From c0ee24f3138fe6fc0978c87d746cd7fcdf88a529 Mon Sep 17 00:00:00 2001
From: psychon <psychon@726aef4b-f618-498e-8847-2d620e286838>
Date: Mon, 4 May 2009 19:21:26 +0000
Subject: [PATCH] Handle SIGCHLD for collecting zombie processes

The old code failed to collect the following command to *shell correctly:
 exec > /dev/null 2> /dev/null < /dev/null ; sleep 10

The timeout in CExecSock::close2() was over before the child processes exited
and a zombie was left behind. Plus we used some ugly busy looping while
waiting for the child to exit. Using SIGCHLD for collecting zombies is
soooooo much nicer.


git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1504 726aef4b-f618-498e-8847-2d620e286838
---
 FileUtils.cpp | 7 +------
 main.cpp      | 9 +++++++++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/FileUtils.cpp b/FileUtils.cpp
index c436b81a..d9150223 100644
--- a/FileUtils.cpp
+++ b/FileUtils.cpp
@@ -556,11 +556,6 @@ int CExecSock::popen2(int & iReadFD, int & iWriteFD, const CString & sCommand) {
 void CExecSock::close2(int iPid, int iReadFD, int iWriteFD) {
 	close(iReadFD);
 	close(iWriteFD);
-	u_int iNow = time(NULL);
-	while (waitpid(iPid, NULL, WNOHANG) == 0) {
-		if ((time(NULL) - iNow) > 5)
-			break;	// giveup
-		usleep(100);
-	}
+	// If a zombie is left behind, SIGCHLD will handle it
 	return;
 }
diff --git a/main.cpp b/main.cpp
index a77cd2f7..7ff172f9 100644
--- a/main.cpp
+++ b/main.cpp
@@ -8,6 +8,7 @@
 
 #include "znc.h"
 #include <getopt.h>
+#include <sys/wait.h>
 
 static const struct option g_LongOpts[] = {
 	{ "help",			no_argument,	0,	'h' },
@@ -61,6 +62,11 @@ static void rehash(int sig) {
 	CZNC::Get().SetNeedRehash(true);
 }
 
+static void reapChilds(int sig) {
+	while (waitpid(-1, NULL, WNOHANG) > 0) {
+	}
+}
+
 static bool isRoot() {
 	// User root? If one of these were root, we could switch the others to root, too
 	if (geteuid() == 0 || getuid() == 0)
@@ -242,6 +248,9 @@ int main(int argc, char** argv) {
 	sa.sa_handler = rehash;
 	sigaction(SIGHUP,  &sa, (struct sigaction*) NULL);
 
+	sa.sa_handler = reapChilds;
+	sigaction(SIGCHLD, &sa, (struct sigaction*) NULL);
+
 	// Once this signal is caught, the signal handler is reset
 	// to SIG_DFL. This avoids endless loop with signals.
 	sa.sa_flags = SA_RESETHAND;