kernel: replace kern_handle_duplicate with the more powerful kern_handle_transfer

this syscall can move and copy handles within the current task, or from/to
other tasks

include/kernel/syscall.h

@@ -143,9 +143,13 @@ extern kern_status_t sys_address_space_release(
 
 extern kern_status_t sys_kern_log(const char *s);
 extern kern_status_t sys_kern_handle_close(kern_handle_t handle);
-extern kern_status_t sys_kern_handle_duplicate(
+extern kern_status_t sys_kern_handle_transfer(
-	kern_handle_t handle,
+	kern_handle_t src_task_handle,
-	kern_handle_t *out);
+	kern_handle_t src_handle,
+	kern_handle_t dest_task_handle,
+	kern_handle_t dest_handle,
+	unsigned int mode,
+	kern_handle_t *out_handle);
 extern kern_status_t sys_kern_config_get(
 	kern_config_key_t key,
 	void *ptr,

libmango/arch/x86_64/syscall.S

@@ -83,7 +83,7 @@ SYSCALL_GATE address_space_release SYS_ADDRESS_SPACE_RELEASE 3
 
 SYSCALL_GATE kern_log SYS_KERN_LOG 1
 SYSCALL_GATE kern_handle_close SYS_KERN_HANDLE_CLOSE 1
-SYSCALL_GATE kern_handle_duplicate SYS_KERN_HANDLE_DUPLICATE 2
+SYSCALL_GATE kern_handle_transfer SYS_KERN_HANDLE_TRANSFER 6
 SYSCALL_GATE kern_config_get SYS_KERN_CONFIG_GET 3
 SYSCALL_GATE kern_config_set SYS_KERN_CONFIG_SET 3
 

libmango/include-user/mango/handle.h

@@ -5,8 +5,12 @@
 #include <mango/types.h>
 
 extern kern_status_t kern_handle_close(kern_handle_t handle);
-extern kern_status_t kern_handle_duplicate(
+extern kern_status_t kern_handle_transfer(
-	kern_handle_t handle,
+	kern_handle_t src_task,
-	kern_handle_t *out);
+	kern_handle_t src_handle,
+	kern_handle_t dest_task,
+	kern_handle_t dest_handle,
+	unsigned int mode,
+	kern_handle_t *out_handle);
 
 #endif

libmango/include/mango/syscall.h

@@ -3,7 +3,7 @@
 
 #define SYS_KERN_LOG                    1
 #define SYS_KERN_HANDLE_CLOSE           2
-#define SYS_KERN_HANDLE_DUPLICATE       3
+#define SYS_KERN_HANDLE_TRANSFER        3
 #define SYS_KERN_CONFIG_GET             4
 #define SYS_KERN_CONFIG_SET             5
 #define SYS_KERN_OBJECT_WAIT            6

syscall/dispatch.c

@@ -27,7 +27,7 @@ static const virt_addr_t syscall_table[] = {
 	SYSCALL_TABLE_ENTRY(ADDRESS_SPACE_RELEASE, address_space_release),
 	SYSCALL_TABLE_ENTRY(KERN_LOG, kern_log),
 	SYSCALL_TABLE_ENTRY(KERN_HANDLE_CLOSE, kern_handle_close),
-	SYSCALL_TABLE_ENTRY(KERN_HANDLE_DUPLICATE, kern_handle_duplicate),
+	SYSCALL_TABLE_ENTRY(KERN_HANDLE_TRANSFER, kern_handle_transfer),
 	SYSCALL_TABLE_ENTRY(KERN_CONFIG_GET, kern_config_get),
 	SYSCALL_TABLE_ENTRY(KERN_CONFIG_SET, kern_config_set),
 	SYSCALL_TABLE_ENTRY(CHANNEL_CREATE, channel_create),

syscall/handle.c

@@ -8,32 +8,132 @@ kern_status_t sys_kern_handle_close(kern_handle_t handle)
 	return task_close_handle(self, handle);
 }
 
-kern_status_t sys_kern_handle_duplicate(
+kern_status_t sys_kern_handle_transfer(
-	kern_handle_t handle,
+	kern_handle_t src_task_handle,
-	kern_handle_t *out)
+	kern_handle_t src_handle,
+	kern_handle_t dest_task_handle,
+	kern_handle_t dest_handle,
+	unsigned int mode,
+	kern_handle_t *out_handle)
 {
+	switch (mode) {
+	case HANDLE_TRANSFER_MOVE:
+	case HANDLE_TRANSFER_COPY:
+		break;
+	default:
+		return KERN_INVALID_ARGUMENT;
+	}
+
 	struct task *self = current_task();
 
-	if (!validate_access_w(self, out, sizeof *out)) {
+	if (out_handle
+	    && !validate_access_w(self, out_handle, sizeof *out_handle)) {
 		return KERN_MEMORY_FAULT;
 	}
 
 	unsigned long flags;
 	task_lock_irqsave(self, &flags);
 
+	struct object *src_object = NULL;
+	struct task *src_task = NULL;
+	struct task *dest_task = NULL;
+	kern_status_t status = KERN_OK;
+
 	struct object *obj = NULL;
 	handle_flags_t handle_flags = 0;
-	kern_status_t status
+
-		= task_resolve_handle(self, handle, &obj, &handle_flags);
+	if (src_task_handle != KERN_HANDLE_INVALID) {
-	if (status != KERN_OK) {
+		status = task_resolve_handle(
-		task_unlock_irqrestore(self, flags);
+			self,
-		return status;
+			src_task_handle,
+			&obj,
+			&handle_flags);
+		if (status != KERN_OK) {
+			task_unlock_irqrestore(self, flags);
+			goto cleanup;
+		}
+
+		src_task = task_cast(obj);
+		if (!src_task) {
+			status = KERN_INVALID_ARGUMENT;
+			goto cleanup;
+		}
+	} else {
+		src_task = self;
 	}
 
-	status = task_open_handle(self, obj, handle_flags, out);
+	if (dest_task_handle != KERN_HANDLE_INVALID) {
-	object_unref(obj);
+		status = task_resolve_handle(
+			self,
+			dest_task_handle,
+			&obj,
+			&handle_flags);
+		if (status != KERN_OK) {
+			task_unlock_irqrestore(self, flags);
+			goto cleanup;
+		}
+
+		dest_task = task_cast(obj);
+		if (!dest_task) {
+			status = KERN_INVALID_ARGUMENT;
+			goto cleanup;
+		}
+	} else {
+		dest_task = self;
+	}
+
+	status = task_resolve_handle(
+		self,
+		src_handle,
+		&src_object,
+		&handle_flags);
+	if (status != KERN_OK) {
+		goto cleanup;
+	}
 
 	task_unlock_irqrestore(self, flags);
 
+	struct handle *dest = NULL;
+	task_lock_irqsave(dest_task, &flags);
+	status = handle_table_alloc_handle(
+		dest_task->t_handles,
+		dest_handle,
+		&dest,
+		&dest_handle);
+	task_unlock_irqrestore(dest_task, flags);
+
+	if (status != KERN_OK) {
+		goto cleanup;
+	}
+
+	if (mode == HANDLE_TRANSFER_MOVE) {
+		object_ref(src_object);
+		task_lock_irqsave(src_task, &flags);
+		handle_table_free_handle(src_task->t_handles, src_handle);
+		task_unlock_irqrestore(src_task, flags);
+	}
+
+	dest->h_object = src_object;
+	dest->h_flags = handle_flags;
+
+	if (out_handle) {
+		*out_handle = dest_handle;
+	}
+
+	return KERN_OK;
+
+cleanup:
+	if (src_task && src_task_handle != KERN_HANDLE_INVALID) {
+		object_unref(&src_task->t_base);
+	}
+
+	if (dest_task && dest_task_handle != KERN_HANDLE_INVALID) {
+		object_unref(&dest_task->t_base);
+	}
+
+	if (src_object) {
+		object_unref(src_object);
+	}
+
 	return status;
 }