Re: DLLs and facets
On Thu, 11 Jan 2007 13:33:24 -0000, "Andrew Jarvis" <someone@somewhere>
wrote:
"Joe" <jgreer@nsisoftware.com> wrote in message
news:1161353488.123264.32050@k70g2000cwa.googlegroups.com...
We are having an interesting problem. In our application, we
dynamically load a dll. The code at some point in this dll uses
ostringstream to format a message. The use of ostringstream causes a
facet to be added to the global list of facets in the CRT. At
shutdown, we unload the dll. As the application is exiting, we get an
access violation due to the facet created by the dll being destroyed.
(This is because the facets vtbl points into code that has now been
unloaded.)
Does anyone know of a way to either prevent this facet from being
created; have the facet created by the main program; unload the facet
as the dll exits; or some other work around? I would hate to have to
resort to the sprintf family to do my formatting.
Any help you could offer would be appreciated,
joe
I have just spent the morning tracking down a similar problem.
I am using an object of type std::basic_ifstream<BYTE,
std::char_traits<BYTE> > in a DLL called by an COM exe.
The exe exit code calls CoUninitialize and the allocated facets disappear.
The _Fac_tidy function (in locale0.cpp) is subsequently called and promptly
crashes.
Has a solution been found in the last two months?
It sounds like the EXE and DLL are using the same CRT DLL, and so your DLL
is affecting the EXE's CRT state. The solution to this is simple - link
your DLL to the static version of the CRT. This should be SOP for all DLLs
that are intended to be black boxes. Indeed, linking dynamically to the CRT
must be regarded as equivalent to static linking in terms of melding your
DLL with other modules in the process that link to the same CRT. This means
all such modules must be compiled with the same compiler and recompiled
whenever you update the compiler. If you don't follow this guideline, then
each module that dynamically links to the CRT must be very careful not to
step into the CRT state of other such modules.
--
Doug Harrison
Visual C++ MVP