From 5c25f0c4db9584adacd8b0446fdc0d5524fe7b31 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Wed, 30 Jan 2019 19:35:38 +0100
Subject: [PATCH] Destroy all remaining windows in a process when it dies.

---
 Kernel/Process.cpp             |  8 +++++---
 Kernel/Process.h               |  1 +
 Kernel/ProcessGUI.cpp          |  9 +++++++++
 WindowServer/WSMessage.h       |  1 +
 WindowServer/WSMessageLoop.cpp | 10 ++++++++--
 WindowServer/WSMessageLoop.h   |  2 +-
 WindowServer/WSWindow.cpp      |  5 +++++
 7 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 7abf42786e..62963947bf 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -1490,9 +1490,10 @@ int Process::reap(Process& process)
 
     if (process.ppid()) {
         auto* parent = Process::from_pid(process.ppid());
-        ASSERT(parent);
-        parent->m_ticks_in_user_for_dead_children += process.m_ticks_in_user + process.m_ticks_in_user_for_dead_children;
-        parent->m_ticks_in_kernel_for_dead_children += process.m_ticks_in_kernel + process.m_ticks_in_kernel_for_dead_children;
+        if (parent) {
+            parent->m_ticks_in_user_for_dead_children += process.m_ticks_in_user + process.m_ticks_in_user_for_dead_children;
+            parent->m_ticks_in_kernel_for_dead_children += process.m_ticks_in_kernel + process.m_ticks_in_kernel_for_dead_children;
+        }
     }
 
     dbgprintf("reap: %s(%u) {%s}\n", process.name().characters(), process.pid(), toString(process.state()));
@@ -2143,4 +2144,5 @@ void Process::die()
 {
     set_state(Dead);
     m_fds.clear();
+    destroy_all_windows();
 }
diff --git a/Kernel/Process.h b/Kernel/Process.h
index 66f6676ce4..a17e9da359 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -216,6 +216,7 @@ public:
     static void initialize();
     static void initialize_gui_statics();
     int make_window_id();
+    void destroy_all_windows();
 
     void crash() NORETURN;
     static int reap(Process&) WARN_UNUSED_RESULT;
diff --git a/Kernel/ProcessGUI.cpp b/Kernel/ProcessGUI.cpp
index f5aee91423..db9fd52d56 100644
--- a/Kernel/ProcessGUI.cpp
+++ b/Kernel/ProcessGUI.cpp
@@ -257,3 +257,12 @@ int Process::gui$set_global_cursor_tracking_enabled(int window_id, bool enabled)
     window.set_global_cursor_tracking_enabled(enabled);
     return 0;
 }
+
+void Process::destroy_all_windows()
+{
+    for (auto& it : m_windows) {
+        auto message = make<WSMessage>(WSMessage::WM_DestroyWindow);
+        WSMessageLoop::the().post_message(it.value.leakPtr(), move(message), true);
+    }
+    m_windows.clear();
+}
diff --git a/WindowServer/WSMessage.h b/WindowServer/WSMessage.h
index 5a15837ef4..87211001b0 100644
--- a/WindowServer/WSMessage.h
+++ b/WindowServer/WSMessage.h
@@ -14,6 +14,7 @@ public:
         WM_SetWindowTitle,
         WM_SetWindowRect,
         WM_DeferredCompose,
+        WM_DestroyWindow,
         MouseMove,
         MouseDown,
         MouseUp,
diff --git a/WindowServer/WSMessageLoop.cpp b/WindowServer/WSMessageLoop.cpp
index f158c861cc..00f4b9a63b 100644
--- a/WindowServer/WSMessageLoop.cpp
+++ b/WindowServer/WSMessageLoop.cpp
@@ -71,9 +71,15 @@ int WSMessageLoop::exec()
     }
 }
 
-void WSMessageLoop::post_message(WSMessageReceiver* receiver, OwnPtr<WSMessage>&& message)
+void WSMessageLoop::post_message(WSMessageReceiver* receiver, OwnPtr<WSMessage>&& message, bool unsafe)
 {
-    ASSERT_INTERRUPTS_ENABLED();
+    if (unsafe) {
+        // FIXME: This is such a hack. It should not exist.
+        m_queued_messages.append({ receiver, move(message) });
+        if (current != m_server_process)
+            m_server_process->request_wakeup();
+        return;
+    }
     LOCKER(m_lock);
 #ifdef WSEVENTLOOP_DEBUG
     dbgprintf("WSMessageLoop::post_message: {%u} << receiver=%p, message=%p\n", m_queued_messages.size(), receiver, message.ptr());
diff --git a/WindowServer/WSMessageLoop.h b/WindowServer/WSMessageLoop.h
index e9d32306e0..0d232b7c7b 100644
--- a/WindowServer/WSMessageLoop.h
+++ b/WindowServer/WSMessageLoop.h
@@ -15,7 +15,7 @@ public:
 
     int exec();
 
-    void post_message(WSMessageReceiver* receiver, OwnPtr<WSMessage>&&);
+    void post_message(WSMessageReceiver* receiver, OwnPtr<WSMessage>&&, bool unsafe = false);
 
     static WSMessageLoop& the();
 
diff --git a/WindowServer/WSWindow.cpp b/WindowServer/WSWindow.cpp
index 81a24ef20e..dfaebea425 100644
--- a/WindowServer/WSWindow.cpp
+++ b/WindowServer/WSWindow.cpp
@@ -107,12 +107,17 @@ void WSWindow::on_message(WSMessage& message)
     case WSMessage::WM_SetWindowTitle:
         set_title(static_cast<WSSetWindowTitleMessage&>(message).title());
         return;
+    case WSMessage::WM_DestroyWindow:
+        delete this;
+        return;
     case WSMessage::WindowActivated:
         gui_event.type = GUI_Event::Type::WindowActivated;
         break;
     case WSMessage::WindowDeactivated:
         gui_event.type = GUI_Event::Type::WindowDeactivated;
         break;
+    default:
+        break;
     }
 
     if (gui_event.type == GUI_Event::Type::Invalid)