Support compile with clang on MacOS

[rabits]

A number of changes to make the code compile on MacOS with clang.

The other patches in series:

• Build on MacOS with TLS support go-dqlite#132
• Build on MacOS raft#173

[stgraber]

Needs a few tweaks to make travis happy :)

[stgraber]

Can you rebase this into a single commit?

[rabits]

Oh, sure)

[stgraber]

What's defining those variables?
I'm not seeing matching autotools changes which would detect and set:

• HAVE_SYS_UCRED_H
• HAVE_DECL_LOCAL_PEERCRED
• HAVE_DECL_SO_PEERCRED

[rabits]

Good catch! My bad, will adjust the configs

[rabits]

Yep, actually need to rewrite the bsd-part, it compiled just because definitions was not set...

[rabits]

@stgraber could you please suggest how to test it properly? I use go-dqlite, so where I will see it's working or not?

[stgraber]

Should add error checking for this.

[rabits]

Yep, fixed

[stgraber]

I'm not all that familiar with the internals of dqlite, I certainly understand the goal of this logic but am not sure what's the best way to test it. I tried connecting to a number of the pipes held by LXD here, but that's not going anywhere, presumably because those are already connected, so I'm never hitting the code that would reject the connection (just stuck waiting for accept basically).

@freeekanayaka would definitely be able to assist there, maybe @MathieuBordere somehow already looked at that part of the codebase too but he's mostly been focused on raft issues so far ;)

[MathieuBordere]

I'm not all that familiar with the internals of dqlite, I certainly understand the goal of this logic but am not sure what's the best way to test it. I tried connecting to a number of the pipes held by LXD here, but that's not going anywhere, presumably because those are already connected, so I'm never hitting the code that would reject the connection (just stuck waiting for accept basically).

@freeekanayaka would definitely be able to assist there, maybe @MathieuBordere somehow already looked at that part of the codebase too but he's mostly been focused on raft issues so far ;)

Not too familiar with this part of the codebase, will have a look eventually if this stays open :-)

[freeekanayaka]

If you run the go-dqlite tests (in particular the ones in the go-dqlite/app sub-package`), that should be enough to test the part that you are modifying. Essentially the code path that you touch in this PR gets triggered if you tell the dqlite engine to listen to an abstract unix socket rather to a TCP port (so for example you can proxy incoming connections with TLS). In that case you want to make sure that incoming connections are coming from the same process (e.g. a Go process performing the TLS proxy dance), otherwise any process on the host would be able to connect.

[rabits]

Thanks, folks - figured out there is other changes required after I compiled go-dqlite demo. Will continue to test and come back with a solution)

[rabits]

Ok, that was a journey. To run the node and walk through demo it will also require libraft changes, and some other adjustments, but ended up with the networking issues - seems the custom aligned_alloc is not working well and causing a mess in the communication protocol... Will prepare the changes and try to find some help with debugging.