From 5b5fc677b313908b8d1a775cd6af08202841d908 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <goliath@infraroot.at>
Date: Thu, 14 May 2020 16:31:49 +0200
Subject: Move handling of dead children back to SIGCHLD handler

Signed-off-by: David Oberhollenzer <goliath@infraroot.at>
---
 initd/config.c | 20 ++++++--------------
 initd/init.h   |  3 ---
 initd/main.c   | 52 ++++++++++++++++++++++------------------------------
 initd/runsvc.c |  1 +
 4 files changed, 29 insertions(+), 47 deletions(-)

diff --git a/initd/config.c b/initd/config.c
index fa12ab2..3a4eac2 100644
--- a/initd/config.c
+++ b/initd/config.c
@@ -69,18 +69,6 @@ void config_set_waiting(svc_run_data_t *rt)
 	waiting = rt;
 }
 
-bool config_is_waiting(void)
-{
-	if (waiting != NULL) {
-		if (waiting->state == STATE_RUNNING)
-			return true;
-
-		waiting = NULL;
-	}
-
-	return false;
-}
-
 svc_run_data_t *config_rt_data_by_pid(pid_t pid)
 {
 	size_t i;
@@ -98,8 +86,12 @@ svc_run_data_t *config_rt_data_by_pid(pid_t pid)
 
 svc_run_data_t *config_dequeue(void)
 {
-	if (config_is_waiting())
-		return NULL;
+	if (waiting != NULL) {
+		if (waiting->state == STATE_RUNNING)
+			return NULL;
+
+		waiting = NULL;
+	}
 
 	if (queue_idx >= queue_count[target])
 		return NULL;
diff --git a/initd/init.h b/initd/init.h
index 61101c7..5618ccd 100644
--- a/initd/init.h
+++ b/initd/init.h
@@ -64,9 +64,6 @@ bool config_should_respawn(void);
 /* refuse to dequeue further services until this one terminates */
 void config_set_waiting(svc_run_data_t *rt);
 
-/* are we currently waiting for a service to terminate? */
-bool config_is_waiting(void);
-
 /********** print_status.c **********/
 
 void print_status(const svc_run_data_t *rt);
diff --git a/initd/main.c b/initd/main.c
index 6485842..d92a823 100644
--- a/initd/main.c
+++ b/initd/main.c
@@ -22,31 +22,6 @@ fail:
 	return;
 }
 
-static svc_run_data_t *wait_for_process(void)
-{
-	svc_run_data_t *rt;
-	int status;
-	pid_t pid;
-
-	do {
-		pid = wait(&status);
-
-		if (pid == -1) {
-			if (errno == EINTR)
-				return NULL;
-
-			if (errno == ECHILD)
-				exit(EXIT_FAILURE);
-		}
-
-		rt = config_rt_data_by_pid(pid);
-	} while (rt == NULL);
-
-	rt->status = WIFEXITED(status) ? WEXITSTATUS(status) : EXIT_FAILURE;
-	rt->pid = -1;
-	return rt;
-}
-
 static void handle_exited(svc_run_data_t *rt)
 {
 	if (rt->svc->type == SVC_RESPAWN) {
@@ -85,6 +60,10 @@ static void start_service(svc_run_data_t *rt)
 
 static void handle_signal(int signo)
 {
+	svc_run_data_t *rt;
+	int status;
+	pid_t pid;
+
 	switch (signo) {
 	case SIGTERM:
 		config_set_target(TGT_SHUTDOWN);
@@ -92,6 +71,22 @@ static void handle_signal(int signo)
 	case SIGINT:
 		config_set_target(TGT_REBOOT);
 		break;
+	case SIGCHLD:
+		while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
+			rt = config_rt_data_by_pid(pid);
+			if (rt == NULL)
+				continue;
+
+			if (WIFEXITED(status)) {
+				rt->status = WEXITSTATUS(status);
+			} else {
+				rt->status = EXIT_FAILURE;
+			}
+
+			rt->pid = -1;
+			handle_exited(rt);
+		}
+		break;
 	case SIGHUP:
 		break;
 	case SIGUSR1:
@@ -114,6 +109,7 @@ int main(void)
 	sigaction(SIGINT, &act, NULL);
 	sigaction(SIGHUP, &act, NULL);
 	sigaction(SIGUSR1, &act, NULL);
+	sigaction(SIGCHLD, &act, NULL);
 
 	if (reboot(LINUX_REBOOT_CMD_CAD_OFF))
 		perror("cannot disable CTRL+ALT+DEL");
@@ -122,11 +118,7 @@ int main(void)
 		rt = config_dequeue();
 
 		if (rt == NULL) {
-			rt = wait_for_process();
-			if (rt == NULL)
-				continue;
-
-			handle_exited(rt);
+			pause();
 		} else {
 			start_service(rt);
 		}
diff --git a/initd/runsvc.c b/initd/runsvc.c
index df5a656..5495f15 100644
--- a/initd/runsvc.c
+++ b/initd/runsvc.c
@@ -205,6 +205,7 @@ pid_t runsvc(service_t *svc)
 
 		act.sa_handler = SIG_DFL;
 		sigaction(SIGUSR1, &act, NULL);
+		sigaction(SIGCHLD, &act, NULL);
 
 		if (setup_env())
 			exit(EXIT_FAILURE);
-- 
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