DBMS database creation

[hcoop/domtool2.git] / src / tycheck.sml

diff --git a/src/tycheck.sml b/src/tycheck.sml
index 9467b64..007a0fe 100644 (file)
--- a/src/tycheck.sml
+++ b/src/tycheck.sml
@@ -24,6 +24,10 @@ open Ast Print Env
 
 structure SM = StringMap
 
+val externFlag = ref false
+fun allowExterns () = externFlag := true
+fun disallowExterns () = externFlag := false
+
 local
     val unifCount = ref 0
 in
@@ -703,8 +707,18 @@ fun checkUnit G (eAll as (_, loc)) =
 
 fun checkDecl G (d, _, loc) =
     case d of
-       DExternType name => bindType G name
-      | DExternVal (name, t) => bindVal G (name, checkTyp G t, NONE)
+       DExternType name =>
+       if !externFlag then
+           bindType G name
+       else
+           (ErrorMsg.error (SOME loc) "'extern type' not allowed in untrusted code";
+            G)
+      | DExternVal (name, t) =>
+       if !externFlag then
+           bindVal G (name, checkTyp G t, NONE)
+       else
+           (ErrorMsg.error (SOME loc) "'extern val' not allowed in untrusted code";
+            G)
       | DVal (name, to, e) =>
        let
            val to =