commit 17052240ae193aad162610db65ea6ed95f098c69
author Vernon Mauery <vernon.mauery@linux.intel.com> Tue Sep 25 12:34:25 2018 -0700
committer William A. Kennington III <wak@google.com> Thu Sep 27 22:48:10 2018 +0000
tree c047a918a8db448b78ad606a8d504ef79366e4d7
parent 18fe17451f08d5ef394613faa9367c06cfd44561

Allow copy constructor/assignment operator for message::message

This change enables copies and assignments of messages, specifically,
copy constructors and copy assignment operators and the default empty
constructor. A boost::asio::yield_context needs to be able to store the
result of the async operation (a message::message) in a helper struct,
which results in a default construction (with a null msg_t) and later an
assignment to replace it when the result is ready. But adding the
appropriate sd_bus_message_ref/unref calls makes this possible.

While the default-constructed object does not sit around for long, this
change also adds in some asserts to catch any invalid accesses of the
object in that state.

Change-Id: I2059cb677fc5a30a3c7e3c2b81ed4199e5460dde
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>

sdbusplus/message.hpp

diff --git a/sdbusplus/message.hpp b/sdbusplus/message.hpp
index ac468dc..a989a48 100644
--- a/sdbusplus/message.hpp
+++ b/sdbusplus/message.hpp
@@ -49,17 +49,13 @@
 class message
 {
     /* Define all of the basic class operations:
-     *     Not allowed:
-     *         - Default constructor to avoid nullptrs.
-     *         - Copy operations due to internal unique_ptr.
      *     Allowed:
+     *         - Default constructor
+     *         - Copy operations.
      *         - Move operations.
      *         - Destructor.
      */
   public:
-    message() = delete;
-    message(const message&) = delete;
-    message& operator=(const message&) = delete;
     message(message&&) = default;
     message& operator=(message&&) = default;
     ~message() = default;
@@ -74,7 +70,7 @@
      *  Takes increment ref-count of the msg-pointer and release when
      *  destructed.
      */
-    explicit message(msgp_t m) : message(m, &sdbus_impl)
+    explicit message(msgp_t m = nullptr) : message(m, &sdbus_impl)
     {
     }
 
@@ -91,6 +87,26 @@
     {
     }
 
+    /** @brief Copy constructor for 'message'.
+     *
+     *  Copies the message class and increments the ref on _msg
+     */
+    message(const message& other) :
+        _intf(other._intf), _msg(sd_bus_message_ref(other._msg.get()))
+    {
+    }
+
+    /** @brief Assignment operator for 'message'.
+     *
+     *  Copies the message class and increments the ref on _msg
+     */
+    message& operator=(const message& other)
+    {
+        _msg.reset(sd_bus_message_ref(other._msg.get()));
+        _intf = other._intf;
+        return *this;
+    }
+
     /** @brief Release ownership of the stored msg-pointer. */
     msgp_t release()
     {