orb_advert_t changed to void * and checks changed to nullptr

The existing orb_advert_t use thoughout the code sometimes tries
to treat it as a file descriptor and there are checks for < 0
and ::close calls on orb_advert_t types which is an invalid use
of an object pointer, which is what orb_advert_t really is.

Initially I had changed the -1 initializations to 0 but it was
suggested that this should be nullptr. That was a good recommendation
but the definition of orb_advert_t had to change to void * because
you cannot initialize a uintptr_t as nullptr.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/modules/uORB/Publication.hpp

@@ -64,7 +64,7 @@ public:
 	 */
 	PublicationBase(const struct orb_metadata *meta) :
 		_meta(meta),
-		_handle(-1) {
+		_handle(nullptr) {
 	}
 
 	/**
@@ -72,7 +72,7 @@ public:
 	 * @param data The uORB message struct we are updating.
 	 */
 	void update(void * data) {
-		if (_handle > 0) {
+		if (_handle != nullptr) {
 			orb_publish(getMeta(), getHandle(), data);
 		} else {
 			setHandle(orb_advertise(getMeta(), data));
@@ -83,11 +83,10 @@ public:
 	 * Deconstructor
 	 */
 	virtual ~PublicationBase() {
-		orb_unsubscribe(getHandle());
 	}
 // accessors
 	const struct orb_metadata *getMeta() { return _meta; }
-	int getHandle() { return _handle; }
+	orb_advert_t getHandle() { return _handle; }
 protected:
 // accessors
 	void setHandle(orb_advert_t handle) { _handle = handle; }

src/modules/uORB/uORB.h

@@ -135,7 +135,7 @@ __BEGIN_DECLS
  * a file-descriptor-based handle would not otherwise be in scope for the
  * publisher.
  */
-typedef uintptr_t	orb_advert_t;
+typedef void *	orb_advert_t;
 
 /**
  * Advertise as the publisher of a topic.

src/modules/uORB/uORBManager.hpp

@@ -73,11 +73,11 @@ class uORB::Manager
    * @param data    A pointer to the initial data to be published.
    *      For topics updated by interrupt handlers, the advertisement
    *      must be performed from non-interrupt context.
-   * @return    ERROR on error, otherwise returns a handle
+   * @return    nullptr on error, otherwise returns an object pointer
    *      that can be used to publish to the topic.
    *      If the topic in question is not known (due to an
    *      ORB_DEFINE with no corresponding ORB_DECLARE)
-   *      this function will return -1 and set errno to ENOENT.
+   *      this function will return nullptr and set errno to ENOENT.
    */
   orb_advert_t orb_advertise(const struct orb_metadata *meta, const void *data);
 

src/modules/uORB/uORBManager_posix.cpp

@@ -94,7 +94,7 @@ orb_advert_t uORB::Manager::orb_advertise_multi(const struct orb_metadata *meta,
   fd = node_open(PUBSUB, meta, data, true, instance, priority);
   if (fd == ERROR) {
     warnx("node_open as advertiser failed.");
-    return 0;
+    return nullptr;
   }
 
   /* get the advertiser handle and close the node */
@@ -102,14 +102,14 @@ orb_advert_t uORB::Manager::orb_advertise_multi(const struct orb_metadata *meta,
   px4_close(fd);
   if (result == ERROR) {
     warnx("px4_ioctl ORBIOCGADVERTISER  failed. fd = %d", fd);
-    return 0;
+    return nullptr;
   }
 
   /* the advertiser must perform an initial publish to initialise the object */
   result = orb_publish(meta, advertiser, data);
   if (result == ERROR) {
     warnx("orb_publish failed");
-    return 0;
+    return nullptr;
   }
 
   return advertiser;

src/modules/uORB/uORBTest_UnitTest.cpp

@@ -192,7 +192,7 @@ int uORBTest::UnitTest::test()
   test_note("try multi-topic support");
 
   int instance0;
-  int pfd0 = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance0, ORB_PRIO_MAX);
+  orb_advert_t pfd0 = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance0, ORB_PRIO_MAX);
 
   test_note("advertised");