fix possible segmentation fault when connecting (#153)

* fix Segmentation fault on lastest libhdfs3

* Allow setting effective user

Plus, specify the type for the sedonc parameter to hdfsBuilderConnect

hdfs3/core.py

@@ -57,7 +57,7 @@ def __init__(self, host=MyNone, port=MyNone, connect=True, autoconf=True,
                 of the cluster that can be found in "fs.defaultFS" option.
             port : int (8020)
                 namenode RPC port usually 8020, in HA mode port mast be None
-            user, ticket_cache, token : str
+            user, ticket_cache, token, effective_user : str
                 kerberos things
         """
         self.conf = conf.copy() if autoconf else {}
@@ -120,6 +120,7 @@ def connect(self):
         user = conf.pop('user', None)
         if user is not None:
             _lib.hdfsBuilderSetUserName(o, ensure_bytes(user))
+        effective_user = ensure_bytes(conf.pop('effective_user', None))
 
         ticket_cache = conf.pop('ticket_cache', None)
         if ticket_cache is not None:
@@ -134,7 +135,7 @@ def connect(self):
                                               ensure_bytes(val)) == 0:
                 warnings.warn('Setting conf parameter %s failed' % par)
 
-        fs = _lib.hdfsBuilderConnect(o)
+        fs = _lib.hdfsBuilderConnect(o, effective_user)
         _lib.hdfsFreeBuilder(o)
         if fs:
             logger.debug("Connect to handle %d", fs.contents.filesystem)

hdfs3/lib.py

@@ -203,7 +203,7 @@ class hdfsFS(ct.Structure):
 hdfsConnectNewInstance.__doc__ = "New structure for connection information"
 
 hdfsBuilderConnect = _lib.hdfsBuilderConnect
-hdfsBuilderConnect.argtypes = [ct.POINTER(hdfsBuilder)]
+hdfsBuilderConnect.argtypes = [ct.POINTER(hdfsBuilder), ct.c_char_p]
 hdfsBuilderConnect.restype = ct.POINTER(hdfsFS)
 hdfsBuilderConnect.__doc__ = """Connect to HDFS using the parameters defined by the builder.