Re: sigprocmask.2: s/kernel_sigset_t/sigset_t/

["Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>]

On 2/13/21 5:05 PM, Michael Kerrisk (man-pages) wrote:
> Hi Alex,
> 
> On 2/12/21 4:28 PM, Alejandro Colomar (man-pages) wrote:
>> Hi Michael,
>>
>> AFAICT, the syscalls [rt_]sigprocmask use '[old_]sigset_t' (there's the
>> '__user' modifier too), so 'kernel_' should be removed from the types,
>> shouldn't it?
> 
> Looks like you're right. Will you send a patch?
> 
> Thanks,
> 
> Michael

Hi Michael,

I was wrong!

Thanks,

Alex

[[
   C library/kernel differences
       The kernel's definition of sigset_t differs  in  size  from
       that  used by the C library.  In this manual page, the for‐
       mer is referred to as kernel_sigset_t (it  is  nevertheless
       named sigset_t in the kernel sources).

       The  glibc  wrapper function for sigprocmask() silently ig‐
       nores attempts to block the two real-time signals that  are
       used  internally by the NPTL threading implementation.  See
       nptl(7) for details.

       The original Linux system  call  was  named  sigprocmask().
       However,  with  the  addition of real-time signals in Linux
       2.2,  the  fixed-size,  32-bit  sigset_t  (referred  to  as
       old_kernel_sigset_t  in this manual page) type supported by
       that system call was no longer  fit  for  purpose.   Conse‐
       quently,  a new system call, rt_sigprocmask(), was added to
       support an enlarged sigset_t  type  (referred  to  as  ker‐
       nel_sigset_t  in  this  manual  page).  The new system call
       takes a fourth argument, size_t sigsetsize, which specifies
       the  size  in  bytes  of the signal sets in set and oldset.
       This argument is currently required to have a fixed  archi‐
       tecture specific value (equal to sizeof(kernel_sigset_t)).

       The  glibc  sigprocmask()  wrapper function hides these de‐
       tails from us, transparently calling rt_sigprocmask()  when
       the kernel provides it.
]]



-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/