Factorize removing comments and empty lines from string

This will also be used for verifying the file storage directory.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Bernardo Dal Seno <bdalseno@google.com>

lib/http/auth.py

@@ -29,6 +29,7 @@ import binascii
 
 from ganeti import compat
 from ganeti import http
+from ganeti import utils
 
 from cStringIO import StringIO
 
@@ -305,13 +306,7 @@ def ParsePasswordFile(contents):
   """
   users = {}
 
-  for line in contents.splitlines():
-    line = line.strip()
-
-    # Ignore empty lines and comments
-    if not line or line.startswith("#"):
-      continue
-
+  for line in utils.FilterEmptyLinesAndComments(contents):
     parts = line.split(None, 2)
     if len(parts) < 2:
       # Invalid line

lib/utils/text.py

@@ -589,3 +589,21 @@ def Truncate(text, length):
     return text
   else:
     return text[:length - len(_ASCII_ELLIPSIS)] + _ASCII_ELLIPSIS
+
+
+def FilterEmptyLinesAndComments(text):
+  """Filters empty lines and comments from a line-based string.
+
+  Whitespace is also removed from the beginning and end of all lines.
+
+  @type text: string
+  @param text: Input string
+  @rtype: generator
+
+  """
+  for line in text.splitlines():
+    line = line.strip()
+
+    # Ignore empty lines and comments
+    if line and not line.startswith("#"):
+      yield line