windows-server-2003/shell/themes/themeui/dllmain.cpp

/*****************************************************************************\
    FILE: dllmain.cpp

    DESCRIPTION:
       This file will take care of the DLL lifetime.

    BryanSt 4/4/2000 (Bryan Starbuck)
    Copyright (C) Microsoft Corp 2000-2000. All rights reserved.
\*****************************************************************************/

#include "priv.h"

extern HANDLE g_hLogFile;

/*****************************************************************************
 *
 *  Dynamic Globals.  There should be as few of these as possible.
 *
 *  All access to dynamic globals must be thread-safe.
 *
 *****************************************************************************/

ULONG g_cRef = 0;           // Global reference count
CRITICAL_SECTION g_csDll;   // The shared critical section


#ifdef DEBUG
DWORD g_TlsMem = 0xffffffff;
#endif // DEBUG

CComModule _Module;

BEGIN_OBJECT_MAP(ObjectMap)
END_OBJECT_MAP()

/*****************************************************************************
 *
 *  DllAddRef / DllRelease
 *
 *  Maintain the DLL reference count.
 *
 *****************************************************************************/

void DllAddRef(void)
{
    InterlockedIncrement((LPLONG)&g_cRef);
}

void DllRelease(void)
{
    ASSERT( 0 != g_cRef );
    InterlockedDecrement((LPLONG)&g_cRef);
}

/*****************************************************************************
 *
 *  DllGetClassObject
 *
 *  OLE entry point.  Produces an IClassFactory for the indicated GUID.
 *
 *  The artificial refcount inside DllGetClassObject helps to
 *  avoid the race condition described in DllCanUnloadNow.  It's
 *  not perfect, but it makes the race window much smaller.
 *
 *****************************************************************************/

STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID * ppvObj)
{
    HRESULT hres;

    DllAddRef();
    
    hres = CClassFactory_Create(rclsid, riid, ppvObj);
    
    DllRelease();
    return hres;
}

/*****************************************************************************
 *
 *  DllCanUnloadNow
 *
 *  OLE entry point.  Fail iff there are outstanding refs.
 *
 *  There is an unavoidable race condition between DllCanUnloadNow
 *  and the creation of a new IClassFactory:  Between the time we
 *  return from DllCanUnloadNow() and the caller inspects the value,
 *  another thread in the same process may decide to call
 *  DllGetClassObject, thus suddenly creating an object in this DLL
 *  when there previously was none.
 *
 *  It is the caller's responsibility to prepare for this possibility;
 *  there is nothing we can do about it.
 *
 *****************************************************************************/

STDMETHODIMP DllCanUnloadNow(void)
{
    HRESULT hres;

    ENTERCRITICAL;

    hres = g_cRef ? S_FALSE : S_OK;

    if (S_OK == hres)
    {
        hres = (_Module.GetLockCount()==0) ? S_OK : S_FALSE;
    }

    TraceMsg(TF_WMTHEME, "DllCanUnloadNow() returning hres=%#08lx. (S_OK means yes)", hres);

    LEAVECRITICAL;

    return hres;
}

/*****************************************************************************
 *
 *  Entry32
 *
 *  DLL entry point.
 *
 *****************************************************************************/
STDAPI_(BOOL) DllEntry(HINSTANCE hinst, DWORD dwReason, LPVOID lpReserved)
{
    static s_hresOle = E_FAIL;

    switch (dwReason)
    {
        case DLL_PROCESS_ATTACH:
        {
#ifdef DEBUG
            CcshellGetDebugFlags();
#endif

            InitializeCriticalSection(&g_csDll);

            g_hinst = hinst;
            DisableThreadLibraryCalls(hinst);

            SHFusionInitializeFromModuleID(hinst, 124);
            break;
        }

        case DLL_PROCESS_DETACH:
        {
            DeleteCriticalSection(&g_csDll);
            if (INVALID_HANDLE_VALUE != g_hLogFile)
            {
                CloseHandle(g_hLogFile);
            }

            SHFusionUninitialize();

            break;
        }
    }
    return 1;
}