Fixed bug in prompt-for-password.

diff --git a/v7/src/edwin/prompt.scm b/v7/src/edwin/prompt.scm
index bb8444db683e0e1d139337476cb7cb31f274397b..fee36d533e9d56b6817416c4b4a52f8716a31227 100644 (file)
--- a/v7/src/edwin/prompt.scm
+++ b/v7/src/edwin/prompt.scm
@@ -1,6 +1,6 @@
 ;;; -*-Scheme-*-
 ;;;
-;;;    $Id: prompt.scm,v 1.155 1992/09/17 23:18:04 cph Exp $
+;;;    $Id: prompt.scm,v 1.156 1992/11/29 20:22:37 bal Exp $
 ;;;
 ;;;    Copyright (c) 1986, 1989-92 Massachusetts Institute of Technology
 ;;;
@@ -793,10 +793,13 @@ Whilst editing the command, the following commands are available:
                   ((char=? input #\C-g)
                    (abort-current-command))
                   ((char=? input #\Rubout)
-                   (let ((new-string (string-head ts (-1+ (string-length ts)))))
-                     (set-typein-string!
-                      (make-string (string-length new-string) #\.) true)
-                     (loop new-string)))
+                   (let ((ts-len (string-length ts)))
+                     (if (> ts-len 0)
+                         (let ((new-string (string-head ts (-1+ ts-len))))
+                           (set-typein-string!
+                            (make-string (string-length new-string) #\.) true)
+                           (loop new-string))
+                         (loop ts))))
                   (else
                    (set-typein-string!
                     (make-string (1+ (string-length ts)) #\.) true)