[PATCH v2 5/7] linux: Remove SIGCANCEL/SIGSETXID handling on sigprocmask

[Adhemerval Zanella]

On 12/12/2019 09:54, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> The sigfillset already does it, and this is the canonical way to operate
>> on sigset_t.  The only way to actually broke this assumption is if caller
>> initialize sigset with memset or something similar, i.e, bypassing glibc
>> (and again this is not a valid construction).
> 
> Is you argument that sigfillset already does this, and there is no way
> to compute the complement of a signal set, so the bits for
> SIGCANCEL and SIGSETXID can never become set?

Yes.

> 
> I think it's possible to set them directly using sigaddset.  I don't see
> why using SIGCANCEL/SIGSETXID with that function would be undefined.

sigaddset filter out SIGCANCEL/SIGSETXID through __is_internal_signal, 
returning EINVAL for such case.