mod_posix: Move POSIX signal handling into util.startup to avoid race

When libunbound is initialized, it spawns a thread to work in.
In case a module initializes libunbound, e.g. by triggering a s2s
connection, Prosody would not handle signals, instead immediately quit
on e.g. the reload (SIGHUP) signal. Likely because the libunbound thread
would not have inherited the signal mask from the main Prosody thread.

Thanks Menel, riau and franck-x for reporting and help narrowing down

2 files changed, 43 insertions, 50 deletions

diff --git a/plugins/mod_posix.lua b/plugins/mod_posix.lua
index 3aa6a895..383769a2 100644
--- a/plugins/mod_posix.lua
+++ b/plugins/mod_posix.lua
@@ -15,10 +15,6 @@ if pposix._VERSION ~= want_pposix_version then
 		.. "Perhaps you need to recompile?", tostring(pposix._VERSION), want_pposix_version);
 end
 
-local have_signal, signal = pcall(require, "prosody.util.signal");
-if not have_signal then
-	module:log("warn", "Couldn't load signal library, won't respond to SIGTERM");
-end
 
 local lfs = require "lfs";
 local stat = lfs.attributes;
@@ -124,49 +120,3 @@ else
 end
 
 module:hook("server-stopped", remove_pidfile);
-
--- Set signal handlers
-if have_signal then
-	module:add_timer(0, function ()
-		signal.signal("SIGTERM", function ()
-			module:log("warn", "Received SIGTERM");
-			prosody.main_thread:run(function ()
-				prosody.unlock_globals();
-				prosody.shutdown("Received SIGTERM");
-				prosody.lock_globals();
-			end);
-		end);
-
-		signal.signal("SIGHUP", function ()
-			module:log("info", "Received SIGHUP");
-			prosody.main_thread:run(function ()
-				prosody.reload_config();
-			end);
-			-- this also reloads logging
-		end);
-
-		signal.signal("SIGINT", function ()
-			module:log("info", "Received SIGINT");
-			prosody.main_thread:run(function ()
-				prosody.unlock_globals();
-				prosody.shutdown("Received SIGINT");
-				prosody.lock_globals();
-			end);
-		end);
-
-		signal.signal("SIGUSR1", function ()
-			module:log("info", "Received SIGUSR1");
-			module:fire_event("signal/SIGUSR1");
-		end);
-
-		signal.signal("SIGUSR2", function ()
-			module:log("info", "Received SIGUSR2");
-			module:fire_event("signal/SIGUSR2");
-		end);
-	end);
-end
-
--- For other modules to reference
-features = {
-	signal_events = true;
-};
diff --git a/util/startup.lua b/util/startup.lua
index ba2a7cf6..37f9359f 100644
--- a/util/startup.lua
+++ b/util/startup.lua
@@ -671,6 +671,48 @@ function startup.make_dummy_hosts()
 	end
 end
 
+function startup.hook_posix_signals()
+	if prosody.platform ~= "posix" then return end
+	local have_signal, signal = pcall(require, "prosody.util.signal");
+	if not have_signal then
+		log("warn", "Couldn't load signal library, won't respond to SIGTERM");
+		return
+	end
+	signal.signal("SIGTERM", function()
+		log("warn", "Received SIGTERM");
+		prosody.main_thread:run(function()
+			prosody.unlock_globals();
+			prosody.shutdown("Received SIGTERM");
+			prosody.lock_globals();
+		end);
+	end);
+
+	signal.signal("SIGHUP", function()
+		log("info", "Received SIGHUP");
+		prosody.main_thread:run(function() prosody.reload_config(); end);
+		-- this also reloads logging
+	end);
+
+	signal.signal("SIGINT", function()
+		log("info", "Received SIGINT");
+		prosody.main_thread:run(function()
+			prosody.unlock_globals();
+			prosody.shutdown("Received SIGINT");
+			prosody.lock_globals();
+		end);
+	end);
+
+	signal.signal("SIGUSR1", function()
+		log("info", "Received SIGUSR1");
+		fire_event("signal/SIGUSR1");
+	end);
+
+	signal.signal("SIGUSR2", function()
+		log("info", "Received SIGUSR2");
+		fire_event("signal/SIGUSR2");
+	end);
+end
+
 function startup.cleanup()
 	prosody.log("info", "Shutdown status: Cleaning up");
 	prosody.events.fire_event("server-cleanup");
@@ -748,6 +790,7 @@ function startup.prosody()
 	startup.init_http_client();
 	startup.init_data_store();
 	startup.init_global_protection();
+	startup.hook_posix_signals();
 	startup.prepare_to_start();
 	startup.notify_started();
 end