poke: exit with status 5 if prefix registration fails

Change-Id: I2147570c37146011c9a4e8c024b74bcafdf18e4e
diff --git a/tools/peek/ndnpoke/ndnpoke.hpp b/tools/peek/ndnpoke/ndnpoke.hpp
index af5ad34..e47da81 100644
--- a/tools/peek/ndnpoke/ndnpoke.hpp
+++ b/tools/peek/ndnpoke/ndnpoke.hpp
@@ -56,15 +56,27 @@
 public:
   NdnPoke(Face& face, KeyChain& keyChain, std::istream& input, const PokeOptions& options);
 
+  enum class Result {
+    DATA_SENT = 0,
+    UNKNOWN = 1,
+    // 2 is reserved for "malformed command line"
+    TIMEOUT = 3,
+    // 4 is reserved for "nack"
+    PREFIX_REG_FAIL = 5,
+  };
+
+  /**
+   * @return the result of NdnPoke execution
+   */
+  Result
+  getResult() const
+  {
+    return m_result;
+  }
+
   void
   start();
 
-  bool
-  didSendData() const
-  {
-    return m_didSendData;
-  }
-
 private:
   shared_ptr<Data>
   createData() const;
@@ -77,7 +89,7 @@
   Scheduler m_scheduler;
   ScopedRegisteredPrefixHandle m_registeredPrefix;
   scheduler::ScopedEventId m_timeoutEvent;
-  bool m_didSendData = false;
+  Result m_result = Result::UNKNOWN;
 };
 
 } // namespace peek