OS X build: Detect the users desired language correctly. Also fix parsing of ambiguous dates in mm/dd vs dd/mm formats, based on the users locale settings in OS X.

src/calibre/utils/date.py

@@ -13,7 +13,7 @@ from functools import partial
 from dateutil.tz import tzlocal, tzutc, EPOCHORDINAL
 
 from calibre import strftime
-from calibre.constants import iswindows
+from calibre.constants import iswindows, isosx, plugins
 from calibre.utils.localization import lcdata
 
 class SafeLocalTimeZone(tzlocal):
@@ -68,6 +68,12 @@ if iswindows:
     except:
         parse_date_day_first = False
     del ctypes, LOCALE_SSHORTDATE, buf, LOCALE_USER_DEFAULT
+elif isosx:
+    try:
+        date_fmt = plugins['usbobserver'][0].date_format()
+        parse_date_day_first = date_fmt.index(u'd') < date_fmt.index(u'M')
+    except:
+        parse_date_day_first = False
 else:
     try:
         def first_index(raw, queries):

src/calibre/utils/localization.py

@@ -23,7 +23,7 @@ def available_translations():
     return _available_translations
 
 def get_system_locale():
-    from calibre.constants import iswindows
+    from calibre.constants import iswindows, isosx, plugins
     lang = None
     if iswindows:
         try:
@@ -34,6 +34,13 @@ def get_system_locale():
                 lang = None
         except:
             pass  # Windows XP does not have the GetUserDefaultLocaleName fn
+    elif isosx:
+        try:
+            lang = plugins['usbobserver'][0].user_locale() or None
+        except:
+            # Fallback to environment vars if something bad happened
+            import traceback
+            traceback.print_exc()
     if lang is None:
         try:
             lang = locale.getdefaultlocale(['LANGUAGE', 'LC_ALL', 'LC_CTYPE',