fs: rpmsgfs_client: process host message as ns_announcement

Threat unsolicited messages from the host as ns_announcement messages.
It unlocks the client flow by calling rpmsg_post() on the semaphore.
Without this or an NS announcement, the client's semaphore will wait
forever.

This is practical when the server side is running from linux userspace
using ioctl where controlling NS announcements is problematic.

Signed-off-by: Andre Heinemans <andre.heinemans@nxp.com>

Author: AndreHeinemans-NXP

fs/rpmsgfs/rpmsgfs_client.c

@@ -49,6 +49,7 @@ struct rpmsgfs_s
   struct rpmsg_endpoint ept;
   char                  cpuname[RPMSG_NAME_SIZE];
   sem_t                 wait;
+  bool                  connected;
 };
 
 struct rpmsgfs_cookie_s
@@ -291,10 +292,14 @@ static FAR void *rpmsgfs_get_tx_payload_buffer(FAR struct rpmsgfs_s *priv,
   return rpmsg_get_tx_payload_buffer(&priv->ept, len, true);
 }
 
-static void rpmsgfs_ns_bound(struct rpmsg_endpoint *ept)
+static void rpmsgfs_set_connected(struct rpmsg_endpoint *ept)
 {
   FAR struct rpmsgfs_s *priv = ept->priv;
-  rpmsg_post(&priv->ept, &priv->wait);
+  if (!priv->connected)
+    {
+      priv->connected = true;
+      rpmsg_post(&priv->ept, &priv->wait);
+    }
 }
 
 static void rpmsgfs_device_created(FAR struct rpmsg_device *rdev,
@@ -306,7 +311,7 @@ static void rpmsgfs_device_created(FAR struct rpmsg_device *rdev,
   if (strcmp(priv->cpuname, rpmsg_get_cpuname(rdev)) == 0)
     {
       priv->ept.priv = priv;
-      priv->ept.ns_bound_cb = rpmsgfs_ns_bound;
+      priv->ept.ns_bound_cb = rpmsgfs_set_connected;
       snprintf(buf, sizeof(buf), "%s%p", RPMSGFS_NAME_PREFIX, priv);
       rpmsg_create_ept(&priv->ept, rdev, buf,
                        RPMSG_ADDR_ANY, RPMSG_ADDR_ANY,
@@ -329,9 +334,15 @@ static int rpmsgfs_ept_cb(FAR struct rpmsg_endpoint *ept,
                           FAR void *data, size_t len, uint32_t src,
                           FAR void *priv)
 {
+  FAR struct rpmsgfs_s *ept_priv = ept->priv;
   FAR struct rpmsgfs_header_s *header = data;
   uint32_t command = header->command;
 
+  if (!ept_priv->connected)
+    {
+      rpmsgfs_set_connected(ept);
+    }
+
   if (command < nitems(g_rpmsgfs_handler))
     {
       return g_rpmsgfs_handler[command](ept, data, len, src, priv);