Merge lp:~smoser/cloud-init/trunk.dmidecode-null into lp:~cloud-init-dev/cloud-init/trunk

[Scott Moser]

dmi data: fix failure of reading dmi data for unset dmi values

it is not uncommon to find dmi data in /sys full of 'ff'. utf-8
decoding of those would fail, causing warning and stacktrace.

Return '.' instead of \xff. This maps to what dmidecode would return

$ dmidecode --string system-product-name

[lp:~smoser/cloud-init/trunk.dmidecode-null]

1180. By Scott Moser on 2016-03-10

dmi data: fix failure of reading dmi data for unset dmi values

it is not uncommon to find dmi data in /sys full of 'ff'. utf-8
decoding of those would fail, causing warning and stacktrace.

Return '.' instead of \xff. This maps to what dmidecode would return

$ dmidecode --string system-product-name
.................................

[lp:~smoser/cloud-init/trunk.dmidecode-null]

1181. By Scott Moser on 2016-03-10

improve comment

[Ryan Harper (raharper)]

We might want that as well in the test-case; but easily enough found in the code comments.

review: Approve

=== modified file 'ChangeLog'
--- ChangeLog	2016-03-10 01:47:27 +0000
+++ ChangeLog	2016-03-10 17:48:09 +0000
@@ -88,6 +88,7 @@
  - No longer run pollinate in seed_random (LP: #1554152)
  - groups: add defalt user to 'lxd' group.  Create groups listed
    for a user if they do not exist. (LP: #1539317)
+ - dmi data: fix failure of reading dmi data for unset dmi values
 
 0.7.6:
  - open 0.7.6

=== modified file 'cloudinit/util.py'
--- cloudinit/util.py	2016-03-03 23:16:13 +0000
+++ cloudinit/util.py	2016-03-10 17:48:09 +0000
@@ -2140,13 +2140,19 @@
             LOG.debug("did not find %s", dmi_key_path)
             return None
 
-        key_data = load_file(dmi_key_path)
+        key_data = load_file(dmi_key_path, decode=False)
         if not key_data:
             LOG.debug("%s did not return any data", dmi_key_path)
             return None
 
-        LOG.debug("dmi data %s returned %s", dmi_key_path, key_data)
-        return key_data.strip()
+        # uninitialized dmi values show as all \xff and /sys appends a '\n'. 
+        # in that event, return a string of '.' in the same length.
+        if key_data == b'\xff' * (len(key_data) - 1) + b'\n':
+            key_data = b'.' * (len(key_data) - 1) + b'\n'
+
+        str_data = key_data.decode('utf8').strip()
+        LOG.debug("dmi data %s returned %s", dmi_key_path, str_data)
+        return str_data
 
     except Exception:
         logexc(LOG, "failed read of %s", dmi_key_path)

=== modified file 'tests/unittests/test_util.py'
--- tests/unittests/test_util.py	2015-05-14 21:06:39 +0000
+++ tests/unittests/test_util.py	2016-03-10 17:48:09 +0000
@@ -385,6 +385,15 @@
         self.patch_mapping({})
         self.assertEqual(None, util.read_dmi_data('expect-fail'))
 
+    def test_dots_returned_instead_of_foxfox(self):
+        my_len = 32
+        dmi_value = b'\xff' * my_len + b'\n'
+        expected = '.' * my_len
+        dmi_key = 'system-product-name'
+        sysfs_key = 'product_name'
+        self._create_sysfs_file(sysfs_key, dmi_value)
+        self.assertEqual(expected, util.read_dmi_data(dmi_key))
+
 
 class TestMultiLog(helpers.FilesystemMockingTestCase):