Fixes local timezone loading for unix systems

pendulum/tz/loader.py

@@ -38,6 +38,14 @@ def load(cls, name):
         except _compat.FileNotFoundError:
             raise ValueError('Unknown timezone [{}]'.format(name))
 
+    @classmethod
+    def load_from_file(cls, filepath):
+        try:
+            with open(filepath, 'rb') as f:
+                return cls._load(f)
+        except _compat.FileNotFoundError:
+            raise ValueError('Unable to load file [{}]'.format(filepath))
+
     @classmethod
     def _load(cls, fp):
         head_fmt = '>4s c 15x 6l'

pendulum/tz/local_timezone.py

@@ -86,16 +86,14 @@ def get_tz_name_for_windows(cls):
         return get_localzone_name()
 
     @classmethod
-    def get_tz_name_for_unix(cls):
+    def get_tz_name_for_unix(cls, _root='/'):
         tzenv = os.environ.get('TZ')
         if tzenv:
             try:
                 return _tz_from_env(tzenv)
             except ValueError:
                 pass
 
-        _root = '/'
-
         # Now look for distribution specific configuration files
         # that contain the timezone name.
         tzpath = os.path.join(_root, 'etc/timezone')
@@ -150,22 +148,23 @@ def get_tz_name_for_unix(cls):
         tzpath = os.path.join(_root, 'etc/localtime')
         if os.path.exists(tzpath) and os.path.islink(tzpath):
             tzpath = os.path.realpath(tzpath)
-            start = tzpath.find("/") + 1
-            while start is not 0:
-                tzpath = tzpath[start:]
+            parts = tzpath.split('/')[-2:]
+            while parts:
+                tzpath = '/'.join(parts)
                 try:
                     return Timezone.load(tzpath)
-                except ValueError:
+                except (ValueError, IOError, OSError):
                     pass
-                start = tzpath.find("/") + 1
+
+                parts.pop(0)
 
         # No explicit setting existed. Use localtime
         for filename in ('etc/localtime', 'usr/local/etc/localtime'):
             tzpath = os.path.join(_root, filename)
 
             if not os.path.exists(tzpath):
                 continue
-            return Timezone('', *Loader.load(tzpath))
+            return Timezone('', *Loader.load_from_file(tzpath))
 
         raise RuntimeError('Can not find any timezone configuration')
 

tests/fixtures/__init__.py

@@ -0,0 +1,2 @@
+# -*- coding: utf-8 -*-
+

tests/fixtures/tz/symlink/etc/localtime

@@ -0,0 +1 @@
+../usr/share/zoneinfo/Europe/Paris

tests/tz_tests/test_loader.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import os
 from .. import AbstractTestCase
 from pendulum.tz.loader import Loader
 
@@ -11,3 +12,19 @@ def test_load_bad_timezone(self):
 
     def test_load_valid(self):
         self.assertTrue(Loader.load('America/Toronto'))
+
+    def test_load_from_file(self):
+        local_path = os.path.join(os.path.split(__file__)[0], '..')
+        tz_file = os.path.join(local_path, 'fixtures', 'tz', 'Paris')
+        (transitions,
+         transition_types,
+         default_transition_type) = Loader.load_from_file(tz_file)
+
+        self.assertGreater(len(transitions), 0)
+        self.assertGreater(len(transition_types), 0)
+        self.assertIsNotNone(default_transition_type)
+
+    def test_load_from_file_invalid(self):
+        local_path = os.path.join(os.path.split(__file__)[0], '..')
+        tz_file = os.path.join(local_path, 'fixtures', 'tz', 'NOT_A_TIMEZONE')
+        self.assertRaises(ValueError, Loader.load_from_file, tz_file)

tests/tz_tests/test_local_timezone.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+
+import os
+from .. import AbstractTestCase
+from pendulum.tz import LocalTimezone
+
+
+class LocalTimezoneTest(AbstractTestCase):
+
+    def test_unix_symlink(self):
+        # A ZONE setting in the target path of a symbolic linked localtime, f ex systemd distributions
+        local_path = os.path.join(os.path.split(__file__)[0], '..')
+        tz = LocalTimezone.get_tz_name_for_unix(
+            _root=os.path.join(local_path, 'fixtures', 'tz', 'symlink')
+        )
+
+        self.assertEqual(tz.name, 'Europe/Paris')