From a9a685cc0024a4e0dad5d7abd9ca6fb880ae4f8e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Thu, 14 Jun 2018 23:08:08 +0200
Subject: [PATCH] offload: Gracefully handle invalid results from
 'machines.scm'.

* guix/scripts/offload.scm (build-machines): Check the result of FILE.
Ignore it if it's not a list of <build-machine>.
---
 guix/scripts/offload.scm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/guix/scripts/offload.scm b/guix/scripts/offload.scm
index fb61d7c059..664497bcd5 100644
--- a/guix/scripts/offload.scm
+++ b/guix/scripts/offload.scm
@@ -124,7 +124,15 @@ determined."
       (save-module-excursion
        (lambda ()
          (set-current-module %user-module)
-         (primitive-load file))))
+         (match (primitive-load file)
+           (((? build-machine? machines) ...)
+            machines)
+           (_
+            ;; Instead of crashing, assume the empty list.
+            (warning (G_ "'~a' did not return a list of build machines; \
+ignoring it~%")
+                     file)
+            '())))))
     (lambda args
       (match args
         (('system-error . rest)