From cf6c813002bcd742aef2fce32ed81da7e09bea80 Mon Sep 17 00:00:00 2001
From: hakril <project@hakril.net>
Date: Sat, 24 Nov 2018 21:42:07 +0100
Subject: [PATCH] ComInterface now expose a callback for ctypes error handling.
 Allow COM interface to change/handle the raised Exception

---
 ctypes_generation/definitions/com/template.py | 35 ++++++++++++++++++-
 windows/winproxy/error.py                     |  7 +---
 2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/ctypes_generation/definitions/com/template.py b/ctypes_generation/definitions/com/template.py
index b07145e..1de40cf 100644
--- a/ctypes_generation/definitions/com/template.py
+++ b/ctypes_generation/definitions/com/template.py
@@ -4,13 +4,38 @@ import ctypes
 
 generate_IID = IID.from_raw
 
+
+class COMHRESULT(HRESULT):
+    _type_ = HRESULT._type_
+    def _check_retval_(self):
+        # We CAN NOT try to adapt the self.value and transform it with flags
+        # here, we need to do it with the errcheck
+        # So we have the peer-interface callback system on errcheck :)
+        return self.value # The value will be send to errcheck :)
+
 class COMInterface(ctypes.c_void_p):
     _functions_ = {
     }
 
+    # So COMInterface completely bypass the HRESULT
+    # return value check on restype by setting the restype to COMHRESULT
+    # But we add the 'errcheck' callbakc capacity for all COMInterface and subclasses
+    # So the default implem of the callbakc must have the same behavior as
+    # standard HRESULT restype.
+    # This is why default errcheck callback call ctypes._check_HRESULT
+    def _default_errcheck(self, result, func, args):
+        ctypes._check_HRESULT(result)
+        return args
+
     def __getattr__(self, name):
         if name in self._functions_:
-            return functools.partial(self._functions_[name], self)
+            winfunc = self._functions_[name]
+            # Hacking the HRESULT _check_retval_ and
+            # letting COMInterface.errcheck do the work of validating / raising
+            winfunc.restype = COMHRESULT
+            effective_errcheck = getattr(self, "errcheck", self._default_errcheck)
+            winfunc.errcheck = effective_errcheck
+            return functools.partial(winfunc, self)
         return super(COMInterface, self).__getattribute__(name)
 
     def __repr__(self):
@@ -23,3 +48,11 @@ class COMInterface(ctypes.c_void_p):
         self.QueryInterface(interface.IID, interface)
         return interface
 
+
+
+
+
+
+
+
+
diff --git a/windows/winproxy/error.py b/windows/winproxy/error.py
index c1769c3..315a915 100644
--- a/windows/winproxy/error.py
+++ b/windows/winproxy/error.py
@@ -25,12 +25,7 @@ class WinproxyError(WindowsError):
 
 
 # winproxy Error check
-
-# Try None instead :')
-def no_error_check(func_name, result, func, args):
-    """No error check"""
-    return args
-
+no_error_check = None
 
 def fail_on_minus_one(func_name, result, func, args):
     """Raise WinproxyError if call result is -1"""