Add support for mounting external containers

Continue progress on use of external containers.

This PR adds the ability to mount, umount and list the
storage containers whether they are in libpod or not.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

test/system/060-mount.bats

@@ -2,7 +2,6 @@
 
 load helpers
 
-
 @test "podman mount - basic test" {
     # Only works with root (FIXME: does it work with rootless + vfs?)
     skip_if_rootless "mount does not work rootless"
@@ -151,4 +150,34 @@ load helpers
     run_podman rm -f $cid
 }
 
+@test "podman mount external container - basic test" {
+    # Only works with root (FIXME: does it work with rootless + vfs?)
+    skip_if_rootless "mount does not work rootless"
+    skip_if_remote "mounting remote is meaningless"
+
+    # Create a container that podman does not know about
+    external_cid=$(buildah from $IMAGE)
+
+    run_podman mount $external_cid
+    mount_path=$output
+
+    # Test image will always have this file, and will always have the tag
+    test -d $mount_path
+    is $(< "$mount_path/home/podman/testimage-id") "$PODMAN_TEST_IMAGE_TAG"  \
+       "Contents of well-known file in image"
+
+    # Make sure that 'podman mount' (no args) returns the expected path
+    run_podman mount --notruncate
+
+    reported_mountpoint=$(echo "$output" | awk '{print $2}')
+    is $reported_mountpoint $mount_path "mountpoint reported by 'podman mount'"
+
+    # umount, and make sure files are gone
+    run_podman umount $external_cid
+    if [ -d "$mount_path" ]; then
+        die "'podman umount' did not umount"
+    fi
+    buildah rm $external_cid
+}
+
 # vim: filetype=sh