reworking signal system

CMakeLists.txt

@@ -91,6 +91,7 @@ add_custom_command( OUTPUT signames.lua
 #
 set( DEFAULT_CODE
 	${PROJECT_SOURCE_DIR}/default/default.lua
+	${PROJECT_SOURCE_DIR}/default/signal.lua
 	${PROJECT_SOURCE_DIR}/default/rsync.lua
 	${PROJECT_SOURCE_DIR}/default/rsyncssh.lua
 	${PROJECT_SOURCE_DIR}/default/direct.lua

core/mci.c

@@ -773,8 +773,10 @@ mci_load_default(
 	// loads the default sync implementations
 	if( luaL_loadbuffer( L, default_out, default_size, "default" ) )
 	{
-		printlogf( L, "Error",
-			"loading default sync implementations: %s", lua_tostring( L, -1 ) );
+		printlogf(
+			L, "Error",
+			"loading default sync implementations: %s", lua_tostring( L, -1 )
+		);
 
 		exit( -1 );
 	}
@@ -787,8 +789,10 @@ mci_load_default(
 	// prepares the default sync implementations
 	if( lua_pcall( L, 0, 0, 0 ) )
 	{
-		printlogf( L, "Error",
-			"preparing default sync implementations: %s", lua_tostring( L, -1 ) );
+		printlogf(
+			L, "Error",
+			"preparing default sync implementations: %s", lua_tostring( L, -1 )
+		);
 
 		exit( -1 );
 	}

core/signal.c

@@ -60,16 +60,14 @@ volatile sig_atomic_t sigcode = 0;
 /*
 | signal handler
 */
-/*
 static void
 signal_child( int sig )
 {
 	// Nothing!
 	//
 	// This signal handler is just installed so the kernel
-	// keeps finished child processes as zombies waiting to be reaped.
+	// keeps finished sub-processes as zombies waiting to be reaped.
 }
-*/
 
 
 /*
@@ -132,6 +130,7 @@ l_onsignal(
 	int ok;
 	int h;
 	struct sigaction act;
+	bool have_sig_child = false;
 
 	// the block mask includes all signals that have registered handlers.
 	// it is used to block all signals outside the select() call
@@ -158,7 +157,8 @@ l_onsignal(
 		int signum = lua_tointegerx( L, -1 , &ok );
 		if( !ok ) continue;
 
-		// unsets this signal from the handlers buffer
+		// marks this signal to be used again in the
+		// new signal handler table.
 		for( h = 0; h < handlers_len; h++ )
 		{
 			if( handlers[ h ] == signum )
@@ -170,7 +170,8 @@ l_onsignal(
 		sigc++;
 	}
 
-	// resets no longer handlerd signals to default action
+	// resets no longer handled signals
+	// to their system default action
 	for( h = 0; h < handlers_len; h++ )
 	{
 		int signum = handlers[ h ];
@@ -224,15 +225,23 @@ l_onsignal(
 		int signum = lua_tointegerx( L, -1 , &ok );
 		if( !ok ) continue;
 
+		if( signum == SIGCHLD ) have_sig_child = true;
+
 		// stores registered signal handlers
 		handlers[ handlers_len++ ] = signum;
 
 		sigaction( signum, &act, 0 );
 	}
 
-	// FIXME listen to SIGCHLD if not specified
-	// Listens to SIGCHLD, but blocks it until pselect( )
-	// opens the signal handler up.
+	// If there is no custom SIGCHLD handler add one
+	// that will do nothing. This is needed by the OS
+	// so the Lsyncd subprocesses are zombified and
+	// can be reaped.
+	if( !have_sig_child )
+	{
+		act.sa_handler = &signal_child;
+		sigaction( SIGCHLD, &act, 0 );
+	}
 
 	return 0;
 }

default/signal.lua

@@ -0,0 +1,62 @@
+--
+-- signal.lua from Lsyncd -- the Live (Mirror) Syncing Demon
+--
+--
+-- The default signal handles for HUP, INT and TERM.
+--
+--
+-- License: GPLv2 (see COPYING) or any later version
+-- Authors: Axel Kittenberger <axkibe@gmail.com>
+--
+if not default then error( 'default not loaded' ) end
+
+
+default.signal = { }
+
+
+local function sighup
+( )
+	print( 'GOT A HUP SIGNAL' )
+
+	os.exit( 1 )
+end
+
+
+local function sigint
+( )
+	print( 'GOT AN INT SIGNAL' )
+
+	os.exit( 1 )
+end
+
+
+local function sigterm
+( )
+	print( 'GOT A TERM SIGNAL' )
+
+	os.exit( 1 )
+end
+
+
+--
+-- Sets up the default HUP/INT/TERM signal handlers.
+--
+-- Called after user scripts finished
+--
+init =
+	function
+( )
+	local hup = getsignal( 'HUP' )
+	local int = getsignal( 'INT' )
+	local term = getsignal( 'TERM' )
+
+	if hup ~= false then hup = sighup end
+	if int ~= false then int = sigint end
+	if term ~= false then term = sigterm end
+
+	onsignal(
+		'HUP', hup,
+		'INT', int,
+		'TERM', iterm
+	)
+end

mantle/mci.lua

@@ -386,7 +386,7 @@ function mci.initialize
 		os.exit( -1 )
 	end
 
-	initSignalHandlers( firstTime )
+	if userENV.init then userENV.init( ) end
 
 	lastReportedWaiting = false
 
@@ -496,7 +496,7 @@ end
 --
 function mci.getAlarm
 ( )
-	log( 'Function', 'getAlarm( )' )
+	log( 'Function', 'getAlarm( )', lsyncdStatus )
 
 	if lsyncdStatus ~= 'run' then return false end
 
@@ -537,10 +537,7 @@ function mci.getAlarm
 			checkAlarm( s:getAlarm( ) )
 		end
 	else
-		log(
-			'Alarm',
-			'at global process limit.'
-		)
+		log( 'Alarm', 'at global process limit.' )
 	end
 
 	-- checks if a statusfile write has been delayed

mantle/signal.lua

@@ -38,90 +38,88 @@ local sigHandlerCount = 0
 
 
 --
--- Prepares an onsignal handle.
--- It changes the mantle data, but does not yet tell the core about it.
+-- transforms a signal name or number to
+-- a valid number. 'false' is left be 'false'
 --
--- To be used only internally to combine multiple changes into one.
+-- In case of a invalid signal specifie an error is raised.
 --
-local function onsignalPrep
+local function toSignum
 (
-	signal, -- signal number or name
-	handler -- function to call
-	--      -- or nil to unload the handle
-	--      -- or false to disable default signal handlers
+	signal
 )
-	local signum
-
 	if type( signal ) == 'number'
 	then
 		if signal < 0
 		or signal ~= signal
 		or signal - floor( signal ) ~= 0
 		then
-			error( 'signal ' .. signal .. ' is an invalid number.' , 2 )
+			error( 'signal ' .. signal .. ' is an invalid number.' , 3 )
 		end
-		signum = signal
+
+		return signal
 	elseif type( signal ) == 'string'
 	then
 		signum = signums[ signal ]
+
 		if signum == nil
 		then
-			error( 'signal "' .. signal .. '" unknown.' , 2 )
+			error( 'signal "' .. signal .. '" unknown.' , 3 )
 		end
-	else
-		error( 'signal of type ' .. type( signal ) .. ' invalid.', 2 )
-	end
 
-	sigHandlers[ signum ] = handler
+		return signum
+	elseif signal == false
+	then
+		return false
+	else
+		error( 'signal of type ' .. type( signal ) .. ' invalid.', 3 )
+	end
 end
 
+
 --
 -- The onsignal( ) function exported to userEnv.
 --
 function onsignal
 (
-	signal, -- signal number or name
-	handler -- function to call
-	--      -- or nil to unload the handle
-	--      -- or false to disable default signal handlers
+	...
+	--- signal1, -- signal number or name
+	--- handler1 -- function to call
+	--           -- or nil to unload the handle
+	--           -- or false to disable default signal handlers
+	-- signal2, handler2
+	-- signal3, handler3
+	-- and so on
 )
-	onsignalPrep( signal, handler )
+	local n = select( '#', ... )
+	local arg = {...}
+
+	if n % 2 ~= 0
+	then
+		error( 'onsignal with uneven number of arguments called', 2 )
+	end
+
+	for a = 1, n, 2
+	do
+		local signal = arg[ a ]
+		local handler = arg[ a + 1 ]
+
+		local signum = toSignum( signal )
+
+		sigHandlers[ signum ] = handler
+	end
 
 	core.onsignal( sigHandlers )
 end
 
 
 --
--- Sets up the default HUP/INT/TERM signal handlers.
+-- Returns signal handler registered for 'signum'
 --
--- Called after user scripts finished
---
-function initSignalHandlers
+function getsignal
 (
-	firstTime --- TODO check if needed
+	signum
 )
-	onsignalPrep(
-		'HUP',
-		function( )
-			print( 'GOT A HUP SIGNAL' )
-		end
-	)
-
-	onsignalPrep(
-		'INT',
-		function( )
-			print( 'GOT A INT SIGNAL' )
-		end
-	)
-
-	onsignalPrep(
-		'TERM',
-		function( )
-			print( 'GOT A TERM SIGNAL' )
-		end
-	)
-
-	core.onsignal( sigHandlers )
+	return sigHandlers[ signum ];
 end
 
 

mantle/userenv.lua

@@ -21,6 +21,7 @@ userENV =
 	dofile = dofile,
 	error = error,
 	getmetatable = getmetable,
+	getsignal = getsignal,
 	io = io,
 	ipairs = ipairs,
 	load = load,
@@ -29,6 +30,7 @@ userENV =
 	math = math,
 	module = module,
 	next = next,
+	onsignal = onsignal,
 	os = os,
 	package = package,
 	pairs = pairs,