From b839ad32b9bf4541583ecbe68a0bd5dd9f12345a Mon Sep 17 00:00:00 2001
From: Scott Moser <smoser@ubuntu.com>
Date: Thu, 10 Mar 2016 12:32:46 -0500
Subject: 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
.................................
---
 ChangeLog                    |  1 +
 cloudinit/util.py            | 13 ++++++++++---
 tests/unittests/test_util.py |  9 +++++++++
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index da1ca9ee..ebaacf6a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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
diff --git a/cloudinit/util.py b/cloudinit/util.py
index e7407ea4..1d50edc9 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -2140,13 +2140,20 @@ def _read_dmi_syspath(key):
             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()
+        # in the event that this is all \xff and a carriage return
+        # then return '.' in its place.
+        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)
diff --git a/tests/unittests/test_util.py b/tests/unittests/test_util.py
index 95990165..542e4075 100644
--- a/tests/unittests/test_util.py
+++ b/tests/unittests/test_util.py
@@ -385,6 +385,15 @@ class TestReadDMIData(helpers.FilesystemMockingTestCase):
         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):
 
-- 
cgit v1.2.3


From be38478cd8e11b0e29c70bb881a676628e9f74d5 Mon Sep 17 00:00:00 2001
From: Scott Moser <smoser@ubuntu.com>
Date: Thu, 10 Mar 2016 12:47:55 -0500
Subject: improve comment

---
 cloudinit/util.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/cloudinit/util.py b/cloudinit/util.py
index 1d50edc9..1a517c79 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -2145,13 +2145,12 @@ def _read_dmi_syspath(key):
             LOG.debug("%s did not return any data", dmi_key_path)
             return None
 
-        # in the event that this is all \xff and a carriage return
-        # then return '.' in its place.
+        # 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
 
-- 
cgit v1.2.3