mem.cpp

很好用的ftp源码

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

#include "priv.h"

/*****************************************************************************
 *
 *	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 ReallocCbPpv(UINT cb, LPVOID * ppvArg)
{
    HRESULT hres;
    LPVOID * ppv = ppvArg;
    HLOCAL hloc = *ppv;

    if (cb)
    {			    /* Alloc or realloc */
        if (hloc)
        {		    /* Realloc */
            HLOCAL h = LocalReAlloc(hloc, cb, LMEM_MOVEABLE+LMEM_ZEROINIT);
            hloc = h;
        }
        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 AllocCbPpv(UINT cb, LPVOID * ppv)
{
    *ppv = 0;
    return ReallocCbPpv(cb, ppv);
}