From 2cb64e48fcd664067f4bd87e8f46fad694c3c979 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@tele2.at>
Date: Sun, 15 Apr 2018 13:21:34 +0200
Subject: [PATCH] Move initd signal setup to platform specific file

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
---
 initd/Makemodule.am  |  2 +-
 initd/init.h         | 25 ++++++++++++++++++++++
 initd/main.c         | 20 +++--------------
 initd/runlst.c       |  4 +---
 initd/signal_linux.c | 51 ++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 81 insertions(+), 21 deletions(-)
 create mode 100644 initd/signal_linux.c

diff --git a/initd/Makemodule.am b/initd/Makemodule.am
index 752978b..67515cc 100644
--- a/initd/Makemodule.am
+++ b/initd/Makemodule.am
@@ -1,4 +1,4 @@
-init_SOURCES = initd/main.c initd/runlst.c initd/init.h
+init_SOURCES = initd/main.c initd/runlst.c initd/init.h initd/signal_linux.c
 init_SOURCES += initd/status.c initd/mksock.c initd/svclist.c initd/env.c
 init_CPPFLAGS = $(AM_CPPFLAGS)
 init_CFLAGS = $(AM_CFLAGS)
diff --git a/initd/init.h b/initd/init.h
index a43b3f1..3510073 100644
--- a/initd/init.h
+++ b/initd/init.h
@@ -19,7 +19,9 @@
 #define INIT_H
 
 #include <linux/reboot.h>
+#include <sys/signalfd.h>
 #include <sys/reboot.h>
+#include <signal.h>
 
 #include "service.h"
 #include "telinit.h"
@@ -117,5 +119,28 @@ service_t *svclist_remove(pid_t pid);
 */
 int initenv(void);
 
+/********** signal_<platform>.c **********/
+
+/*
+	Setup signal handling. Returns -1 on error, a file descriptor on
+	success.
+
+	The returned file descriptor can be polled and becomes readable
+	when a signal arrives. Reading from it returns a signalfd_siginfo
+	structure.
+
+	The returned file descriptor has the close on exec flag set.
+
+	The kernel is also told to send us SIGINT signals if a user presses
+	the local equivalent of CTRL+ALT+DEL.
+*/
+int sigsetup(void);
+
+/*
+	Undo everything that sigsetup() changed about signal handling and
+	restore the default.
+*/
+void sigreset(void);
+
 #endif /* INIT_H */
 
diff --git a/initd/main.c b/initd/main.c
index 192a49a..05f9271 100644
--- a/initd/main.c
+++ b/initd/main.c
@@ -25,8 +25,6 @@
 #include <errno.h>
 #include <poll.h>
 
-#include <sys/signalfd.h>
-
 #include "init.h"
 
 static service_list_t cfg;
@@ -189,32 +187,20 @@ int main(void)
 {
 	int ti_sock = -1, sfd, ret, count;
 	struct pollfd pfd[2];
-	sigset_t mask;
 
 	if (getpid() != 1) {
 		fputs("init does not have pid 1, terminating!\n", stderr);
 		return EXIT_FAILURE;
 	}
 
-	if (reboot(LINUX_REBOOT_CMD_CAD_OFF))
-		perror("cannot disable CTRL+ALT+DEL");
-
 	if (svcscan(SVCDIR, &cfg)) {
 		fputs("Error reading service list from " SVCDIR "\n"
 			"Trying to continue anyway\n", stderr);
 	}
 
-	sigfillset(&mask);
-	if (sigprocmask(SIG_SETMASK, &mask, NULL) == -1) {
-		perror("sigprocmask");
-		return EXIT_FAILURE;
-	}
-
-	sfd = signalfd(-1, &mask, SFD_CLOEXEC);
-	if (sfd == -1) {
-		perror("signalfd");
-		return EXIT_FAILURE;
-	}
+	sfd = sigsetup();
+	if (sfd < 0)
+		return -1;
 
 	memset(pfd, 0, sizeof(pfd));
 	pfd[0].fd = sfd;
diff --git a/initd/runlst.c b/initd/runlst.c
index d1311a4..83823f9 100644
--- a/initd/runlst.c
+++ b/initd/runlst.c
@@ -26,11 +26,9 @@
 
 static int child_setup(const char *ctty)
 {
-	sigset_t mask;
 	int fd;
 
-	sigemptyset(&mask);
-	sigprocmask(SIG_SETMASK, &mask, NULL);
+	sigreset();
 
 	if (ctty != NULL) {
 		fd = open(ctty, O_RDWR);
diff --git a/initd/signal_linux.c b/initd/signal_linux.c
new file mode 100644
index 0000000..aed049b
--- /dev/null
+++ b/initd/signal_linux.c
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <stdio.h>
+
+#include "init.h"
+
+int sigsetup(void)
+{
+	sigset_t mask;
+	int sfd;
+
+	sigfillset(&mask);
+	if (sigprocmask(SIG_SETMASK, &mask, NULL) == -1) {
+		perror("sigprocmask");
+		return -1;
+	}
+
+	sfd = signalfd(-1, &mask, SFD_CLOEXEC);
+	if (sfd == -1) {
+		perror("signalfd");
+		return -1;
+	}
+
+	if (reboot(LINUX_REBOOT_CMD_CAD_OFF))
+		perror("cannot disable CTRL+ALT+DEL");
+
+	return sfd;
+}
+
+void sigreset(void)
+{
+	sigset_t mask;
+
+	sigemptyset(&mask);
+	sigprocmask(SIG_SETMASK, &mask, NULL);
+}