path: root/apps/nshlib/nsh_parse.c

/****************************************************************************
 * apps/nshlib/nsh_parse.c
 *
 *   Copyright (C) 2007-2013, 2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <debug.h>

#include <apps/nsh.h>

#include "nsh.h"
#include "nsh_console.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Types
 ****************************************************************************/

/* These structure describes the parsed command line */

#ifndef CONFIG_NSH_DISABLEBG
struct cmdarg_s
{
  FAR struct nsh_vtbl_s *vtbl;      /* For front-end interaction */
  int fd;                           /* FD for output redirection */
  int argc;                         /* Number of arguments in argv */
  FAR char *argv[MAX_ARGV_ENTRIES]; /* Argument list */
};
#endif

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

static const char g_token_separator[] = " \t\n";
static const char g_line_separator[]  = "\";\n";
static const char g_redirect1[]       = ">";
static const char g_redirect2[]       = ">>";
static const char g_exitstatus[]      = "$?";
static const char g_success[]         = "0";
static const char g_failure[]         = "1";

/****************************************************************************
 * Public Data
 ****************************************************************************/

/* If NuttX versioning information is available, Include that information
 * in the NSH greeting.
 */

#if CONFIG_VERSION_MAJOR != 0 || CONFIG_VERSION_MINOR != 0
const char g_nshgreeting[]       = "\nNuttShell (NSH) NuttX-" CONFIG_VERSION_STRING "\n";
#else
const char g_nshgreeting[]       = "\nNuttShell (NSH)\n";
#endif

/* Telnet login prompts */

#if defined(CONFIG_NSH_TELNET_LOGIN) && defined(CONFIG_NSH_TELNET)
const char g_telnetgreeting[]    = "\nWelcome to NuttShell(NSH) Telnet Server...\n";
const char g_userprompt[]        = "login: ";
const char g_passwordprompt[]    = "password: ";
const char g_loginsuccess[]      = "\nUser Logged-in!\n";
const char g_badcredentials[]    = "\nInvalid username or password\n";
const char g_loginfailure[]      = "Login failed!\n";
#endif

/* The NSH prompt */

const char g_nshprompt[]         = "nsh> ";

/* Common, message formats */

const char g_nshsyntax[]         = "nsh: %s: syntax error\n";
const char g_fmtargrequired[]    = "nsh: %s: missing required argument(s)\n";
const char g_fmtnomatching[]     = "nsh: %s: no matching %s\n";
const char g_fmtarginvalid[]     = "nsh: %s: argument invalid\n";
const char g_fmtargrange[]       = "nsh: %s: value out of range\n";
const char g_fmtcmdnotfound[]    = "nsh: %s: command not found\n";
const char g_fmtnosuch[]         = "nsh: %s: no such %s: %s\n";
const char g_fmttoomanyargs[]    = "nsh: %s: too many arguments\n";
const char g_fmtdeepnesting[]    = "nsh: %s: nesting too deep\n";
const char g_fmtcontext[]        = "nsh: %s: not valid in this context\n";
#ifdef CONFIG_NSH_STRERROR
const char g_fmtcmdfailed[]      = "nsh: %s: %s failed: %s\n";
#else
const char g_fmtcmdfailed[]      = "nsh: %s: %s failed: %d\n";
#endif
const char g_fmtcmdoutofmemory[] = "nsh: %s: out of memory\n";
const char g_fmtinternalerror[]  = "nsh: %s: Internal error\n";
#ifndef CONFIG_DISABLE_SIGNALS
const char g_fmtsignalrecvd[]    = "nsh: %s: Interrupted by signal\n";
#endif

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nsh_releaseargs
 ****************************************************************************/

#ifndef CONFIG_NSH_DISABLEBG
static void nsh_releaseargs(struct cmdarg_s *arg)
{
  FAR struct nsh_vtbl_s *vtbl = arg->vtbl;
  int i;

#if CONFIG_NFILE_STREAMS > 0
  /* If the output was redirected, then file descriptor should
   * be closed.  The created task has its one, independent copy of
   * the file descriptor
   */

  if (vtbl->np.np_redirect)
    {
      (void)close(arg->fd);
    }
#endif

  /* Released the cloned vtbl instance */

  nsh_release(vtbl);

  /* Release the cloned args */

  for (i = 0; i < arg->argc; i++)
    {
      free(arg->argv[i]);
    }
  free(arg);
}
#endif

/****************************************************************************
 * Name: nsh_child
 ****************************************************************************/

#ifndef CONFIG_NSH_DISABLEBG
static pthread_addr_t nsh_child(pthread_addr_t arg)
{
  struct cmdarg_s *carg = (struct cmdarg_s *)arg;
  int ret;

  dbg("BG %s\n", carg->argv[0]);

  /* Execute the specified command on the child thread */

  ret = nsh_command(carg->vtbl, carg->argc, carg->argv);

  /* Released the cloned arguments */

  dbg("BG %s complete\n", carg->argv[0]);
  nsh_releaseargs(carg);
  return (void*)ret;
}
#endif

/****************************************************************************
 * Name: nsh_cloneargs
 ****************************************************************************/

#ifndef CONFIG_NSH_DISABLEBG
static inline struct cmdarg_s *nsh_cloneargs(FAR struct nsh_vtbl_s *vtbl,
                                             int fd, int argc, char *argv[])
{
  struct cmdarg_s *ret = (struct cmdarg_s *)zalloc(sizeof(struct cmdarg_s));
  int i;

  if (ret)
    {
      ret->vtbl = vtbl;
      ret->fd   = fd;
      ret->argc = argc;

      for (i = 0; i < argc; i++)
        {
          ret->argv[i] = strdup(argv[i]);
        }
    }

  return ret;
}
#endif

/****************************************************************************
 * Name: nsh_argument
 ****************************************************************************/

static char *nsh_argument(FAR struct nsh_vtbl_s *vtbl, char **saveptr)
{
  char *pbegin = *saveptr;
  char *pend   = NULL;
  const char *term;
#ifndef CONFIG_DISABLE_ENVIRON
  bool quoted = false;
#endif

  /* Find the beginning of the next token */

  for (;
       *pbegin && strchr(g_token_separator, *pbegin) != NULL;
       pbegin++);

  /* If we are at the end of the string with nothing but delimiters found,
   * then return NULL, meaning that there are no further arguments on the line.
   */

  if (!*pbegin)
    {
      return NULL;
    }

  /* Does the token begin with '>' -- redirection of output? */

  if (*pbegin == '>')
    {
      /* Yes.. does it begin with ">>"? */

      if (*(pbegin + 1) == '>')
        {
          *saveptr = pbegin + 2;
          pbegin   = (char*)g_redirect2;
        }
      else
        {
          *saveptr = pbegin + 1;
          pbegin   = (char*)g_redirect1;
        }
    }

  /* Does the token begin with '#' -- comment */

  else if (*pbegin == '#')
    {
      /* Return NULL meaning that we are at the end of the line */

      *saveptr = pbegin;
      pbegin   = NULL;
    }
  else
    {
      /* Otherwise, we are going to have to parse to find the end of
       * the token.  Does the token begin with '"'?
       */

      if (*pbegin == '"')
        {
          /* Yes.. then only another '"' can terminate the string */

          pbegin++;
          term = "\"";
#ifndef CONFIG_DISABLE_ENVIRON
          quoted = true;
#endif
        }
      else
        {
          /* No, then any of the usual separators will terminate the argument */

          term = g_token_separator;
        }

      /* Find the end of the string */

      for (pend = pbegin + 1;
           *pend && strchr(term, *pend) == NULL;
           pend++);

      /* pend either points to the end of the string or to
       * the first delimiter after the string.
       */

      if (*pend)
        {
          /* Turn the delimiter into a null terminator */

          *pend++ = '\0';
        }

      /* Save the pointer where we left off */

      *saveptr = pend;

#ifndef CONFIG_DISABLE_ENVIRON
      /* Check for references to environment variables */

      if (pbegin[0] == '$' && !quoted)
        {
          /* Check for built-in variables */

          if (strcmp(pbegin, g_exitstatus) == 0)
            {
              if (vtbl->np.np_fail)
                {
                  return (char*)g_failure;
                }
              else
                {
                  return (char*)g_success;
                }
            }

          /* Not a built-in? Return the value of the environment variable
           * with this name
           */

          else
            {
              char *value = getenv(pbegin+1);
              if (value)
                {
                  return value;
                }
              else
                {
                  return (char*)"";
                }
            }
        }
#endif
    }

  /* Return the beginning of the token. */

  return pbegin;
}

/****************************************************************************
 * Name: nsh_cmdenabled
 ****************************************************************************/

#ifndef CONFIG_NSH_DISABLESCRIPT
static inline bool nsh_cmdenabled(FAR struct nsh_vtbl_s *vtbl)
{
  struct nsh_parser_s *np = &vtbl->np;
  bool ret = !np->np_st[np->np_ndx].ns_disabled;
  if (ret)
    {
      switch (np->np_st[np->np_ndx].ns_state)
        {
          case NSH_PARSER_NORMAL :
          case NSH_PARSER_IF:
          default:
            break;

          case NSH_PARSER_THEN:
            ret = !np->np_st[np->np_ndx].ns_ifcond;
            break;

          case NSH_PARSER_ELSE:
            ret = np->np_st[np->np_ndx].ns_ifcond;
            break;
        }
    }

  return ret;
}
#endif

/****************************************************************************
 * Name: nsh_ifthenelse
 ****************************************************************************/

#ifndef CONFIG_NSH_DISABLESCRIPT
static inline int nsh_ifthenelse(FAR struct nsh_vtbl_s *vtbl,
                                 FAR char **ppcmd, FAR char **saveptr)
{
  struct nsh_parser_s *np = &vtbl->np;
  FAR char *cmd = *ppcmd;
  bool disabled;

  if (cmd)
    {
      /* Check if the command is preceeded by "if" */

      if (strcmp(cmd, "if") == 0)
        {
          /* Get the cmd following the if */

          *ppcmd = nsh_argument(vtbl, saveptr);
          if (!*ppcmd)
            {
              nsh_output(vtbl, g_fmtarginvalid, "if");
              goto errout;
            }

          /* Verify that "if" is valid in this context */

          if (np->np_st[np->np_ndx].ns_state != NSH_PARSER_NORMAL &&
              np->np_st[np->np_ndx].ns_state != NSH_PARSER_THEN &&
              np->np_st[np->np_ndx].ns_state != NSH_PARSER_ELSE)
            {
              nsh_output(vtbl, g_fmtcontext, "if");
              goto errout;
            }

          /* Check if we have exceeded the maximum depth of nesting */

          if (np->np_ndx >= CONFIG_NSH_NESTDEPTH-1)
            {
              nsh_output(vtbl, g_fmtdeepnesting, "if");
              goto errout;
            }

          /* "Push" the old state and set the new state */

          disabled                          = !nsh_cmdenabled(vtbl);
          np->np_ndx++;
          np->np_st[np->np_ndx].ns_state    = NSH_PARSER_IF;
          np->np_st[np->np_ndx].ns_disabled = disabled;
          np->np_st[np->np_ndx].ns_ifcond   = false;
        }
      else if (strcmp(cmd, "then") == 0)
        {
          /* Get the cmd following the then -- there shouldn't be one */

          *ppcmd = nsh_argument(vtbl, saveptr);
          if (*ppcmd)
            {
              nsh_output(vtbl, g_fmtarginvalid, "then");
              goto errout;
            }

          /* Verify that "then" is valid in this context */

          if (np->np_st[np->np_ndx].ns_state != NSH_PARSER_IF)
            {
              nsh_output(vtbl, g_fmtcontext, "then");
              goto errout;
            }
          np->np_st[np->np_ndx].ns_state = NSH_PARSER_THEN;
        }
      else if (strcmp(cmd, "else") == 0)
        {
          /* Get the cmd following the else -- there shouldn't be one */

          *ppcmd = nsh_argument(vtbl, saveptr);
          if (*ppcmd)
            {
              nsh_output(vtbl, g_fmtarginvalid, "else");
              goto errout;
            }

          /* Verify that "then" is valid in this context */

          if (np->np_st[np->np_ndx].ns_state != NSH_PARSER_THEN)
            {
              nsh_output(vtbl, g_fmtcontext, "else");
              goto errout;
            }
          np->np_st[np->np_ndx].ns_state = NSH_PARSER_ELSE;
        }
      else if (strcmp(cmd, "fi") == 0)
        {
          /* Get the cmd following the fi -- there should be one */

          *ppcmd = nsh_argument(vtbl, saveptr);
          if (*ppcmd)
            {
              nsh_output(vtbl, g_fmtarginvalid, "fi");
              goto errout;
            }

          /* Verify that "fi" is valid in this context */

          if (np->np_st[np->np_ndx].ns_state != NSH_PARSER_THEN &&
              np->np_st[np->np_ndx].ns_state != NSH_PARSER_ELSE)
            {
              nsh_output(vtbl, g_fmtcontext, "fi");
              goto errout;
            }

          if (np->np_ndx < 1) /* Shouldn't happen */
            {
              nsh_output(vtbl, g_fmtinternalerror, "if");
              goto errout;
            }

          /* "Pop" the previous state */

          np->np_ndx--;
        }
      else if (np->np_st[np->np_ndx].ns_state == NSH_PARSER_IF)
        {
          nsh_output(vtbl, g_fmtcontext, cmd);
          goto errout;
        }
    }
  return OK;

errout:
  np->np_ndx               = 0;
  np->np_st[0].ns_state    = NSH_PARSER_NORMAL;
  np->np_st[0].ns_disabled = false;
  np->np_st[0].ns_ifcond   = false;
  return ERROR;
}
#endif

/****************************************************************************
 * Name: nsh_saveresult
 ****************************************************************************/

static inline int nsh_saveresult(FAR struct nsh_vtbl_s *vtbl, bool result)
{
  struct nsh_parser_s *np = &vtbl->np;

#ifndef CONFIG_NSH_DISABLESCRIPT
  if (np->np_st[np->np_ndx].ns_state == NSH_PARSER_IF)
    {
      np->np_fail = false;
      np->np_st[np->np_ndx].ns_ifcond = result;
      return OK;
    }
  else
#endif
    {
      np->np_fail = result;
      return result ? ERROR : OK;
    }
}

/****************************************************************************
 * Name: nsh_nice
 ****************************************************************************/

#ifndef CONFIG_NSH_DISABLEBG
static inline int nsh_nice(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
                           FAR char **saveptr)
{
  FAR char *cmd = *ppcmd;

  vtbl->np.np_nice = 0;
  if (cmd)
    {
      /* Check if the command is preceded by "nice" */

      if (strcmp(cmd, "nice") == 0)
        {
          /* Nicenesses range from -20 (most favorable scheduling) to 19
           * (least  favorable).  Default is 10.
           */

          vtbl->np.np_nice = 10;

          /* Get the cmd (or -d option of nice command) */

          cmd = nsh_argument(vtbl, saveptr);
          if (cmd && strcmp(cmd, "-d") == 0)
            {
              FAR char *val = nsh_argument(vtbl, saveptr);
              if (val)
                {
                  char *endptr;
                  vtbl->np.np_nice = (int)strtol(val, &endptr, 0);
                  if (vtbl->np.np_nice > 19 || vtbl->np.np_nice < -20 ||
                      endptr == val || *endptr != '\0')
                    {
                      nsh_output(vtbl, g_fmtarginvalid, "nice");
                      return ERROR;
                    }
                  cmd = nsh_argument(vtbl, saveptr);
                }
            }

          /* Return the real command name */

          *ppcmd = cmd;
        }
    }

  return OK;
}
#endif

/****************************************************************************
 * Name: nsh_parse_command
 *
 * Description:
 *   This function parses and executes one NSH command from the command line.
 *
 ****************************************************************************/

static int nsh_parse_command(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
{
  FAR char *argv[MAX_ARGV_ENTRIES];
  FAR char *saveptr;
  FAR char *cmd;
#if CONFIG_NFILE_STREAMS > 0
  FAR char *redirfile = NULL;
  int       oflags = 0;
  int       fd = -1;
#endif
  int       argc;
  int       ret;

  /* Initialize parser state */

  memset(argv, 0, MAX_ARGV_ENTRIES*sizeof(FAR char *));
#ifndef CONFIG_NSH_DISABLEBG
  vtbl->np.np_bg       = false;
#endif
#if CONFIG_NFILE_STREAMS > 0
  vtbl->np.np_redirect = false;
#endif

  /* Parse out the command at the beginning of the line */

  saveptr = cmdline;
  cmd = nsh_argument(vtbl, &saveptr);

  /* Handler if-then-else-fi */

#ifndef CONFIG_NSH_DISABLESCRIPT
  if (nsh_ifthenelse(vtbl, &cmd, &saveptr) != 0)
    {
      goto errout;
    }
#endif

  /* Handle nice */

#ifndef CONFIG_NSH_DISABLEBG
  if (nsh_nice(vtbl, &cmd, &saveptr) != 0)
    {
      goto errout;
    }
#endif

  /* Check if any command was provided -OR- if command processing is
   * currently disabled.
   */

#ifndef CONFIG_NSH_DISABLESCRIPT
  if (!cmd || !nsh_cmdenabled(vtbl))
#else
  if (!cmd)
#endif
    {
      /* An empty line is not an error and an unprocessed command cannot
       * generate an error, but neither should they change the last
       * command status.
       */

      return OK;
    }

  /* Parse all of the arguments following the command name.  The form
   * of argv is:
   *
   *   argv[0]:      The command name.
   *   argv[1]:      The beginning of argument (up to CONFIG_NSH_MAXARGUMENTS)
   *   argv[argc-3]: Possibly '>' or '>>'
   *   argv[argc-2]: Possibly <file>
   *   argv[argc-1]: Possibly '&'
   *   argv[argc]:   NULL terminating pointer
   *
   * Maximum size is CONFIG_NSH_MAXARGUMENTS+5
   */

  argv[0] = cmd;
  for (argc = 1; argc < MAX_ARGV_ENTRIES-1; argc++)
    {
      argv[argc] = nsh_argument(vtbl, &saveptr);
      if (!argv[argc])
        {
          break;
        }
    }

  argv[argc] = NULL;

  /* Check if the command should run in background */

#ifndef CONFIG_NSH_DISABLEBG
  if (argc > 1 && strcmp(argv[argc-1], "&") == 0)
    {
      vtbl->np.np_bg = true;
      argv[argc-1] = NULL;
      argc--;
    }
#endif

#if CONFIG_NFILE_STREAMS > 0
  /* Check if the output was re-directed using > or >> */

  if (argc > 2)
    {
      /* Check for redirection to a new file */

      if (strcmp(argv[argc-2], g_redirect1) == 0)
        {
          vtbl->np.np_redirect = true;
          oflags               = O_WRONLY|O_CREAT|O_TRUNC;
          redirfile            = nsh_getfullpath(vtbl, argv[argc-1]);
          argc                -= 2;
        }

      /* Check for redirection by appending to an existing file */

      else if (strcmp(argv[argc-2], g_redirect2) == 0)
        {
          vtbl->np.np_redirect = true;
          oflags               = O_WRONLY|O_CREAT|O_APPEND;
          redirfile            = nsh_getfullpath(vtbl, argv[argc-1]);
          argc                -= 2;
        }
    }
#endif

  /* Check if the maximum number of arguments was exceeded */

  if (argc > CONFIG_NSH_MAXARGUMENTS)
    {
      nsh_output(vtbl, g_fmttoomanyargs, cmd);
    }

  /* Does this command correspond to an application filename?
   * nsh_fileapp() returns:
   *
   *   -1 (ERROR)  if the application task corresponding to 'argv[0]' could not
   *               be started (possibly because it does not exist).
   *    0 (OK)     if the application task corresponding to 'argv[0]' was
   *               and successfully started.  If CONFIG_SCHED_WAITPID is
   *               defined, this return value also indicates that the
   *               application returned successful status (EXIT_SUCCESS)
   *    1          If CONFIG_SCHED_WAITPID is defined, then this return value
   *               indicates that the application task was spawned successfully
   *               but returned failure exit status.
   *
   * Note the priority if not effected by nice-ness.
   */

#ifdef CONFIG_NSH_FILE_APPS
  ret = nsh_fileapp(vtbl, argv[0], argv, redirfile, oflags);
  if (ret >= 0)
    {
      /* nsh_fileapp() returned 0 or 1.  This means that the built-in
       * command was successfully started (although it may not have ran
       * successfully).  So certainly it is not an NSH command.
       */

      /* Free the redirected output file path */

      if (redirfile)
        {
          nsh_freefullpath(redirfile);
        }

      /* Save the result:  success if 0; failure if 1 */

      return nsh_saveresult(vtbl, ret != OK);
    }

  /* No, not a file name command (or, at least, we were unable to start a
   * program of that name).  Maybe it is a built-in application or an NSH
   * command.
   */

#endif

  /* Does this command correspond to a built-in command?
   * nsh_builtin() returns:
   *
   *   -1 (ERROR)  if the application task corresponding to 'argv[0]' could not
   *               be started (possibly because it doesn not exist).
   *    0 (OK)     if the application task corresponding to 'argv[0]' was
   *               and successfully started.  If CONFIG_SCHED_WAITPID is
   *               defined, this return value also indicates that the
   *               application returned successful status (EXIT_SUCCESS)
   *    1          If CONFIG_SCHED_WAITPID is defined, then this return value
   *               indicates that the application task was spawned successfully
   *               but returned failure exit status.
   *
   * Note the priority if not effected by nice-ness.
   */

#if defined(CONFIG_NSH_BUILTIN_APPS) && (!defined(CONFIG_NSH_FILE_APPS) || !defined(CONFIG_FS_BINFS))
#if CONFIG_NFILE_STREAMS > 0
  ret = nsh_builtin(vtbl, argv[0], argv, redirfile, oflags);
#else
  ret = nsh_builtin(vtbl, argv[0], argv, NULL, 0);
#endif
  if (ret >= 0)
    {
      /* nsh_builtin() returned 0 or 1.  This means that the built-in
       * command was successfully started (although it may not have ran
       * successfully).  So certainly it is not an NSH command.
       */

#if CONFIG_NFILE_STREAMS > 0
      /* Free the redirected output file path */

      if (redirfile)
        {
          nsh_freefullpath(redirfile);
        }
#endif

      /* Save the result:  success if 0; failure if 1 */

      return nsh_saveresult(vtbl, ret != OK);
    }

  /* No, not a built in command (or, at least, we were unable to start a
   * built-in command of that name).  Treat it like an NSH command.
   */

#endif

#if CONFIG_NFILE_STREAMS > 0
  /* Redirected output? */

  if (vtbl->np.np_redirect)
    {
      /* Open the redirection file.  This file will eventually
       * be closed by a call to either nsh_release (if the command
       * is executed in the background) or by nsh_undirect if the
       * command is executed in the foreground.
       */

      fd = open(redirfile, oflags, 0666);
      nsh_freefullpath(redirfile);
      redirfile = NULL;

      if (fd < 0)
        {
          nsh_output(vtbl, g_fmtcmdfailed, cmd, "open", NSH_ERRNO);
          goto errout;
        }
    }
#endif

  /* Handle the case where the command is executed in background.
   * However is app is to be started as builtin new process will
   * be created anyway, so skip this step.
   */

#ifndef CONFIG_NSH_DISABLEBG
  if (vtbl->np.np_bg)
    {
      struct sched_param param;
      struct nsh_vtbl_s *bkgvtbl;
      struct cmdarg_s *args;
      pthread_attr_t attr;
      pthread_t thread;

      /* Get a cloned copy of the vtbl with reference count=1.
       * after the command has been processed, the nsh_release() call
       * at the end of nsh_child() will destroy the clone.
       */

      bkgvtbl = nsh_clone(vtbl);
      if (!bkgvtbl)
        {
          goto errout_with_redirect;
        }

      /* Create a container for the command arguments */

      args = nsh_cloneargs(bkgvtbl, fd, argc, argv);
      if (!args)
        {
          nsh_release(bkgvtbl);
          goto errout_with_redirect;
        }

#if CONFIG_NFILE_STREAMS > 0
      /* Handle redirection of output via a file descriptor */

      if (vtbl->np.np_redirect)
        {
          (void)nsh_redirect(bkgvtbl, fd, NULL);
        }
#endif

      /* Get the execution priority of this task */

      ret = sched_getparam(0, &param);
      if (ret != 0)
        {
          nsh_output(vtbl, g_fmtcmdfailed, cmd, "sched_getparm", NSH_ERRNO);
          nsh_releaseargs(args);
          nsh_release(bkgvtbl);
          goto errout;
        }

      /* Determine the priority to execute the command */

      if (vtbl->np.np_nice != 0)
        {
          int priority = param.sched_priority - vtbl->np.np_nice;
          if (vtbl->np.np_nice < 0)
            {
              int max_priority = sched_get_priority_max(SCHED_NSH);
              if (priority > max_priority)
                {
                  priority = max_priority;
                }
            }
          else
            {
              int min_priority = sched_get_priority_min(SCHED_NSH);
              if (priority < min_priority)
                {
                  priority = min_priority;
                }
            }

          param.sched_priority = priority;
        }

      /* Set up the thread attributes */

      (void)pthread_attr_init(&attr);
      (void)pthread_attr_setschedpolicy(&attr, SCHED_NSH);
      (void)pthread_attr_setschedparam(&attr, &param);

      /* Execute the command as a separate thread at the appropriate priority */

      ret = pthread_create(&thread, &attr, nsh_child, (pthread_addr_t)args);
      if (ret != 0)
        {
          nsh_output(vtbl, g_fmtcmdfailed, cmd, "pthread_create", NSH_ERRNO_OF(ret));
          nsh_releaseargs(args);
          nsh_release(bkgvtbl);
          goto errout;
        }

      /* Detach from the pthread since we are not going to join with it.
       * Otherwise, we would have a memory leak.
       */

      (void)pthread_detach(thread);

      nsh_output(vtbl, "%s [%d:%d]\n", cmd, thread, param.sched_priority);
    }
  else
#endif
    {
#if CONFIG_NFILE_STREAMS > 0
      uint8_t save[SAVE_SIZE];

      /* Handle redirection of output via a file descriptor */

      if (vtbl->np.np_redirect)
        {
          nsh_redirect(vtbl, fd, save);
        }
#endif

      /* Then execute the command in "foreground" -- i.e., while the user waits
       * for the next prompt.  nsh_command will return:
       *
       * -1 (ERRROR) if the command was unsuccessful
       *  0 (OK)     if the command was successful
       */

      ret = nsh_command(vtbl, argc, argv);

#if CONFIG_NFILE_STREAMS > 0
      /* Restore the original output.  Undirect will close the redirection
       * file descriptor.
       */

      if (vtbl->np.np_redirect)
        {
          nsh_undirect(vtbl, save);
        }
#endif

      /* Mark errors so that it is possible to test for non-zero return values
       * in nsh scripts.
       */

      if (ret < 0)
        {
          goto errout;
        }
    }

  /* Return success if the command succeeded (or at least, starting of the
   * command task succeeded).
   */

  return nsh_saveresult(vtbl, false);

#ifndef CONFIG_NSH_DISABLEBG
errout_with_redirect:
#if CONFIG_NFILE_STREAMS > 0
  if (vtbl->np.np_redirect)
    {
      close(fd);
    }
#endif
#endif

errout:
  return nsh_saveresult(vtbl, true);
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nsh_parse
 *
 * Description:
 *   This function parses and executes the line of text received from the
 *   user.  This may consist of one or more NSH commands.  Multiple NSH
 *   commands are separated by semi-colons.
 *
 ****************************************************************************/

int nsh_parse(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
{
#ifdef NSH_DISABLE_SEMICOLON
  return nsh_parse_command(vtbl, cmdline);

#else
  FAR char *start   = cmdline;
  FAR char *working = cmdline;
  FAR char *ptr;
  size_t len;
  int ret;

  /* Loop until all of the commands on the command line have been processed */

  for (;;)
    {
      /* A command may be terminated with a newline character, the end of the
       * line, or a semicolon.  NOTE that the set of delimiting characters
       * includes the quotation mark.  We need to handle quotation marks here
       * because a semicolon or newline character within a quoted string must
       * be ignored.
       */

      len = strcspn(working, g_line_separator);
      ptr = working + len;

      /* Check for the last command on the line.  This means that the none
       * of the delimiting characters was found or that the newline character
       * was found.  Anything after the newline character is ignored (there
       * should not be anything.
       */

      if (*ptr == '\0' || *ptr == '\n')
        {
          /* Parse the last command on the line */

          return nsh_parse_command(vtbl, start);
        }

      /* Check for a command terminated with ';'.  There is probably another
       * command on the command line after this one.
       */

      else if (*ptr == ';')
        {
          /* Terminate the line */

          *ptr++ = '\0';

          /* Parse this command */

          ret = nsh_parse_command(vtbl, start);
          if (ret != OK)
            {
              /* nsh_parse_command may return (1) -1 (ERROR) meaning that the
               * command failed or we failed to start the command application
               * or (2) 1 meaning that the application task was spawned
               * successfully but returned failure exit status.
               */

              return ret;
            }

          /* Then set the start of the next command on the command line */

          start   = ptr;
          working = ptr;
        }

      /* Check if we encountered a quoted string */

      else /* if (*ptr == '"') */
        {
          /* Find the closing quotation mark */

          FAR char *tmp = strchr(ptr, '"');
          if (!tmp)
            {
              /* No closing quotation mark! */

              nsh_output(vtbl, g_fmtnomatching, "[\"]", "[\"]");
              return ERROR;
            }

          /* Otherwise, continue parsing after the closing quotation mark */

          working = tmp++;
        }
    }
#endif
}