comment.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	/*
	 * Fetch the trigger tuple from pg_trigger.  There can be only one because
	 * of the unique index.
	 */
	pg_trigger = heap_open(TriggerRelationId, AccessShareLock);
	ScanKeyInit(&entry[0],
				Anum_pg_trigger_tgrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(RelationGetRelid(relation)));
	ScanKeyInit(&entry[1],
				Anum_pg_trigger_tgname,
				BTEqualStrategyNumber, F_NAMEEQ,
				CStringGetDatum(trigname));
	scan = systable_beginscan(pg_trigger, TriggerRelidNameIndexId, true,
							  SnapshotNow, 2, entry);
	triggertuple = systable_getnext(scan);

	/* If no trigger exists for the relation specified, notify user */

	if (!HeapTupleIsValid(triggertuple))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("trigger \"%s\" for table \"%s\" does not exist",
						trigname, RelationGetRelationName(relation))));

	oid = HeapTupleGetOid(triggertuple);

	systable_endscan(scan);

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

	/* Done, but hold lock on relation */

	heap_close(pg_trigger, AccessShareLock);
	heap_close(relation, NoLock);
}


/*
 * CommentConstraint --
 *
 * Enable commenting on constraints held within the pg_constraint
 * table.  A qualified name is required as constraint names are
 * unique per relation.
 */
static void
CommentConstraint(List *qualname, char *comment)
{
	int			nnames;
	List	   *relName;
	char	   *conName;
	RangeVar   *rel;
	Relation	pg_constraint,
				relation;
	HeapTuple	tuple;
	SysScanDesc scan;
	ScanKeyData skey[1];
	Oid			conOid = InvalidOid;

	/* Separate relname and constraint name */
	nnames = list_length(qualname);
	if (nnames < 2)				/* parser messed up */
		elog(ERROR, "must specify relation and constraint");
	relName = list_truncate(list_copy(qualname), nnames - 1);
	conName = 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));

	/*
	 * Fetch the constraint tuple from pg_constraint.  There may be more than
	 * one match, because constraints are not required to have unique names;
	 * if so, error out.
	 */
	pg_constraint = heap_open(ConstraintRelationId, AccessShareLock);

	ScanKeyInit(&skey[0],
				Anum_pg_constraint_conrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(RelationGetRelid(relation)));

	scan = systable_beginscan(pg_constraint, ConstraintRelidIndexId, true,
							  SnapshotNow, 1, skey);

	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
	{
		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);

		if (strcmp(NameStr(con->conname), conName) == 0)
		{
			if (OidIsValid(conOid))
				ereport(ERROR,
						(errcode(ERRCODE_DUPLICATE_OBJECT),
				 errmsg("table \"%s\" has multiple constraints named \"%s\"",
						RelationGetRelationName(relation), conName)));
			conOid = HeapTupleGetOid(tuple);
		}
	}

	systable_endscan(scan);

	/* If no constraint exists for the relation specified, notify user */
	if (!OidIsValid(conOid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("constraint \"%s\" for table \"%s\" does not exist",
						conName, RelationGetRelationName(relation))));

	/* Call CreateComments() to create/drop the comments */
	CreateComments(conOid, ConstraintRelationId, 0, comment);

	/* Done, but hold lock on relation */
	heap_close(pg_constraint, AccessShareLock);
	heap_close(relation, NoLock);
}

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

	conversionOid = FindConversionByName(qualname);
	if (!OidIsValid(conversionOid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("conversion \"%s\" does not exist",
						NameListToString(qualname))));

	/* Check object security */
	if (!pg_conversion_ownercheck(conversionOid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CONVERSION,
					   NameListToString(qualname));

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

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

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

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

	/* Check object security */
	if (!superuser())
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
			 errmsg("must be superuser to comment on procedural language")));

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

/*
 * CommentOpClass --
 *
 * This routine is used to allow a user to provide comments on an
 * operator class. The operator class for commenting is determined by both
 * its name and its argument list which defines the index method
 * the operator class is used for. The argument list is expected to contain
 * a single name (represented as a string Value node).
 */
static void
CommentOpClass(List *qualname, List *arguments, char *comment)
{
	char	   *amname;
	char	   *schemaname;
	char	   *opcname;
	Oid			amID;
	Oid			opcID;
	HeapTuple	tuple;

	Assert(list_length(arguments) == 1);
	amname = strVal(linitial(arguments));

	/*
	 * Get the access method's OID.
	 */
	amID = GetSysCacheOid(AMNAME,
						  CStringGetDatum(amname),
						  0, 0, 0);
	if (!OidIsValid(amID))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("access method \"%s\" does not exist",
						amname)));

	/*
	 * Look up the opclass.
	 */

	/* deconstruct the name list */
	DeconstructQualifiedName(qualname, &schemaname, &opcname);

	if (schemaname)
	{
		/* Look in specific schema only */
		Oid			namespaceId;

		namespaceId = LookupExplicitNamespace(schemaname);
		tuple = SearchSysCache(CLAAMNAMENSP,
							   ObjectIdGetDatum(amID),
							   PointerGetDatum(opcname),
							   ObjectIdGetDatum(namespaceId),
							   0);
	}
	else
	{
		/* Unqualified opclass name, so search the search path */
		opcID = OpclassnameGetOpcid(amID, opcname);
		if (!OidIsValid(opcID))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
							opcname, amname)));
		tuple = SearchSysCache(CLAOID,
							   ObjectIdGetDatum(opcID),
							   0, 0, 0);
	}

	if (!HeapTupleIsValid(tuple))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
						NameListToString(qualname), amname)));

	opcID = HeapTupleGetOid(tuple);

	/* Permission check: must own opclass */
	if (!pg_opclass_ownercheck(opcID, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_OPCLASS,
					   NameListToString(qualname));

	ReleaseSysCache(tuple);

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

/*
 * CommentLargeObject --
 *
 * This routine is used to add/drop any user-comments a user might
 * have regarding a LARGE OBJECT. The large object is specified by OID
 * and, if found, and the user has appropriate permissions, a
 * comment will be added/dropped using the CreateComments() routine.
 * The large object's OID and the comment are the parameters to this routine.
 */
static void
CommentLargeObject(List *qualname, char *comment)
{
	Oid			loid;
	Node	   *node;

	Assert(list_length(qualname) == 1);
	node = (Node *) linitial(qualname);

	switch (nodeTag(node))
	{
		case T_Integer:
			loid = intVal(node);
			break;
		case T_Float:

			/*
			 * Values too large for int4 will be represented as Float
			 * constants by the lexer.	Accept these if they are valid OID
			 * strings.
			 */
			loid = DatumGetObjectId(DirectFunctionCall1(oidin,
											 CStringGetDatum(strVal(node))));
			break;
		default:
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(node));
			/* keep compiler quiet */
			loid = InvalidOid;
	}

	/* check that the large object exists */
	if (!LargeObjectExists(loid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("large object %u does not exist", loid)));

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

/*
 * CommentCast --
 *
 * This routine is used to add/drop any user-comments a user might
 * have regarding a CAST. The cast is specified by source and destination types
 * and, if found, and the user has appropriate permissions, a
 * comment will be added/dropped using the CreateComments() routine.
 * The cast's source type is passed as the "name", the destination type
 * as the "arguments".
 */
static void
CommentCast(List *qualname, List *arguments, char *comment)
{
	TypeName   *sourcetype;
	TypeName   *targettype;
	Oid			sourcetypeid;
	Oid			targettypeid;
	HeapTuple	tuple;
	Oid			castOid;

	Assert(list_length(qualname) == 1);
	sourcetype = (TypeName *) linitial(qualname);
	Assert(IsA(sourcetype, TypeName));
	Assert(list_length(arguments) == 1);
	targettype = (TypeName *) linitial(arguments);
	Assert(IsA(targettype, TypeName));

	sourcetypeid = typenameTypeId(sourcetype);
	if (!OidIsValid(sourcetypeid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("source data type %s does not exist",
						TypeNameToString(sourcetype))));

	targettypeid = typenameTypeId(targettype);
	if (!OidIsValid(targettypeid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("target data type %s does not exist",
						TypeNameToString(targettype))));

	tuple = SearchSysCache(CASTSOURCETARGET,
						   ObjectIdGetDatum(sourcetypeid),
						   ObjectIdGetDatum(targettypeid),
						   0, 0);
	if (!HeapTupleIsValid(tuple))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("cast from type %s to type %s does not exist",
						TypeNameToString(sourcetype),
						TypeNameToString(targettype))));

	/* Get the OID of the cast */
	castOid = HeapTupleGetOid(tuple);

	/* Permission check */
	if (!pg_type_ownercheck(sourcetypeid, GetUserId())
		&& !pg_type_ownercheck(targettypeid, GetUserId()))
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
				 errmsg("must be owner of type %s or type %s",
						TypeNameToString(sourcetype),
						TypeNameToString(targettype))));

	ReleaseSysCache(tuple);

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