reworking signal system

CMakeLists.txt

@@ -65,10 +65,10 @@ set( MANTLE_CODE
 	${PROJECT_SOURCE_DIR}/mantle/syncmaster.lua
 	${PROJECT_SOURCE_DIR}/mantle/monitor.lua
 	${PROJECT_SOURCE_DIR}/mantle/fwriter.lua
-	${PROJECT_SOURCE_DIR}/mantle/signal.lua
 	${PROJECT_SOURCE_DIR}/mantle/statusfile.lua
 	${PROJECT_SOURCE_DIR}/mantle/useralarm.lua
 	${PROJECT_SOURCE_DIR}/mantle/mci.lua
+	${PROJECT_SOURCE_DIR}/mantle/signal.lua
 	${PROJECT_SOURCE_DIR}/mantle/user.lua
 	${PROJECT_SOURCE_DIR}/mantle/string.lua
 	${PROJECT_SOURCE_DIR}/mantle/version.lua

core/mci.c

@@ -460,6 +460,7 @@ l_stackdump( lua_State * L )
 	return 0;
 }
 
+
 /*
 | Reads the directories entries.
 |
@@ -650,7 +651,7 @@ static const luaL_Reg corelib[ ] =
 	{ "now",            l_now           },
 	{ "nonobserve_fd",  l_nonobserve_fd },
 	{ "observe_fd",     l_observe_fd    },
-//	{ "onsignal",       l_onsignal      },
+	{ "onsignal",       l_onsignal      },
 	{ "readdir",        l_readdir       },
 	{ "realdir",        l_realdir       },
 	{ "stackdump",      l_stackdump     },

core/mem.c

@@ -27,7 +27,7 @@
 #include "log.h"
 
 /*
-| "Secured" calloc
+| "Secured" calloc.
 */
 extern void *
 s_calloc( size_t nmemb, size_t size )
@@ -63,7 +63,7 @@ s_malloc( size_t size )
 
 
 /*
-| "Secured" realloc
+| "Secured" realloc.
 */
 extern void *
 s_realloc( void * ptr, size_t size )
@@ -81,7 +81,7 @@ s_realloc( void * ptr, size_t size )
 
 
 /*
-| "Secured" strdup
+| "Secured" strdup.
 */
 extern char *
 s_strdup( const char *src )

core/observe.c

@@ -240,11 +240,12 @@ observe_select
 	// that puts Lsyncd to sleep until anything worth noticing
 	// happens
 
-	pr = pselect(
-		observances[ observances_len - 1 ].fd + 1,
-		&rfds, &wfds, NULL,
-		timeout, &sigset
-	);
+	pr =
+		pselect(
+			observances[ observances_len - 1 ].fd + 1,
+			&rfds, &wfds, NULL,
+			timeout, &sigset
+		);
 
 	// FIXME handle signals
 

core/signal.c

@@ -10,7 +10,9 @@
 */
 #include "feature.h"
 
+#include <stdbool.h>
 #include <stddef.h>
+#include <stdlib.h>
 #include <signal.h>
 #include <string.h>
 
@@ -19,6 +21,7 @@
 #include <lualib.h>
 #include <lauxlib.h>
 
+#include "log.h"
 #include "mem.h"
 
 
@@ -26,13 +29,6 @@ static volatile sig_atomic_t * queue;
 static int queue_len;
 static int queue_pos;
 
-/*
-| XXX
-*/
-static int *handlers;
-static int handlers_len;
-static int handlers_maxlen;
-
 
 /*
 | Set by TERM or HUP signal handler
@@ -49,7 +45,8 @@ volatile sig_atomic_t sigcode = 0;
 /*
 | signal handler
 */
-static void signal_child( int sig )
+static void
+signal_child( int sig )
 {
 	// Nothing!
 	//
@@ -64,23 +61,24 @@ static void signal_child( int sig )
 static void
 signal_handler( int sig )
 {
-	switch( sig )
+	// looks if this signal is already queued
+	for( int i = 0; i < queue_pos; i++ )
 	{
-		case SIGTERM:
-		case SIGINT:
-			term = 1;
-			sigcode = sig;
-			return;
-
-		case SIGHUP:
-			hup = 1;
-			return;
+		// if so it is dropped
+		if( queue[ i ] == sig ) return;
 	}
+
+	if( queue_pos + 1 >= queue_len )
+	{
+		// this should never ever happen
+		logstring( "Error", "Signal queue overflow!" );
+		exit( -1 );
+	}
+
+	queue[ queue_pos++ ] = sig;
 }
 
 
-
-
 /*
 | Initializes signal handling.
 |
@@ -93,22 +91,90 @@ signal_init( )
 	queue_len = 5;
 	queue = s_malloc( queue_len * sizeof( sig_atomic_t ) );
 	queue_pos = 0;
-
-	handlers_maxlen = 5;
-	handlers_len = 0;
-	handlers = s_malloc( handlers_maxlen * sizeof( int * ) );
 }
 
+
 /*
-	sigset_t set;
-	sigemptyset( &set );
-	sigaddset( &set, SIGCHLD );
-	signal( SIGCHLD, signal_child );
-	sigprocmask( SIG_BLOCK, &set, NULL );
-
-	signal( SIGHUP,  signal_handler );
-	signal( SIGTERM, signal_handler );
-	signal( SIGINT,  signal_handler );
-}
+| Registers (or deregisters) a signal handlers.
+|
+| Params on Lua stack:
+|     1: table of all signal handlers
+|
+| Returns on Lua stack:
+|
+|     true if the signal could be registered with the kernel/libc
+|     false if they denied it
 */
+int
+l_onsignal( lua_State *L )
+{
+	int sigc = 0;
+	int ok;
+
+	// the block mask includes all signals that have registered handlers.
+	// it is used to block all signals outside the select() call
+	// and also during the core signal handler runs.
+	sigset_t blockmask;
+	sigemptyset( &blockmask );
+	sigaddset( &blockmask, SIGCHLD );
+
+	// first time iterates the signal handler table to build
+	// the blockmask
+
+	lua_pushnil( L );
+	while( lua_next( L, -2 ) )
+	{
+		int htype = lua_type( L, -1 ); // the handle
+
+		// pops the value, leaves the key on stack
+		lua_pop( L, 1 );
+
+		// not a handler function (probably false)
+		if( htype != LUA_TFUNCTION ) continue;
+
+		int signum = lua_tointegerx( L, -1 , &ok );
+		if( !ok ) continue;
+
+		sigc++;
+	}
+
+	// and block those signals
+	sigprocmask( SIG_BLOCK, &blockmask, NULL );
+
+	// if there are more signal handlers than
+	// the signal queue allows, it is enlarged.
+	if( sigc >= queue_len )
+	{
+		while( sigc >= queue_len ) queue_len *= 2;
+		queue = s_realloc( (sig_atomic_t *)( queue ), queue_len * sizeof( sig_atomic_t ) );
+	}
+
+	// now iterates the signal handler table
+	// once again to register the signal handlers.
+
+	struct sigaction act;
+	memset (&act, '\0', sizeof(act));
+	act.sa_mask = blockmask;
+
+	lua_pushnil( L );
+	while( lua_next( L, -2 ) )
+	{
+		int htype = lua_type( L, -1 ); // the handle
+		act.sa_handler = &signal_handler;
+
+
+		// pops the value, leaves the key on stack
+		lua_pop( L, 1 );
+
+		// not a handler function (probably false)
+		if( htype != LUA_TFUNCTION ) continue;
+
+		int signum = lua_tointegerx( L, -1 , &ok );
+		if( !ok ) continue;
+
+		sigaction( signum, &act, 0 );
+	}
+
+	return 0;
+}
 

core/signal.h

@@ -18,4 +18,7 @@ extern volatile sig_atomic_t sigcode;
 // Initializes signal handling.
 extern void signal_init( );
 
+// FIXME
+int l_onsignal( lua_State *L );
+
 #endif

mantle/mci.lua

@@ -244,12 +244,6 @@ function mci.configure(
 	args,     -- arguments given by user
 	monitors  -- list of monitors the core can do
 )
-	print( "mci.configure", #args )
-
-	for k, v in pairs( args ) do
-		print( 'a', k, v )
-	end
-
 	Monitor.initialize( monitors )
 
 	--
@@ -268,10 +262,7 @@ function mci.configure(
 		delay =
 		{
 			1,
-			function
-			(
-				secs
-			)
+			function( secs )
 				clSettings.delay = secs + 0
 			end
 		},
@@ -281,10 +272,7 @@ function mci.configure(
 		logfile =
 		{
 			1,
-			function
-			(
-				file
-			)
+			function( file )
 				clSettings.logfile = file
 			end
 		},
@@ -292,8 +280,7 @@ function mci.configure(
 		version =
 		{
 			0,
-			function
-			( )
+			function( )
 				io.stdout:write( 'Version: ', lsyncd_version, '\n' )
 
 				os.exit( 0 )

mantle/signal.lua

@@ -25,17 +25,27 @@ end
 
 
 -- a table of all registered signal handlers
-local sigHandlers = { }
+--
+-- keys are signal numbers
+-- values are functions to be called
+-- or 'false' in case of disabled default signals
+--
+-- On signal the core will directly look up this table.
+mci.sigHandlers = { }
 
 -- counter of signal handlers
 -- used to tell the core to enlarge the signal queue if needed
 -- (the queue must be as large as the number of different signals listened for)
 local sigHandlerCount = 0
 
+
 --
--- onsignal function exported to userEnv
+-- Prepares an onsignal handle.
+-- It changes the mantle data, but does not yet tell the core about it.
 --
-function onsignal
+-- To be used only internally to combine multiple changes into one.
+--
+local function onsignalPrep
 (
 	signal, -- signal number or name
 	handler -- function to call
@@ -52,12 +62,10 @@ function onsignal
 		then
 			error( 'signal ' .. signal .. ' is an invalid number.' , 2 )
 		end
-
 		signum = signal
 	elseif type( signal ) == 'string'
 	then
 		signum = signums[ signal ]
-
 		if signum == nil
 		then
 			error( 'signal "' .. signal .. '" unknown.' , 2 )
@@ -66,10 +74,22 @@ function onsignal
 		error( 'signal of type ' .. type( signal ) .. ' invalid.', 2 )
 	end
 
-	-- FIXME store the handler in a table
-	-- FIXME tell core of max queue size
+	mci.sigHandlers[ signum ] = handler
+end
 
-	core.onsignal( signum, handler );
+--
+-- 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
+)
+	onsignalPrep( signal, handler )
+
+	core.onsignal( mci.sigHandlers )
 end
 
 
@@ -82,24 +102,27 @@ function initSignalHandlers
 (
 	firstTime --- TODO check if needed
 )
-	onsignal(
+	onsignalPrep(
 		'HUP',
 		function( )
 			console.log( 'GOT A HUP SIGNAL' );
 		end
 	)
 
-	onsignal(
+	onsignalPrep(
 		'INT',
 		function( )
 			console.log( 'GOT A INT SIGNAL' );
 		end
 	)
 
-	onsignal(
+	onsignalPrep(
 		'TERM',
 		function( )
 			console.log( 'GOT A TERM SIGNAL' );
 		end
 	)
+
+	core.onsignal( mci.sigHandlers )
 end
+