windows-server-2003/shell/ext/keyremap/mem.c

/*****************************************************************************
 *
 *	mem.c - Memory management
 *
 *	WARNING!  These do not go through OLE allocation.  Use these
 *	only for private allocation.
 *
 *****************************************************************************/

#include "map.h"

#ifdef NEED_REALLOC

/*****************************************************************************
 *
 *	ReallocCbPpv
 *
 *	Change the size of some zero-initialized memory.
 *
 *	This is the single place where all memory is allocated, resized,
 *	and freed.
 *
 *	If you realloc from a null pointer, memory is allocated.
 *	If you realloc to zero-size, memory is freed.
 *
 *	These semantics avoid boundary cases.  For example, it is no
 *	longer a problem trying to realloc something down to zero.
 *	You don't have to worry about special-casing an alloc of 0 bytes.
 *
 *	If an error is returned, the original pointer is UNCHANGED.
 *	This saves you from having to the double-switch around a realloc.
 *
 *****************************************************************************/

STDMETHODIMP EXTERNAL
ReallocCbPpv(UINT cb, PV ppvArg)
{
    HRESULT hres;
    PPV ppv = ppvArg;
    HLOCAL hloc = *ppv;
    if (cb) {			    /* Alloc or realloc */
	if (hloc) {		    /* Realloc */
	    hloc = LocalReAlloc(hloc, cb,
				LMEM_MOVEABLE+LMEM_ZEROINIT);
	} else {		/* Alloc */
	    hloc = LocalAlloc(LPTR, cb);
	}
	hres = hloc ? S_OK : E_OUTOFMEMORY;
    } else {			/* Freeing */
	if (hloc) {
	    LocalFree(hloc);
	    hloc = 0;
	    hres = S_OK;	/* All gone */
	} else {
	    hres = S_OK;	/* Nothing to free */
	}
    }

    if (SUCCEEDED(hres)) {
	*ppv = hloc;
    }
    return hres;
}

/*****************************************************************************
 *
 *	AllocCbPpv
 *
 *	Simple wrapper that forces *ppvObj = 0 before calling Realloc.
 *
 *****************************************************************************/

STDMETHODIMP EXTERNAL
AllocCbPpv(UINT cb, PPV ppv)
{
    *ppv = 0;
    return ReallocCbPpv(cb, ppv);
}

#else

/*****************************************************************************
 *
 *	AllocCbPpv
 *
 *	Allocate memory into the ppv.
 *
 *****************************************************************************/

STDMETHODIMP EXTERNAL
AllocCbPpv(UINT cb, PPV ppv)
{
    HRESULT hres;
    *ppv = LocalAlloc(LPTR, cb);
    hres = *ppv ? S_OK : E_OUTOFMEMORY;
    return hres;
}

#endif