Re: ntdll/file.c: Fix a possible NULL dereferencing.

[Rob Shearman]

2008/8/27 Nikolay Sivov :
> Henri Verbeet wrote:
> > 2008/8/27 Nikolay Sivov :
> > > Markus Hitter wrote:
> > > > if (!attr || !attr->ObjectName) return STATUS_INVALID_PARAMETER;
> > >
> > > Shouldn't this be splitted? It isn't safe to rely on evaluation order.
> > > Or is it a default compiler setting for us?
> >
> > This is well defined in C. !attr will be evaluated first, and if it
> > evaluates to true, the rest of the condition won't be evaluated. This
> > is also known as short-circuit evaluation.
>
> I thought it's possible to override this: not a evaluation order of
> course but the completeness of
> evaluation for debug purpose.

All C89/C99-compliant compilers will always respect the order of
evaluation of the operands of the logical AND and OR operators. I
don't know what "debug purpose" you are referring to, but the code
generated for "if (!attr || !attr->ObjectName)" is guaranteed by the C
standard to never crash on a NULL pointer.