Hi,
there is an easy test, if Stefan is right and I'm wrong.
1. cast an INVALID Pointer to "aObj"
2. call "method_base(&aObj->obj,...)"
-> if stefan is right than "method_base" is called with an INVALID aObj
as Pointer
-> if I am right than your software will CRASH :-)
that is the reason why I require the "frienddef".
mfg AO
On 03.02.20 09:16, aotto wrote:
Hi,
Can someone confirm that *aObj->obj does NOT create any extray "code"
and does NOT do any
POINTER resolution? -> if so than "gcc" already uses the "friend"
logic I require :-)
→ I don't think that "gcc" do this already
Hi, the following scenario has a "definition hole" in the "C" language
code example:
-------------------------
struct base {
...
};
struct A {
struct base obj;
...
} aObj;
struct B {
struct base obj;
...
} bObj;
void method_base (struct base * hdl, ...);
method_base(&aObj, ...)
method_base(&bObj, ...)
------------------------
-----Ursprüngliche Nachricht-----
Von: aotto <aotto1968@xxxxxxxxxxx>
Gesendet: Montag, 3. Februar 2020 09:02
An: Stefan Franke <stefan@xxxxxxxxx>
Betreff: Re: AW: Feature request for "friendship" of pointers in "C"
This is not the same!
1. usually the aObj is a Pointer:
-> &aObj.obj => &(aObj->obj)
2. this DOUBLE indirect access creates definitely a CRASH if
aObj is invalid or freed
3. I use a internal a Pointer typecheck… where I can detect if
"my" pointer is valid or freed… but a "&(aObj->obj)" you
don't survive.
mfg
* Please reply at the bottom.
Ad 1: there is no need for '(' ')' if it's a pointer
&aObj->obj
Ad 2: this is not a double indirect access, the resulting address is the
same as aObj as long obj is the first element of your struct, only the
type changes
(void *)aObj == (void*)&aObj->obj
Ad 3: since the address is the same, your check will work.
Your issues aren't related to gcc - you might consider improving your C
skills.
Cheers
Stefan
