Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!asuvax!ukma!seismo!uunet!microsoft!bobsc
From: bobsc@microsoft.UUCP (Bob SCHMIDT)
Newsgroups: comp.windows.ms
Subject: Re: Does free() Work On Locked Pointers?
Keywords: memory management free
Message-ID: <72799@microsoft.UUCP>
Date: 7 Jun 91 04:55:39 GMT
References: <1991Jun3.195715.24598@iti.org>
Reply-To: bobsc@microsoft.UUCP (Bob SCHMIDT)
Distribution: na
Organization: Microsoft Corp., Redmond WA
Lines: 36

In article <1991Jun3.195715.24598@iti.org> kam@iti.org (Keith A. McNabb) writes:
%% Does anyone know if the the regular C free() function works in Windows
%% 3.0 *IF* you've previously allocated memory with LocalAlloc() and then
%% obtained the pointer with LocalLock()?
%% 
%% I'm modifying some existing C code, and I don't want to have to keep up
%% with handles; it's just a linked list, so the memory blocks are tiny.
%% I'm hoping that I can free memory for freed list elements with the
%% regular free function, passing it the pointer .  LocalFree() requires a
%% handle.
%% 
%% uSoft SDK documentation says only:  "You can use ... malloc, calloc, 
%% realloc, and free, but [...] you may get unexpected results."
%% 
%% ??????????
%% 
%% Keith McNabb
%% kam@iti.org

There is a better way...

The Windows API 'LocalHandle' will convert a LocalLocked pointer to its
corresponding local handle.  Thus, you can create your own 'Free' which
is essentially

    HANDLE Free(void _near *Pointer)
        {
        return LocalFree(LocalHandle(Pointer));
        }

This code is naive and has no error checking, but does show the idea.
--
--  Bob Schmidt             bobsc@microsoft.UUCP
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