[kernel] Add channel objects

Add the channel object for sending messages between threads. Currently
no good of passing channels to other threads, but global variables in a
single process work. Currently channels are slow and do double copies,
need to refine more.

Tags: ipc

src/kernel/syscalls/channel.cpp

@@ -0,0 +1,76 @@
+#include "j6/errors.h"
+#include "j6/types.h"
+
+#include "objects/channel.h"
+#include "objects/thread.h"
+#include "objects/process.h"
+#include "scheduler.h"
+
+namespace syscalls {
+
+j6_status_t
+channel_create(j6_handle_t *handle)
+{
+	scheduler &s = scheduler::get();
+	TCB *tcb = s.current();
+	thread *parent = thread::from_tcb(tcb);
+	process &p = parent->parent();
+
+	channel *c = new channel;
+	*handle = p.add_handle(c);
+
+	return j6_status_ok;
+}
+
+j6_status_t
+channel_close(j6_handle_t handle)
+{
+	scheduler &s = scheduler::get();
+	TCB *tcb = s.current();
+	thread *parent = thread::from_tcb(tcb);
+	process &p = parent->parent();
+
+	kobject *o = p.lookup_handle(handle);
+	if (!o || o->get_type() != kobject::type::channel)
+		return j6_err_invalid_arg;
+
+	p.remove_handle(handle);
+	channel *c = static_cast<channel*>(o);
+	c->close();
+
+	return j6_status_ok;
+}
+
+j6_status_t
+channel_send(j6_handle_t handle, size_t len, void *data)
+{
+	scheduler &s = scheduler::get();
+	TCB *tcb = s.current();
+	thread *parent = thread::from_tcb(tcb);
+	process &p = parent->parent();
+
+	kobject *o = p.lookup_handle(handle);
+	if (!o || o->get_type() != kobject::type::channel)
+		return j6_err_invalid_arg;
+
+	channel *c = static_cast<channel*>(o);
+	return c->enqueue(len, data);
+}
+
+j6_status_t
+channel_receive(j6_handle_t handle, size_t *len, void *data)
+{
+	scheduler &s = scheduler::get();
+	TCB *tcb = s.current();
+	thread *parent = thread::from_tcb(tcb);
+	process &p = parent->parent();
+
+	kobject *o = p.lookup_handle(handle);
+	if (!o || o->get_type() != kobject::type::channel)
+		return j6_err_invalid_arg;
+
+	channel *c = static_cast<channel*>(o);
+	return c->dequeue(len, data);
+}
+
+} // namespace syscalls