hyperic-hq-discuss

Re: [Hyperic-hq-discuss] PATCH: handle and mem leak on the win32 side

[Jan K. <jan...@my...>]

Doug MacEachern wrote:
> On Mar 7, 2007, at 3:43 PM, Doug MacEachern wrote:
> ...
>>
>> I'll re-consider use of goto/error in the future, perhaps starting with 
>> cleanup of of the kdll handles :)
>>
> I had forgotten about this, but here's the reason there's no
> FreeLibrary(kdll):
> 
> "The GetModuleHandle function returns a handle to a mapped module
> without incrementing its reference count. Therefore, use care when
> passing the handle to the FreeLibrary function, because doing so can
> cause a DLL module to be unmapped prematurely."
> 
> See: http://msdn2.microsoft.com/en-us/library/ms683199.aspx

I see 3 ways to handle this:
1. open a extra handle in the init-function to make sure the ref-count
never becomes zero
2. get the handle once in the init function and close in shutdown
3. get the handle once in the get_remote_proc_env function and close on
sigar-shutdown.

  if (!sigar->kdll_...) {
    sigar->kdll_... = GetModuleHandle(...);
  }

sigar_shutdown() {
  if (sigar->kdll_...) CloseHandle(sigar->kdll...);
  ...
}

That way they are only open once and the sigar_shutdown() can cleanup at
the end.

Jan
-- 
Jan Kneschke, MySQL GmbH, Radlkoferstr. 2, D-81373 München
Geschäftsführer: Hans von Bell, Kaj Arnö - HRB München 162140

Re: [Hyperic-hq-discuss] PATCH: handle and mem leak on the win32 side

[Doug M. <do...@hy...>]

I was pointing out "without incrementing its reference count".  I =20
don't think CloseHandle() has any effect on the handle returned by =20
GetModuleHandle(), does it?

On Mar 8, 2007, at 2:13 AM, Jan Kneschke wrote:

> Doug MacEachern wrote:
> > On Mar 7, 2007, at 3:43 PM, Doug MacEachern wrote:
> > ...
> >>
> >> I'll re-consider use of goto/error in the future, perhaps =20
> starting with
> >> cleanup of of the kdll handles :)
> >>
> > I had forgotten about this, but here's the reason there's no
> > FreeLibrary(kdll):
> >
> > "The GetModuleHandle function returns a handle to a mapped module
> > without incrementing its reference count. Therefore, use care when
> > passing the handle to the FreeLibrary function, because doing so can
> > cause a DLL module to be unmapped prematurely."
> >
> > See: http://msdn2.microsoft.com/en-us/library/ms683199.aspx
>
> I see 3 ways to handle this:
> 1. open a extra handle in the init-function to make sure the ref-count
> never becomes zero
> 2. get the handle once in the init function and close in shutdown
> 3. get the handle once in the get_remote_proc_env function and =20
> close on
> sigar-shutdown.
>
>   if (!sigar->kdll_...) {
>     sigar->kdll_... =3D GetModuleHandle(...);
>   }
>
> sigar_shutdown() {
>   if (sigar->kdll_...) CloseHandle(sigar->kdll...);
>   ...
> }
>
> That way they are only open once and the sigar_shutdown() can =20
> cleanup at
> the end.
>
> Jan
> --
> Jan Kneschke, MySQL GmbH, Radlkoferstr. 2, D-81373 M=FCnchen
> Gesch=E4ftsf=FChrer: Hans von Bell, Kaj Arn=F6 - HRB M=FCnchen 162140
>
>