Function SendBaseBackup

src/backend/replication/basebackup.c:1072–1097

* SendBaseBackup() - send a complete base backup. * * The function will put the system into backup mode like pg_start_backup() * does, so that the backup is consistent even though we read directly from * the filesystem, bypassing the buffer cache. */

 * the filesystem, bypassing the buffer cache.
 */
void
SendBaseBackup(BaseBackupCmd *cmd)
{
	basebackup_options opt;
	SessionBackupState status = get_backup_status();

	if (status == SESSION_BACKUP_NON_EXCLUSIVE)
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("a backup is already in progress in this session")));

	parse_basebackup_options(cmd->options, &opt);

	WalSndSetState(WALSNDSTATE_BACKUP);

	if (update_process_title)
	{
		char		activitymsg[50];

		snprintf(activitymsg, sizeof(activitymsg), "sending backup \"%s\"",
				 opt.label);
		set_ps_display(activitymsg);
	}

	perform_base_backup(&opt);
}

static void
send_int8_string(StringInfoData *buf, int64 intval)