Re: LoadLibrary call hangs ..sometime

From:

=?Utf-8?B?R3VydQ==?= <Guru@discussions.microsoft.com>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 29 May 2007 01:36:02 -0700

Message-ID:

<57D57FD0-1AC4-4BAC-AEA1-06E2845E7BDD@microsoft.com>

Hi,
Sorry for any confusion here, my code is something like this

///////////////////START//////////////////////////
BOOL APIENTRY DllMain( HANDLE hModule,
                       DWORD ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    switch (ul_reason_for_call)
    {
        case DLL_PROCESS_ATTACH:
        case DLL_THREAD_ATTACH:
        case DLL_THREAD_DETACH:
        case DLL_PROCESS_DETACH:
            break;
    }
    return TRUE;
}

extern "C"
{
      __declspec(dllexport) int init (void);
      void __declspec(dllexport) execute (IMServiceFunc::ExecuteInfo ei);
}

static BDRimLoad *myLoad = NULL;

int init()
{
   myLoad = new BDRimLoad();

   int success = myLoad->Init(); //this int will call the functions from
other dll
   if( success )
       return IMServiceFunc::INIT_ERROR;
   else
       return IMServiceFunc::INIT_OK;
}

void execute( IMServiceFunc::ExecuteInfo info )
{
   myLoad->Run( &info );
}

////////////////////////END///////////////////////////////
1)Once my dll is loaded using loadlibrary i found out the addresses of init
and execute.
2)Then I call this init (of my Dll see above) and execute() which internally
calls the class's routine which are part of my dll.

Is there anything wrong in my design ??

Thanks for the reply
Guru

"Bruno van Dooren" wrote:

Although ctor' does not do much but its Init() calls the third party dll
funcions which I believe make some checks with system called Rimage (CD
burner machine)..but the part of calling this ctor' (allocating memory
etc.)
is in extern "C" Init() function for which i need to load my dll into the
memory..

If I understand correctly, the ctor of your static object in your dll calls
an Init function that resides in another dll.
If this is the case, your design is violating the rules that apply to
DllMain, which also apply to static constructors and destructors.

There is no guaranteed load order for Dlls in a process, and depending on
the order in which the Dlls are loaded, you could see
a) no problems at all
b) a deadlock
c) a crash

There is little you can do about it. You might be able to change things
enough that your problem could go away, but you really should not work with
static objects like that. complex static initialization is evil and can
cause a lot of problems.

If you cannot force the application to explicitly do something to initialize
the objects, you can have each function in your DLL check upon entry whether
the object is initialized or not, and then initialize it if it isn't. Guard
the initalization with a critical section to prevent race conditions and you
should be fine.

--
Kind regards,
    Bruno van Dooren MVP - VC++
    http://msmvps.com/blogs/vanDooren
    bruno_nos_pam_van_dooren@hotmail.com