Function BackendInitialize

src/backend/postmaster/postmaster.c:4885–5074

* BackendInitialize -- initialize an interactive (postmaster-child) * backend process, and collect the client's startup packet. * * returns: nothing. Will not return at all if there's any failure. * * Note: this code does not depend on having any access to shared memory. * Indeed, our approach to SIGTERM/timeout handling *requires* that * shared memory not have been touched yet; see com

 * but have not yet set up most of our local pointers to shmem structures.
 */
static void
BackendInitialize(Port *port)
{
	int			status;
	int			ret;
	char		remote_host[NI_MAXHOST];
	char		remote_port[NI_MAXSERV];
	StringInfoData ps_data;

	/* Save port etc. for ps status */
	MyProcPort = port;

	/* Tell fd.c about the long-lived FD associated with the port */
	ReserveExternalFD();

	/*
	 * PreAuthDelay is a debugging aid for investigating problems in the
	 * authentication cycle: it can be set in postgresql.conf to allow time to
	 * attach to the newly-forked backend with a debugger.  (See also
	 * PostAuthDelay, which we allow clients to pass through PGOPTIONS, but it
	 * is not honored until after authentication.)
	 */
	if (PreAuthDelay > 0)
		pg_usleep(PreAuthDelay * 1000000L);

	/* This flag will remain set until InitPostgres finishes authentication */
	ClientAuthInProgress = true;	/* limit visibility of log messages */

	/* set these to empty in case they are needed before we set them up */
	port->remote_host = "";
	port->remote_port = "";

	/*
	 * Initialize libpq and enable reporting of ereport errors to the client.
	 * Must do this now because authentication uses libpq to send messages.
	 */
	pq_init();					/* initialize libpq to talk to client */
	whereToSendOutput = DestRemote; /* now safe to ereport to client */

	/*
	 * We arrange to do _exit(1) if we receive SIGTERM or timeout while trying
	 * to collect the startup packet; while SIGQUIT results in _exit(2).
	 * Otherwise the postmaster cannot shutdown the database FAST or IMMED
	 * cleanly if a buggy client fails to send the packet promptly.
	 *
	 * Exiting with _exit(1) is only possible because we have not yet touched
	 * shared memory; therefore no outside-the-process state needs to get
	 * cleaned up.
	 */
	pqsignal(SIGTERM, process_startup_packet_die);
	/* SIGQUIT handler was already set up by InitPostmasterChild */
	InitializeTimeouts();		/* establishes SIGALRM handler */
	PG_SETMASK(&StartupBlockSig);

	/*
	 * Get the remote host name and port for logging and status display.
	 */
	remote_host[0] = '\0';