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getopt.c

/* Getopt for GNU.
   Copyright (C) 1987, 1989 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 1, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */



/* This version of `getopt' appears to the caller like standard Unix `getopt'
   but it behaves differently for the user, since it allows the user
   to intersperse the options with the other arguments.

   As `getopt' works, it permutes the elements of `argv' so that,
   when it is done, all the options precede everything else.  Thus
   all application programs are extended to handle flexible argument order.

   Setting the environment variable _POSIX_OPTION_ORDER disables permutation.
   Then the behavior is completely standard.

   GNU application programs can use a third alternative mode in which
   they can distinguish the relative order of options and other arguments.  */

#include <stdio.h>

#ifdef sparc
#include <alloca.h>
#endif
#ifdef USG
#define bcopy(s, d, l) memcpy((d), (s), (l))
#endif

/* For communication from `getopt' to the caller.
   When `getopt' finds an option that takes an argument,
   the argument value is returned here.
   Also, when `ordering' is RETURN_IN_ORDER,
   each non-option ARGV-element is returned here.  */

char *optarg = 0;

/* Index in ARGV of the next element to be scanned.
   This is used for communication to and from the caller
   and for communication between successive calls to `getopt'.

   On entry to `getopt', zero means this is the first call; initialize.

   When `getopt' returns EOF, this is the index of the first of the
   non-option elements that the caller should itself scan.

   Otherwise, `optind' communicates from one call to the next
   how much of ARGV has been scanned so far.  */

int optind = 0;

/* The next char to be scanned in the option-element
   in which the last option character we returned was found.
   This allows us to pick up the scan where we left off.

   If this is zero, or a null string, it means resume the scan
   by advancing to the next ARGV-element.  */

static char *nextchar;

/* Callers store zero here to inhibit the error message
   for unrecognized options.  */

int opterr = 1;

/* Describe how to deal with options that follow non-option ARGV-elements.

   UNSPECIFIED means the caller did not specify anything;
   the default is then REQUIRE_ORDER if the environment variable
   _OPTIONS_FIRST is defined, PERMUTE otherwise.

   REQUIRE_ORDER means don't recognize them as options.
   Stop option processing when the first non-option is seen.
   This is what Unix does.

   PERMUTE is the default.  We permute the contents of `argv' as we scan,
   so that eventually all the options are at the end.  This allows options
   to be given in any order, even with programs that were not written to
   expect this.

   RETURN_IN_ORDER is an option available to programs that were written
   to expect options and other ARGV-elements in any order and that care about
   the ordering of the two.  We describe each non-option ARGV-element
   as if it were the argument of an option with character code zero.
   Using `-' as the first character of the list of option characters
   requests this mode of operation.

   The special argument `--' forces an end of option-scanning regardless
   of the value of `ordering'.  In the case of RETURN_IN_ORDER, only
   `--' can cause `getopt' to return EOF with `optind' != ARGC.  */

static enum { REQUIRE_ORDER, PERMUTE, RETURN_IN_ORDER } ordering;

/* Handle permutation of arguments.  */

/* Describe the part of ARGV that contains non-options that have
   been skipped.  `first_nonopt' is the index in ARGV of the first of them;
   `last_nonopt' is the index after the last of them.  */

static int first_nonopt;
static int last_nonopt;

/* Exchange two adjacent subsequences of ARGV.
   One subsequence is elements [first_nonopt,last_nonopt)
    which contains all the non-options that have been skipped so far.
   The other is elements [last_nonopt,optind), which contains all
    the options processed since those non-options were skipped.

   `first_nonopt' and `last_nonopt' are relocated so that they describe
    the new indices of the non-options in ARGV after they are moved.  */

static void
exchange (argv)
     char **argv;
{
  int nonopts_size
    = (last_nonopt - first_nonopt) * sizeof (char *);
  char **temp = (char **) alloca (nonopts_size);

  /* Interchange the two blocks of data in argv.  */

  bcopy (&argv[first_nonopt], temp, nonopts_size);
  bcopy (&argv[last_nonopt], &argv[first_nonopt],
       (optind - last_nonopt) * sizeof (char *));
  bcopy (temp, &argv[first_nonopt + optind - last_nonopt],
       nonopts_size);

  /* Update records for the slots the non-options now occupy.  */

  first_nonopt += (optind - last_nonopt);
  last_nonopt = optind;
}

/* Scan elements of ARGV (whose length is ARGC) for option characters
   given in OPTSTRING.

   If an element of ARGV starts with '-', and is not exactly "-" or "--",
   then it 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 theoption characters
   from each of the option elements.

   If `getopt' finds another option character, it returns that character,
   updating `optind' and `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 `EOF'.
   Then `optind' is the index in ARGV of the first ARGV-element
   that is not an option.  (The ARGV-elements have been permuted
   so that those that are not options now come last.)

   OPTSTRING is a string containing the legitimate option characters.
   A colon in OPTSTRING means that the previous character is an option
   that wants an argument.  The argument is taken from the rest of the
   current ARGV-element, or from the following ARGV-element,
   and returned in `optarg'.

   If an option character is seen that is not listed in OPTSTRING,
   return '?' after printing an error message.  If you set `opterr' to
   zero, the error message is suppressed but we still return '?'.

   If a char in OPTSTRING is followed by a colon, that means it wants an arg,
   so the following text in the same ARGV-element, or the text of the following
   ARGV-element, is returned in `optarg.  Two colons mean an option that
   wants an optional arg; if there is text in the current ARGV-element,
   it is returned in `optarg'.

   If OPTSTRING starts with `-', it requests a different method of handling the
   non-option ARGV-elements.  See the comments about RETURN_IN_ORDER, above.  */

int
getopt (argc, argv, optstring)
     int argc;
     char **argv;
     char *optstring;
{
  /* Initialize the internal data when the first call is made.
     Start processing options with ARGV-element 1 (since ARGV-element 0
     is the program name); the sequence of previously skipped
     non-option ARGV-elements is empty.  */

  if (optind == 0)
    {
      first_nonopt = last_nonopt = optind = 1;

      nextchar = 0;

      /* Determine how to handle the ordering of options and nonoptions.  */

      if (optstring[0] == '-')
      ordering = RETURN_IN_ORDER;
      else if (getenv ("_POSIX_OPTION_ORDER") != 0)
      ordering = REQUIRE_ORDER;
      else
      ordering = PERMUTE;
    }

  if (nextchar == 0 || *nextchar == 0)
    {
      if (ordering == PERMUTE)
      {
        /* If we have just processed some options following some non-options,
           exchange them so that the options come first.  */

        if (first_nonopt != last_nonopt && last_nonopt != optind)
          exchange (argv);
        else if (last_nonopt != optind)
          first_nonopt = optind;

        /* Now skip any additional non-options
           and extend the range of non-options previously skipped.  */

        while (optind < argc
             && (argv[optind][0] != '-'
                 || argv[optind][1] == 0))
          optind++;
        last_nonopt = optind;
      }

      /* Special ARGV-element `--' means premature end of options.
       Skip it like a null option,
       then exchange with previous non-options as if it were an option,
       then skip everything else like a non-option.  */

      if (optind != argc && !strcmp (argv[optind], "--"))
      {
        optind++;

        if (first_nonopt != last_nonopt && last_nonopt != optind)
          exchange (argv);
        else if (first_nonopt == last_nonopt)
          first_nonopt = optind;
        last_nonopt = argc;

        optind = argc;
      }

      /* If we have done all the ARGV-elements, stop the scan
       and back over any non-options that we skipped and permuted.  */

      if (optind == argc)
      {
        /* Set the next-arg-index to point at the non-options
           that we previously skipped, so the caller will digest them.  */
        if (first_nonopt != last_nonopt)
          optind = first_nonopt;
        return EOF;
      }
       
      /* If we have come to a non-option and did not permute it,
       either stop the scan or describe it to the caller and pass it by.  */

      if (argv[optind][0] != '-' || argv[optind][1] == 0)
      {
        if (ordering == REQUIRE_ORDER)
          return EOF;
        optarg = argv[optind++];
        return 0;
      }

      /* We have found another option-ARGV-element.
       Start decoding its characters.  */

      nextchar = argv[optind] + 1;
    }

  /* Look at and handle the next option-character.  */

  {
    char c = *nextchar++;
    char *temp = (char *) index (optstring, c);

    /* Increment `optind' when we start to process its last character.  */
    if (*nextchar == 0)
      optind++;

    if (temp == 0 || c == ':')
      {
      if (opterr != 0)
        {
          if (c < 040 || c >= 0177)
            fprintf (stderr, "%s: unrecognized option, character code 0%o\n",
                   argv[0], c);
          else
            fprintf (stderr, "%s: unrecognized option `-%c'\n",
                   argv[0], c);
        }
      return '?';
      }
    if (temp[1] == ':')
      {
      if (temp[2] == ':')
        {
          /* This is an option that accepts an argument optionally.  */
          if (*nextchar != 0)
            {
              optarg = nextchar;
            optind++;
            }
          else
            optarg = 0;
          nextchar = 0;
        }
      else
        {
          /* This is an option that requires an argument.  */
          if (*nextchar != 0)
            {
            optarg = nextchar;
            /* If we end this ARGV-element by taking the rest as an arg,
               we must advance to the next element now.  */
            optind++;
            }
          else if (optind == argc)
            {
            if (opterr != 0)
              fprintf (stderr, "%s: no argument for `-%c' option\n",
                     argv[0], c);
            c = '?';
            }
          else
            /* We already incremented `optind' once;
             increment it again when taking next ARGV-elt as argument.  */
            optarg = argv[optind++];
          nextchar = 0;
        }
      }
    return c;
  }
}

#ifdef TEST

/* Compile with -DTEST to make an executable for use in testing
   the above definition of `getopt'.  */

int
main (argc, argv)
     int argc;
     char **argv;
{
  char c;
  int digit_optind = 0;

  while (1)
    {
      int this_option_optind = optind;
      if ((c = getopt (argc, argv, "abc:d:0123456789")) == EOF)
      break;

      switch (c)
      {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        if (digit_optind != 0 && digit_optind != this_option_optind)
          printf ("digits occur in two different argv-elements.\n");
        digit_optind = this_option_optind;
        printf ("option %c\n", c);
        break;

      case 'a':
        printf ("option a\n");
        break;

      case 'b':
        printf ("option b\n");
        break;

      case 'c':
        printf ("option c with value `%s'\n", optarg);
        break;

      case '?':
        break;

      default:
        printf ("?? getopt returned character code 0%o ??\n", c);
      }
    }

  if (optind < argc)
    {
      printf ("non-option ARGV-elements: ");
      while (optind < argc)
      printf ("%s ", argv[optind++]);
      printf ("\n");
    }

  return 0;
}

#endif /* TEST */

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