes (implicit) */

 		heap_freetuple(newtuple);

 		/* Update owner dependency reference */
 		changeDependencyOnOwner(ExtprotocolRelationId, ptcId, newOwnerId);
 	}

 	heap_close(rel, NoLock);
 }

 /*
  * Change external protocol owner
  */
 void
 RenameExtProtocol(const char *oldname, const char *newname)
 {
 	HeapTuple	tup;
 	Relation	rel;
 	Oid			ptcId;
 	Oid			ownerId;
 	bool		isNull;
 	cqContext	cqc;
 	cqContext  *pcqCtx;
 	Datum		ownerDatum;

 	/*
 	 * Check the pg_extprotocol relation to be certain the protocol
 	 * is there.
 	 */
 	rel = heap_open(ExtprotocolRelationId, RowExclusiveLock);

 	pcqCtx = caql_addrel(cqclr(&cqc), rel);

 	tup = caql_getfirst(
 			pcqCtx,
 			cql("SELECT * FROM pg_extprotocol "
 				" WHERE ptcname = :1 "
 				" FOR UPDATE ",
 				CStringGetDatum(oldname)));

 	if (!HeapTupleIsValid(tup))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("protocol \"%s\" does not exist",
 						oldname)));

 	ptcId = HeapTupleGetOid(tup);

 	ownerDatum = caql_getattr(pcqCtx,
 							  Anum_pg_extprotocol_ptcowner,
 							  &isNull);

 	if(isNull)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("internal error: protocol \"%s\"  has no owner defined",
 						 oldname)));

 	ownerId = DatumGetObjectId(ownerDatum);

 	if (strcmp(oldname, newname) != 0)
 	{
 		Datum		values[Natts_pg_extprotocol];
 		bool		nulls[Natts_pg_extprotocol];
 		bool		replaces[Natts_pg_extprotocol];
 		HeapTuple	newtuple;

 		/* Superusers can always do it */
 		if (!superuser())
 		{
 			/* Must be owner */
 			if (!pg_extprotocol_ownercheck(ptcId, GetUserId()))
 				aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_EXTPROTOCOL,
 							   oldname);
 		}

 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, false, sizeof(nulls));
 		MemSet(replaces, false, sizeof(replaces));

 		replaces[Anum_pg_extprotocol_ptcname - 1] = true;
 		values[Anum_pg_extprotocol_ptcname - 1] = CStringGetDatum(newname);

 		newtuple = caql_modify_current(pcqCtx, values,
 									   nulls, replaces);

 		caql_update_current(pcqCtx, newtuple);
 		/* and Update indexes (implicit) */

 		heap_freetuple(newtuple);
 	}

 	heap_close(rel, NoLock);
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	/*-------------------------------------------------------------------------
	*
	* extprotocolcmds.c
	*
	* Routines for external protocol-manipulation commands
	*
	* Portions Copyright (c) 2011, Greenplum/EMC.
	* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
	* Portions Copyright (c) 1994, Regents of the University of California
	*
	*-------------------------------------------------------------------------
	*/
	#include "postgres.h"

	#include "access/heapam.h"
	#include "access/genam.h"
	#include "catalog/catquery.h"
	#include "catalog/dependency.h"
	#include "catalog/indexing.h"
	#include "catalog/pg_extprotocol.h"
	#include "catalog/pg_proc.h"
	#include "catalog/pg_type.h"
	#include "commands/defrem.h"
	#include "commands/extprotocolcmds.h"
	#include "miscadmin.h"
	#include "parser/parse_func.h"
	#include "parser/parse_type.h"
	#include "utils/acl.h"
	#include "utils/builtins.h"
	#include "utils/lsyscache.h"
	#include "utils/syscache.h"
	#include "utils/fmgroids.h"

	#include "cdb/cdbvars.h"
	#include "cdb/cdbdisp.h"
	#include "cdb/dispatcher.h"


	/*
	* DefineExtprotocol
	*/
	void
	DefineExtProtocol(List name, List parameters, Oid newOid, bool trusted)
	{
	char *protName;
	List *readfuncName = NIL;
	List *writefuncName = NIL;
	List *validatorfuncName = NIL;
	ListCell *pl;
	Oid protOid;

	protName = strVal(linitial(name));

	foreach(pl, parameters)
	{
	DefElem defel = (DefElem ) lfirst(pl);

	if (pg_strcasecmp(defel->defname, "readfunc") == 0)
	readfuncName = defGetQualifiedName(defel);
	else if (pg_strcasecmp(defel->defname, "writefunc") == 0)
	writefuncName = defGetQualifiedName(defel);
	else if (pg_strcasecmp(defel->defname, "validatorfunc") == 0)
	validatorfuncName = defGetQualifiedName(defel);
	else if (gp_upgrade_mode && pg_strcasecmp(defel->defname, "oid") == 0) /* OID */
	{
	int64 oid = defGetInt64(defel);
	Assert(oid < FirstBootstrapObjectId);
	newOid = (Oid)oid;
	}
	else
	ereport(ERROR,
	(errcode(ERRCODE_SYNTAX_ERROR),
	errmsg("protocol attribute \"%s\" not recognized",
	defel->defname)));
	}

	/*
	* make sure we have our required definitions
	*/
	if (readfuncName == NULL && writefuncName == NULL)
	ereport(ERROR,
	(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
	errmsg("protocol must be specify at least a readfunc or a writefunc")));


	/*
	* Most of the argument-checking is done inside of ExtProtocolCreate
	*/
	protOid = ExtProtocolCreateWithOid(protName, /* protocol name */
	readfuncName, /* read function name */
	writefuncName, /* write function name */
	validatorfuncName, /* validator function name */
	newOid,
	trusted);

	if (Gp_role == GP_ROLE_DISPATCH)
	{
	DefineStmt * stmt = makeNode(DefineStmt);
	stmt->kind = OBJECT_EXTPROTOCOL;
	stmt->oldstyle = false;
	stmt->defnames = name;
	stmt->args = NIL;
	stmt->definition = parameters;
	stmt->newOid = protOid;
	stmt->shadowOid = 0;
	stmt->ordered = false;
	stmt->trusted = trusted;
	dispatch_statement_node((Node *) stmt, NULL, NULL, NULL);
	}
	}


	/*
	* RemoveExtProtocol
	* Deletes an external protocol.
	*/
	void
	RemoveExtProtocol(List *names, DropBehavior behavior, bool missing_ok)
	{
	char *protocolName;
	Oid protocolOid = InvalidOid;
	ObjectAddress object;

	/*
	* General DROP (object) syntax allows fully qualified names, but
	* protocols are global objects that do not live in schemas, so
	* it is a syntax error if a fully qualified name was given.
	*/
	if (list_length(names) != 1)
	ereport(ERROR,
	(errcode(ERRCODE_SYNTAX_ERROR),
	errmsg("protocol name may not be qualified")));
	protocolName = strVal(linitial(names));

	/* find protocol Oid. error inline if doesn't exist */
	protocolOid = LookupExtProtocolOid(protocolName, missing_ok);

	if (!OidIsValid(protocolOid))
	{
	if (!missing_ok)
	{
	ereport(ERROR,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("protocol \"%s\" does not exist",
	protocolName)));
	}
	else
	{
	if (Gp_role != GP_ROLE_EXECUTE)
	ereport(NOTICE,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("protocol \"%s\" does not exist, skipping",
	protocolName)));
	}

	return;
	}

	/* Permission check: must own protocol */
	if (!pg_extprotocol_ownercheck(protocolOid, GetUserId()))
	aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_EXTPROTOCOL, protocolName);

	/*
	* Do the deletion
	*/
	object.classId = ExtprotocolRelationId;
	object.objectId = protocolOid;
	object.objectSubId = 0;

	performDeletion(&object, behavior);

	}

	/*
	* Drop PROTOCOL by OID. This is the guts of deletion.
	* This is called to clean up dependencies.
	*/
	void
	RemoveExtProtocolById(Oid protOid)
	{
	ExtProtocolDeleteByOid(protOid);
	}

	/*
	* Change external protocol owner
	*/
	void
	AlterExtProtocolOwner(const char *name, Oid newOwnerId)
	{
	HeapTuple tup;
	Relation rel;
	Oid ptcId;
	Oid ownerId;
	AclResult aclresult;
	bool isNull;
	bool isTrusted;
	Datum ownerDatum;
	Datum trustedDatum;
	cqContext cqc;
	cqContext *pcqCtx;

	/*
	* Check the pg_extprotocol relation to be certain the protocol
	* is there.
	*/
	rel = heap_open(ExtprotocolRelationId, RowExclusiveLock);

	pcqCtx = caql_addrel(cqclr(&cqc), rel);

	tup = caql_getfirst(
	pcqCtx,
	cql("SELECT * FROM pg_extprotocol "
	" WHERE ptcname = :1 "
	" FOR UPDATE ",
	CStringGetDatum(name)));

	if (!HeapTupleIsValid(tup))
	ereport(ERROR,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("protocol \"%s\" does not exist",
	name)));

	ptcId = HeapTupleGetOid(tup);

	ownerDatum = caql_getattr(pcqCtx,
	Anum_pg_extprotocol_ptcowner,
	&isNull);

	if(isNull)
	ereport(ERROR,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("internal error: protocol \"%s\" has no owner defined",
	name)));

	ownerId = DatumGetObjectId(ownerDatum);

	trustedDatum = caql_getattr(pcqCtx,
	Anum_pg_extprotocol_ptctrusted,
	&isNull);

	if(isNull)
	ereport(ERROR,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("internal error: protocol \"%s\" has no trust attribute defined",
	name)));

	isTrusted = DatumGetBool(trustedDatum);

	if (ownerId != newOwnerId)
	{
	Acl *newAcl;
	Datum values[Natts_pg_extprotocol];
	bool nulls[Natts_pg_extprotocol];
	bool replaces[Natts_pg_extprotocol];
	HeapTuple newtuple;
	Datum aclDatum;

	/* Superusers can always do it */
	if (!superuser())
	{
	/* Must be owner */
	if (!pg_extprotocol_ownercheck(ptcId, GetUserId()))
	aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_EXTPROTOCOL,
	name);

	/* Must be able to become new owner */
	check_is_member_of_role(GetUserId(), newOwnerId);

	/* New owner must have USAGE privilege on protocol */
	aclresult = pg_extprotocol_aclcheck(ptcId, newOwnerId, ACL_USAGE);

	if (aclresult != ACLCHECK_OK)
	aclcheck_error(aclresult, ACL_KIND_EXTPROTOCOL, name);
	}

	/* MPP-14592: untrusted? don't allow ALTER OWNER to non-super user */
	if(!isTrusted && !superuser_arg(newOwnerId))
	ereport(ERROR,
	(errcode(ERRCODE_WRONG_OBJECT_TYPE),
	errmsg("untrusted protocol \"%s\" can't be owned by non superuser",
	name)));


	MemSet(values, 0, sizeof(values));
	MemSet(nulls, false, sizeof(nulls));
	MemSet(replaces, false, sizeof(replaces));

	replaces[Anum_pg_extprotocol_ptcowner - 1] = true;
	values[Anum_pg_extprotocol_ptcowner - 1] = ObjectIdGetDatum(newOwnerId);

	aclDatum = caql_getattr(pcqCtx,
	Anum_pg_extprotocol_ptcacl,
	&isNull);

	if (!isNull)
	{
	newAcl = aclnewowner(DatumGetAclP(aclDatum),
	ownerId, newOwnerId);
	replaces[Anum_pg_extprotocol_ptcacl - 1] = true;
	values[Anum_pg_extprotocol_ptcacl - 1] = PointerGetDatum(newAcl);
	}

	newtuple = caql_modify_current(pcqCtx, values,
	nulls, replaces);

	caql_update_current(pcqCtx, newtuple);
	/* and Update indexes (implicit) */

	heap_freetuple(newtuple);

	/* Update owner dependency reference */
	changeDependencyOnOwner(ExtprotocolRelationId, ptcId, newOwnerId);
	}

	heap_close(rel, NoLock);
	}

	/*
	* Change external protocol owner
	*/
	void
	RenameExtProtocol(const char oldname, const char newname)
	{
	HeapTuple tup;
	Relation rel;
	Oid ptcId;
	Oid ownerId;
	bool isNull;
	cqContext cqc;
	cqContext *pcqCtx;
	Datum ownerDatum;

	/*
	* Check the pg_extprotocol relation to be certain the protocol
	* is there.
	*/
	rel = heap_open(ExtprotocolRelationId, RowExclusiveLock);

	pcqCtx = caql_addrel(cqclr(&cqc), rel);

	tup = caql_getfirst(
	pcqCtx,
	cql("SELECT * FROM pg_extprotocol "
	" WHERE ptcname = :1 "
	" FOR UPDATE ",
	CStringGetDatum(oldname)));

	if (!HeapTupleIsValid(tup))
	ereport(ERROR,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("protocol \"%s\" does not exist",
	oldname)));

	ptcId = HeapTupleGetOid(tup);

	ownerDatum = caql_getattr(pcqCtx,
	Anum_pg_extprotocol_ptcowner,
	&isNull);

	if(isNull)
	ereport(ERROR,
	(errcode(ERRCODE_UNDEFINED_OBJECT),
	errmsg("internal error: protocol \"%s\" has no owner defined",
	oldname)));

	ownerId = DatumGetObjectId(ownerDatum);

	if (strcmp(oldname, newname) != 0)
	{
	Datum values[Natts_pg_extprotocol];
	bool nulls[Natts_pg_extprotocol];
	bool replaces[Natts_pg_extprotocol];
	HeapTuple newtuple;

	/* Superusers can always do it */
	if (!superuser())
	{
	/* Must be owner */
	if (!pg_extprotocol_ownercheck(ptcId, GetUserId()))
	aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_EXTPROTOCOL,
	oldname);
	}

	MemSet(values, 0, sizeof(values));
	MemSet(nulls, false, sizeof(nulls));
	MemSet(replaces, false, sizeof(replaces));

	replaces[Anum_pg_extprotocol_ptcname - 1] = true;
	values[Anum_pg_extprotocol_ptcname - 1] = CStringGetDatum(newname);

	newtuple = caql_modify_current(pcqCtx, values,
	nulls, replaces);

	caql_update_current(pcqCtx, newtuple);
	/* and Update indexes (implicit) */

	heap_freetuple(newtuple);
	}

	heap_close(rel, NoLock);
	}