namespace.c

PostgreSQL7.4.6 for Linux

 * an extra argument for the index AM OID.
 */
Oid
OpclassnameGetOpcid(Oid amid, const char *opcname)
{
	Oid			opcid;
	List	   *lptr;

	recomputeNamespacePath();

	foreach(lptr, namespaceSearchPath)
	{
		Oid			namespaceId = lfirsto(lptr);

		opcid = GetSysCacheOid(CLAAMNAMENSP,
							   ObjectIdGetDatum(amid),
							   PointerGetDatum(opcname),
							   ObjectIdGetDatum(namespaceId),
							   0);
		if (OidIsValid(opcid))
			return opcid;
	}

	/* Not found in path */
	return InvalidOid;
}

/*
 * OpclassIsVisible
 *		Determine whether an opclass (identified by OID) is visible in the
 *		current search path.  Visible means "would be found by searching
 *		for the unqualified opclass name".
 */
bool
OpclassIsVisible(Oid opcid)
{
	HeapTuple	opctup;
	Form_pg_opclass opcform;
	Oid			opcnamespace;
	bool		visible;

	opctup = SearchSysCache(CLAOID,
							ObjectIdGetDatum(opcid),
							0, 0, 0);
	if (!HeapTupleIsValid(opctup))
		elog(ERROR, "cache lookup failed for opclass %u", opcid);
	opcform = (Form_pg_opclass) GETSTRUCT(opctup);

	recomputeNamespacePath();

	/*
	 * Quick check: if it ain't in the path at all, it ain't visible.
	 * Items in the system namespace are surely in the path and so we
	 * needn't even do oidMember() for them.
	 */
	opcnamespace = opcform->opcnamespace;
	if (opcnamespace != PG_CATALOG_NAMESPACE &&
		!oidMember(opcnamespace, namespaceSearchPath))
		visible = false;
	else
	{
		/*
		 * If it is in the path, it might still not be visible; it could
		 * be hidden by another opclass of the same name earlier in the
		 * path. So we must do a slow check to see if this opclass would
		 * be found by OpclassnameGetOpcid.
		 */
		char	   *opcname = NameStr(opcform->opcname);

		visible = (OpclassnameGetOpcid(opcform->opcamid, opcname) == opcid);
	}

	ReleaseSysCache(opctup);

	return visible;
}

/*
 * ConversionGetConid
 *		Try to resolve an unqualified conversion name.
 *		Returns OID if conversion found in search path, else InvalidOid.
 *
 * This is essentially the same as RelnameGetRelid.
 */
Oid
ConversionGetConid(const char *conname)
{
	Oid			conid;
	List	   *lptr;

	recomputeNamespacePath();

	foreach(lptr, namespaceSearchPath)
	{
		Oid			namespaceId = lfirsto(lptr);

		conid = GetSysCacheOid(CONNAMENSP,
							   PointerGetDatum(conname),
							   ObjectIdGetDatum(namespaceId),
							   0, 0);
		if (OidIsValid(conid))
			return conid;
	}

	/* Not found in path */
	return InvalidOid;
}

/*
 * ConversionIsVisible
 *		Determine whether a conversion (identified by OID) is visible in the
 *		current search path.  Visible means "would be found by searching
 *		for the unqualified conversion name".
 */
bool
ConversionIsVisible(Oid conid)
{
	HeapTuple	contup;
	Form_pg_conversion conform;
	Oid			connamespace;
	bool		visible;

	contup = SearchSysCache(CONOID,
							ObjectIdGetDatum(conid),
							0, 0, 0);
	if (!HeapTupleIsValid(contup))
		elog(ERROR, "cache lookup failed for conversion %u", conid);
	conform = (Form_pg_conversion) GETSTRUCT(contup);

	recomputeNamespacePath();

	/*
	 * Quick check: if it ain't in the path at all, it ain't visible.
	 * Items in the system namespace are surely in the path and so we
	 * needn't even do oidMember() for them.
	 */
	connamespace = conform->connamespace;
	if (connamespace != PG_CATALOG_NAMESPACE &&
		!oidMember(connamespace, namespaceSearchPath))
		visible = false;
	else
	{
		/*
		 * If it is in the path, it might still not be visible; it could
		 * be hidden by another conversion of the same name earlier in the
		 * path. So we must do a slow check to see if this conversion
		 * would be found by ConversionGetConid.
		 */
		char	   *conname = NameStr(conform->conname);

		visible = (ConversionGetConid(conname) == conid);
	}

	ReleaseSysCache(contup);

	return visible;
}

/*
 * DeconstructQualifiedName
 *		Given a possibly-qualified name expressed as a list of String nodes,
 *		extract the schema name and object name.
 *
 * *nspname_p is set to NULL if there is no explicit schema name.
 */
void
DeconstructQualifiedName(List *names,
						 char **nspname_p,
						 char **objname_p)
{
	char	   *catalogname;
	char	   *schemaname = NULL;
	char	   *objname = NULL;

	switch (length(names))
	{
		case 1:
			objname = strVal(lfirst(names));
			break;
		case 2:
			schemaname = strVal(lfirst(names));
			objname = strVal(lsecond(names));
			break;
		case 3:
			catalogname = strVal(lfirst(names));
			schemaname = strVal(lsecond(names));
			objname = strVal(lthird(names));

			/*
			 * We check the catalog name and then ignore it.
			 */
			if (strcmp(catalogname, get_database_name(MyDatabaseId)) != 0)
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				errmsg("cross-database references are not implemented")));
			break;
		default:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
			errmsg("improper qualified name (too many dotted names): %s",
				   NameListToString(names))));
			break;
	}

	*nspname_p = schemaname;
	*objname_p = objname;
}

/*
 * LookupExplicitNamespace
 *		Process an explicitly-specified schema name: look up the schema
 *		and verify we have USAGE (lookup) rights in it.
 *
 * Returns the namespace OID.  Raises ereport if any problem.
 */
Oid
LookupExplicitNamespace(const char *nspname)
{
	Oid			namespaceId;
	AclResult	aclresult;

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

	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_USAGE);
	if (aclresult != ACLCHECK_OK)
		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
					   nspname);

	return namespaceId;
}

/*
 * QualifiedNameGetCreationNamespace
 *		Given a possibly-qualified name for an object (in List-of-Values
 *		format), determine what namespace the object should be created in.
 *		Also extract and return the object name (last component of list).
 *
 * This is *not* used for tables.  Hence, the TEMP table namespace is
 * never selected as the creation target.
 */
Oid
QualifiedNameGetCreationNamespace(List *names, char **objname_p)
{
	char	   *schemaname;
	char	   *objname;
	Oid			namespaceId;

	/* deconstruct the name list */
	DeconstructQualifiedName(names, &schemaname, &objname);

	if (schemaname)
	{
		/* use exact schema given */
		namespaceId = GetSysCacheOid(NAMESPACENAME,
									 CStringGetDatum(schemaname),
									 0, 0, 0);
		if (!OidIsValid(namespaceId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_SCHEMA),
					 errmsg("schema \"%s\" does not exist", schemaname)));
		/* we do not check for USAGE rights here! */
	}
	else
	{
		/* use the default creation namespace */
		recomputeNamespacePath();
		namespaceId = defaultCreationNamespace;
		if (!OidIsValid(namespaceId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_SCHEMA),
					 errmsg("no schema has been selected to create in")));
	}

	/* Note: callers will check for CREATE rights when appropriate */

	*objname_p = objname;
	return namespaceId;
}

/*
 * makeRangeVarFromNameList
 *		Utility routine to convert a qualified-name list into RangeVar form.
 */
RangeVar *
makeRangeVarFromNameList(List *names)
{
	RangeVar   *rel = makeRangeVar(NULL, NULL);

	switch (length(names))
	{
		case 1:
			rel->relname = strVal(lfirst(names));
			break;
		case 2:
			rel->schemaname = strVal(lfirst(names));
			rel->relname = strVal(lsecond(names));
			break;
		case 3:
			rel->catalogname = strVal(lfirst(names));
			rel->schemaname = strVal(lsecond(names));
			rel->relname = strVal(lthird(names));
			break;
		default:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
			 errmsg("improper relation name (too many dotted names): %s",
					NameListToString(names))));
			break;
	}

	return rel;
}

/*
 * NameListToString
 *		Utility routine to convert a qualified-name list into a string.
 *
 * This is used primarily to form error messages, and so we do not quote
 * the list elements, for the sake of legibility.
 */
char *
NameListToString(List *names)
{
	StringInfoData string;
	List	   *l;

	initStringInfo(&string);

	foreach(l, names)
	{
		if (l != names)
			appendStringInfoChar(&string, '.');
		appendStringInfoString(&string, strVal(lfirst(l)));
	}

	return string.data;
}

/*
 * NameListToQuotedString
 *		Utility routine to convert a qualified-name list into a string.
 *
 * Same as above except that names will be double-quoted where necessary,
 * so the string could be re-parsed (eg, by textToQualifiedNameList).
 */
char *
NameListToQuotedString(List *names)
{
	StringInfoData string;
	List	   *l;

	initStringInfo(&string);

	foreach(l, names)
	{
		if (l != names)
			appendStringInfoChar(&string, '.');
		appendStringInfoString(&string, quote_identifier(strVal(lfirst(l))));
	}

	return string.data;
}

/*
 * isTempNamespace - is the given namespace my temporary-table namespace?
 */
bool
isTempNamespace(Oid namespaceId)
{
	if (OidIsValid(myTempNamespace) && myTempNamespace == namespaceId)
		return true;
	return false;
}

/*
 * isOtherTempNamespace - is the given namespace some other backend's
 * temporary-table namespace?
 */
bool
isOtherTempNamespace(Oid namespaceId)
{
	bool		result;
	char	   *nspname;

	/* If it's my own temp namespace, say "false" */
	if (isTempNamespace(namespaceId))
		return false;
	/* Else, if the namespace name starts with "pg_temp_", say "true" */
	nspname = get_namespace_name(namespaceId);
	if (!nspname)
		return false;			/* no such namespace? */
	result = (strncmp(nspname, "pg_temp_", 8) == 0);
	pfree(nspname);
	return result;
}

/*
 * PushSpecialNamespace - push a "special" namespace onto the front of the
 * search path.
 *
 * This is a slightly messy hack intended only for support of CREATE SCHEMA.
 * Although the API is defined to allow a stack of pushed namespaces, we
 * presently only support one at a time.
 *
 * The pushed namespace will be removed from the search path at end of
 * transaction, whether commit or abort.
 */
void
PushSpecialNamespace(Oid namespaceId)
{
	Assert(!OidIsValid(mySpecialNamespace));
	mySpecialNamespace = namespaceId;
	namespaceSearchPathValid = false;
}

/*
 * PopSpecialNamespace - remove previously pushed special namespace.
 */
void
PopSpecialNamespace(Oid namespaceId)
{
	Assert(mySpecialNamespace == namespaceId);
	mySpecialNamespace = InvalidOid;
	namespaceSearchPathValid = false;
}

/*
 * FindConversionByName - find a conversion by possibly qualified name
 */
Oid
FindConversionByName(List *name)
{
	char	   *schemaname;
	char	   *conversion_name;
	Oid			namespaceId;
	Oid			conoid;
	List	   *lptr;

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

	if (schemaname)
	{
		/* use exact schema given */
		namespaceId = LookupExplicitNamespace(schemaname);
		return FindConversion(conversion_name, namespaceId);
	}
	else
	{
		/* search for it in search path */
		recomputeNamespacePath();

		foreach(lptr, namespaceSearchPath)
		{
			namespaceId = lfirsto(lptr);
			conoid = FindConversion(conversion_name, namespaceId);
			if (OidIsValid(conoid))
				return conoid;
		}
	}

	/* Not found in path */
	return InvalidOid;
}

/*
 * FindDefaultConversionProc - find default encoding conversion proc
 */
Oid
FindDefaultConversionProc(int4 for_encoding, int4 to_encoding)
{
	Oid			proc;
	List	   *lptr;

	recomputeNamespacePath();

	foreach(lptr, namespaceSearchPath)
	{
		Oid			namespaceId = lfirsto(lptr);