container: Gracefully report mount errors in the child process.

Fixes <http://bugs.gnu.org/23306>.

* gnu/build/linux-container.scm (run-container): Use 'socketpair'
instead of 'pipe'.  Rename 'in' to 'child' and 'out' to 'parent'.  Send
a 'ready message or an exception argument list from the child to the
parent; adjust the parent accordingly.
* tests/containers.scm ("call-with-container, mnt namespace, wrong bind
mount"): New test.
* tests/guix-environment-container.sh: Add test with
--expose=/does-not-exist.

2 files changed, 22 insertions, 0 deletions

diff --git a/tests/containers.scm b/tests/containers.scm
index c11cdd1ce55..5a0f9937bb8 100644
--- a/tests/containers.scm
+++ b/tests/containers.scm
@@ -79,6 +79,18 @@
        (assert-exit (file-exists? "/testing")))
      #:namespaces '(user mnt))))
 
+(test-equal "call-with-container, mnt namespace, wrong bind mount"
+  `(system-error ,ENOENT)
+  ;; An exception should be raised; see <http://bugs.gnu.org/23306>.
+  (catch 'system-error
+    (lambda ()
+      (call-with-container '(("/does-not-exist" device "/foo"
+                              "none" (bind-mount) #f #f))
+        (const #t)
+        #:namespaces '(user mnt)))
+    (lambda args
+      (list 'system-error (system-error-errno args)))))
+
 (test-assert "call-with-container, all namespaces"
   (zero?
    (call-with-container '()
diff --git a/tests/guix-environment-container.sh b/tests/guix-environment-container.sh
index 0a7ea481fca..5ea6c49263d 100644
--- a/tests/guix-environment-container.sh
+++ b/tests/guix-environment-container.sh
@@ -44,6 +44,16 @@ else
     test $? = 42
 fi
 
+# Make sure file-not-found errors in mounts are reported.
+if guix environment --container --ad-hoc --bootstrap guile-bootstrap \
+        --expose=/does-not-exist -- guile -c 1 2> "$tmpdir/error"
+then
+    false
+else
+    grep "/does-not-exist" "$tmpdir/error"
+    grep "[Nn]o such file" "$tmpdir/error"
+fi
+
 # Make sure that the right directories are mapped.
 mount_test_code="
 (use-modules (ice-9 rdelim)