[PATCH librados2-perl] do not shut down the handle twice if a signal arrives at exit

[Kefu Chai <k.chai@proxmox.com>]

When a pveceph worker finishes, the CLI sends SIGTERM to its process
group, which includes the pverados child. That child is often already
shutting down the handle after seeing EOF, so the handler then calls
rados_shutdown() on the freed handle and the child segfaults.

The handlers outlived the eval anyway, as the 'local' only covered
$SIG{HUP}. So ignore the signals before shutting down, and install the
handlers first thing in the child.

Signed-off-by: Kefu Chai <k.chai@proxmox.com>
---
 PVE/RADOS.pm | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/PVE/RADOS.pm b/PVE/RADOS.pm
index 5a79235..deb4912 100644
--- a/PVE/RADOS.pm
+++ b/PVE/RADOS.pm
@@ -200,6 +200,17 @@ sub new {
     } else { # child
 	$0 = 'pverados';
 
+	my @signals = qw(HUP INT QUIT TERM);
+
+	# ignore signals from here on, the handler must not shut down a freed handle
+	my $shutdown = sub {
+	    @SIG{@signals} = ('IGNORE') x @signals;
+	    pve_rados_shutdown($self->{conn}) if $self->{conn};
+	};
+
+	# override signal handlers inherited from the parent
+	@SIG{@signals} = (sub { $shutdown->(); POSIX::_exit(1); }) x @signals;
+
 	eval {
 	    PVE::INotify::inotify_close();
 
@@ -207,12 +218,6 @@ sub new {
 		&$atfork();
 	    }
 
-	    # override signal handlers inherited from the parent
-	    local $SIG{HUP} = $SIG{INT} = $SIG{QUIT} = $SIG{TERM} = sub {
-		pve_rados_shutdown($self->{conn}) if $self->{conn};
-		POSIX::_exit(1);
-	    };
-
 	    # fixme: timeout?
 
 	    close $child;
@@ -222,7 +227,7 @@ sub new {
 	my $err = $@;
 	warn $err if $err;
 
-	pve_rados_shutdown($self->{conn}) if $self->{conn};
+	$shutdown->();
 	POSIX::_exit($err ? 1 : 0);
     }
 
-- 
2.47.3