Index: sauthorize.scm
==================================================================
--- sauthorize.scm
+++ sauthorize.scm
@@ -189,10 +189,27 @@
           (set! name (conc (current-user-name) "_" group))
           (begin
             (print "You cannot open areas that you dont own!!")  
              (exit 1)))))
 name))
+
+(define (sauthorize:valid-unix-user username)
+    (let* ((ret-val #f))
+    (let-values (((inp oup pid)
+              (process "/usr/bin/id" (list username))))
+        (let loop ((inl (read-line inp)))
+          (if (string? inl) 
+          (if (string-contains inl  "No such user") 
+            (set! ret-val #f)
+             (set! ret-val #t)))   
+          (if (eof-object? inl)
+              (begin
+                   (close-input-port inp)
+                  (close-output-port oup))
+            (loop (read-line inp)))))
+            ret-val))
+
 
 ;check if a paths/codes are vaid and if area is alrady open  
 (define (open-area group path code access-type)
    (let* ((exe-name (get-exe-name path group))
            (path-obj (get-obj-by-path path))
@@ -284,17 +301,22 @@
        (sauthorize:db-do   (lambda (db)
              (sauthorize:db-qry db (conc "INSERT INTO actions (cmd,user_id,area_id,action_type ) VALUES ('sauthorize open " path " --code " code " --group " group " --" access-type "'," (car (get-user user)) "," (car (get-area code)) ", 'open' )"))))
          (print "Area has " path "  been opened for " access-type ))))
 
 (define (sauthorize:grant auser guser area exp-date access-type restrict)
-    ; check if user exist
+    ; check if user exist in db
     (let* ((area-obj (get-area area))
            (auser-obj (get-user auser)) 
            (user-obj (get-user guser)))
           
         (if (null? user-obj)
            (begin
+            ;; is guser a valid unix user
+            (if (not (sauthorize:valid-unix-user guser))
+               (begin  
+                (print "User " guser " is Invalid unix user!!")
+                 (exit 1)))
             (sauthorize:db-do   (lambda (db)
              (sauthorize:db-qry db (conc "insert into users (username, is_admin) values ('" guser "', 'no') "))))
              (set! user-obj (get-user guser))))
         (let* ((perm-obj (get-perm (car user-obj) (car area-obj))))
           (if(null? perm-obj)