[kernel] Consolodate koid and close syscalls

A number of object types had _close or _koid syscalls. Moved those to be
generic for kobject.

src/kernel/objects/channel.cpp

@@ -78,8 +78,8 @@ channel::dequeue(size_t *len, void *data)
 void
 channel::close()
 {
+	kobject::close();
 	g_kernel_buffers.return_buffer(m_data);
-	assert_signal(j6_signal_channel_closed);
 }
 
 void

src/kernel/objects/channel.h

@@ -37,10 +37,7 @@ public:
 
 	/// Mark this channel as closed, all future calls to enqueue or
 	/// dequeue messages will fail with j6_status_closed.
-	void close();
-
-	/// Check if this channel has been closed
-	inline bool closed() { return check_signal(j6_signal_channel_closed); }
+	virtual void close() override;
 
 protected:
 	virtual void on_no_handles() override;

src/kernel/objects/endpoint.cpp

@@ -10,14 +10,15 @@ endpoint::endpoint() :
 
 endpoint::~endpoint()
 {
-	if (!check_signal(j6_signal_endpoint_closed))
+	if (!check_signal(j6_signal_closed))
 		close();
 }
 
 void
 endpoint::close()
 {
-	assert_signal(j6_signal_endpoint_closed);
+	kobject::close();
+
 	for (auto &data : m_blocked) {
 		if (data.th)
 			data.th->wake_on_result(this, j6_status_closed);

src/kernel/objects/endpoint.h

@@ -16,7 +16,7 @@ public:
 	static constexpr kobject::type type = kobject::type::endpoint;
 
 	/// Close the endpoint, waking all waiting processes with an error
-	void close();
+	virtual void close() override;
 
 	/// Check if the endpoint has space for a message to be sent
 	inline bool can_send() const { return check_signal(j6_signal_endpoint_can_send); }

src/kernel/objects/kobject.cpp

@@ -61,6 +61,12 @@ kobject::notify_signal_observers()
 	}
 }
 
+void
+kobject::close()
+{
+	assert_signal(j6_signal_closed);
+}
+
 void
 kobject::on_no_handles()
 {

src/kernel/objects/kobject.h

@@ -3,6 +3,7 @@
 /// Definition of base type for user-interactable kernel objects
 
 #include "j6/errors.h"
+#include "j6/signals.h"
 #include "j6/types.h"
 #include "kutil/vector.h"
 
@@ -76,6 +77,12 @@ public:
 	/// Remove the given thread from the list of threads waiting on this object.
 	inline void remove_blocked_thread(thread *t) { m_blocked_threads.remove_swap(t); }
 
+	/// Perform any cleanup actions necessary to mark this object closed
+	virtual void close();
+
+	/// Check if this object has been closed
+	inline bool closed() const { return check_signal(j6_signal_closed); }
+
 protected:
 	/// Interface for subclasses to handle when all handles are closed. Subclasses
 	/// should either call the base version, or assert j6_signal_no_handles.

src/kernel/objects/process.cpp

@@ -1,4 +1,3 @@
-#include "j6/signals.h"
 #include "kutil/assert.h"
 #include "kutil/no_construct.h"
 #include "cpu.h"
@@ -62,7 +61,7 @@ process::exit(unsigned code)
 		thread->exit(code);
 	}
 	m_return_code = code;
-	assert_signal(j6_signal_process_exit);
+	close();
 
 	if (this == bsp_cpu_data.p)
 		scheduler::get().schedule();

src/kernel/objects/thread.cpp

@@ -139,7 +139,7 @@ thread::exit(uint32_t code)
 	m_return_code = code;
 	set_state(state::exited);
 	clear_state(state::ready);
-	assert_signal(j6_signal_thread_exit);
+	close();
 
 	schedule_if_current(this);
 }