Index: openacs-4/packages/categories/www/cadmin/category-link-add-3.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/categories/www/cadmin/category-link-add-3.tcl,v
diff -u -N -r1.8 -r1.8.2.1
--- openacs-4/packages/categories/www/cadmin/category-link-add-3.tcl	29 Jun 2018 17:27:18 -0000	1.8
+++ openacs-4/packages/categories/www/cadmin/category-link-add-3.tcl	15 Mar 2019 11:44:09 -0000	1.8.2.1
@@ -17,7 +17,17 @@
 permission::require_permission -object_id $tree_id -privilege category_tree_write
 
 db_transaction {
-    foreach link_category_id [db_list check_link_target_permissions ""] {
+    foreach link_category_id [db_list check_link_target_permissions [subst {
+        select c.category_id as link_category_id
+        from categories c
+        where c.category_id in ([join $link_category_id ,])
+        and acs_permission.permission_p(c.tree_id,:user_id,'category_tree_write') = 't'
+        and c.category_id <> :category_id
+        and not exists (select 1
+                        from category_links l
+                        where l.from_category_id = :category_id
+                        and l.to_category_id = c.category_id)
+    }]] {
 	category_link::add -from_category_id $category_id -to_category_id $link_category_id
     }
 } on_error {