On Mon, Jul 1, 2013 at 2:43 AM, Roland Mainz <[email protected]> wrote:
> Hi!
>
> ----
>
> Erm... why does ksh93's kill(1) implementation always send SIGCONT
> after sending the requested signal ?
>
> The following code...
> -- snip --
>   1210                          if(pid>=0)
>   1211                          {
>   1212                                  if(qflag)
>   1213                                  {
>   1214                                          if(pid==0)
>   1215                                                  goto no_sigqueue;
>   1216                                          r = sigqueue(pid,sig,sig_val);
>   1217                                  }
>   1218                                  else
>   1219                                          r = kill(pid,sig);
>   1220                                  if(r>=0 && !stopsig)
>   1221                                  {
>   1222                                          if(pw->p_flag&P_STOPPED)
>   1223                                                  pw->p_flag &=
> ~(P_STOPPED|P_SIGNALLED);
>   1224                                          if(sig)
>   1225                                                  kill(pid,SIGCONT);
>   1226                                  }
>   1227                          }
> -- snip --
> ... always sends SIGCONT when the original signal delivery was
> successfull... but why is this neccesary ? Technically signals are
> queued anyway if the child is stopped and maybe the user _wants_ the
> child to continue in the stopped state.

I may have been a good intention to wake the target process up to
guarantee it consumes the signal but IMHO its still a standard
violation.
It clearly says "The kill utility shall send a signal to the process
or processes specified by each pid operand.". It does not say "a
SIGCONT signal is send with each signal to ensure the target process
is listening".

Irek
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