How to deference a pointer to pointer

[Zhiwei Ying]

Thanks.

Zhiwei

On Tue, Apr 19, 2011 at 10:41 PM, Frank Ch. Eigler <fche@redhat.com> wrote:
> Zhiwei Ying <zhiwei.ying@gmail.com> writes:
>
>> [...]
>> I know systematap has limited support on tracing of struct field.
>
> Yes, you can navigate pointers/array.  The syntax for this is similar
> to but not the same as C.
>
>> Can it trace a field in a pointer to pointer?
>> struct A
>> {
>>   int x;
>> };
>> void foo(struct A **a);
>>
>> How can I trace the field x in struct A?
>
> Yes, this is one of those cases where the syntax doesn't help enough.
>
> probe FOO.function("foo") { println($a->x) }
>
> So two levels of dereferencing are hidden in the single ->.
>
> - FChE
>