From be2de06b09ae5523fb64ca5a913242cda9572679 Mon Sep 17 00:00:00 2001
From: Devaev Maxim <mdevaev@gmail.com>
Date: Thu, 10 Oct 2019 12:00:42 +0300
Subject: [PATCH] manual check if the parent process is alive after prctl()

---
 src/options.c |  6 +++++-
 src/process.h | 16 +++++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/options.c b/src/options.c
index 5e3045d..7430a9c 100644
--- a/src/options.c
+++ b/src/options.c
@@ -338,7 +338,11 @@ int parse_options(int argc, char *argv[], struct device_t *dev, struct encoder_t
 #			endif
 
 #			ifdef HAS_PDEATHSIG
-			case _O_EXIT_ON_PARENT_DEATH:	process_set_pdeathsig_sigterm(); break;
+			case _O_EXIT_ON_PARENT_DEATH:
+				if (process_track_parent_death() < 0) {
+					return -1;
+				};
+				break;
 #			endif
 
 			case _O_LOG_LEVEL:			OPT_NUMBER("--log-level", log_level, LOG_LEVEL_INFO, LOG_LEVEL_DEBUG, 0);
diff --git a/src/process.h b/src/process.h
index 965e68a..e8b89fe 100644
--- a/src/process.h
+++ b/src/process.h
@@ -33,6 +33,7 @@
 
 #ifdef HAS_PDEATHSIG
 #	include <signal.h>
+#	include <unistd.h>
 
 #	if defined(__linux__)
 #		include <sys/prctl.h>
@@ -42,18 +43,27 @@
 
 #	include "logging.h"
 
-INLINE void process_set_pdeathsig_sigterm(void) {
+
+INLINE int process_track_parent_death(void) {
 	int signum = SIGTERM;
-#	ifdef __linux__
+#	if defined(__linux__)
 	int retval = prctl(PR_SET_PDEATHSIG, signum);
-#	elif __FreeBSD__
+#	elif defined(__FreeBSD__)
 	int retval = procctl(P_PID, 0, PROC_PDEATHSIG_CTL, &signum);
 #	else
 #		error WTF?
 #	endif
 	if (retval < 0) {
 		LOG_PERROR("Can't set to receive SIGTERM on parent process death");
+		return -1;
 	}
+
+	if (kill(getppid(), 0) < 0) {
+		LOG_PERROR("The parent process is already dead");
+		return -1;
+	}
+
+	return 0;
 }
 
 #endif // HAS_PDEATHSIG