Fix thinko in recent patch to change temp-table permissions behavior:

this is an aclmask function and does not have the same return convention
as aclcheck functions.  Also adjust the behavior so that users without
CREATE TEMP permission still have USAGE permission on their session's
temp schema.  This allows privileged code to create a temp table and
make it accessible to code that's not got the same privilege.  (Since
the default permissions on a table are no-access, an explicit grant on
the table will still be needed; but I see no reason that the temp schema
itself should prohibit such access.)

src/backend/catalog/aclchk.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/aclchk.c,v 1.100 2004/05/26 18:35:32 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/aclchk.c,v 1.101 2004/05/28 16:17:14 tgl Exp $
  *
  * NOTES
  *	  See acl.h.
@@ -1347,20 +1347,30 @@ pg_namespace_aclmask(Oid nsp_oid, AclId userid,
 		return mask;
 
 	/*
-	 * If we have been assigned this namespace as a temp
-	 * namespace, check to make sure we have CREATE permissions on
-	 * the database.
+	 * If we have been assigned this namespace as a temp namespace,
+	 * check to make sure we have CREATE TEMP permission on the database,
+	 * and if so act as though we have all standard (but not GRANT OPTION)
+	 * permissions on the namespace.  If we don't have CREATE TEMP, act as
+	 * though we have only USAGE (and not CREATE) rights.
 	 *
-	 * Instead of returning ACLCHECK_NO_PRIV, should we return via
-	 * ereport() with a message about trying to create an object
-	 * in a TEMP namespace when GetUserId() doesn't have perms?
+	 * This may seem redundant given the check in InitTempTableNamespace,
+	 * but it really isn't since current user ID may have changed since then.
+	 * The upshot of this behavior is that a SECURITY INVOKER function can
+	 * create temp tables that can then be accessed (if permission is granted)
+	 * by code that doesn't have permissions to create temp tables.
+	 *
+	 * XXX Would it be safe to ereport a special error message as
+	 * InitTempTableNamespace does?  Returning zero here means we'll get a
+	 * generic "permission denied for schema pg_temp_N" message, which is not
+	 * remarkably user-friendly.
 	 */
-	if (isTempNamespace(nsp_oid)) {
-	  if (pg_database_aclcheck(MyDatabaseId, GetUserId(),
-				   ACL_CREATE_TEMP) == ACLCHECK_OK)
-	    return ACLCHECK_OK;
-	  else
-	    return ACLCHECK_NO_PRIV;
+	if (isTempNamespace(nsp_oid))
+	{
+		if (pg_database_aclcheck(MyDatabaseId, GetUserId(),
+								 ACL_CREATE_TEMP) == ACLCHECK_OK)
+			return mask & ACL_ALL_RIGHTS_NAMESPACE;
+		else
+			return mask & ACL_USAGE;
 	}
 
 	/*

src/backend/catalog/namespace.c

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.65 2004/05/26 18:35:32 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.66 2004/05/28 16:17:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1640,9 +1640,10 @@ InitTempTableNamespace(void)
 	 * tables.	We use a nonstandard error message here since
 	 * "databasename: permission denied" might be a tad cryptic.
 	 *
-	 * ACL_CREATE_TEMP perms are also checked in
-	 * pg_namespace_aclcheck() that way only users who have TEMP
-	 * perms can create objects.
+	 * Note that ACL_CREATE_TEMP rights are rechecked in pg_namespace_aclmask;
+	 * that's necessary since current user ID could change during the session.
+	 * But there's no need to make the namespace in the first place until a
+	 * temp table creation request is made by someone with appropriate rights.
 	 */
 	if (pg_database_aclcheck(MyDatabaseId, GetUserId(),
 							 ACL_CREATE_TEMP) != ACLCHECK_OK)