From: Roy Marples <roy@marples.name>
Date: Mon, 26 May 2008 19:19:11 +0000 (+0000)
Subject: Fix a signal race when daemonising.
X-Git-Tag: v4.0.2~331
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e0496aa9eb35c9006f105e5db6bb8d27270c0c25;p=thirdparty%2Fdhcpcd.git

Fix a signal race when daemonising.
---

diff --git a/client.c b/client.c
index 07bed64c..9342a43b 100644
--- a/client.c
+++ b/client.c
@@ -164,6 +164,8 @@ daemonise(struct if_state *state, const struct options *options)
 		case 0:
 			setsid();
 			close_fds();
+			/* Clear pending signals */
+			signal_clear();
 			break;
 		default:
 			/* Reset signals as we're the parent about to exit. */
diff --git a/signals.c b/signals.c
index d8c7a7e9..0cf59023 100644
--- a/signals.c
+++ b/signals.c
@@ -134,30 +134,36 @@ signal_init(void)
 }
 
 static int
-signal_handle(void (*func)(int))
+signal_handle(void (*func)(int), int restore)
 {
 	unsigned int i;
-	struct sigaction sa;
+	struct sigaction sa, sa_old;
 
 	memset(&sa, 0, sizeof(sa));
 	sa.sa_handler = func;
 	sigemptyset(&sa.sa_mask);
 
 	for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++)
-		if (sigaction(handle_sigs[i], &sa, NULL) == -1)
+		if (sigaction(handle_sigs[i], &sa, &sa_old) == -1)
 			return -1;
-
+		if (restore && sigaction(handle_sigs[i], &sa_old, NULL) == -1)
+				return -1;
 	return 0;
 }
 
 int
 signal_setup(void)
 {
-	return signal_handle(signal_handler);
+	return signal_handle(signal_handler, 0);
 }
 
 int
 signal_reset(void)
 {
-	return signal_handle(SIG_DFL);
+	return signal_handle(SIG_DFL, 0);
+}
+
+int
+signal_clear(void)
+	return signal_handle(SIG_IGN, 1);
 }
diff --git a/signals.h b/signals.h
index 948099d2..6101b728 100644
--- a/signals.h
+++ b/signals.h
@@ -33,6 +33,7 @@
 int signal_init(void);
 int signal_setup(void);
 int signal_reset(void);
+int signal_clear(void);
 int signal_fd(void);
 int signal_exists(const struct pollfd *);
 int signal_read(struct pollfd *);