installer: Add dry-run?

This allows running the installer without root privileges.  Do something like

    ./pre-inst-env guix repl
    ,use (guix)
    ,use (gnu installer)
    (installer-program #:dry-run? #t)
    ,build $1
    =>
    "/gnu/store/...-installer-program"

and run

    /gnu/store/...-installer-program

* gnu/installer/newt.scm (locale-page): Add #:dry-run? parameter.
(keymap-page): Likewise.
* gnu/installer/newt/keymap.scm (run-keymap-page): Likewise.
* gnu/installer/steps.scm (run-installer-steps): Likewise.  Use it to skip
writing to socket.
* gnu/installer/newt/final.scm (run-final-page): Rename to...
(run-final-page-install): ...this.
(dry-run-final-page, run-final-page): New procedures.
* gnu/installer/parted.scm (bootloader-configuration): Cater for empty user
partitions.
* gnu/installer/utils.scm (dry-run-command): New procedure.
* gnu/installer.scm (compute-locale-step): Add #:dry-run? parameter.  Use it
to avoid actually applying locale.
(compute-keymap-step): Add dry-run? parameter.  Pass it to
keymap-page.
(installer-program): Add #:dry-run? parameter.  If #:true
avoid writing to /proc, use dry-run-command, skip sync and reboot, and pass
dry-run? to...
(installer-steps): ...here.  Add #:dry-run? parameter.  Use it to disable
skip network, substitutes, partitioning pages, and pass it to...
compute-locale-step, compute-keymap-step, and final-page.

Change-Id: I0ff4c3b0a0c69539af617c27ba37654beed44619

1 files changed, 11 insertions, 5 deletions

diff --git a/gnu/installer/steps.scm b/gnu/installer/steps.scm
index 0c505e40e4..de0a852f02 100644
--- a/gnu/installer/steps.scm
+++ b/gnu/installer/steps.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018, 2019 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2020-2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2024 Janneke Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -84,7 +85,8 @@
 (define* (run-installer-steps #:key
                               steps
                               (rewind-strategy 'previous)
-                              (menu-proc (const #f)))
+                              (menu-proc (const #f))
+                              dry-run?)
   "Run the COMPUTE procedure of all <installer-step> records in STEPS
 sequentially, inside a the 'installer-step prompt.  When aborted to with a
 parameter of 'abort, fallback to a previous install-step, accordingly to the
@@ -191,10 +193,14 @@ computation is over."
   ;; prematurely.
   (sigaction SIGPIPE SIG_IGN)
 
-  (with-server-socket
-    (run '()
-         #:todo-steps steps
-         #:done-steps '())))
+  (if dry-run?
+      (run '()
+           #:todo-steps steps
+           #:done-steps '())
+      (with-server-socket
+        (run '()
+             #:todo-steps steps
+             #:done-steps '()))))
 
 (define (find-step-by-id steps id)
   "Find and return the step in STEPS whose id is equal to ID."