From 6ff8785c9277c5978e6dc01cb1b3da25d6bae2db Mon Sep 17 00:00:00 2001
From: Eric Wong <BOFH@YHBT.net>
Date: Mon, 5 Jun 2023 10:12:52 +0000
Subject: [PATCH 23/23] LISTEN_FDS-inherited sockets are immortal across SIGHUP

When using systemd-style socket activation, consider the
inherited socket immortal and do not drop it on SIGHUP.
This means configs w/o any `listen' directives at all can
continue to work after SIGHUP.

I only noticed this while writing some tests in Perl 5 and
the test suite is two lines shorter to test this feature :>
---
 lib/unicorn/http_server.rb  | 7 ++++++-
 t/client_body_buffer_size.t | 1 -
 t/integration.t             | 1 -
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb
index dd92b38..f1b4a54 100644
--- a/lib/unicorn/http_server.rb
+++ b/lib/unicorn/http_server.rb
@@ -77,6 +77,7 @@ def initialize(app, options = {})
     options[:use_defaults] = true
     self.config = Unicorn::Configurator.new(options)
     self.listener_opts = {}
+    @immortal = [] # immortal inherited sockets from systemd
 
     # We use @self_pipe differently in the master and worker processes:
     #
@@ -158,6 +159,7 @@ def listeners=(listeners)
     end
     set_names = listener_names(listeners)
     dead_names.concat(cur_names - set_names).uniq!
+    dead_names -= @immortal.map { |io| sock_name(io) }
 
     LISTENERS.delete_if do |io|
       if dead_names.include?(sock_name(io))
@@ -807,17 +809,20 @@ def inherit_listeners!
     # inherit sockets from parents, they need to be plain Socket objects
     # before they become Kgio::UNIXServer or Kgio::TCPServer
     inherited = ENV['UNICORN_FD'].to_s.split(',')
+    immortal = []
 
     # emulate sd_listen_fds() for systemd
     sd_pid, sd_fds = ENV.values_at('LISTEN_PID', 'LISTEN_FDS')
     if sd_pid.to_i == $$ # n.b. $$ can never be zero
       # 3 = SD_LISTEN_FDS_START
-      inherited.concat((3...(3 + sd_fds.to_i)).to_a)
+      immortal = (3...(3 + sd_fds.to_i)).to_a
+      inherited.concat(immortal)
     end
     # to ease debugging, we will not unset LISTEN_PID and LISTEN_FDS
 
     inherited.map! do |fd|
       io = Socket.for_fd(fd.to_i)
+      @immortal << io if immortal.include?(fd)
       io.autoclose = false
       io = server_cast(io)
       set_server_sockopt(io, listener_opts[sock_name(io)])
diff --git a/t/client_body_buffer_size.t b/t/client_body_buffer_size.t
index b1a99f3..3067f28 100644
--- a/t/client_body_buffer_size.t
+++ b/t/client_body_buffer_size.t
@@ -36,7 +36,6 @@ POSIX::mkfifo($fifo, 0600) or die "mkfifo: $!";
 seek($conf_fh, 0, SEEK_SET);
 truncate($conf_fh, 0);
 print $conf_fh <<EOM;
-listen "$host_port" # TODO: remove this requirement for SIGHUP
 after_fork { |_,_| File.open('$fifo', 'w') { |fp| fp.write "pid=#\$\$" } }
 EOM
 $ar->do_kill('HUP');
diff --git a/t/integration.t b/t/integration.t
index a568758..bb2ab51 100644
--- a/t/integration.t
+++ b/t/integration.t
@@ -17,7 +17,6 @@ my $u1 = "$tmpdir/u1";
 print $conf_fh <<EOM;
 early_hints true
 listen "$u1"
-listen "$host_port" # TODO: remove this requirement for SIGHUP
 EOM
 my $ar = unicorn(qw(-E none t/integration.ru -c), $conf, { 3 => $srv });
 my $curl = which('curl');