obj: implement link objects

obj/namespace.c

@@ -128,27 +128,143 @@ kern_status_t object_namespace_get_object(struct object_namespace *ns, const cha
 
 	unsigned long flags;
 	while (tok) {
-		object_lock(cur, &flags);
+		object_lock_irqsave(cur, &flags);
 
 		struct object *next;
 		kern_status_t status = object_get_child_named(cur, tok, &next);
 		if (status != KERN_OK) {
-			object_unlock(cur, flags);
+			object_unlock_irqrestore(cur, flags);
 			kfree(rpath);
 			return status;
 		}
 
-		object_unlock(cur, flags);
+		object_unlock_irqrestore(cur, flags);
 		cur = next;
 		tok = strtok_r(NULL, "/", &sp);
+
+		object_lock_irqsave(cur, &flags);
+		if (!object_is_link(cur)) {
+			object_unlock_irqrestore(cur, flags);
+			continue;
+		}
+
+		struct object *dest_obj;
+		dest_obj = link_read_ptr(cur);
+		object_unlock_irqrestore(cur, flags);
+
+		if (!dest_obj) {
+			kfree(rpath);
+			/* TODO better error code for broken links */
+			return KERN_INVALID_ARGUMENT;
+		}
+
+		object_deref(cur);
+		cur = dest_obj;
 	}
 
 	kfree(rpath);
 
-	*out = object_ref(cur);
+	if (object_is_link(cur)) {
+		struct object *link_dest = link_read_ptr(cur);
+		object_deref(cur);
+		cur = object_ref(link_dest);
+	}
+
+	*out = cur;
 	return KERN_OK;
 }
 
+kern_status_t object_namespace_create_link(struct object_namespace *ns, const char *linkpath, struct object *dest)
+{
+	if (*linkpath != '/') {
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	while (*linkpath == '/') {
+		linkpath++;
+	}
+
+	size_t path_len = strlen(linkpath);
+	if (path_len == 0) {
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	size_t parts = 0;
+	char *rpath = kmalloc(path_len, 0);
+	if (!rpath) {
+		return KERN_NO_MEMORY;
+	}
+
+	memcpy(rpath, linkpath, path_len);
+	cleanup_object_path(rpath, path_len, &parts);
+
+	char *p = rpath + strlen(rpath) - 1;
+	while (*p != '/' && p >= rpath) {
+		p--;
+	}
+
+	if (p == rpath) {
+		kfree(rpath);
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	*p = '\0';
+	const char *linkname = p + 1;
+
+	char *sp;
+	char *tok = strtok_r(rpath, "/", &sp);
+	struct object *cur = object_ref(ns->ns_root);
+
+	unsigned long flags;
+	while (tok) {
+		object_lock_irqsave(cur, &flags);
+
+		struct object *next;
+		kern_status_t status = object_get_child_named(cur, tok, &next);
+		if (status == KERN_NO_ENTRY) {
+			next = set_create(tok);
+			if (!next) {
+				object_unlock_irqrestore(cur, flags);
+				object_deref(cur);
+				kfree(rpath);
+				return KERN_NO_MEMORY;
+			}
+
+			status = set_add_object(cur, next);
+
+			object_unlock_irqrestore(cur, flags);
+			object_deref(cur);
+		} else {
+			object_unlock_irqrestore(cur, flags);
+		}
+
+		if (status != KERN_OK) {
+			kfree(rpath);
+			return status;
+		}
+
+		cur = next;
+		tok = strtok_r(NULL, "/", &sp);
+	}
+
+	struct object *link = link_create(linkname, dest);
+	kfree(rpath);
+
+	if (!link) {
+		object_deref(cur);
+		return KERN_NO_MEMORY;
+	}
+
+	object_lock_irqsave(cur, &flags);
+	kern_status_t status = set_add_object(cur, link);
+	object_unlock_irqrestore(cur, flags);
+
+	object_deref(cur);
+	object_deref(link);
+
+	return status;
+}
+
 kern_status_t object_publish(struct object_namespace *ns, const char *path, struct object *obj)
 {
 	if (*path != '/') {
@@ -179,14 +295,14 @@ kern_status_t object_publish(struct object_namespace *ns, const char *path, stru
 
 	unsigned long flags;
 	while (tok) {
-		object_lock(cur, &flags);
+		object_lock_irqsave(cur, &flags);
 
 		struct object *next;
 		kern_status_t status = object_get_child_named(cur, tok, &next);
 		if (status == KERN_NO_ENTRY) {
 			next = set_create(tok);
 			if (!next) {
-				object_unlock(cur, flags);
+				object_unlock_irqrestore(cur, flags);
 				kfree(rpath);
 				return KERN_NO_MEMORY;
 			}
@@ -195,12 +311,12 @@ kern_status_t object_publish(struct object_namespace *ns, const char *path, stru
 		}
 
 		if (status != KERN_OK) {
-			object_unlock(cur, flags);
+			object_unlock_irqrestore(cur, flags);
 			kfree(rpath);
 			return status;
 		}
 
-		object_unlock(cur, flags);
+		object_unlock_irqrestore(cur, flags);
 		cur = next;
 		tok = strtok_r(NULL, "/", &sp);
 	}