util: fix mounting of vfat on *BSD (#637)

Fix mounting of vfat filesystems by normalizing the different names for
vfat to "msdos" which works across BSDs.

2 files changed, 45 insertions, 4 deletions

diff --git a/cloudinit/tests/test_util.py b/cloudinit/tests/test_util.py
index 77714928..b7a302f1 100644
--- a/cloudinit/tests/test_util.py
+++ b/cloudinit/tests/test_util.py
@@ -730,6 +730,41 @@ class TestMountCb:
         """already_mounted_device_and_mountdict, but return only the device"""
         return already_mounted_device_and_mountdict[0]
 
+    @pytest.mark.parametrize(
+        "mtype,expected",
+        [
+            # While the filesystem is called iso9660, the mount type is cd9660
+            ("iso9660", "cd9660"),
+            # vfat is generally called "msdos" on BSD
+            ("vfat", "msdos"),
+            # judging from man pages, only FreeBSD has this alias
+            ("msdosfs", "msdos"),
+            # Test happy path
+            ("ufs", "ufs")
+        ],
+    )
+    @mock.patch("cloudinit.util.is_Linux", autospec=True)
+    @mock.patch("cloudinit.util.is_BSD", autospec=True)
+    @mock.patch("cloudinit.util.subp.subp")
+    @mock.patch("cloudinit.temp_utils.tempdir", autospec=True)
+    def test_normalize_mtype_on_bsd(
+        self, m_tmpdir, m_subp, m_is_BSD, m_is_Linux, mtype, expected
+    ):
+        m_is_BSD.return_value = True
+        m_is_Linux.return_value = False
+        m_tmpdir.return_value.__enter__ = mock.Mock(
+            autospec=True, return_value="/tmp/fake"
+        )
+        m_tmpdir.return_value.__exit__ = mock.Mock(
+            autospec=True, return_value=True
+        )
+        callback = mock.Mock(autospec=True)
+
+        util.mount_cb('/dev/fake0', callback, mtype=mtype)
+        assert mock.call(
+            ["mount", "-o", "ro", "-t", expected, "/dev/fake0", "/tmp/fake"],
+            update_env=None) in m_subp.call_args_list
+
     @pytest.mark.parametrize("invalid_mtype", [int(0), float(0.0), dict()])
     def test_typeerror_raised_for_invalid_mtype(self, invalid_mtype):
         with pytest.raises(TypeError):
diff --git a/cloudinit/util.py b/cloudinit/util.py
index 83727544..b8856af1 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -418,6 +418,11 @@ def multi_log(text, console=True, stderr=True,
 
 
 @lru_cache()
+def is_Linux():
+    return 'Linux' in platform.system()
+
+
+@lru_cache()
 def is_BSD():
     return 'BSD' in platform.system()
 
@@ -1661,16 +1666,17 @@ def mount_cb(device, callback, data=None, mtype=None,
                 _type=type(mtype)))
 
     # clean up 'mtype' input a bit based on platform.
-    platsys = platform.system().lower()
-    if platsys == "linux":
+    if is_Linux():
         if mtypes is None:
             mtypes = ["auto"]
-    elif platsys.endswith("bsd"):
+    elif is_BSD():
         if mtypes is None:
-            mtypes = ['ufs', 'cd9660', 'vfat']
+            mtypes = ['ufs', 'cd9660', 'msdos']
         for index, mtype in enumerate(mtypes):
             if mtype == "iso9660":
                 mtypes[index] = "cd9660"
+            if mtype in ["vfat", "msdosfs"]:
+                mtypes[index] = "msdos"
     else:
         # we cannot do a smart "auto", so just call 'mount' once with no -t
         mtypes = ['']