Source code of Windows XP (NT5)
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//+-------------------------------------------------------------------------
//
// Microsoft Windows
// Copyright (C) Microsoft Corporation, 1995 - 1996.
//
// File: dynload.cxx
//
// Contents: Wrappers for functions exported by DLLs that are loaded only
// when needed.
//
// Classes:
//
// Functions: FreeDynLoadLibs
//
// History: 07-Oct-96 AnirudhS Created.
//
//--------------------------------------------------------------------------
#include "..\pch\headers.hxx"
#pragma hdrstop
#include <debug.hxx>
#include "dynload.hxx"
//
// These typedefs must match the function prototypes in objbase.h
//
typedef LPVOID (STDAPICALLTYPE *PF_CoTaskMemAlloc) (ULONG cb);
typedef LPVOID (STDAPICALLTYPE *PF_CoTaskMemRealloc) (LPVOID pv, ULONG cb);
typedef void (STDAPICALLTYPE *PF_CoTaskMemFree) (LPVOID pv);
//
// Local functions
//
void
LoadOleFunction(
FARPROC * pfCurrentValue,
LPCSTR pszFunctionName
);
//
// Static data
//
HMODULE hOle32Dll;
//+----------------------------------------------------------------------------
//
// Function: GetProcAddressInModule
//
// Synopsis: Gets the address of the specified function exported by the
// specified module.
//
// Arguments: [pszFunction] - Name of the function desired.
// [ptszModule] - Name of the module. This must already be loaded.
//
//-----------------------------------------------------------------------------
FARPROC
GetProcAddressInModule(
LPCSTR pszFunction,
LPCTSTR ptszModule
)
{
HMODULE hMod = GetModuleHandle(ptszModule);
schAssert(hMod != NULL);
return (GetProcAddress(hMod, pszFunction));
}
//+----------------------------------------------------------------------------
//
// Function: LoadOleFunction
//
// Synopsis: Loads OLE32.DLL if it hasn't been loaded, and gets the address
// of the specified function exported by it.
//
// Arguments: [pfCurrentValue] - Address where the function pointer will be
// returned. If this is not NULL on entry it is assumed to
// already point to the function.
// [pszFunctionName] - Name of the function desired.
//
//-----------------------------------------------------------------------------
void
LoadOleFunction(
FARPROC * pfCurrentValue,
LPCSTR pszFunctionName
)
{
if (*pfCurrentValue != NULL)
{
schAssert(hOle32Dll != NULL);
return;
}
if (hOle32Dll != NULL
|| (hOle32Dll = LoadLibrary(TEXT("OLE32.DLL"))) != NULL)
{
*pfCurrentValue = GetProcAddress(hOle32Dll, pszFunctionName);
}
}
//+----------------------------------------------------------------------------
//
// Function: FreeDynLoadLibs
//
// Synopsis: Unloads DLLs that have been dynamically loaded.
//
// Arguments: None.
//
// Notes: WARNING: This will make all the function pointers invalid.
// Therefore, this function should only be called if this
// module is being unloaded.
//
//-----------------------------------------------------------------------------
void
FreeDynLoadLibs(void)
{
if (hOle32Dll != NULL)
{
FreeLibrary(hOle32Dll);
#if DBG == 1
hOle32Dll = NULL;
#endif
}
}
//+----------------------------------------------------------------------------
//
// Function wrappers
//
//-----------------------------------------------------------------------------
LPVOID
WrapCoTaskMemAlloc(
ULONG cb
)
{
static PF_CoTaskMemAlloc pf_CoTaskMemAlloc;
LoadOleFunction((FARPROC *) &pf_CoTaskMemAlloc, "CoTaskMemAlloc");
if (pf_CoTaskMemAlloc != NULL)
{
return pf_CoTaskMemAlloc(cb);
}
else
{
return NULL;
}
}
LPVOID
WrapCoTaskMemRealloc(
LPVOID pv,
ULONG cb
)
{
static PF_CoTaskMemRealloc pf_CoTaskMemRealloc;
LoadOleFunction((FARPROC *) &pf_CoTaskMemRealloc, "CoTaskMemRealloc");
if (pf_CoTaskMemRealloc != NULL)
{
return pf_CoTaskMemRealloc(pv, cb);
}
else
{
return NULL;
}
}
void
WrapCoTaskMemFree(
LPVOID pv
)
{
static PF_CoTaskMemFree pf_CoTaskMemFree;
LoadOleFunction((FARPROC *) &pf_CoTaskMemFree, "CoTaskMemFree");
if (pf_CoTaskMemFree != NULL)
{
pf_CoTaskMemFree(pv);
}
}