From: Roy Marples <roy@marples.name>
Date: Tue, 27 May 2008 19:06:48 +0000 (+0000)
Subject: Replace the signal clear with a pipe so child can notify parent when to exit.
X-Git-Tag: v4.0.2~320
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=caecf62c79ac0cf15a8b02f365c4976f28621606;p=thirdparty%2Fdhcpcd.git

Replace the signal clear with a pipe so child can notify parent when to exit.
---

diff --git a/client.c b/client.c
index 9342a43b..70f7a3ab 100644
--- a/client.c
+++ b/client.c
@@ -145,6 +145,9 @@ daemonise(struct if_state *state, const struct options *options)
 #ifdef THERE_IS_NO_FORK
 	char **argv;
 	int i;
+#else
+	char buf = '\0';
+	int sidpipe[2];
 #endif
 
 	if (state->options & DHCPCD_DAEMONISED ||
@@ -155,6 +158,12 @@ daemonise(struct if_state *state, const struct options *options)
 	sigprocmask(SIG_SETMASK, &full, &old);
 
 #ifndef THERE_IS_NO_FORK
+	/* Setup a signal pipe so parent knows when to exit. */
+	if (pipe(sidpipe) == -1) {
+		logger(LOG_ERR,"pipe: %s", strerror(errno));
+		return -1;
+	}
+
 	logger(LOG_DEBUG, "forking to background");
 	switch (pid = fork()) {
 		case -1:
@@ -163,13 +172,17 @@ daemonise(struct if_state *state, const struct options *options)
 			/* NOTREACHED */
 		case 0:
 			setsid();
+			/* Notify parent it's safe to exit as we've detached. */
+			write(sidpipe[1], &buf, 1);
 			close_fds();
-			/* Clear pending signals */
-			signal_clear();
 			break;
 		default:
 			/* Reset signals as we're the parent about to exit. */
 			signal_reset();
+			/* Wait for child to detach */
+			close(sidpipe[1]);
+			read(sidpipe[0], &buf, 1);
+			close(sidpipe[0]);
 			break;
 	}
 #else
diff --git a/signals.c b/signals.c
index c0b60e31..4559749c 100644
--- a/signals.c
+++ b/signals.c
@@ -134,38 +134,29 @@ signal_init(void)
 }
 
 static int
-signal_handle(void (*func)(int), int restore)
+signal_handle(void (*func)(int))
 {
 	unsigned int i;
-	struct sigaction sa, sa_old;
+	struct sigaction sa;
 
 	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, &sa_old) == -1)
+	for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++)
+		if (sigaction(handle_sigs[i], &sa, NULL) == -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, 0);
+	return signal_handle(signal_handler);
 }
 
 int
 signal_reset(void)
 {
-	return signal_handle(SIG_DFL, 0);
-}
-
-int
-signal_clear(void) 
-{
-	return signal_handle(SIG_IGN, 1);
+	return signal_handle(SIG_DFL);
 }
diff --git a/signals.h b/signals.h
index 6101b728..948099d2 100644
--- a/signals.h
+++ b/signals.h
@@ -33,7 +33,6 @@
 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 *);