乐山

int nsh_session(FAR struct console_stdio_s *pstate)
{
  int ret;

  DEBUGASSERT(pstate);

  /* Present a greeting */

  fputs(g_nshgreeting, pstate->cn_outstream);
  fflush(pstate->cn_outstream);

  /* Execute the login script */

#ifdef CONFIG_NSH_ROMFSRC
  (void)nsh_loginscript(&pstate->cn_vtbl);
#endif

  /* Then enter the command line parsing loop */

  for (;;)
    {
      /* For the case of debugging the USB console... dump collected USB trace data */

#ifdef CONFIG_NSH_USBDEV_TRACE
      nsh_usbtrace();
#endif

      /* Display the prompt string */

      fputs(g_nshprompt, pstate->cn_outstream);
      fflush(pstate->cn_outstream);

      /* Get the next line of input. readline() returns EOF on end-of-file
       * or any read failure.
       */

      ret = readline(pstate->cn_line, CONFIG_NSH_LINELEN,
                     INSTREAM(pstate), OUTSTREAM(pstate));
      if (ret != EOF)
        {
          /* Parse process the command */

          (void)nsh_parse(&pstate->cn_vtbl, pstate->cn_line);
          fflush(pstate->cn_outstream);
        }

      /* Readline normally returns the number of characters read,
       * but will return EOF on end of file or if an error occurs.
       * EOF will cause the session to terminate.
       */

      else
        {
          fprintf(pstate->cn_outstream, g_fmtcmdfailed, "nsh_session", 
                  "readline", NSH_ERRNO_OF(-ret));
          return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
        }
    }

  /* We do not get here, but this is necessary to keep some compilers happy.
   * But others will complain that this code is not reachable.
   */

  return EXIT_SUCCESS;
}