Warn about read-passwd in batch mode

* doc/lispref/minibuf.texi (Intro to Minibuffers): Batch mode is basic.
(Reading a Password): Mention batch mode. 

* lisp/subr.el (read-passwd): Warn about batch mode.

Fixes: debbugs:17839

2 files changed, 10 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 6c8f118c8a..0cc5b7fe71 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2014-06-26  Glenn Morris  <[email protected]>
+
+	* subr.el (read-passwd): Warn about batch mode.  (Bug#17839)
+
 2014-06-26  Daiki Ueno  <[email protected]>
 
 	* emacs-lisp/package.el (package--check-signature):
diff --git a/lisp/subr.el b/lisp/subr.el
index 700c072a81..ac0e130b4e 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2006,6 +2006,7 @@ If optional CONFIRM is non-nil, read the password twice to make sure.
 Optional DEFAULT is a default password to use instead of empty input.
 
 This function echoes `.' for each character that the user types.
+Note that in batch mode, the input is not hidden!
 
 Once the caller uses the password, it can erase the password
 by doing (clear-string STRING)."
@@ -2045,7 +2046,11 @@ by doing (clear-string STRING)."
             (add-hook 'after-change-functions hide-chars-fun nil 'local))
         (unwind-protect
             (let ((enable-recursive-minibuffers t))
-              (read-string prompt nil t default)) ; t = "no history"
+              (read-string
+               (if noninteractive
+                   (format "%s[INPUT WILL NOT BE HIDDEN!] " prompt) ; bug#17839
+                 prompt)
+               nil t default)) ; t = "no history"
           (when (buffer-live-p minibuf)
             (with-current-buffer minibuf
               ;; Not sure why but it seems that there might be cases where the