Extend PyWin_SetAPIError (#2188)

Author: CristiFati

win32/src/PyWinTypes.h

@@ -101,7 +101,10 @@ extern PYWINTYPES_EXPORT BOOL PyWin_RegisterErrorMessageModule(DWORD first, DWOR
 extern PYWINTYPES_EXPORT HINSTANCE PyWin_GetErrorMessageModule(DWORD err);
 
 /* A global function that sets an API style error (ie, (code, fn, errTest)) */
-PYWINTYPES_EXPORT PyObject *PyWin_SetAPIError(char *fnName, long err = 0);
+PYWINTYPES_EXPORT PyObject *PyWin_SetAPIError(char *fnName, long err = ERROR_SUCCESS);
+
+// A PyWin_SetAPIError variant that returns None (Py_None) on success.
+PYWINTYPES_EXPORT PyObject *PyWin_SetAPIErrorOrReturnNone(char *fnName, long err = ERROR_SUCCESS);
 
 /* Basic COM Exception handling.  The main COM exception object
    is actually defined here.  However, the most useful functions

win32/src/PyWinTypesmodule.cpp

@@ -275,9 +275,9 @@ HINSTANCE PyWin_GetErrorMessageModule(DWORD err)
 }
 
 /* error helper - GetLastError() is provided, but this is for exceptions */
-PyObject *PyWin_SetAPIError(char *fnName, long err /*= 0*/)
+PyObject *PyWin_SetAPIError(char *fnName, long err /*= ERROR_SUCCESS*/)
 {
-    DWORD errorCode = err == 0 ? GetLastError() : err;
+    DWORD errorCode = err == ERROR_SUCCESS ? GetLastError() : err;
     DWORD flags = FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_IGNORE_INSERTS;
     // try and find the hmodule providing this error.
     HMODULE hmodule = PyWin_GetErrorMessageModule(errorCode);
@@ -308,6 +308,15 @@ PyObject *PyWin_SetAPIError(char *fnName, long err /*= 0*/)
     return NULL;
 }
 
+/* error helper - like PyWin_SetAPIError, but returns None on success */
+PyObject *PyWin_SetAPIErrorOrReturnNone(char *fnName, long err /*= ERROR_SUCCESS*/)
+{
+    DWORD errorCode = err == ERROR_SUCCESS ? GetLastError() : err;
+    if (errorCode == ERROR_SUCCESS)
+        Py_RETURN_NONE;
+    return PyWin_SetAPIError(fnName, errorCode);
+}
+
 // This function sets a basic COM error - it is a valid COM
 // error, but may not contain rich error text about the error.
 // Designed to be used before pythoncom has been loaded.