From 765ccfa18c91b623891f588f6d766e2cec96dd07 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Mon, 3 Jun 2024 17:58:24 +0300
Subject: [PATCH] Kernel: Deliver SIGCHLD on process exit and ignore it
 properly

---
 kernel/include/kernel/Process.h |  5 +++++
 kernel/kernel/Process.cpp       |  4 ++++
 kernel/kernel/Thread.cpp        | 26 +++++++++++++++++++++++---
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index 84bc6b96..9a09082b 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -220,6 +220,11 @@ namespace Kernel
 			ASSERT(signal >= _SIGMIN);
 			ASSERT(signal <= _SIGMAX);
 			ASSERT(signal < 64);
+			vaddr_t handler = m_signal_handlers[signal];
+			if (handler == (vaddr_t)SIG_IGN)
+				return;
+			if (handler == (vaddr_t)SIG_DFL && (signal == SIGCHLD || signal == SIGURG))
+				return;
 			if (signal < 32)
 				m_signal_pending_mask[0] |= (uint32_t)1 << signal;
 			else
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index ac737e58..3dfd5b10 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -195,8 +195,12 @@ namespace Kernel
 		{
 			SpinLockGuard _(s_process_lock);
 			for (size_t i = 0; i < s_processes.size(); i++)
+			{
+				if (m_parent && s_processes[i]->pid() == m_parent)
+					s_processes[i]->add_pending_signal(SIGCHLD);
 				if (s_processes[i] == this)
 					s_processes.remove(i);
+			}
 		}
 
 		ProcFileSystem::get().on_process_delete(*this);
diff --git a/kernel/kernel/Thread.cpp b/kernel/kernel/Thread.cpp
index 7ecef600..75c60570 100644
--- a/kernel/kernel/Thread.cpp
+++ b/kernel/kernel/Thread.cpp
@@ -279,8 +279,21 @@ namespace Kernel
 		auto& interrupt_stack = *reinterpret_cast<InterruptStack*>(kernel_stack_top() - sizeof(InterruptStack));
 		if (!GDT::is_user_segment(interrupt_stack.cs))
 			return false;
-		uint64_t full_pending_mask = m_signal_pending_mask | process().signal_pending_mask();;
-		return full_pending_mask & ~m_signal_block_mask;
+
+		uint64_t full_pending_mask = m_signal_pending_mask | process().signal_pending_mask();
+		uint64_t signals = full_pending_mask & ~m_signal_block_mask;
+		for (uint8_t i = 0; i < _SIGMAX; i++)
+		{
+			if (!(signals & ((uint64_t)1 << i)))
+				continue;
+			vaddr_t handler = m_process->m_signal_handlers[i];
+			if (handler == (vaddr_t)SIG_IGN)
+				continue;
+			if (handler == (vaddr_t)SIG_DFL && (i == SIGCHLD || i == SIGURG))
+				continue;
+			return true;
+		}
+		return false;
 	}
 
 	bool Thread::can_add_signal_to_execute() const
@@ -395,7 +408,14 @@ namespace Kernel
 	bool Thread::add_signal(int signal)
 	{
 		SpinLockGuard _(m_signal_lock);
-
+		if (m_process)
+		{
+			vaddr_t handler = m_process->m_signal_handlers[signal];
+			if (handler == (vaddr_t)SIG_IGN)
+				return false;
+			if (handler == (vaddr_t)SIG_DFL && (signal == SIGCHLD || signal == SIGURG))
+				return false;
+		}
 		uint64_t mask = 1ull << signal;
 		if (!(m_signal_block_mask & mask))
 		{