cnl_ls: Ignore non-cnl-files (e.g., README.txt)

cnl_library.py

@@ -92,14 +92,18 @@ def read_header(f):
     return header
 
 
-
 class CNLParser:
+    class WrongFileFormat_Exception(Exception):
+        pass
+
+
     def __init__(self, filename):
         self.filename = filename
 
         with open( self.filename ) as in_file:
             ## Check file format version.
-            assert( in_file.readline() == "%% CPUnetLOGv1\n" )
+            if ( not in_file.readline() == "%% CPUnetLOGv1\n" ):
+                raise self.WrongFileFormat_Exception()
 
             ## Read JSON header.
             self.header = read_header(in_file)

cnlls.py

@@ -125,7 +125,12 @@ if __name__ == "__main__":
 
     ## Parse files and store them in a dict (of lists) according to their hostname.
     for filename in filenames:
-        cnl_file = CNLParser(filename)
+        try:
+            cnl_file = CNLParser(filename)
+        except CNLParser.WrongFileFormat_Exception:
+            print( "Skipping: {}".format(filename) )
+            continue
+
         hostname = cnl_file.get_hostname()
         cnl_files[hostname].append( cnl_file )