[bugfix] Fix use-after-free memory corruption of RtcAlarmManager objects

[Crypter]

Because this class uses dynamic memory allocation for the _alarms variable, the default copy constructor and assignment operators would cause copy of the reference only, not the data itself. This solves the issue by copying the data on new allocated memory.

Unwanted symptoms by this bug

• The memory this reference points to may be freed by the source object later on, and the overwritten by something else as it's now free memory. Use-after-free and data corruption.
• Modification of _alarms in either the source or the destination object will reflect a change in the other. Data corruption.

How to replicate and verify this bug:

RtcAlarmManager<callback> destination = RtcAlarmManager<callback>(1);
// print the value of the _alarms pointer and compare, _alarms needs to be made public
// Serial.printf("%p == %p", destination._alarms, source._alarms);

[Makuna]

While you are pointing out a good bug, your provided solution is not the right direction.

As a "manager" object, it is meant to be a "singleton" and not copied. What would it mean to have two active managers with the same alarms in them? Why would you need it?

Any passing of the object as an argument should be by reference or by pointer as to not copy it. The class should try to enforce this and there are ways.

Further, as a true singleton it shouldn't be passed or stored at all. It just should be accessed from the static single instance. The normal Arduino model of "singleton" is to have a global in your sketch. Another is like String.

If you search up Singleton Pattern you will see the way it should be done.
Please add an "issue" for tracking this.