Andrew Hewus Fresh <[email protected]> wrote:
> I noticed this when testing how signal handling worked in fw_update, it
> turns out that if you `pkill -KILL -f fw_update` it may leave behind a perl
> process that is locking the package database. Instead of just waiting
> to be killed, we can have that process check to see if its parent is
> still around and exit if not.
>
> Is there a more appropriate solution to this?
> What's the right way to notice your parent exited?
Your approach is racey. Instead, pass the soon-to-be-parent pid as an
argument to the perl script. I don't know if there is a better solution
to "detect if your parent exited".
-Lucas
diff /usr/src
commit - e425abdca99af75b418563580e5a2e31165f6f10
path + /usr/src
blob - 53efe8160238c66dc5628ea8d56e37e42988a9b4
file + usr.sbin/fw_update/fw_update.sh
--- usr.sbin/fw_update/fw_update.sh
+++ usr.sbin/fw_update/fw_update.sh
@@ -213,7 +213,7 @@ lock_db() {
[ -e /usr/bin/perl ] || return 0
set -o monitor
- perl <<'EOL' |&
+ perl - "$$" <<'EOL' |&
use v5.16;
use warnings;
no lib ('/usr/local/libdata/perl5/site_perl');
@@ -221,10 +221,15 @@ lock_db() {
$|=1;
+ $0 = "fw_update: lock_db"
lock_db(0);
say $$;
- sleep;
+
+ # If our parent exits unexpectedly,
+ # ppid will become init and we should exit.
+ my $parent = shift;
+ sleep 1 while getppid == $parent;
EOL
set +o monitor
