Support parent death signal & Refactor do_exit

regression/apps/scripts/process.sh

@@ -23,6 +23,7 @@ itimer/timer_create
 mmap/map_shared_anon
 pthread/pthread_test
 pty/open_pty
+signal_c/parent_death_signal
 signal_c/signal_test
 "
 

regression/apps/signal_c/parent_death_signal.c

@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: MPL-2.0
+
+#define _GNU_SOURCE
+#include <sys/prctl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+void signal_handler(int signum)
+{
+	if (signum == SIGTERM) {
+		printf("child process reveives SIGTERM\n");
+		exit(EXIT_SUCCESS);
+	}
+}
+
+int main()
+{
+	pid_t pid = fork();
+
+	if (pid == -1) {
+		perror("fork");
+		return EXIT_FAILURE;
+	}
+
+	if (pid > 0) {
+		printf("Parent PID: %d\n", getpid());
+		// Ensure parent won't exit before child process runs
+		sleep(1);
+	} else {
+		printf("CHild PID: %d\n", getpid());
+
+		prctl(PR_SET_PDEATHSIG, SIGTERM);
+
+		struct sigaction sa;
+		sa.sa_handler = signal_handler;
+		sigemptyset(&sa.sa_mask);
+		sa.sa_flags = 0;
+		sigaction(SIGTERM, &sa, NULL);
+
+		// Child waits for signal from parent death
+		while (1) {
+			sleep(1);
+		}
+	}
+
+	return EXIT_SUCCESS;
+}