comment.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

					   RelationGetRelationName(relation));

	/* Now, fetch the attribute number from the system cache */

	attnum = get_attnum(RelationGetRelid(relation), attrname);
	if (attnum == InvalidAttrNumber)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_COLUMN),
				 errmsg("column \"%s\" of relation \"%s\" does not exist",
						attrname, RelationGetRelationName(relation))));

	/* Create the comment using the relation's oid */
	CreateComments(RelationGetRelid(relation), RelationRelationId,
				   (int32) attnum, comment);

	/* Done, but hold lock until commit */

	relation_close(relation, NoLock);
}

/*
 * CommentDatabase --
 *
 * This routine is used to add/drop any user-comments a user might
 * have regarding the specified database. The routine will check
 * security for owner permissions, and, if successful, will then
 * attempt to find the oid of the database specified. Once found,
 * a comment is added/dropped using the CreateComments() routine.
 */
static void
CommentDatabase(List *qualname, char *comment)
{
	char	   *database;
	Oid			oid;

	if (list_length(qualname) != 1)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("database name may not be qualified")));
	database = strVal(linitial(qualname));

	/*
	 * We cannot currently support cross-database comments (since other DBs
	 * cannot see pg_description of this database).  So, we reject attempts to
	 * comment on a database other than the current one. Someday this might be
	 * improved, but it would take a redesigned infrastructure.
	 *
	 * When loading a dump, we may see a COMMENT ON DATABASE for the old name
	 * of the database.  Erroring out would prevent pg_restore from completing
	 * (which is really pg_restore's fault, but for now we will work around
	 * the problem here).  Consensus is that the best fix is to treat wrong
	 * database name as a WARNING not an ERROR.
	 */

	/* First get the database OID */
	oid = get_database_oid(database);
	if (!OidIsValid(oid))
	{
		ereport(WARNING,
				(errcode(ERRCODE_UNDEFINED_DATABASE),
				 errmsg("database \"%s\" does not exist", database)));
		return;
	}

	/* Only allow comments on the current database */
	if (oid != MyDatabaseId)
	{
		ereport(WARNING,		/* throw just a warning so pg_restore doesn't
								 * fail */
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("database comments may only be applied to the current database")));
		return;
	}

	/* Check object security */
	if (!pg_database_ownercheck(oid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_DATABASE,
					   database);

	/* Call CreateComments() to create/drop the comments */
	CreateComments(oid, DatabaseRelationId, 0, comment);
}

/*
 * CommentNamespace --
 *
 * This routine is used to add/drop any user-comments a user might
 * have regarding the specified namespace. The routine will check
 * security for owner permissions, and, if successful, will then
 * attempt to find the oid of the namespace specified. Once found,
 * a comment is added/dropped using the CreateComments() routine.
 */
static void
CommentNamespace(List *qualname, char *comment)
{
	Oid			oid;
	char	   *namespace;

	if (list_length(qualname) != 1)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("schema name may not be qualified")));
	namespace = strVal(linitial(qualname));

	oid = GetSysCacheOid(NAMESPACENAME,
						 CStringGetDatum(namespace),
						 0, 0, 0);
	if (!OidIsValid(oid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_SCHEMA),
				 errmsg("schema \"%s\" does not exist", namespace)));

	/* Check object security */
	if (!pg_namespace_ownercheck(oid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_NAMESPACE,
					   namespace);

	/* Call CreateComments() to create/drop the comments */
	CreateComments(oid, NamespaceRelationId, 0, comment);
}

/*
 * CommentRule --
 *
 * This routine is used to add/drop any user-comments a user might
 * have regarding a specified RULE. The rule for commenting is determined by
 * both its name and the relation to which it refers. The arguments to this
 * function are the rule name and relation name (merged into a qualified
 * name), and the comment to add/drop.
 *
 * Before PG 7.3, rules had unique names across the whole database, and so
 * the syntax was just COMMENT ON RULE rulename, with no relation name.
 * For purposes of backwards compatibility, we support that as long as there
 * is only one rule by the specified name in the database.
 */
static void
CommentRule(List *qualname, char *comment)
{
	int			nnames;
	List	   *relname;
	char	   *rulename;
	RangeVar   *rel;
	Relation	relation;
	HeapTuple	tuple;
	Oid			reloid;
	Oid			ruleoid;
	AclResult	aclcheck;

	/* Separate relname and trig name */
	nnames = list_length(qualname);
	if (nnames == 1)
	{
		/* Old-style: only a rule name is given */
		Relation	RewriteRelation;
		HeapScanDesc scanDesc;
		ScanKeyData scanKeyData;

		rulename = strVal(linitial(qualname));

		/* Search pg_rewrite for such a rule */
		ScanKeyInit(&scanKeyData,
					Anum_pg_rewrite_rulename,
					BTEqualStrategyNumber, F_NAMEEQ,
					PointerGetDatum(rulename));

		RewriteRelation = heap_open(RewriteRelationId, AccessShareLock);
		scanDesc = heap_beginscan(RewriteRelation, SnapshotNow,
								  1, &scanKeyData);

		tuple = heap_getnext(scanDesc, ForwardScanDirection);
		if (HeapTupleIsValid(tuple))
		{
			reloid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
			ruleoid = HeapTupleGetOid(tuple);
		}
		else
		{
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("rule \"%s\" does not exist", rulename)));
			reloid = ruleoid = 0;		/* keep compiler quiet */
		}

		if (HeapTupleIsValid(tuple = heap_getnext(scanDesc,
												  ForwardScanDirection)))
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_OBJECT),
				   errmsg("there are multiple rules named \"%s\"", rulename),
				errhint("Specify a relation name as well as a rule name.")));

		heap_endscan(scanDesc);
		heap_close(RewriteRelation, AccessShareLock);

		/* Open the owning relation to ensure it won't go away meanwhile */
		relation = heap_open(reloid, AccessShareLock);
	}
	else
	{
		/* New-style: rule and relname both provided */
		Assert(nnames >= 2);
		relname = list_truncate(list_copy(qualname), nnames - 1);
		rulename = strVal(lfirst(list_tail(qualname)));

		/* Open the owning relation to ensure it won't go away meanwhile */
		rel = makeRangeVarFromNameList(relname);
		relation = heap_openrv(rel, AccessShareLock);
		reloid = RelationGetRelid(relation);

		/* Find the rule's pg_rewrite tuple, get its OID */
		tuple = SearchSysCache(RULERELNAME,
							   ObjectIdGetDatum(reloid),
							   PointerGetDatum(rulename),
							   0, 0);
		if (!HeapTupleIsValid(tuple))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("rule \"%s\" for relation \"%s\" does not exist",
							rulename, RelationGetRelationName(relation))));
		Assert(reloid == ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class);
		ruleoid = HeapTupleGetOid(tuple);
		ReleaseSysCache(tuple);
	}

	/* Check object security */
	aclcheck = pg_class_aclcheck(reloid, GetUserId(), ACL_RULE);
	if (aclcheck != ACLCHECK_OK)
		aclcheck_error(aclcheck, ACL_KIND_CLASS,
					   get_rel_name(reloid));

	/* Call CreateComments() to create/drop the comments */
	CreateComments(ruleoid, RewriteRelationId, 0, comment);

	heap_close(relation, NoLock);
}

/*
 * CommentType --
 *
 * This routine is used to add/drop any user-comments a user might
 * have regarding a TYPE. The type is specified by name
 * and, if found, and the user has appropriate permissions, a
 * comment will be added/dropped using the CreateComments() routine.
 * The type's name and the comments are the parameters to this routine.
 */
static void
CommentType(List *typename, char *comment)
{
	TypeName   *tname;
	Oid			oid;

	/* XXX a bit of a crock; should accept TypeName in COMMENT syntax */
	tname = makeNode(TypeName);
	tname->names = typename;
	tname->typmod = -1;

	/* Find the type's oid */

	oid = typenameTypeId(tname);

	/* Check object security */

	if (!pg_type_ownercheck(oid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TYPE,
					   TypeNameToString(tname));

	/* Call CreateComments() to create/drop the comments */
	CreateComments(oid, TypeRelationId, 0, comment);
}

/*
 * CommentAggregate --
 *
 * This routine is used to allow a user to provide comments on an
 * aggregate function. The aggregate function is determined by both
 * its name and its argument type, which, with the comments are
 * the three parameters handed to this routine.
 */
static void
CommentAggregate(List *aggregate, List *arguments, char *comment)
{
	TypeName   *aggtype = (TypeName *) linitial(arguments);
	Oid			baseoid,
				oid;

	/* First, attempt to determine the base aggregate oid */
	if (aggtype)
		baseoid = typenameTypeId(aggtype);
	else
		baseoid = ANYOID;

	/* Now, attempt to find the actual tuple in pg_proc */

	oid = find_aggregate_func(aggregate, baseoid, false);

	/* Next, validate the user's attempt to comment */

	if (!pg_proc_ownercheck(oid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC,
					   NameListToString(aggregate));

	/* Call CreateComments() to create/drop the comments */
	CreateComments(oid, ProcedureRelationId, 0, comment);
}

/*
 * CommentProc --
 *
 * This routine is used to allow a user to provide comments on an
 * procedure (function). The procedure is determined by both
 * its name and its argument list. The argument list is expected to
 * be a series of parsed nodes pointed to by a List object. If the
 * comments string is empty, the associated comment is dropped.
 */
static void
CommentProc(List *function, List *arguments, char *comment)
{
	Oid			oid;

	/* Look up the procedure */

	oid = LookupFuncNameTypeNames(function, arguments, false);

	/* Now, validate the user's ability to comment on this function */

	if (!pg_proc_ownercheck(oid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC,
					   NameListToString(function));

	/* Call CreateComments() to create/drop the comments */
	CreateComments(oid, ProcedureRelationId, 0, comment);
}

/*
 * CommentOperator --
 *
 * This routine is used to allow a user to provide comments on an
 * operator. The operator for commenting is determined by both
 * its name and its argument list which defines the left and right
 * hand types the operator will operate on. The argument list is
 * expected to be a couple of parse nodes pointed to be a List
 * object.
 */
static void
CommentOperator(List *opername, List *arguments, char *comment)
{
	TypeName   *typenode1 = (TypeName *) linitial(arguments);
	TypeName   *typenode2 = (TypeName *) lsecond(arguments);
	Oid			oid;

	/* Look up the operator */
	oid = LookupOperNameTypeNames(opername, typenode1, typenode2, false);

	/* Valid user's ability to comment on this operator */
	if (!pg_oper_ownercheck(oid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_OPER,
					   NameListToString(opername));

	/* Call CreateComments() to create/drop the comments */
	CreateComments(oid, OperatorRelationId, 0, comment);
}

/*
 * CommentTrigger --
 *
 * This routine is used to allow a user to provide comments on a
 * trigger event. The trigger for commenting is determined by both
 * its name and the relation to which it refers. The arguments to this
 * function are the trigger name and relation name (merged into a qualified
 * name), and the comment to add/drop.
 */
static void
CommentTrigger(List *qualname, char *comment)
{
	int			nnames;
	List	   *relname;
	char	   *trigname;
	RangeVar   *rel;
	Relation	pg_trigger,
				relation;
	HeapTuple	triggertuple;
	SysScanDesc scan;
	ScanKeyData entry[2];
	Oid			oid;

	/* Separate relname and trig name */
	nnames = list_length(qualname);
	if (nnames < 2)				/* parser messed up */
		elog(ERROR, "must specify relation and trigger");
	relname = list_truncate(list_copy(qualname), nnames - 1);
	trigname = strVal(lfirst(list_tail(qualname)));

	/* Open the owning relation to ensure it won't go away meanwhile */
	rel = makeRangeVarFromNameList(relname);
	relation = heap_openrv(rel, AccessShareLock);

	/* Check object security */

	if (!pg_class_ownercheck(RelationGetRelid(relation), GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
					   RelationGetRelationName(relation));