gnu: Add 'inputs' field to <user-account>; make 'shell' a monadic value.

* gnu/system/shadow.scm (<user-account>)[inputs]: New field.
  (passwd-file): Bind the 'shell' field of each account.
* gnu/system/vm.scm (%demo-operating-system): Remove 'shell' field.
* gnu/system/dmd.scm (guix-build-accounts): Store a monadic value in
  'shell'.  Add 'inputs' field.
* gnu/system.scm (operating-system-derivation): Remove 'shell' field for
  'root' account.  Add all the 'user-account-inputs' to EXTRAS.

gnu/system.scm

@@ -281,8 +281,7 @@ alias ll='ls -l'
                             (password "")
                             (uid 0) (gid 0)
                             (comment "System administrator")
-                            (home-directory "/")
-                            (shell bash-file))
+                            (home-directory "/"))
                           (append (operating-system-users os)
                                   (append-map service-user-accounts
                                               services))))
@@ -320,22 +319,22 @@ alias ll='ls -l'
                            (initrd initrd))))
        (grub.cfg (grub-configuration-file entries))
        (extras   (links (delete-duplicates
-                         (append-map service-inputs services)))))
+                         (append (append-map service-inputs services)
+                                 (append-map user-account-inputs accounts))))))
     (file-union `(("boot" ,boot)
                   ("kernel" ,kernel-dir)
                   ("initrd" ,initrd-file)
                   ("dmd.conf" ,dmd-conf)
-                  ("bash" ,bash-file) ; XXX: should be a <user-account> input?
                   ("profile" ,profile)
                   ("grub.cfg" ,grub.cfg)
                   ("etc" ,etc)
-                  ("service-inputs" ,(derivation->output-path extras)))
+                  ("system-inputs" ,(derivation->output-path extras)))
                 #:inputs `(("kernel" ,kernel)
                            ("initrd" ,initrd)
                            ("bash" ,bash)
                            ("profile" ,profile-drv)
                            ("etc" ,etc-drv)
-                           ("service-inputs" ,extras))
+                           ("system-inputs" ,extras))
                 #:name "system")))
 
 ;;; system.scm ends here

gnu/system/dmd.scm

@@ -181,18 +181,18 @@
                               (shadow shadow))
   "Return a list of COUNT user accounts for Guix build users, with UIDs
 starting at FIRST-UID, and under GID."
-  (mlet* %store-monad ((gid* -> gid)
-                       (no-login (package-file shadow "sbin/nologin")))
+  (with-monad %store-monad
     (return (unfold (cut > <> count)
                     (lambda (n)
                       (user-account
                        (name (format #f "guixbuilder~2,'0d" n))
                        (password "!")
                        (uid (+ first-uid n -1))
-                       (gid gid*)
+                       (gid gid)
                        (comment (format #f "Guix Build User ~2d" n))
                        (home-directory "/var/empty")
-                       (shell no-login)))
+                       (shell (package-file shadow "sbin/nologin"))
+                       (inputs `(("shadow" ,shadow)))))
                     1+
                     1))))
 

gnu/system/shadow.scm

@@ -23,6 +23,7 @@
   #:use-module (guix monads)
   #:use-module ((gnu packages system)
                 #:select (shadow))
+  #:use-module (gnu packages bash)
   #:use-module (srfi srfi-1)
   #:use-module (ice-9 match)
   #:export (user-account
@@ -34,6 +35,7 @@
             user-account-comment
             user-account-home-directory
             user-account-shell
+            user-account-inputs
 
             user-group
             user-group?
@@ -61,7 +63,9 @@
   (gid            user-account-gid)
   (comment        user-account-comment (default ""))
   (home-directory user-account-home-directory)
-  (shell          user-account-shell (default "/bin/sh")))
+  (shell          user-account-shell              ; monadic value
+                  (default (package-file bash "bin/bash")))
+  (inputs         user-account-inputs (default `(("bash" ,bash)))))
 
 (define-record-type* <user-group>
   user-group make-user-group
@@ -93,12 +97,14 @@
 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
+  (define (contents)
+    (with-monad %store-monad
       (let loop ((accounts accounts)
                  (result   '()))
         (match accounts
-        ((($ <user-account> name pass uid gid comment home-dir shell)
+          ((($ <user-account> name pass uid gid comment home-dir mshell)
             rest ...)
+           (mlet %store-monad ((shell mshell))
              (loop rest
                    (cons (if shadow?
                              (string-append name
@@ -109,10 +115,11 @@ file."
                                             ":" (number->string uid)
                                             ":" (number->string gid)
                                             ":" comment ":" home-dir ":" shell))
-                     result)))
+                         result))))
           (()
-         (string-join (reverse result) "\n" 'suffix)))))
+           (return (string-join (reverse result) "\n" 'suffix)))))))
 
-  (text-file (if shadow? "shadow" "passwd") contents))
+  (mlet %store-monad ((contents (contents)))
+    (text-file (if shadow? "shadow" "passwd") contents)))
 
 ;;; shadow.scm ends here

gnu/system/vm.scm

@@ -415,9 +415,7 @@ such as /etc files."
                  (password "")
                  (uid 1000) (gid 100)
                  (comment "Guest of GNU")
-                 (home-directory "/home/guest")
-                 ;; (shell bash-file)
-                 )))
+                 (home-directory "/home/guest"))))
    (packages `(("coreutils" ,coreutils)
                ("bash" ,bash)
                ("guile" ,guile-2.0)