2 files changed, 65 insertions, 0 deletions
diff --git a/cloudinit/util.py b/cloudinit/util.py
index b3332acd..f36e2733 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -1889,3 +1889,28 @@ def expand_dotted_devname(dotted):
         return toks
     else:
         return (dotted, None)
+
+
+def pathprefix2dict(base, required=None, optional=None, delim=os.path.sep):
+    # return a dictionary populated with keys in 'required' and 'optional'
+    # by reading files in prefix + delim + entry
+    if required is None:
+        required = []
+    if optional is None:
+        optional = []
+
+    missing = []
+    ret = {}
+    for f in required + optional:
+        try:
+            ret[f] = load_file(base + delim + f, quiet=False)
+        except IOError as e:
+            if e.errno != errno.ENOENT:
+                raise
+            if f in required:
+                missing.append(f)
+
+    if len(missing):
+        raise ValueError("Missing required files: %s", ','.join(missing))
+
+    return ret
diff --git a/tests/unittests/test_pathprefix2dict.py b/tests/unittests/test_pathprefix2dict.py
new file mode 100644
index 00000000..c68c263c
--- /dev/null
+++ b/tests/unittests/test_pathprefix2dict.py
@@ -0,0 +1,40 @@
+from cloudinit import util
+
+from mocker import MockerTestCase
+from tests.unittests.helpers import populate_dir
+
+
+class TestPathPrefix2Dict(MockerTestCase):
+
+    def setUp(self):
+        self.tmp = self.makeDir()
+
+    def test_required_only(self):
+        dirdata = {'f1': 'f1content', 'f2': 'f2content'}
+        populate_dir(self.tmp, dirdata)
+
+        ret = util.pathprefix2dict(self.tmp, required=['f1', 'f2'])
+        self.assertEqual(dirdata, ret)
+
+    def test_required_missing(self):
+        dirdata = {'f1': 'f1content'}
+        populate_dir(self.tmp, dirdata)
+        kwargs = {'required': ['f1', 'f2']}
+        self.assertRaises(ValueError, util.pathprefix2dict, self.tmp, **kwargs)
+
+    def test_no_required_and_optional(self):
+        dirdata = {'f1': 'f1c', 'f2': 'f2c'}
+        populate_dir(self.tmp, dirdata)
+
+        ret = util.pathprefix2dict(self.tmp, required=None,
+                                  optional=['f1', 'f2'])
+        self.assertEqual(dirdata, ret)
+
+    def test_required_and_optional(self):
+        dirdata = {'f1': 'f1c', 'f2': 'f2c'}
+        populate_dir(self.tmp, dirdata)
+
+        ret = util.pathprefix2dict(self.tmp, required=['f1'], optional=['f2'])
+        self.assertEqual(dirdata, ret)
+
+# vi: ts=4 expandtab