>>>>> Anatoly A Kazantsev <[email protected]> writes:
[…]
> @@ -348,9 +349,17 @@ main(int argc, char *argv[])
> break;
> default: /* Parent. */
> - if (waitpid (pid, NULL, 0) == -1)
> + if (waitpid (pid, &status, 0) == -1)
> error (8, errno, "waitpid");
> + if (WIFSIGNALED (status))
> + error (WTERMSIG (status) + 128, 0,
> + "%s for child", strsignal (WTERMSIG (status)));
> +
> + if (WIFEXITED (status))
> + error (WEXITSTATUS (status), 0,
> + "Error %d for child", WEXITSTATUS (status));
> +
> err = fsys_goaway (active_control, goaway_flags);
> if (err && err != EBUSY)
> error (9, err, "fsys_goaway");
> I have a question: why in case WIFSIGNALED the value of status is
> increased by 128?
When a program is terminated by a signal, its exit code is 128
plus the number of that signal; consider, e. g.:
$ bash -c 'kill -8 -- $$' ; echo "Exit code: $?, Signal: $(($? - 128))"
/bin/bash: line 1: 11876 Floating point exceptionbash -c 'kill -8 -- $$'
Exit code: 136, Signal: 8
$
In this case, the utilities have to pass that exit code through,
which is implemented as:
1. “decoding” the status into a “terminated due to a signal”
flag and /either/ the “plain” exit code /or/ the signal
number;
2. “encoding” these two values back into a single exit code,
which is passed to exit () via error ().
I don’t know where exactly this convention originated from, but
I’m pretty sure that it was in every revision of POSIX ever
published, and probably is almost as old as Unix itself.
[…]
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