[bug#44623] [PATCH] archive: Warn about replacing an ACL symlink.

[Tobias Geerinckx-Rice]

* guix/scripts/archive.scm (authorize-key): Warn when %ACL-FILE is a
symbolic link and print an additional hint for Guix System users.
---
 guix/scripts/archive.scm | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/guix/scripts/archive.scm b/guix/scripts/archive.scm
index 02557ce454..d284196f41 100644
--- a/guix/scripts/archive.scm
+++ b/guix/scripts/archive.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2019, 2020 Ludovic Courtès 
<ludo@gnu.org>
+;;; Copyright © 2020 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -310,6 +311,16 @@ the input port."
         (leave (G_ "failed to read public key: ~a: ~a~%")
                (error-source err) (error-string err)))))
 
+  ;; Warn about potentially volatile ACLs, but continue: system reconfiguration
+  ;; might not be possible without (newly-authorized) substitutes.
+  (when (and (access? %acl-file F_OK)
+             (eq? 'symlink (stat:type (lstat %acl-file))))
+    (warning (G_ "replacing symbolic link ~a with a regular file~%")
+             %acl-file)
+    (when (string-prefix? (%store-prefix) (readlink %acl-file))
+      (display-hint (G_ "On Guix System, add public keys to the
+@code{authorized-keys} field of your @code{operating-system} instead."))))
+
   (let ((key (read-key))
         (acl (current-acl)))
     (unless (eq? 'public-key (canonical-sexp-nth-data key 0))
-- 
2.29.2