From 274b0260f7624c29ca7066f7e503f2ebd0cc6b01 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Fri, 1 Mar 2019 15:47:07 +0100
Subject: [PATCH] Kernel: Don't send SIGCHLD to parent process if he has
 SA_NOCLDWAIT set.

Just transfer ownership of the dead process to the colonel and let the
scheduler reap it on next iteration.
---
 Applications/FileManager/main.cpp | 11 +++++++++++
 Kernel/Process.cpp                |  7 ++++++-
 Kernel/Scheduler.cpp              |  2 +-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/Applications/FileManager/main.cpp b/Applications/FileManager/main.cpp
index 454207e5d86..602af8fa7e0 100644
--- a/Applications/FileManager/main.cpp
+++ b/Applications/FileManager/main.cpp
@@ -7,11 +7,22 @@
 #include <LibGUI/GMenuBar.h>
 #include <LibGUI/GAction.h>
 #include <unistd.h>
+#include <signal.h>
 #include <stdio.h>
 #include "DirectoryTableView.h"
 
 int main(int argc, char** argv)
 {
+    struct sigaction act;
+    memset(&act, 0, sizeof(act));
+    act.sa_flags = SA_NOCLDWAIT;
+    act.sa_handler = SIG_IGN;
+    int rc = sigaction(SIGCHLD, &act, nullptr);
+    if (rc < 0) {
+        perror("sigaction");
+        return 1;
+    }
+
     GApplication app(argc, argv);
 
     auto mkdir_action = GAction::create("New directory...", GraphicsBitmap::load_from_file(GraphicsBitmap::Format::RGBA32, "/res/icons/mkdir16.rgb", { 16, 16 }), [] (const GAction&) {
diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 5a859c0b0f0..7d0e549c3bc 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -2202,7 +2202,12 @@ void Process::finalize()
     {
         InterruptDisabler disabler;
         if (auto* parent_process = Process::from_pid(m_ppid)) {
-            parent_process->send_signal(SIGCHLD, this);
+            if (parent_process->m_signal_action_data[SIGCHLD].flags & SA_NOCLDWAIT) {
+                // NOTE: If the parent doesn't care about this process, let it go.
+                m_ppid = 0;
+            } else {
+                parent_process->send_signal(SIGCHLD, this);
+            }
         }
     }
 
diff --git a/Kernel/Scheduler.cpp b/Kernel/Scheduler.cpp
index 8b89f4e4fb0..d0e091ee346 100644
--- a/Kernel/Scheduler.cpp
+++ b/Kernel/Scheduler.cpp
@@ -138,7 +138,7 @@ bool Scheduler::pick_next()
         }
 
         if (process.state() == Process::Dead) {
-            if (current != &process && !Process::from_pid(process.ppid())) {
+            if (current != &process && (!process.ppid() || !Process::from_pid(process.ppid()))) {
                 auto name = process.name();
                 auto pid = process.pid();
                 auto exit_status = Process::reap(process);