fixing select usage

[kojo1]

• Set timeout in tcp_select
  timeout.tv_sec = to_sec;

• Set non-blocking to "connd", as well.
  fcntl(connd, F_SETFL, O_NONBLOCK)

• tcp_select(connd,...) for wolfSSL_accept, read, write

• make all 3 args non-NULL for select. NULL arg derives error on MacOS.

====

Totally changed to a single polling point.

SV_CTX *sv_poll() {
        poll();
        return next_ctx;
}

int main() {
    while(1) {
        switch (sv_main(sv_ctx = sv_poll())) {
        case NB_CONTINUE:
            break;
    }
}

[julek-wolfssl]

Since we do not check the return of tcp_select, it would be better to change the return to a void. Alternatively, the return of this function should be checked in the main loop.

[kojo1]

Updated to poll() version as Daniele suggested. It looks like behaving as expected.

Will eliminate the return value as soon as debugging is completed.

[danielinux]

The example looks clear now.
I like the idea of a state machine with a switch-case with these FALL_THROUGH, however sv_main is a bit too long, perhaps it could be split into more functions for readability.

Please fix the spelling of macros NB_FATAL and SV_VERBOSE.

[julek-wolfssl]

Shouldn't this be return 1 so that execution is stopped?