spiceproxy: keep socket open on restart

bin/spiceproxy

@@ -61,17 +61,37 @@ sub init {
     my $lockfh = IO::File->new(">>${accept_lock_fn}") ||
 	die "unable to open lock file '${accept_lock_fn}' - $!\n";
 
-    my $socket = IO::Socket::INET->new(
-	LocalAddr => undef, # all interfaces
-	LocalPort => 3128,
-	Listen => SOMAXCONN,
-	Proto  => 'tcp',
-	ReuseAddr => 1) ||
-	die "unable to create socket - $@\n";
-
-    # we often observe delays when using Nagle algorithm,
-    # so we disable that to maximize performance
-    setsockopt($socket, IPPROTO_TCP, TCP_NODELAY, 1);
+    my ($socket, $sockfd);
+
+    if (defined($sockfd = $ENV{PVE_DAEMON_SOCKET_3128}) &&
+	$self->{env_restart_pve_daemon}) {
+
+	die "unable to parse socket fd '$sockfd'\n" 
+	    if $sockfd !~ m/^(\d+)$/;
+	$sockfd = $1; # untaint
+
+	$socket = IO::Socket::INET->new;
+	$socket->fdopen($sockfd, 'w') || 
+	    die "cannot fdopen file descriptor '$sockfd' - $!\n";
+
+    } else {
+	$socket = IO::Socket::INET->new(
+	    LocalAddr => undef, # all interfaces
+	    LocalPort => 3128,
+	    Listen => SOMAXCONN,
+	    Proto  => 'tcp',
+	    ReuseAddr => 1) ||
+	    die "unable to create socket - $@\n";
+
+	# we often observe delays when using Nagle algorithm,
+	# so we disable that to maximize performance
+	setsockopt($socket, IPPROTO_TCP, TCP_NODELAY, 1);
+
+	$ENV{PVE_DAEMON_SOCKET_3128} = $socket->fileno;
+    }
+
+    # remove FD_CLOEXEC bit to reuse on exec
+    $socket->fcntl(Fcntl::F_SETFD(), 0);
 
     $self->{server_config} = {
 	base_handler_class => 'PVE::API2',