Add new 'delayed' signal handlers.

Allows to defer/queue signal processing for execution on the next
event dispatch call, i.e. we can perform any signal action in
normal, non-signal context.

Example uses:
- Reload everything on HUP without writing a global "SIGHUP_received"
  variable
- Dump status of internal Lists on SIGUSR1, etc.

configure.in

@@ -159,7 +159,7 @@ AC_CHECK_FUNCS([ \
 	bind gethostbyaddr gethostbyname gethostname inet_ntoa \
 	setsid setsockopt socket strcasecmp waitpid],,AC_MSG_ERROR([required function missing!]))
 
-AC_CHECK_FUNCS(getaddrinfo getnameinfo inet_aton isdigit sigaction snprintf \
+AC_CHECK_FUNCS(getaddrinfo getnameinfo inet_aton isdigit sigaction sigprocmask snprintf \
  vsnprintf strdup strlcpy strlcat strtok_r)
 
 # -- Configuration options --

src/ngircd/Makefile.am

@@ -21,7 +21,7 @@ sbin_PROGRAMS = ngircd
 ngircd_SOURCES = ngircd.c array.c channel.c client.c conf.c conn.c conn-func.c \
 	conn-ssl.c conn-zip.c hash.c io.c irc.c irc-channel.c irc-info.c irc-login.c \
 	irc-mode.c irc-op.c irc-oper.c irc-server.c irc-write.c lists.c log.c \
-	match.c op.c numeric.c pam.c parse.c proc.c rendezvous.c resolve.c
+	match.c op.c numeric.c pam.c parse.c proc.c rendezvous.c resolve.c sighandlers.c
 
 ngircd_LDFLAGS = -L../portab -L../tool -L../ipaddr
 

src/ngircd/conn.c

@@ -477,11 +477,6 @@ Conn_InitListeners( void )
 	unsigned int created = 0;
 	char *copy, *listen_addr;
 
-	if (!io_library_init(CONNECTION_POOL)) {
-		Log(LOG_EMERG, "Cannot initialize IO routines: %s", strerror(errno));
-		return -1;
-	}
-
 	assert(Conf_ListenAddress);
 
 	/* can't use Conf_ListenAddress directly, see below */

src/ngircd/ngircd.c

@@ -29,7 +29,6 @@
 #include <time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <sys/wait.h>
 #include <fcntl.h>
 #include <pwd.h>
 #include <grp.h>
@@ -46,6 +45,8 @@
 #include "lists.h"
 #include "log.h"
 #include "parse.h"
+#include "sighandlers.h"
+#include "io.h"
 #include "irc.h"
 
 #ifdef ZEROCONF
@@ -56,9 +57,6 @@
 #include "ngircd.h"
 
 
-static void Initialize_Signal_Handler PARAMS(( void ));
-static void Signal_Handler PARAMS(( int Signal ));
-
 static void Show_Version PARAMS(( void ));
 static void Show_Help PARAMS(( void ));
 
@@ -292,8 +290,15 @@ main( int argc, const char *argv[] )
 		 * when not running in "no daemon" mode: */
 		if( ! NGIRCd_NoDaemon ) Log_InitErrorfile( );
 #endif
+		if (!io_library_init(CONNECTION_POOL)) {
+			Log(LOG_ALERT, "Fatal: Cannot initialize IO routines: %s", strerror(errno));
+			exit(1);
+		}
 
-		Initialize_Signal_Handler( );
+		if (!Signals_Init()) {
+			Log(LOG_ALERT, "Fatal: Could not set up signal handlers: %s", strerror(errno));
+			exit(1);
+		}
 
 		/*
 		 * create protocol and server identification.
@@ -475,80 +480,6 @@ NGIRCd_Rehash( void )
 } /* NGIRCd_Rehash */
 
 
-/**
- * Initialize the signal handler.
- */
-static void
-Initialize_Signal_Handler( void )
-{
-#ifdef HAVE_SIGACTION
-	struct sigaction saction;
-
-	memset( &saction, 0, sizeof( saction ));
-	saction.sa_handler = Signal_Handler;
-#ifdef SA_RESTART
-	saction.sa_flags |= SA_RESTART;
-#endif
-#ifdef SA_NOCLDWAIT
-	saction.sa_flags |= SA_NOCLDWAIT;
-#endif
-
-	sigaction(SIGINT, &saction, NULL);
-	sigaction(SIGQUIT, &saction, NULL);
-	sigaction(SIGTERM, &saction, NULL);
-	sigaction(SIGHUP, &saction, NULL);
-	sigaction(SIGCHLD, &saction, NULL);
-
-	/* we handle write errors properly; ignore SIGPIPE */
-	saction.sa_handler = SIG_IGN;
-	sigaction(SIGPIPE, &saction, NULL);
-#else
-	signal(SIGINT, Signal_Handler);
-	signal(SIGQUIT, Signal_Handler);
-	signal(SIGTERM, Signal_Handler);
-	signal(SIGHUP, Signal_Handler);
-	signal(SIGCHLD, Signal_Handler);
-
-	signal(SIGPIPE, SIG_IGN);
-#endif
-} /* Initialize_Signal_Handler */
-
-
-/**
- * Signal handler of ngIRCd.
- * This function is called whenever ngIRCd catches a signal sent by the
- * user and/or the system to it. For example SIGTERM and SIGHUP.
- * @param Signal Number of the signal to handle.
- */
-static void
-Signal_Handler( int Signal )
-{
-	switch( Signal )
-	{
-		case SIGTERM:
-		case SIGINT:
-		case SIGQUIT:
-			/* shut down sever */
-			NGIRCd_SignalQuit = true;
-			break;
-		case SIGHUP:
-			/* re-read configuration */
-			NGIRCd_SignalRehash = true;
-			break;
-		case SIGCHLD:
-			/* child-process exited, avoid zombies */
-			while (waitpid( -1, NULL, WNOHANG) > 0)
-				;
-			break;
-#ifdef DEBUG
-		default:
-			/* unbekanntes bzw. unbehandeltes Signal */
-			Log( LOG_DEBUG, "Got signal %d! Ignored.", Signal );
-#endif
-	}
-} /* Signal_Handler */
-
-
 /**
  * Display copyright and version information of ngIRCd on the console.
  */

src/ngircd/ngircd.h

@@ -21,6 +21,8 @@
 
 #include "defines.h"
 
+#define C_ARRAY_SIZE(x)	(sizeof(x)/sizeof((x)[0]))
+
 
 GLOBAL time_t NGIRCd_Start;		/* Startzeitpunkt des Daemon */
 GLOBAL char NGIRCd_StartStr[64];

src/ngircd/parse.c

@@ -120,8 +120,6 @@ static bool Validate_Args PARAMS(( CONN_ID Idx, REQUEST *Req, bool *Closed ));
 
 static bool Handle_Request PARAMS(( CONN_ID Idx, REQUEST *Req ));
 
-#define ARRAY_SIZE(x)	(sizeof(x)/sizeof((x)[0]))
-
 /**
  * Return the pointer to the global "IRC command structure".
  * This structure, an array of type "COMMAND" describes all the IRC commands
@@ -397,7 +395,7 @@ Handle_Numeric(CLIENT *client, REQUEST *Req)
 		/* This server is the target of the numeric */
 		num = atoi(Req->command);
 
-		for (i = 0; i < (int) ARRAY_SIZE(Numerics); i++) {
+		for (i = 0; i < (int) C_ARRAY_SIZE(Numerics); i++) {
 			if (num == Numerics[i].numeric) {
 				if (!Numerics[i].function)
 					return CONNECTED;

src/ngircd/proc.c

@@ -26,6 +26,7 @@
 #include "conn.h"
 
 #include "exp.h"
+#include "sighandlers.h"
 #include "proc.h"
 
 /**
@@ -67,6 +68,7 @@ Proc_Fork(PROC_STAT *proc, int *pipefds, void (*cbfunc)(int, short), int timeout
 		return -1;
 	case 0:
 		/* New child process: */
+		Signals_Exit();
 		signal(SIGTERM, Proc_GenericSignalHandler);
 		signal(SIGALRM, Proc_GenericSignalHandler);
 		close(pipefds[0]);

src/ngircd/sighandlers.c

@@ -0,0 +1,220 @@
+/*
+ * ngIRCd -- The Next Generation IRC Daemon
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * Please read the file COPYING, README and AUTHORS for more information.
+ */
+
+#include "portab.h"
+
+/**
+ * @file
+ * Signal Handlers: Actions to be performed when the program
+ * receives a signal.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "imp.h"
+#include "io.h"
+#include "log.h"
+#include "ngircd.h"
+#include "sighandlers.h"
+
+static int signalpipe[2];
+
+static void Signal_Block(int sig)
+{
+#ifdef HAVE_SIGPROCMASK
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+
+	sigprocmask(SIG_BLOCK, &set, NULL);
+#endif
+}
+
+
+static void Signal_Unblock(int sig)
+{
+#ifdef HAVE_SIGPROCMASK
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+
+	sigprocmask(SIG_UNBLOCK, &set, NULL);
+#endif
+}
+
+
+/**
+ * Signal handler of ngIRCd.
+ * This function is called whenever ngIRCd catches a signal sent by the
+ * user and/or the system to it. For example SIGTERM and SIGHUP.
+ *
+ * It blocks the signal and queues it for later execution by Signal_Handler_BH.
+ * @param Signal Number of the signal to handle.
+ */
+static void Signal_Handler(int Signal)
+{
+	switch (Signal) {
+	case SIGTERM:
+	case SIGINT:
+	case SIGQUIT:
+		/* shut down sever */
+		NGIRCd_SignalQuit = true;
+		return;
+	case SIGHUP:
+		/* re-read configuration */
+		NGIRCd_SignalRehash = true;
+		return;
+	case SIGCHLD:
+		/* child-process exited, avoid zombies */
+		while (waitpid( -1, NULL, WNOHANG) > 0)
+			;
+		return;
+	}
+
+	/*
+	 * other signal: queue for later execution.
+	 * This has the advantage that we are not restricted
+	 * to functions that can be called safely from signal handlers.
+	 */
+	if (write(signalpipe[1], &Signal, sizeof(Signal)) != -1)
+		Signal_Block(Signal);
+} /* Signal_Handler */
+
+
+/**
+ * Signal processing handler of ngIRCd.
+ * This function is called from the main conn event loop in (io_dispatch)
+ * whenever ngIRCd has queued a signal.
+ *
+ * This function runs in normal context, not from the real signal handler,
+ * thus its not necessary to only use functions that are signal safe.
+ * @param Signal Number of the signal that was queued.
+ */
+static void Signal_Handler_BH(int Signal)
+{
+	switch (Signal) {
+#ifdef DEBUG
+	default:
+		Log(LOG_DEBUG, "Got signal %d! Ignored.", Signal);
+#endif
+	}
+	Signal_Unblock(Signal);
+}
+
+static void Sig_callback(int fd, short UNUSED what)
+{
+	int sig, ret;
+	(void) what;
+
+	do {
+		ret = read(fd, &sig, sizeof(sig));
+		if (ret == sizeof(int))
+			Signal_Handler_BH(sig);
+	} while (ret == sizeof(int));
+
+	if (ret == -1) {
+		if (errno == EAGAIN || errno == EINTR)
+			return;
+
+		Log(LOG_EMERG, "read from signal pipe: %s", strerror(errno));
+		exit(1);
+	}
+
+	Log(LOG_EMERG, "EOF on signal pipe");
+	exit(1);
+}
+
+
+static const int signals_catch[] = { SIGINT, SIGQUIT, SIGTERM, SIGHUP, SIGCHLD, SIGUSR1, SIGUSR2 };
+/**
+ * Initialize the signal handlers, catch
+ * those signals we are interested in and sets SIGPIPE to be ignored.
+ * @return true if initialization was sucessful.
+ */
+bool Signals_Init(void)
+{
+	size_t i;
+#ifdef HAVE_SIGACTION
+	struct sigaction saction;
+#endif
+
+	if (pipe(signalpipe))
+		return false;
+
+	if (!io_setnonblock(signalpipe[0]) ||
+	    !io_setnonblock(signalpipe[1]))
+		return false;
+	if (!io_setcloexec(signalpipe[0]) ||
+	    !io_setcloexec(signalpipe[1]))
+		return false;
+#ifdef HAVE_SIGACTION
+	memset( &saction, 0, sizeof( saction ));
+	saction.sa_handler = Signal_Handler;
+#ifdef SA_RESTART
+	saction.sa_flags |= SA_RESTART;
+#endif
+#ifdef SA_NOCLDWAIT
+	saction.sa_flags |= SA_NOCLDWAIT;
+#endif
+
+	for (i=0; i < C_ARRAY_SIZE(signals_catch) ; i++)
+		sigaction(signals_catch[i], &saction, NULL);
+
+	/* we handle write errors properly; ignore SIGPIPE */
+	saction.sa_handler = SIG_IGN;
+	sigaction(SIGPIPE, &saction, NULL);
+#else
+	for (i=0; i < C_ARRAY_SIZE(signals_catch) ; i++)
+		signal(signals_catch[i], Signal_Handler);
+
+	signal(SIGPIPE, SIG_IGN);
+#endif
+	return io_event_create(signalpipe[0], IO_WANTREAD,
+					Sig_callback);
+} /* Initialize_Signal_Handler */
+
+
+/**
+ * Restores signals to their default behaviour.
+ *
+ * This should be called after a fork() in the new
+ * child prodcess, especially when we are about to call
+ * 3rd party code (e.g. PAM).
+ */
+void Signals_Exit(void)
+{
+	size_t i;
+#ifdef HAVE_SIGACTION
+	struct sigaction saction;
+
+	memset(&saction, 0, sizeof(saction));
+	saction.sa_handler = SIG_DFL;
+
+	for (i=0; i < C_ARRAY_SIZE(signals_catch) ; i++)
+		sigaction(signals_catch[i], &saction, NULL);
+	sigaction(SIGPIPE, &saction, NULL);
+#else
+	for (i=0; i < C_ARRAY_SIZE(signals_catch) ; i++)
+		sigaction(signals_catch[i], &saction, NULL);
+	signal(SIGPIPE, SIG_DFL);
+#endif
+	close(signalpipe[1]);
+	close(signalpipe[0]);
+}
+
+/* -eof- */

src/ngircd/sighandlers.h

@@ -0,0 +1,18 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * Please read the file COPYING, README and AUTHORS for more information.
+ */
+
+#ifndef signals_included_
+#define signals_included_
+
+#include "portab.h"
+
+bool Signals_Init(void);
+void Signals_Exit(void);
+
+
+#endif