installer: Turn passwords into opaque records.

* gnu/installer/user.scm (<secret>, secret?, make-secret,
secret-content): Add opaque <secret> record that boxes its contents,
with a custom printer that doesn't display anything.
* gnu/installer/newt/user.scm (run-user-add-page, run-user-page): Box
it.
* gnu/installer/final.scm (create-user-database): Unbox it.

Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>

gnu/installer/final.scm

@@ -85,8 +85,9 @@ USERS."
                              (uid (if root? 0 #f))
                              (home-directory
                               (user-home-directory user))
-                             (password (crypt (user-password user)
-                                              (salt)))
+                             (password (crypt
+                                        (secret-content (user-password user))
+                                        (salt)))
 
                              ;; We need a string here, not a file-like, hence
                              ;; this choice.

gnu/installer/newt/user.scm

@@ -143,7 +143,7 @@ REAL-NAME, and HOME-DIRECTORY as the initial values in the form."
                              (name name)
                              (real-name real-name)
                              (home-directory home-directory)
-                             (password password))
+                             (password (make-secret password)))
                             (run-user-add-page #:name name
                                                #:real-name real-name
                                                #:home-directory
@@ -266,7 +266,7 @@ administrator (\"root\").")
                   (map (lambda (name real-name home password)
                          (user (name name) (real-name real-name)
                                (home-directory home)
-                               (password password)))
+                               (password (make-secret password))))
                        names real-names homes passwords))))))
           (lambda ()
             (destroy-form-and-pop form))))))
@@ -274,5 +274,5 @@ administrator (\"root\").")
   ;; Add a "root" user simply to convey the root password.
   (cons (user (name "root")
               (home-directory "/root")
-              (password (run-root-password-page)))
+              (password (make-secret (run-root-password-page))))
         (run '())))

gnu/installer/user.scm

@@ -19,7 +19,14 @@
 (define-module (gnu installer user)
   #:use-module (guix records)
   #:use-module (srfi srfi-1)
-  #:export (<user>
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-9 gnu)
+  #:export (<secret>
+            secret?
+            make-secret
+            secret-content
+
+            <user>
             user
             make-user
             user-name
@@ -30,6 +37,16 @@
 
             users->configuration))
 
+(define-record-type <secret>
+  (make-secret content)
+  secret?
+  (content secret-content))
+
+(set-record-type-printer!
+ <secret>
+ (lambda (secret port)
+   (format port "<secret>")))
+
 (define-record-type* <user>
   user make-user
   user?