Function process_startup_options

src/backend/utils/init/postinit.c:1503–1587

* Process any command-line switches and any additional GUC variable * settings passed in the startup packet. */

 * settings passed in the startup packet.
 */
static void
process_startup_options(Port *port, bool am_superuser)
{
	GucContext	gucctx;
	ListCell   *gucopts;

	gucctx = am_superuser ? PGC_SU_BACKEND : PGC_BACKEND;

	/*
	 * First process any command-line switches that were included in the
	 * startup packet, if we are in a regular backend.
	 */
	if (port->cmdline_options != NULL)
	{
		/*
		 * The maximum possible number of commandline arguments that could
		 * come from port->cmdline_options is (strlen + 1) / 2; see
		 * pg_split_opts().
		 */
		char	  **av;
		int			maxac;
		int			ac;

		maxac = 2 + (strlen(port->cmdline_options) + 1) / 2;

		av = (char **) palloc(maxac * sizeof(char *));
		ac = 0;

		av[ac++] = "postgres";

		pg_split_opts(av, &ac, port->cmdline_options);

		av[ac] = NULL;

		Assert(ac < maxac);

		(void) process_postgres_switches(ac, av, gucctx, NULL);
	}

	/*
	 * Process any additional GUC variable settings passed in startup packet.
	 * These are handled exactly like command-line variables.
	 */
	gucopts = list_head(port->guc_options);
	while (gucopts)
	{
		char	   *name;
		char	   *value;

		name = lfirst(gucopts);
		gucopts = lnext(port->guc_options, gucopts);

		value = lfirst(gucopts);
		gucopts = lnext(port->guc_options, gucopts);

		SetConfigOption(name, value, gucctx, PGC_S_CLIENT);
	}