Kernel: Socket EPIPE and send SIGPIPE on write after hang up

kernel/kernel/Networking/TCPSocket.cpp

@@ -439,6 +439,8 @@ namespace Kernel
 
 		LockGuard _(m_mutex);
 
+		const bool hungup_before = has_hungup_impl();
+
 		auto& header = buffer.as<const TCPHeader>();
 		dprintln_if(DEBUG_TCP, "receiving {} {8b}", (uint8_t)m_state, header.flags);
 		dprintln_if(DEBUG_TCP, "  {}", (uint32_t)header.ack_number);
@@ -609,6 +611,9 @@ namespace Kernel
 			}
 		}
 
+		if (!hungup_before && has_hungup_impl())
+			epoll_notify(EPOLLHUP);
+
 		m_thread_blocker.unblock();
 	}
 
@@ -690,9 +695,12 @@ namespace Kernel
 					auto target_address_len = m_connection_info->address_len;
 					if (auto ret = m_network_layer.sendto(*this, {}, target_address, target_address_len); ret.is_error())
 						dwarnln("{}", ret.error());
+					const bool hungup_before = has_hungup_impl();
 					m_state = m_next_state;
 					if (m_state == State::Established)
 						m_has_connected = true;
+					if (!hungup_before && has_hungup_impl())
+						epoll_notify(EPOLLHUP);
 					continue;
 				}
 

kernel/kernel/OpenFileDescriptorSet.cpp

@@ -476,14 +476,25 @@ namespace Kernel
 
 		LockGuard _(inode->m_mutex);
 
+		const auto check_errors =
+			[&inode, is_nonblock]() -> BAN::ErrorOr<void>
+			{
+				if (inode->has_hungup())
+				{
+					Thread::current().add_signal(SIGPIPE);
+					return BAN::Error::from_errno(EPIPE);
+				}
 				if (is_nonblock && !inode->can_write())
 					return BAN::Error::from_errno(EWOULDBLOCK);
+				return {};
+			};
+
+		TRY(check_errors());
 
 		size_t total_sent = 0;
 		while (total_sent < buffer.size())
 		{
-			if (is_nonblock && !inode->can_write())
+			TRY(check_errors());
-				return total_sent;
 			const size_t nsend = TRY(inode->sendto(buffer.slice(total_sent), address, address_len));
 			if (nsend == 0)
 				return 0;