gnu: shadow: Add record type for user accounts.

* gnu/system/shadow.scm (<user-account>): New record type.
  (passwd-file): Use it.
* gnu/system/vm.scm (system-qemu-image): Adjust accordingly.

gnu/system/shadow.scm

@@ -19,7 +19,18 @@
 (define-module (gnu system shadow)
   #:use-module (guix store)
   #:use-module (ice-9 match)
-  #:export (passwd-file))
+  #:use-module (guix records)
+  #:export (user-account
+            user-account?
+            user-account-name
+            user-account-pass
+            user-account-uid
+            user-account-gid
+            user-account-comment
+            user-account-home-directory
+            user-account-shell
+
+            passwd-file))
 
 ;;; Commentary:
 ;;;
@@ -27,16 +38,28 @@
 ;;;
 ;;; Code:
 
+(define-record-type* <user-account>
+  user-account make-user-account
+  user-account?
+  (name           user-account-name)
+  (password       user-account-pass (default ""))
+  (uid            user-account-uid)
+  (gid            user-account-gid)
+  (comment        user-account-comment (default ""))
+  (home-directory user-account-home-directory)
+  (shell          user-account-shell (default "/bin/sh")))
+
 (define* (passwd-file store accounts #:key shadow?)
-  "Return a password file for ACCOUNTS, a list of vectors as returned by
-'getpwnam'.  If SHADOW? is true, then it is a /etc/shadow file, otherwise it
-is a /etc/passwd file."
+  "Return a password file for ACCOUNTS, a list of <user-account> objects.  If
+SHADOW? is true, then it is a /etc/shadow file, otherwise it is a /etc/passwd
+file."
   ;; XXX: The resulting file is world-readable, so beware when SHADOW? is #t!
   (define contents
     (let loop ((accounts accounts)
                (result   '()))
       (match accounts
-        ((#(name pass uid gid comment home-dir shell) rest ...)
+        ((($ <user-account> name pass uid gid comment home-dir shell)
+          rest ...)
          (loop rest
                (cons (if shadow?
                          (string-append name

gnu/system/vm.scm

@@ -475,8 +475,13 @@ Happy birthday, GNU!                                http://www.gnu.org/gnu30
            (dmd-file  (string-append (derivation->output-path dmd-drv)
                                      "/bin/dmd"))
            (dmd-conf  (dmd-configuration-file store %dmd-services))
-           (accounts  (list (vector "root" "" 0 0 "System administrator"
-                                    "/" bash-file)))
+           (accounts  (list (user-account
+                             (name "root")
+                             (password "")
+                             (uid 0) (gid 0)
+                             (comment "System administrator")
+                             (home-directory "/")
+                             (shell bash-file))))
            (passwd    (passwd-file store accounts))
            (shadow    (passwd-file store accounts #:shadow? #t))
            (group     (add-text-to-store store "group"