sinit

commit 170d599d58efee6c9be675a85c6e435d68e8a2de
parent 731f65fc82afcd474f4c682f9f0069e5c80c86dd
Author: sin <sin@2f30.org>
Date:   Sun, 18 Mar 2018 13:35:38 +0000

Ensure children are reaped periodically

There is a pathological case where a parent receives SIGCHLD after its
child dies but does not reap it.  After the parent dies, the child is
reparented to init but SIGCHLD is not redelivered.

To fix this, periodically check if there are zombies pending to be
reaped.

Diffstat:
M
sinit.c
 | 
6
+++++-

1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/sinit.c b/sinit.c
@@ -7,7 +7,8 @@
 #include <stdlib.h>
 #include <unistd.h>
 
-#define LEN(x) (sizeof (x) / sizeof *(x))
+#define LEN(x)	(sizeof (x) / sizeof *(x))
+#define TIMEO	30
 
 static void sigpoweroff(void);
 static void sigreap(void);
@@ -20,6 +21,7 @@ static struct {
 } sigmap[] = {
 	{ SIGUSR1, sigpoweroff },
 	{ SIGCHLD, sigreap     },
+	{ SIGALRM, sigreap     },
 	{ SIGINT,  sigreboot   },
 };
 
@@ -40,6 +42,7 @@ main(void)
 	sigprocmask(SIG_BLOCK, &set, NULL);
 	spawn(rcinitcmd);
 	while (1) {
+		alarm(TIMEO);
 		sigwait(&set, &sig);
 		for (i = 0; i < LEN(sigmap); i++) {
 			if (sigmap[i].sig == sig) {
@@ -63,6 +66,7 @@ sigreap(void)
 {
 	while (waitpid(-1, NULL, WNOHANG) > 0)
 		;
+	alarm(TIMEO);
 }
 
 static void