From 402b93394d7d226cb4903d090e07253e0e4a7a16 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 18 Feb 2015 09:47:12 +0530
Subject: [PATCH] When deleting registry values do not raise an exception if
 the value does not exist

---
 src/calibre/utils/winreg/lib.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/calibre/utils/winreg/lib.py b/src/calibre/utils/winreg/lib.py
index 6b2378d3fd..e96037d7ec 100644
--- a/src/calibre/utils/winreg/lib.py
+++ b/src/calibre/utils/winreg/lib.py
@@ -131,8 +131,15 @@ RegSetKeyValue = cwrap(
 
 RegDeleteTree = cwrap(
     'RegDeleteTreeW', LONG, a('key', HKEY), a('sub_key', LPCWSTR, None))
+
+def delete_value_errcheck(result, func, args):
+    if result == winerror.ERROR_FILE_NOT_FOUND:
+        return args
+    if result != 0:
+        raise ctypes.WinError(result)
+    return args
 RegDeleteKeyValue = cwrap(
-    'RegDeleteKeyValueW', LONG, a('key', HKEY), a('sub_key', LPCWSTR, None), a('name', LPCWSTR, None))
+    'RegDeleteKeyValueW', LONG, a('key', HKEY), a('sub_key', LPCWSTR, None), a('name', LPCWSTR, None), errcheck=delete_value_errcheck)
 RegEnumKeyEx = cwrap(
     'RegEnumKeyExW', LONG, a('key', HKEY), a('index', DWORD), a('name', LPWSTR), a('name_size', LPDWORD), a('reserved', LPDWORD, None),
     a('cls', LPWSTR, None), a('cls_size', LPDWORD, None), a('last_write_time', ctypes.POINTER(FILETIME), in_arg=False),
@@ -176,7 +183,7 @@ class Key(object):
                 yield name_buf.value[:lname_buf.value]
             i += 1
 
-    def delete_value(self, sub_key=None, name=None):
+    def delete_value(self, name=None, sub_key=None):
         ' Delete the named value from this key. If name is None the default value is deleted. '
         RegDeleteKeyValue(self.hkey, sub_key, name)