Add destructor to fs::File which will close the file

[TD-er]

Fs.h doesn't implement a destructor.
It would be nice I guess to have a destructor which calls the close() function, since it is not useful to keep the file open if the File object gets out of scope.
A forgotten call to close() seem to introduce at least a memory leak somewhere, but maybe also other issues I cannot think of yet.

So is it a good idea to add a (virtual) destructor for fs::File ?

[Makuna]

The way its implemented, it relies on the smart pointer to the implementation to do any cleanup as it is needed. It doesn't look like any of the implementations do anything in their destructors though.

[TD-er]

@Makuna Yep, the shared pointer is indeed cleaning up the strict virtual object FileImpl, but like you said the rest doesn't do anything with this destruction action.

In our project we observe some resources still be held when the f.close() is not being called.
So I'm not sure where these resources will be held and maybe eventually be freed?
Maybe in the SPIFFS code?
It is being used like this (without the f.close() when leaving the scope) :

fs::File f = SPIFFS.open(fileName, "r+");

[earlephilhower]

We're redoing the FSImpl interface and this can slide in w/the other changes. I don't think leaking in SPIFFS is possible (you have to pass in memory for the FD and for the buffer from the wrapper class), but it's simple enough to verify.

[earlephilhower]

As far as I can see SPIFFs already calls close() on itself when deleted.

    ~SPIFFSFileImpl() override
    {
        close();
    }

Closing for now, but if you have a MCVE we can run and see something anomalous, please do post it and re-open.