From b8d31252339d41e3c31ec87c79cfa4b350d65a29 Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Wed, 1 Apr 2026 18:40:28 +0100
Subject: [PATCH] syscall: task: initial implementation of task_duplicate

---
 include/kernel/syscall.h |   3 ++
 syscall/dispatch.c       |   1 +
 syscall/task.c           | 101 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 105 insertions(+)

diff --git a/include/kernel/syscall.h b/include/kernel/syscall.h
index 1261a64..a2c9874 100644
--- a/include/kernel/syscall.h
+++ b/include/kernel/syscall.h
@@ -66,6 +66,9 @@ extern kern_status_t sys_task_config_set(
 	kern_config_key_t key,
 	const void *ptr,
 	size_t len);
+extern kern_status_t sys_task_duplicate(
+	kern_handle_t *out_task,
+	kern_handle_t *out_address_space);
 
 extern kern_status_t sys_thread_self(kern_handle_t *out);
 extern kern_status_t sys_thread_start(kern_handle_t thread);
diff --git a/syscall/dispatch.c b/syscall/dispatch.c
index 1446471..0173cea 100644
--- a/syscall/dispatch.c
+++ b/syscall/dispatch.c
@@ -10,6 +10,7 @@ static const virt_addr_t syscall_table[] = {
 	SYSCALL_TABLE_ENTRY(TASK_CREATE, task_create),
 	SYSCALL_TABLE_ENTRY(TASK_CREATE_THREAD, task_create_thread),
 	SYSCALL_TABLE_ENTRY(TASK_GET_ADDRESS_SPACE, task_get_address_space),
+	SYSCALL_TABLE_ENTRY(TASK_DUPLICATE, task_duplicate),
 	SYSCALL_TABLE_ENTRY(THREAD_SELF, thread_self),
 	SYSCALL_TABLE_ENTRY(THREAD_START, thread_start),
 	SYSCALL_TABLE_ENTRY(THREAD_EXIT, thread_exit),
diff --git a/syscall/task.c b/syscall/task.c
index a9077d7..3435cad 100644
--- a/syscall/task.c
+++ b/syscall/task.c
@@ -1,5 +1,6 @@
 #include <kernel/address-space.h>
 #include <kernel/machine/cpu.h>
+#include <kernel/panic.h>
 #include <kernel/printk.h>
 #include <kernel/sched.h>
 #include <kernel/syscall.h>
@@ -440,3 +441,103 @@ kern_status_t sys_thread_config_set(
 
 	return status;
 }
+
+kern_status_t sys_task_duplicate(
+	kern_handle_t *out_task,
+	kern_handle_t *out_address_space)
+{
+	struct task *self = get_current_task();
+
+	if (!validate_access_w(self, out_task, sizeof *out_task)) {
+		put_current_task(self);
+		return KERN_MEMORY_FAULT;
+	}
+
+	if (!validate_access_w(
+		    self,
+		    out_address_space,
+		    sizeof *out_address_space)) {
+		put_current_task(self);
+		return KERN_MEMORY_FAULT;
+	}
+
+	*out_task = KERN_HANDLE_INVALID;
+	*out_address_space = KERN_HANDLE_INVALID;
+
+	kern_status_t status = KERN_OK;
+	unsigned long flags;
+	task_lock_irqsave(self, &flags);
+
+	struct handle *child_handle_slot = NULL, *space_handle_slot = NULL;
+	kern_handle_t child_handle, space_handle;
+	status = handle_table_alloc_handle(
+		self->t_handles,
+		KERN_HANDLE_INVALID,
+		&child_handle_slot,
+		&child_handle);
+	if (status != KERN_OK) {
+		task_unlock_irqrestore(self, flags);
+		put_current_task(self);
+		return status;
+	}
+
+	status = handle_table_alloc_handle(
+		self->t_handles,
+		KERN_HANDLE_INVALID,
+		&space_handle_slot,
+		&space_handle);
+	if (status != KERN_OK) {
+		handle_table_free_handle(self->t_handles, child_handle);
+		task_unlock_irqrestore(self, flags);
+		put_current_task(self);
+		return status;
+	}
+
+	struct task *new_task = task_create(self->t_name, strlen(self->t_name));
+	if (!new_task) {
+		put_current_task(self);
+		return KERN_NO_MEMORY;
+	}
+
+	struct thread *new_thread = task_create_thread(new_task);
+	if (!new_thread) {
+		handle_table_free_handle(self->t_handles, child_handle);
+		handle_table_free_handle(self->t_handles, space_handle);
+		task_unlock_irqrestore(self, flags);
+		object_unref(&new_task->t_base);
+		put_current_task(self);
+		return KERN_NO_MEMORY;
+	}
+
+	struct thread *self_thread = get_current_thread();
+	thread_init_user_clone(new_thread, self_thread, KERN_OK);
+	put_current_thread(self_thread);
+
+	status = address_space_duplicate(
+		new_task->t_address_space,
+		self->t_address_space);
+	if (status != KERN_OK) {
+		handle_table_free_handle(self->t_handles, child_handle);
+		handle_table_free_handle(self->t_handles, space_handle);
+		task_unlock_irqrestore(self, flags);
+		object_unref(&new_thread->tr_base);
+		object_unref(&new_task->t_base);
+		put_current_task(self);
+		return status;
+	}
+
+	schedule_thread_on_cpu(new_thread);
+
+	child_handle_slot->h_object = &new_task->t_base;
+	space_handle_slot->h_object = &new_task->t_address_space->s_base;
+	task_unlock_irqrestore(self, flags);
+
+	*out_task = child_handle;
+	*out_address_space = space_handle;
+
+	/* clear TLB */
+	pmap_switch(self->t_pmap);
+	put_current_task(self);
+
+	return KERN_OK;
+}