comctl32: realloc or free and alloc

[Alexey Fisher]

On So, 2011-05-01 at 19:11 +0400, Nikolay Sivov wrote:
> On 5/1/2011 13:07, Alexey Fisher wrote:
> >
> > There is a new patch in the attachment.
> 
> >   BOOL Str_SetPtrAtoW (LPWSTR *lppDest, LPCSTR lpSrc)
> >   {
> > -    TRACE("(%p %s)\n", lppDest, lpSrc);
> > +    TRACE("(%p, %s)\n", *lppDest, debugstr_a(lpSrc));
> > +
> > +    if (*lppDest) {
> > +        ERR("lppDest should be NULL!");
> > +        return FALSE;
> > +    }
> It's an internal call, so it's better to require a caller to pass valid 
> parameters. That's why ERR is too much here, cause you completely 
> control passed parameters in a first place.

The problem is, this function return FALSE if some thing going wrong,
but caller never check it. So if we pass fresh not NULL, not Alloc'd
pointer. We have some garbage in pointers target before the call. After
ReAlloc and Str_SetPtrAtoW failed, caller continues to use old pointers
target, also old garbage. The App get garbage instead of the string and
will crash in some conditions. This all make it hard to find the cause
of the crash. 

> Please open a bug with a test C application so we can look at initial 
> problem.

Das Not ReAllocing not Alloc'd memory is bug? or it is future?

Here is part of man realloc:

> realloc() changes the size of the memory block pointed  to  by  ptr  to
>        size  bytes.   The contents will be unchanged to the minimum of the old
>        and new sizes; newly allocated memory will be uninitialized.  If ptr is
>        NULL,  then  the  call is equivalent to malloc(size), for all values of
>        size; if size is equal to zero, and ptr is not NULL, then the  call  is
>        equivalent  to  free(ptr).   Unless  ptr  is  NULL,  it  must have been
>        returned by an earlier call to malloc(), calloc() or realloc().  If the
>        area pointed to was moved, a free(ptr) is done.

-- 
Regards,
        Alexey