obj: implement link objects

include/socks/object.h

@@ -13,6 +13,7 @@ extern "C" {
 
 #define OBJECT_MAGIC 0xBADDCAFE
 #define OBJECT_NAME_MAX 64
+#define OBJECT_PATH_MAX 256
 
 #define OBJECT_CAST(to_type, to_type_member, p) \
 	((to_type *)((uintptr_t)p) - offsetof(to_type, to_type_member))
@@ -76,14 +77,17 @@ extern struct object_namespace *global_namespace(void);
 extern struct object_namespace *object_namespace_create(void);
 extern struct object *ns_header(struct object_namespace *ns);
 extern kern_status_t object_namespace_get_object(struct object_namespace *ns, const char *path, struct object **out);
+extern kern_status_t object_namespace_create_link(struct object_namespace *ns, const char *linkpath, struct object *dest);
 extern kern_status_t object_publish(struct object_namespace *ns, const char *path, struct object *obj);
 extern kern_status_t object_unpublish(struct object_namespace *ns, struct object *obj);
 
 extern struct object *object_create(struct object_type *type);
 extern struct object *object_ref(struct object *obj);
 extern void object_deref(struct object *obj);
-extern void object_lock(struct object *obj, unsigned long *flags);
-extern void object_unlock(struct object *obj, unsigned long flags);
+extern void object_lock(struct object *obj);
+extern void object_unlock(struct object *obj);
+extern void object_lock_irqsave(struct object *obj, unsigned long *flags);
+extern void object_unlock_irqrestore(struct object *obj, unsigned long flags);
 static inline kern_status_t object_get(const char *path, struct object **out)
 {
 	return object_namespace_get_object(global_namespace(), path, out);
@@ -99,7 +103,12 @@ extern kern_status_t set_add_object(struct object *set, struct object *obj);
 extern kern_status_t set_remove_object(struct object *set, struct object *obj);
 extern bool object_is_set(struct object *obj);
 
+extern struct object *link_create(const char *name, struct object *dest);
+extern struct object *link_read_ptr(struct object *link);
+extern bool object_is_link(struct object *obj);
+
 extern void init_set_objects(void);
+extern void init_link_objects(void);
 extern void init_global_namespace(void);
 
 #ifdef __cplusplus

obj/link.c

@@ -0,0 +1,62 @@
+#include <socks/object.h>
+
+#define LINK_CAST(p) OBJECT_C_CAST(struct link, l_base, &link_type, p)
+
+struct link {
+	struct object l_base;
+	char l_name[OBJECT_NAME_MAX];
+	struct object *l_dest;
+};
+
+static struct object_type link_type;
+
+static kern_status_t link_query_name(struct object *obj, char out[OBJECT_NAME_MAX])
+{
+	struct link *link = LINK_CAST(obj);
+	strncpy(out, link->l_name, OBJECT_NAME_MAX - 1);
+	out[OBJECT_NAME_MAX - 1] = 0;
+
+	return KERN_OK;
+}
+
+static struct object_type link_type = {
+	.ob_name = "link",
+	.ob_size = sizeof(struct link),
+	.ob_header_offset = offsetof(struct link, l_base),
+	.ob_ops = {
+		.query_name = link_query_name,
+	},
+};
+
+void init_link_objects(void)
+{
+	object_type_register(&link_type);
+}
+
+struct object *link_create(const char *name, struct object *dest)
+{
+	struct object *link_obj = object_create(&link_type);
+	if (!link_obj) {
+		return NULL;
+	}
+
+	struct link *link = LINK_CAST(link_obj);
+
+	strncpy(link->l_name, name, sizeof link->l_name - 1);
+	link->l_name[sizeof link->l_name - 1] = 0;
+
+	link->l_dest = object_ref(dest);
+
+	return link_obj;
+}
+
+struct object *link_read_ptr(struct object *link_obj)
+{
+	struct link *link = LINK_CAST(link_obj);
+	return link->l_dest;
+}
+
+bool object_is_link(struct object *obj)
+{
+	return obj->ob_type == &link_type;
+}

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);
 	}

obj/object.c

@@ -10,6 +10,7 @@ static spin_lock_t object_types_lock = SPIN_LOCK_INIT;
 kern_status_t object_bootstrap(void)
 {
 	init_set_objects();
+	init_link_objects();
 	init_global_namespace();
 	return KERN_OK;
 }
@@ -96,12 +97,22 @@ void object_deref(struct object *obj)
 	vm_cache_free(&obj->ob_type->ob_cache, obj);
 }
 
-void object_lock(struct object *obj, unsigned long *flags)
+void object_lock(struct object *obj)
+{
+	spin_lock(&obj->ob_lock);
+}
+
+void object_unlock(struct object *obj)
+{
+	spin_unlock(&obj->ob_lock);
+}
+
+void object_lock_irqsave(struct object *obj, unsigned long *flags)
 {
 	spin_lock_irqsave(&obj->ob_lock, flags);
 }
 
-void object_unlock(struct object *obj, unsigned long flags)
+void object_unlock_irqrestore(struct object *obj, unsigned long flags)
 {
 	spin_unlock_irqrestore(&obj->ob_lock, flags);
 }