Capture OS signals for proper cleanup

[sean-gilliam]

Since Riftshadow has several threads / connections open, we should consider capturing at least the following signals using signal or sigaction.

• SIGINT : processed when Ctrl+C is used.
• SIGTERM : processed when kill -9 and the like are used
• SIGUSR1 : (optional) processed when reloading a configuration

There may be others. These are the ones that spring to mind though. Note that sigaction is Linux-only I believe.

Example:

int main(void)
{
    signal(SIGINT, sigIntHandler);
}

void sigIntHandler(int signum)
{
   // Some database connection cleanup
   exit(1);
}

int main(void)
{
    struct sigaction psa;
    memset (&psa, 0, sizeof (psa));
    psa.sa_handler = sigIntHandler;
    sigaction (SIGINT, &psa, NULL);
}

void sigIntHandler(int signum)
{
   // Some database connection cleanup
   exit(1);
}