Add auto subscribe support

Add a new property to ubus_subscriber called new_obj_cb. It gets called
everytime a new object appears on the bus. If the callback returns true,
libubus will automatically subscribe to the notifications.

Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/libubus-sub.c b/libubus-sub.c
index 8793133ad05ec54802be86860e032aa10186a99c..e395905f547662a5dc433830e508e78a66b8caf2 100644 (file)
--- a/libubus-sub.c
+++ b/libubus-sub.c
@@ -31,13 +31,66 @@ const struct ubus_method watch_method __hidden = {
        .handler = ubus_subscriber_cb,
 };
 
+static void
+ubus_auto_sub_event_handler_cb(struct ubus_context *ctx,  struct ubus_event_handler *ev,
+                              const char *type, struct blob_attr *msg)
+{
+       enum {
+               EVENT_ID,
+               EVENT_PATH,
+               __EVENT_MAX
+       };
+
+       static const struct blobmsg_policy event_policy[__EVENT_MAX] = {
+               [EVENT_ID] = { .name = "id", .type = BLOBMSG_TYPE_INT32 },
+               [EVENT_PATH] = { .name = "path", .type = BLOBMSG_TYPE_STRING },
+       };
+
+       struct blob_attr *tb[__EVENT_MAX];
+       struct ubus_subscriber *s;
+       const char *path;
+       int id;
+
+       blobmsg_parse(event_policy, __EVENT_MAX, tb, blob_data(msg), blob_len(msg));
+
+       if (!tb[EVENT_ID] || !tb[EVENT_PATH])
+               return;
+
+       path = blobmsg_get_string(tb[EVENT_PATH]);
+       id = blobmsg_get_u32(tb[EVENT_ID]);
+
+       list_for_each_entry(s, &ctx->auto_subscribers, list)
+               if (s->new_obj_cb(ctx, s, path))
+                       ubus_subscribe(ctx, s, id);
+}
+
+static void
+ubus_auto_sub_lookup(struct ubus_context *ctx, struct ubus_object_data *obj,
+                    void *priv)
+{
+       struct ubus_subscriber *s = priv;
+
+       if (s->new_obj_cb(ctx, s, obj->path))
+               ubus_subscribe(ctx, s, obj->id);
+}
+
 int ubus_register_subscriber(struct ubus_context *ctx, struct ubus_subscriber *s)
 {
        struct ubus_object *obj = &s->obj;
 
+       INIT_LIST_HEAD(&s->list);
        obj->methods = &watch_method;
        obj->n_methods = 1;
 
+       if (s->new_obj_cb) {
+               struct ubus_event_handler *ev = &ctx->auto_subscribe_event_handler;
+               list_add(&s->list, &ctx->auto_subscribers);
+               ev->cb = ubus_auto_sub_event_handler_cb;
+               if (!ev->obj.id)
+                       ubus_register_event_handler(ctx, ev, "ubus.object.add");
+               ubus_lookup(ctx, NULL, ubus_auto_sub_lookup, s);
+       }
+
        return ubus_add_object(ctx, obj);
 }
 

diff --git a/libubus.c b/libubus.c
index d625940d8edbf35419ad0c65ea53f2bade3424c6..c9c3c6e5c2484b23b06ffc2407f2cbc476b6eb62 100644 (file)
--- a/libubus.c
+++ b/libubus.c
@@ -298,6 +298,7 @@ int ubus_connect_ctx(struct ubus_context *ctx, const char *path)
 
        INIT_LIST_HEAD(&ctx->requests);
        INIT_LIST_HEAD(&ctx->pending);
+       INIT_LIST_HEAD(&ctx->auto_subscribers);
        avl_init(&ctx->objects, ubus_cmp_id, false, NULL);
        if (ubus_reconnect(ctx, path)) {
                free(ctx->msgbuf.data);

diff --git a/libubus.h b/libubus.h
index 6925514adb0fcea7929e52f67adabc04cbeacfaa..b74a82348e6c5fedb02805db626cfdce406cb060 100644 (file)
--- a/libubus.h
+++ b/libubus.h
@@ -63,6 +63,7 @@ typedef void (*ubus_notify_complete_handler_t)(struct ubus_notify_request *req,
 typedef void (*ubus_notify_data_handler_t)(struct ubus_notify_request *req,
                                           int type, struct blob_attr *msg);
 typedef void (*ubus_connect_handler_t)(struct ubus_context *ctx);
+typedef bool (*ubus_new_object_handler_t)(struct ubus_context *ctx, struct ubus_subscriber *sub, const char *path);
 
 #define UBUS_OBJECT_TYPE(_name, _methods)              \
        {                                               \
@@ -139,10 +140,12 @@ struct ubus_object {
 };
 
 struct ubus_subscriber {
+       struct list_head list;
        struct ubus_object obj;
 
        ubus_handler_t cb;
        ubus_remove_handler_t remove_cb;
+       ubus_new_object_handler_t new_obj_cb;
 };
 
 struct ubus_event_handler {
@@ -170,6 +173,9 @@ struct ubus_context {
        struct ubus_msghdr_buf msgbuf;
        uint32_t msgbuf_data_len;
        int msgbuf_reduction_counter;
+
+       struct list_head auto_subscribers;
+       struct ubus_event_handler auto_subscribe_event_handler;
 };
 
 struct ubus_object_data {
@@ -302,6 +308,8 @@ int ubus_register_subscriber(struct ubus_context *ctx, struct ubus_subscriber *o
 static inline int
 ubus_unregister_subscriber(struct ubus_context *ctx, struct ubus_subscriber *obj)
 {
+       if (!list_empty(&obj->list))
+               list_del_init(&obj->list);
        return ubus_remove_object(ctx, &obj->obj);
 }