From c2b0d5d7be557163d0a3501c456285ddcf8d6f7d Mon Sep 17 00:00:00 2001
From: Stefano Miccoli <stefano.miccoli@polimi.it>
Date: Sun, 6 Apr 2014 20:55:53 +0200
Subject: [PATCH] still working on error handling

pyownet.protocol.Error hierarchy reorganized

better code for fetching errcodes from owserver
---
 pyownet/__init__.py |  2 +-
 pyownet/protocol.py | 51 ++++++++++++++++++++++++++++++---------------
 tests.py            | 13 ++++++------
 3 files changed, 42 insertions(+), 24 deletions(-)

diff --git a/pyownet/__init__.py b/pyownet/__init__.py
index 77e2d9d..fcc9b17 100644
--- a/pyownet/__init__.py
+++ b/pyownet/__init__.py
@@ -17,4 +17,4 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-__version__ = '0.7.1.dev0'
+__version__ = '0.7.1.dev1'
diff --git a/pyownet/protocol.py b/pyownet/protocol.py
index 535f5fa..3d6dc27 100644
--- a/pyownet/protocol.py
+++ b/pyownet/protocol.py
@@ -45,7 +45,7 @@
 import struct
 import socket
 
-# see msg_classification from ow_message.h
+# see 'enum msg_classification' from ow_message.h
 MSG_ERROR = 0
 MSG_NOP = 1
 MSG_READ = 2
@@ -93,6 +93,10 @@
 FLG_FORMAT_FIC =    0x05000000 #  /1067C6697351FF8D
 MSK_DEVFORMAT =     0xFF000000
 
+# useful paths
+PTH_ERRCODES = '/settings/return_codes/text.ALL'
+
+
 # internal constants
 
 # socket timeout (s)
@@ -100,6 +104,7 @@
 # do not attempt to read messages bigger than this (bytes)
 _MAX_PAYLOAD = 65536
 
+
 def str2bytez(s):
     "transform string to zero-terminated bytes"
     if not isinstance(s, basestring):
@@ -123,23 +128,33 @@ class Error(Exception):
 
 
 class ConnError(Error, IOError):
-    """Connection failed"""
+    """raised if no valid connection can be established with owserver"""
     pass
 
 
-class ShortRead(Error):
+class ProtocolError(Error):
+    """raised if no valid server response was received"""
     pass
 
 
-class ShortWrite(Error):
+class MalformedHeader(ProtocolError):
+    def __init__(self, msg, header):
+        self.msg = msg
+        self.header = header
+    def __str__(self):
+        return "{0.msg}: {0.header!s} == {0.header!r}".format(self)
+
+
+class ShortRead(ProtocolError):
     pass
 
 
-class ProtocolError(Error):
+class ShortWrite(ProtocolError):
     pass
 
 
 class OwnetError(Error, EnvironmentError):
+    """raised if owserver returns error code"""
     pass
 
 
@@ -292,11 +307,9 @@ def _read_msg(self):
         if self.verbose: 
             print('<-', repr(header))
         if header.version != 0:
-            raise ProtocolError('got malformed header: %s "%s"' % 
-                                    (repr(header), header))
+            raise MalformedHeader('bad version magic', header)
         if header.payload > _MAX_PAYLOAD:
-            raise ProtocolError('huge data, unwilling to read: %s "%s"' %
-                                    (repr(header), header))
+            raise MalformedHeader('huge data, unwilling to read', header)
         if header.payload > 0:
             payload = self.socket.recv(header.payload)
             if len(payload) < header.payload:
@@ -349,22 +362,26 @@ def __init__(self, host='localhost', port=4304, flags=0,
         # here we have an open connection, close for now
         conn.shutdown()
 
+        # setup self attributes
         self._sockaddr, self._family = sockaddr, family
         self._hostport = (host, port) # for display only
 
         self.verbose = verbose
         self.flags = flags | FLG_OWNET
 
-        # check if owserver on the line
-        self.ping()
+        self.errmess = _errtuple()
 
-        #self.errmess = _dummy()
+        # final sanity checks
+        # does the remote end speak the ownet protocol?
+        self.ping()
 
         # fetch errcodes array from owserver
-        errcodes = '/settings/return_codes/text.ALL'
-        assert self.present(errcodes)
-        self.errmess = _errtuple(
-            m for m in bytes2str(self.read(errcodes)).split(','))
+        try:
+            self.errmess = _errtuple(
+                m for m in bytes2str(self.read(PTH_ERRCODES)).split(','))
+        except OwnetError:
+            # failed, leave the default defined above
+            pass
 
     def __str__(self):
         return "ownet server at %s" % (self._hostport, )
@@ -455,7 +472,7 @@ def _main():
     except ConnError:
         print("No owserver on localhost")
         return 1
-    print("directory on %s:" % proxy)
+    print("directory on {0}:".format(proxy))
     print("id".center(17), "type".center(7))
     for sensor in proxy.dir(slash=False, bus=False):
         stype = bytes2str(proxy.read(sensor + '/type'))
diff --git a/tests.py b/tests.py
index 2780e31..328fd95 100644
--- a/tests.py
+++ b/tests.py
@@ -5,7 +5,10 @@ class TestProtocolModule(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
-        cls.proxy = protocol.OwnetProxy()
+        try:
+            cls.proxy = protocol.OwnetProxy()
+        except protocol.ConnError as exc:
+            raise RuntimeError('no owserver on localhost, got:%s' % exc)
   
     def test_ping(self):
         self.assertIsNone(self.proxy.ping())
@@ -14,15 +17,13 @@ def test_present(self):
         self.assertIs(self.proxy.present('/'), True)
         self.assertIs(self.proxy.present('/nonexistent'), False)
 
-    def test_dir(self):
+    def test_dir_read(self):
         for i in self.proxy.dir(bus=False):
             self.assertTrue(self.proxy.present(i))
             self.assertTrue(self.proxy.present(i + 'type'))
-            stype = self.proxy.read(i + 'type')
+            self.proxy.read(i + 'type')
             if self.proxy.present(i + 'temperature'):
-                temp = self.proxy.read(i + 'temperature')
-            else:
-                temp = ''
+                self.proxy.read(i + 'temperature')
 
     def test_exceptions(self):
         self.assertRaises(protocol.OwnetError, self.proxy.dir, '/nonexistent')