watch: use signalfd for Maildir watching

We can get rid of the janky wannabe
self-using-a-directory-instead-of-pipe thing we needed to
workaround Filesys::Notify::Simple being blocking.

For existing Maildir users, this should be more robust and
immune to missed wakeups for signalfd and kqueue-enabled
systems; as well as being immune to BOFHs clearing $TMPDIR
and preventing notifications from firing.

The IMAP IDLE code still uses normal Perl signals, so it's still
vulnerable to missed wakeups.  That will be addressed in future
commits.

1 files changed, 7 insertions, 12 deletions

diff --git a/lib/PublicInbox/Daemon.pm b/lib/PublicInbox/Daemon.pm
index 2f63bd73..ab0c2226 100644
--- a/lib/PublicInbox/Daemon.pm
+++ b/lib/PublicInbox/Daemon.pm
@@ -18,9 +18,9 @@ use PublicInbox::DS qw(now);
 use PublicInbox::Syscall qw(SFD_NONBLOCK);
 require PublicInbox::Listener;
 require PublicInbox::ParentPipe;
-require PublicInbox::Sigfd;
+use PublicInbox::Sigfd;
 my @CMD;
-my ($set_user, $oldset, $newset);
+my ($set_user, $oldset);
 my (@cfg_listen, $stdout, $stderr, $group, $user, $pid_file, $daemonize);
 my $worker_processes = 1;
 my @listeners;
@@ -72,15 +72,10 @@ sub accept_tls_opt ($) {
         { SSL_server => 1, SSL_startHandshake => 0, SSL_reuse_ctx => $ctx };
 }
 
-sub sig_setmask { sigprocmask(SIG_SETMASK, @_) or die "sigprocmask: $!" }
-
 sub daemon_prepare ($) {
         my ($default_listen) = @_;
         my $listener_names = {}; # sockname => IO::Handle
-        $oldset = POSIX::SigSet->new();
-        $newset = POSIX::SigSet->new();
-        $newset->fillset or die "fillset: $!";
-        sig_setmask($newset, $oldset);
+        my $oldset = PublicInbox::Sigfd::block_signals();
         @CMD = ($0, @ARGV);
         my %opts = (
                 'l|listen=s' => \@cfg_listen,
@@ -515,7 +510,7 @@ EOF
         };
         my $sigfd = PublicInbox::Sigfd->new($sig, 0);
         local %SIG = (%SIG, %$sig) if !$sigfd;
-        sig_setmask($oldset) if !$sigfd;
+        PublicInbox::restore_signals($oldset) if !$sigfd;
         while (1) { # main loop
                 my $n = scalar keys %pids;
                 unless (@listeners) {
@@ -531,7 +526,7 @@ EOF
                 }
                 my $want = $worker_processes - 1;
                 if ($n <= $want) {
-                        sig_setmask($newset) if !$sigfd;
+                        PublicInbox::Sigfd::block_signals() if !$sigfd;
                         for my $i ($n..$want) {
                                 my $pid = fork;
                                 if (!defined $pid) {
@@ -544,7 +539,7 @@ EOF
                                         $pids{$pid} = $i;
                                 }
                         }
-                        sig_setmask($oldset) if !$sigfd;
+                        PubliInbox::Sigfd::set_sigmask($oldset) if !$sigfd;
                 }
 
                 if ($sigfd) { # Linux and IO::KQueue users:
@@ -632,7 +627,7 @@ sub daemon_loop ($$$$) {
         if (!$sigfd) {
                 # wake up every second to accept signals if we don't
                 # have signalfd or IO::KQueue:
-                sig_setmask($oldset);
+                PublicInbox::Sigfd::set_sigmask($oldset);
                 PublicInbox::DS->SetLoopTimeout(1000);
         }
         PublicInbox::DS->EventLoop;