[pywin32-bugs] [ pywin32-Bugs-740417 ] Potential error concealment in COM server initialization

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Bugs item #740417, was opened at 2003-05-20 12:31
Message generated for change (Comment added) made by shiyanovsky
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Max Shiyanovsky (shiyanovsky)
Assigned to: Nobody/Anonymous (nobody)
Summary: Potential error concealment in COM server initialization

Initial Comment:
file win32com\server\policy.py 
class BasicWrapPolicy:
  def _CreateInstance_(self, clsid, reqIID)

this function brings some danger in case of 
win32api.error raise from server initialization routine. 
I'd suggest to move except statement some rows above to
except only CLSID/PythonCom key reading failure.

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>Comment By: Max Shiyanovsky (shiyanovsky)
Date: 2003-05-30 16:01

Message:
Logged In: YES 
user_id=782829

the whole code of _CreateInstance_ lookis like (doc-string 
omitted)
  def _CreateInstance_(self, clsid, reqIID):
    try:
      classSpec = win32api.RegQueryValue
(win32con.HKEY_CLASSES_ROOT,
                                       regSpec % clsid)
      myob = call_func(classSpec)
      self._wrap_(myob)
      return pythoncom.WrapObject(self, reqIID)
    except win32api.error:
      raise error, "The object is not correctly registered - %s 
key can not be read" % (regSpec % clsid)

The call       
myob = call_func(classSpec) may raise an exception and 
furthermore exactly win32api.error. Certainly it's my bug that 
don't handle such an exception in class ctor (in my case 
callable object is a class). But as a result I've got a wrong 
message "object is not correctly registered".
I suggest to wrap in try-except only win32api.RegQueryValue 
call.


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Comment By: Mark Hammond (mhammond)
Date: 2003-05-27 02:01

Message:
Logged In: YES 
user_id=14198

I don't quite follow this.  Object creation should be in the
code:

  if dispatcher:
    retObj = dispatcher(policy, None)
  else:
    retObj = policy(None)
  return retObj._CreateInstance_(clsid, reqIID)

And this is not wrapped in an except handler.  I guess that
getting the dispatcher class could fail, but that seems alot
less likely than the class constructor failing.

Can you please give me a real example of what could fail?

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