From 24ba10b6b119a23ec2a4c5a7fe81276e2fb30cc2 Mon Sep 17 00:00:00 2001
From: Aaron Jones <aaronmdjones@gmail.com>
Date: Sun, 21 Aug 2016 00:34:38 +0000
Subject: [PATCH] Tidy up daemonisation with regard to file descriptor mess

This moves daemonisation to the end of initialisation which
vastly simplifies the reporting logic and eliminates the need
for the child to communicate to the parent.

This is a backport from the release/4 branch.
---
 src/ircd.c | 86 +++++++++++++++++-------------------------------------
 1 file changed, 27 insertions(+), 59 deletions(-)

diff --git a/src/ircd.c b/src/ircd.c
index 5b0648f4..4aeb6c63 100644
--- a/src/ircd.c
+++ b/src/ircd.c
@@ -149,39 +149,6 @@ ircd_shutdown(const char *reason)
 	exit(0);
 }
 
-/*
- * print_startup - print startup information
- */
-static void
-print_startup(int pid)
-{
-	int fd;
-
-	close(1);
-	fd = open("/dev/null", O_RDWR);
-	if (fd == -1) {
-		perror("open /dev/null");
-		exit(EXIT_FAILURE);
-	}
-	if (fd == 0)
-		fd = dup(fd);
-	if (fd != 1)
-		abort();
-
-	inotice("now running in %s mode from %s as pid %d ...",
-	       !server_state_foreground ? "background" : "foreground",
-        	ConfigFileEntry.dpath, pid);
-
-	/* let the parent process know the initialization was successful
-	 * -- jilles */
-	if (!server_state_foreground)
-		write(0, ".", 1);
-	if (dup2(1, 0) == -1)
-		abort();
-	if (dup2(1, 2) == -1)
-		abort();
-}
-
 /*
  * init_sys
  *
@@ -213,17 +180,18 @@ init_sys(void)
 static int
 make_daemon(void)
 {
-	int pid;
-	int pip[2];
-	char c;
+	int pid, nullfd, fdx;
 
-	if (pipe(pip) < 0)
+	/* The below is approximately what daemon(1, 0) does, but
+	   we need control over the parent after forking to print
+	   the startup message -- Aaron */
+
+	if((nullfd = open("/dev/null", O_RDWR)) < 0)
 	{
-		perror("pipe");
+		perror("open /dev/null");
 		exit(EXIT_FAILURE);
 	}
-	dup2(pip[1], 0);
-	close(pip[1]);
+
 	if((pid = fork()) < 0)
 	{
 		perror("fork");
@@ -231,22 +199,20 @@ make_daemon(void)
 	}
 	else if(pid > 0)
 	{
-		close(0);
-		/* Wait for initialization to finish, successfully or
-		 * unsuccessfully. Until this point the child may still
-		 * write to stdout/stderr.
-		 * -- jilles */
-		if (read(pip[0], &c, 1) > 0)
-			exit(EXIT_SUCCESS);
-		else
-			exit(EXIT_FAILURE);
+		inotice("now running in background mode from %s as pid %d ...",
+		        ConfigFileEntry.dpath, pid);
+
+		exit(EXIT_SUCCESS);
 	}
 
-	close(pip[0]);
-	setsid();
-/*	fclose(stdin);
-	fclose(stdout);
-	fclose(stderr); */
+	for(fdx = 0; fdx <= 2; fdx++)
+		if (fdx != nullfd)
+			(void) dup2(nullfd, fdx);
+
+	if(nullfd > 2)
+		(void) close(nullfd);
+
+	(void) setsid();
 
 	return 0;
 }
@@ -619,9 +585,6 @@ main(int argc, char *argv[])
 	if(!testing_conf)
 	{
 		check_pidfile(pidFileName);
-
-		if(!server_state_foreground)
-			make_daemon();
 		inotice("starting %s ...", ircd_version);
 		inotice("%s", rb_lib_version());
 	}
@@ -739,7 +702,6 @@ main(int argc, char *argv[])
 	construct_umodebuf();
 
 	check_class();
-	write_pidfile(pidFileName);
 	load_help();
 	open_logfiles();
 
@@ -758,7 +720,13 @@ main(int argc, char *argv[])
 	if(splitmode)
 		check_splitmode_ev = rb_event_add("check_splitmode", check_splitmode, NULL, 5);
 
-	print_startup(getpid());
+	if(server_state_foreground)
+		inotice("now running in foreground mode from %s as pid %d ...",
+		        ConfigFileEntry.dpath, getpid());
+	else
+		make_daemon();
+
+	write_pidfile(pidFileName);
 
 	rb_lib_loop(0);