timeout: handle zombie grandchildren

timeout previously collected only one child status with wait(2). If this
was one of the grandchildren timeout would return to sigsuspend and wait
until the timeout expired. Instead, loop for all children.

PR:		kern/197608
Reviewed by:	bapt, kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation

1 files changed, 19 insertions, 13 deletions

diff --git a/usr.bin/timeout/timeout.c b/usr.bin/timeout/timeout.c
index 06dc086..a682dde 100644
--- a/usr.bin/timeout/timeout.c
+++ b/usr.bin/timeout/timeout.c
@@ -172,6 +172,7 @@ main(int argc, char **argv)
 	double second_kill;
 	bool timedout = false;
 	bool do_second_kill = false;
+	bool child_done = false;
 	struct sigaction signals;
 	struct procctl_reaper_status info;
 	struct procctl_reaper_kill killemall;
@@ -187,7 +188,6 @@ main(int argc, char **argv)
 
 	foreground = preserve = 0;
 	second_kill = 0;
-	cpid = -1;
 
 	const struct option longopts[] = {
 		{ "preserve-status", no_argument,       &preserve,    1 },
@@ -281,20 +281,26 @@ main(int argc, char **argv)
 
 		if (sig_chld) {
 			sig_chld = 0;
-			while (((cpid = wait(&status)) < 0) && errno == EINTR)
-				continue;
 
-			if (cpid == pid) {
-				pstat = status;
-				if (!foreground)
-					break;
+			while ((cpid = waitpid(-1, &status, WNOHANG)) != 0) {
+				if (cpid < 0) {
+					if (errno == EINTR)
+						continue;
+					else
+						break;
+				} else if (cpid == pid) {
+					pstat = status;
+					child_done = true;
+				}
 			}
-			if (!foreground) {
-				procctl(P_PID, getpid(), PROC_REAP_STATUS,
-				    &info);
-				if (info.rs_children == 0) {
-					cpid = pid;
+			if (child_done) {
+				if (foreground) {
 					break;
+				} else {
+					procctl(P_PID, getpid(),
+					    PROC_REAP_STATUS, &info);
+					if (info.rs_children == 0)
+						break;
 				}
 			}
 		} else if (sig_alrm) {
@@ -336,7 +342,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while (cpid != pid  && wait(&pstat) == -1) {
+	while (!child_done && wait(&pstat) == -1) {
 		if (errno != EINTR)
 			err(EX_OSERR, "waitpid()");
 	}