nuttx/libs/libc/unistd/lib_getopt.c

/****************************************************************************
 * libs/libc/unistd/lib_getopt.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

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

#include <nuttx/config.h>

#include <stdbool.h>
#include <getopt.h>
#include <string.h>

#include "unistd.h"

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

#undef optarg
#undef opterr
#undef optind
#undef optopt

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

/****************************************************************************
 * Name: getopt
 *
 * Description:
 *   getopt() parses command-line arguments.  Its arguments argc and argv
 *   are the argument count and array as passed to the main() function on
 *   program invocation.  An element of argv that starts with '-' is an
 *   option element. The characters of this element (aside from the initial
 *   '-') are option characters. If getopt() is called repeatedly, it
 *   returns successively each of the option characters from each of the
 *   option elements.
 *
 *   If getopt() finds another option character, it returns that character,
 *   updating the external variable optind and a static variable nextchar so
 *   that the next call to getopt() can resume the scan with the following
 *   option character or argv-element.
 *
 *   If there are no more option characters, getopt() returns -1. Then optind
 *   is the index in argv of the first argv-element that is not an option.
 *
 *   The 'optstring' argument is a string containing the legitimate option
 *   characters. If such a character is followed by a colon, this indicates
 *   that the option requires an argument.  If an argument is required for an
 *   option so getopt() places a pointer to the following text in the same
 *   argv-element, or the text of the following argv-element, in optarg.
 *
 *   NOTES:
 *   1. opterr is not supported and this implementation of getopt() never
 *      printfs error messages.
 *   2. getopt is NOT threadsafe!
 *   3. This version of getopt() does not reset global variables until
 *      -1 is returned.  As a result, your command line parsing loops
 *      must call getopt() repeatedly and continue to parse if other
 *      errors are returned ('?' or ':') until getopt() finally returns -1.
 *     (You can also set optind to -1 to force a reset).
 *
 * Returned Value:
 *   If an option was successfully found, then getopt() returns the option
 *   character. If all command-line options have been parsed, then getopt()
 *   returns -1.  If getopt() encounters an option character that was not
 *   in optstring, then '?' is returned. If getopt() encounters an option
 *   with a missing argument, then the return value depends on the first
 *   character in optstring: if it is ':', then ':' is returned; otherwise
 *   '?' is returned.
 *
 ****************************************************************************/

int getopt(int argc, FAR char * const argv[], FAR const char *optstring)
{
  /* Get thread-specific getopt() variables */

  FAR struct getopt_s *go = getoptvars();
  if (go == NULL)
    {
      return '?';
    }

  /* Verify input parameters. */

  if (argv != NULL && optstring != NULL)
    {
      FAR char *optchar;
      int noarg_ret = '?';

      /* The initial value of optind is 1.  If getopt() is called again in
       * the program, optind must be reset to some value <= 1.
       */

      if (go->go_optind < 1 || !go->go_binitialized)
        {
          go->go_optarg       = NULL;
          go->go_optind       = 1;     /* Skip over the program name */
          go->go_optopt       = '?';
          go->go_optptr       = NULL;  /* Start at the beginning of the first argument */
          go->go_binitialized = true;  /* Now we are initialized */
        }

      /* If the first character of opstring s ':', then ':' is in the event
       * of a missing argument. Otherwise '?' is returned.
       */

      if (*optstring == ':')
        {
           noarg_ret = ':';
           optstring++;
        }

      /* Are we resuming in the middle, or at the end of a string of
       * arguments? optptr == NULL means that we are started at the
       * beginning of argv[optind]; *optptr == \0 means that we are
       * starting at the beginning of optind+1
       */

      while (!go->go_optptr || !*go->go_optptr)
        {
          /* We need to start at the beginning of the next argv. Check if we
           * need to increment optind
           */

          if (go->go_optptr)
            {
              /* Yes.. Increment it and check for the case where where we
               * have processed everything in the argv[] array.
               */

              go->go_optind++;
            }

          /* Check for the end of the argument list */

          go->go_optptr = argv[go->go_optind];
          if (!go->go_optptr)
            {
              /* There are no more arguments, we are finished */

              go->go_binitialized = false;
              return ERROR;
            }

          /* We are starting at the beginning of argv[optind].  In this case,
           * the first character must be '-'
           */

          if (*go->go_optptr != '-')
            {
              /* The argument does not start with '-', we are finished */

              go->go_binitialized = false;
              return ERROR;
            }

          /* Skip over the '-' */

          go->go_optptr++;
        }

      /* Special case handling of "-" and "-:" */

      if (!*go->go_optptr)
        {
          go->go_optopt = '\0'; /* We'll fix up optptr the next time we are called */
          return '?';
        }

      /* Handle the case of "-:" */

      if (*go->go_optptr == ':')
        {
          go->go_optopt = ':';
          go->go_optptr++;
          return '?';
        }

      /* go->go_optptr now points at the next option and it is not something
       * crazy. check if the option is in the list of valid options.
       */

      optchar = strchr(optstring, *go->go_optptr);
      if (!optchar)
        {
          /* No this character is not in the list of valid options */

          go->go_optopt = *go->go_optptr;
          go->go_optptr++;
          return '?';
        }

      /* Yes, the character is in the list of valid options.  Does it have an
       * required argument?
       */

      if (optchar[1] != ':')
        {
          /* No, no arguments. Just return the character that we found */

          go->go_optptr++;
          return *optchar;
        }

      /* Yes, it has a required argument.  Is the required argument
       * immediately after the command in this same argument?
       */

      if (go->go_optptr[1] != '\0')
        {
          /* Yes, return a pointer into the current argument */

          go->go_optarg = &go->go_optptr[1];
          go->go_optind++;
          go->go_optptr = NULL;
          return *optchar;
        }

      /* No.. is the optional argument the next argument in argv[] ? */

      if (argv[go->go_optind + 1] && *argv[go->go_optind + 1] != '-')
        {
          /* Yes.. return that */

          go->go_optarg = argv[go->go_optind + 1];
          go->go_optind += 2;
          go->go_optptr = NULL;
          return *optchar;
        }

      /* No argument was supplied */

      go->go_optptr = NULL;
      go->go_optarg = NULL;
      go->go_optopt = *optchar;
      go->go_optind++;
      return noarg_ret;
    }

  /* Restore the initial, uninitialized state */

  go->go_binitialized = false;
  return ERROR;
}

int getopt_long(int argc, FAR char *const argv[],
                FAR const char *shortopts,
                FAR const struct option *longopts,
                FAR int *longind)
{
  return getopt(argc, argv, shortopts);
}