linux-container: Correct test for unprivileged user namespace support.

Fixes <https://bugs.gnu.org/31977>.
Reported by Paul Garlick <pgarlick@tourbillion-technology.com>.

* gnu/build/linux-container.scm (unprivileged-user-namespace-supported?):
Return #f when the 'userns-file' does not exist.

diff --git a/gnu/build/linux-container.scm b/gnu/build/linux-container.scm
index 4a8bed5..3870b50 100644 (file)
--- a/gnu/build/linux-container.scm
+++ b/gnu/build/linux-container.scm
@@ -44,7 +44,7 @@
   (let ((userns-file "/proc/sys/kernel/unprivileged_userns_clone"))
     (if (file-exists? userns-file)
         (eqv? #\1 (call-with-input-file userns-file read-char))
-        #t)))
+        #f)))
 
 (define (setgroups-supported?)
   "Return #t if the setgroups proc file, introduced in Linux-libre 3.19,