Run daemons in their own session.

init/init.c

@@ -313,6 +313,7 @@ struct communication
 
 static pid_t main_pid;
 static pid_t forward_signal_pid = -1;
+static int tty_fd;
 
 static volatile sig_atomic_t caught_exit_signal = -1;
 static sigset_t handled_signals;
@@ -2545,31 +2546,24 @@ static void daemon_start(struct daemon* daemon)
 		fatal("fork: %m");
 	if ( daemon->need_tty )
 	{
-		if ( tcgetattr(0, &daemon->oldtio) )
+		if ( tcgetattr(tty_fd, &daemon->oldtio) )
 			fatal("tcgetattr: %m");
 	}
 	if ( daemon->pid == 0 )
 	{
 		uninstall_signal_handler();
 		close(errfds[0]);
+		if ( setsid() < 0 )
+			exit_errfd(errfds[1], "setsid");
 		if ( chdir(cd) < 0 )
 			exit_errfd(errfds[1], "chdir");
 		if ( daemon->need_tty )
 		{
-			pid_t pid = getpid();
+			if ( ioctl(tty_fd, TIOCSCTTY, 1) < 0 )
-			// TODO: Support for setsid(2).
+				exit_errfd(errfds[1], "TIOCSCTTY");
-			if ( setpgid(0, 0) < 0 )
-				exit_errfd(errfds[1], "setpgid");
-			sigset_t oldset, sigttou;
-			sigemptyset(&sigttou);
-			sigaddset(&sigttou, SIGTTOU);
-			sigprocmask(SIG_BLOCK, &sigttou, &oldset);
-			if ( tcsetpgrp(0, pid) < 0 )
-				exit_errfd(errfds[1], "tcsetpgrp");
 			daemon->oldtio.c_cflag |= CREAD;
-			if ( tcsetattr(0, TCSANOW, &daemon->oldtio) < 0 )
+			if ( tcsetattr(tty_fd, TCSANOW, &daemon->oldtio) < 0 )
 				exit_errfd(errfds[1], "tcsetattr");
-			sigprocmask(SIG_SETMASK, &oldset, NULL);
 			dup3(errfds[1], 3, O_CLOEXEC);
 			closefrom(4);
 		}
@@ -2723,10 +2717,10 @@ static void daemon_on_exit(struct daemon* daemon, int exit_code)
 		sigemptyset(&sigttou);
 		sigaddset(&sigttou, SIGTTOU);
 		sigprocmask(SIG_BLOCK, &sigttou, &oldset);
-		if ( tcsetattr(0, TCSAFLUSH, &daemon->oldtio) )
+		if ( tcsetattr(tty_fd, TCSAFLUSH, &daemon->oldtio) )
 			fatal("tcsetattr: %m");
-		if ( tcsetpgrp(0, getpgid(0)) < 0 )
+		if ( ioctl(tty_fd, TIOCSCTTY, 1) < 0 )
-			fatal("tcsetpgrp: %m");
+			fatal("TIOCSCTTY: %m");
 		sigprocmask(SIG_SETMASK, &oldset, NULL);
 	}
 	daemon_on_finished(daemon);
@@ -3728,12 +3722,8 @@ static void set_hostname(void)
 
 static void set_kblayout(void)
 {
-	int tty_fd = open("/dev/tty", O_RDWR);
-	if ( !tty_fd )
-		return warning("unable to set keyboard layout: /dev/tty: %m");
 	bool unsupported = tcgetblob(tty_fd, "kblayout", NULL, 0) < 0 &&
 	                   (errno == ENOTTY || errno == ENOENT);
-	close(tty_fd);
 	if ( unsupported )
 		return;
 	FILE* fp = fopen("/etc/kblayout", "r");
@@ -3766,9 +3756,6 @@ static void set_kblayout(void)
 
 static void set_videomode(void)
 {
-	int tty_fd = open("/dev/tty", O_RDWR);
-	if ( !tty_fd )
-		return warning("unable to set video mode: /dev/tty: %m");
 	struct tiocgdisplay display;
 	struct tiocgdisplays gdisplays;
 	memset(&gdisplays, 0, sizeof(gdisplays));
@@ -3776,7 +3763,6 @@ static void set_videomode(void)
 	gdisplays.displays = &display;
 	bool unsupported = ioctl(tty_fd, TIOCGDISPLAYS, &gdisplays) < 0 ||
 	                   gdisplays.count == 0;
-	close(tty_fd);
 	if ( unsupported )
 		return;
 	FILE* fp = fopen("/etc/videomode", "r");
@@ -4303,13 +4289,14 @@ int main(int argc, char* argv[])
 	if ( getinit(0) != getpid() )
 		fatal("System is already managed by an init process");
 
-	if ( !isatty(0) || !isatty(1) || !isatty(2)  )
-		fatal("stdin, stdout, and stderr must be the terminal");
-
 	// Register handler that shuts down the system when init exits.
 	if ( atexit(niht) != 0 )
 		fatal("atexit: %m");
 
+	// Remember the controlling terminal to give it away and reclaim it.
+	if ( (tty_fd = open("/dev/tty", O_RDWR | O_CLOEXEC)) < 0 )
+		fatal("/dev/tty: %m");
+
 	// Handle signals but block them until the safe points where we handle them.
 	// All child processes have to uninstall the signal handler and unblock the
 	// signals or they keep blocking the signals.
@@ -4461,9 +4448,6 @@ int main(int argc, char* argv[])
 		chain_location_dev_made = true;
 		close(new_dev_fd);
 		close(old_dev_fd);
-		int tty_fd = open("/dev/tty", O_RDWR | O_CLOEXEC);
-		if ( tty_fd < 0 )
-			fatal("/dev/tty: %m");
 		// TODO: Forward the early init log to the chain init.
 		// Run the chain booted operating system.
 		pid_t child_pid = fork();
@@ -4512,7 +4496,6 @@ int main(int argc, char* argv[])
 		forward_signal_pid = -1; // Racy with waitpid.
 		if ( ioctl(tty_fd, TIOCSCTTY, 1) < 0 )
 			fatal("ioctl: TIOCSCTTY: %m");
-		close(tty_fd);
 		if ( WIFEXITED(status) )
 			return WEXITSTATUS(status);
 		else if ( WIFSIGNALED(status) )