Initial revision

[cfd] / mdwopt.c

/* -*-c-*-
 *
 * $Id: mdwopt.c,v 1.1 1999/05/05 19:23:47 mdw Exp $
 *
 * Options parsing, similar to GNU @getopt_long@
 *
 * (c) 1996 Mark Wooding
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of many programs.
 *
 * `mdwopt' is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * `mdwopt' 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 Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with `mdwopt'; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------*
 *
 * $Log: mdwopt.c,v $
 * Revision 1.1  1999/05/05 19:23:47  mdw
 * Initial revision
 *
 * --- Previous lives ---
 *
 * %Log: mdwopt.c,v %
 * Revision 1.7  1997/09/11 09:19:11  mdw
 * (mo__nextWord): Arrrgh.  Don't free the environment variable buffer!
 * People are still using it!
 *
 * Revision 1.6  1997/09/11 09:05:54  mdw
 * (mo__nextWord): Fix bug which returns too many words from environment
 * variables.
 *
 * Revision 1.5  1997/08/09 20:27:59  mdw
 * Fix spelling of `Licensing'.
 *
 * Revision 1.4  1997/07/29 21:11:35  mdw
 * Reformatted.  Fixed buffer overflow when dealing with environment
 * variables.  Included NT in list of daft operating systems with `\' as a
 * path separator.  Fixed address of the FSF.
 *
 * Revision 1.3  1997/02/26 00:41:10  mdw
 * Added GPL notice to the top.  Slight formatting changes.
 *
 * Revision 1.2  1996/10/28 13:12:13  mdw
 * Fixed calls to ctype.h routines.  Arguments are cast to unsigned char
 * to avoid invoking undefined behaviour caused by signedness of chars.
 *
 * Revision 1.1  1996/09/24 18:01:28  mdw
 * Initial revision
 *
 */

/*----- External dependencies ---------------------------------------------*/

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "mdwopt.h"

/*----- Configuration things ----------------------------------------------*/

#if defined(__riscos)
#  define PATHSEP '.'
#elif defined(__OS2__) || defined(__MSDOS__) || defined(__WINNT__)
#  define PATHSEP '\\'
#else /* Assume a sane filing system */
#  define PATHSEP '/'
#endif

/*----- Global variables --------------------------------------------------*/

mdwopt_data mdwopt_global = {0, 0, 0, 1, 0, 0, 0, 0, 0};

enum {
  ord__permute = 0,                     /* Permute the options (default) */
  ord__return = 1,                      /* Return non-option things */
  ord__posix = 2,                       /* Do POSIX-type hacking */
  ord__negate = 4                       /* Magic negate-next-thing flag */
};

/*----- Main code ---------------------------------------------------------*/

/* --- @mo__nextWord@ --- *
 *
 * Arguments:   @int argc@ = number of command line options
 *              @char *argv[]@ = pointer to command line options
 *              @mdwopt_data *data@ = pointer to persistent state
 *
 * Returns:     Pointer to the next word to handle, or 0
 *
 * Use:         Extracts the next word from the command line or environment
 *              variable.
 */

static char *mo__nextWord(int argc, char *const *argv, mdwopt_data *data)
{
  if (data->ind == -1) {
    char *p = data->env;
    char *q;
    while (isspace((unsigned char)*p))
      p++;
    q = p;
    while (*p && !isspace((unsigned char)*p))
      p++;
    data->env = p;
    if (*p)
      *p++ = 0;
    if (p != q)
      return (q);
    data->env = 0;
    data->ind = 1;
  }

  if (data->next == argc)
    return (0);
  return (argv[data->next++]);
}

/* --- @mo__permute@ --- *
 *
 * Arguments:   @char *argv[]@ = pointer to command line arguments
 *              @mdwopt_data *data@ = pointer to persistent data
 *
 * Returns:     --
 *
 * Use:         Moves a command line option into the right place.
 */

static void mo__permute(char *const *argv, mdwopt_data *data)
{
  char **v = (char **)argv;
  if (data->ind != -1) {
    int i = data->next - 1;
    char *p = v[i];
    while (i > data->ind) {
      v[i] = v[i - 1];
      i--;
    }
    v[i] = p;
    data->ind++;
  }
}

/* --- @mo__findOpt@ --- *
 *
 * Arguments:   @int o@ = which option to search for
 *              @const char *shortopt@ = short options string to search
 *              @mdwopt_data *data@ = pointer to persistant state
 *
 * Returns:     Pointer to rest of short options string (including magic
 *              characters)
 *
 * Use:         Looks up a short option in the given string.
 */

static const char *mo__findOpt(int o, const char *shortopt,
                               mdwopt_data *data)
{
  const char *p = shortopt;             /* Point to short opts table */
  for (;;) {
    if (!*p)                            /* No more options left */
      return (0);

    if (o != *p || (p[1] != '+' && data->order & ord__negate)) {
      p++;                              /* Skip this option entry */
      while (*p == '+')                 /* Jump a `%|+|%' sign */
        p++;
      while (*p == ':')                 /* And jump any `%|:|%' characters */
        p++;                            /* Just in case there are any */
    }
    else
      return (p + 1);
  }
}

/* --- @mdwopt@ --- *
 *
 * Arguments:   @int argc@ = number of command line arguments
 *              @char * const *argv@ = pointer to command line arguments
 *              @const char *shortopt@ = pointer to short options information
 *              @const struct option *longopts@ = pointer to long opts info
 *              @int *longind@ = where to store matched longopt
 *              @mdwopt_data *data@ = persistent state for the parser
 *              @int flags@ = various useful flags
 *
 * Returns:     Value of option found next, or an error character, or
 *              @EOF@ for the last thing.
 *
 * Use:         Reads options.  The routine should be more-or-less compatible
 *              with standard getopts, although it provides many more
 *              features even than the standard GNU implementation.
 *
 *              The precise manner of options parsing is determined by
 *              various flag settings, which are described below.  By setting
 *              flag values appropriately, you can achieve behaviour very
 *              similar to most other getopt routines.
 *
 *
 *          How options parsing appears to users
 *
 *              A command line consists of a number of `words' (which may
 *              contain spaces, according to various shell quoting
 *              conventions).  A word may be an option, an argument to an
 *              option, or a non-option.  An option begins with a special
 *              character, usually `%|-|%', although `%|+|%' is also used
 *              sometimes.  As special exceptions, the word containing only a
 *              `%|-|%' is considered to be a non-option, since it usually
 *              represents standard input or output as a filename, and the
 *              word containing a double-dash `%|--|%' is used to mark all
 *              following words as being non-options regardless of their
 *              initial character.
 *
 *              Traditionally, all words after the first non-option have been
 *              considered to be non-options automatically, so that options
 *              must be specified before filenames.  However, this
 *              implementation can extract all the options from the command
 *              line regardless of their position.  This can usually be
 *              disabled by setting one of the environment variables
 *              `%|POSIXLY_CORRECT|%' or `%|_POSIX_OPTION_ORDER|%'.
 *
 *              There are two different styles of options: `short' and
 *              `long'.
 *
 *              Short options are the sort which Unix has known for ages: an
 *              option is a single letter, preceded by a `%|-|%'.  Short
 *              options can be joined together to save space (and possibly to
 *              make silly words): e.g., instead of giving options
 *              `%|-x -y|%', a user could write `%|-xy|%'.  Some short
 *              options can have arguments, which appear after the option
 *              letter, either immediately following, or in the next `word'
 *              (so an option with an argument could be written as
 *              `%|-o foo|%' or as `%|-ofoo|%').  Note that options with
 *              optional arguments must be written in the second style.
 *
 *              When a short option controls a flag setting, it is sometimes
 *              possible to explicitly turn the flag off, as well as turning
 *              it on, (usually to override default options).  This is
 *              usually done by using a `%|+|%' instead of a `%|-|%' to
 *              introduce the option.
 *
 *              Long options, as popularised by the GNU utilities, are given
 *              long-ish memorable names, preceded by a double-dash `%|--|%'.
 *              Since their names are more than a single character, long
 *              options can't be combined in the same way as short options.
 *              Arguments to long options may be given either in the same
 *              `word', separated from the option name by an equals sign, or
 *              in the following `word'.
 *
 *              Long option names can be abbreviated if necessary, as long
 *              as the abbreviation is unique.  This means that options can
 *              have sensible and memorable names but still not require much
 *              typing from an experienced user.
 *
 *              Like short options, long options can control flag settings.
 *              The options to manipulate these settings come in pairs: an
 *              option of the form `%|--set-flag|%' might set the flag, while
 *              an option of the form `%|--no-set-flag|%' might clear it.
 *
 *              It is usual for applications to provide both short and long
 *              options with identical behaviour.  Some applications with
 *              lots of options may only provide long options (although they
 *              will often be only two or three characters long).  In this
 *              case, long options can be preceded with a single `%|-|%'
 *              character, and negated by a `%|+|%' character.
 *
 *              Finally, some (older) programs accept arguments of the form
 *              `%%@.{"-"<number>}%%', to set some numerical parameter,
 *              typically a line count of some kind.
 *
 *
 *          How programs parse options
 *
 *              An application parses its options by calling mdwopt
 *              repeatedly.  Each time it is called, mdwopt returns a value
 *              describing the option just read, and stores information about
 *              the option in a data block.  The value %$-1$% is returned
 *              when there are no more options to be read.  The `%|?|%'
 *              character is returned when an error is encountered.
 *
 *              Before starting to parse options, the value @data->ind@ must
 *              be set to 0 or 1. The value of @data->err@ can also be set,
 *              to choose whether errors are reported by mdwopt.
 *
 *              The program's `@argc@' and `@argv@' arguments are passed to
 *              the options parser, so that it can read the command line.  A
 *              flags word is also passed, allowing the program fine control
 *              over parsing.  The flags are described above.
 *
 *              Short options are described by a string, which once upon a
 *              time just contained the permitted option characters.  Now the
 *              options string begins with a collection of flag characters,
 *              and various flag characters can be put after options
 *              characters to change their properties.
 *
 *              If the first character of the short options string is
 *              `%|+|%', `%|-|%' or `%|!|%', the order in which options are
 *              read is modified, as follows:
 *
 *              `%|+|%' forces the POSIX order to be used. As soon as a non-
 *                      option is found, mdwopt returns %$-1$%.
 *
 *              `%|-|%' makes mdwopt treat non-options as being `special'
 *                      sorts of option. When a non-option word is found, the
 *                      value 0 is returned, and the actual text of the word
 *                      is stored as being the option's argument.
 *
 *              `%|!|%' forces the default order to be used.  The entire
 *                      command line is scanned for options, which are
 *                      returned in order.  However, during this process,
 *                      the options are moved in the @argv@ array, so that
 *                      they appear before the non- options.
 *
 *              A `%|:|%' character may be placed after the ordering flag (or
 *              at the very beginning if no ordering flag is given) which
 *              indicates that the character `%|:|%', rather than `%|?|%',
 *              should be returned if a missing argument error is detected.
 *
 *              Each option in the string can be followed by a `%|+|%' sign,
 *              indicating that it can be negated, a `%|:|%' sign indicating
 *              that it requires an argument, or a `%|::|%' string,
 *              indicating an optional argument.  Both `%|+|%' and `%|:|%' or
 *              `%|::|%' may be given, although the `%|+|%' must come first.
 *
 *              If an option is found, the option character is returned to
 *              the caller.  A pointer to an argument is stored in
 *              @data->arg@, or @NULL@ is stored if there was no argument.
 *              If a negated option was found, the option character is
 *              returned ORred with @gFlag_negated@ (bit 8 set).
 *
 *              Long options are described in a table.  Each entry in the
 *              table is of type @struct option@, and the table is terminated
 *              by an entry whose @name@ field is null.  Each option has
 *              a flags word which, due to historical reasons, is called
 *              @has_arg@.  This describes various properties of the option,
 *              such as what sort of argument it takes, and whether it can
 *              be negated.
 *
 *              When mdwopt finds a long option, it looks the name up in the
 *              table. The index of the matching entry is stored in the
 *              @longind@ variable, passed to mdwopt (unless @longind@ is 0):
 *              a value of %$-1$% indicates that no long option was
 *              found. The behaviour is then dependent on the values in the
 *              table entry.  If @flag@ is nonzero, it points to an integer
 *              to be modified by mdwopt.  Usually the value in the @val@
 *              field is simply stored in the @flag@ variable. If the flag
 *              @gFlag_switch@ is set, however, the value is combined with
 *              the existing value of the flags using a bitwise OR.  If
 *              @gFlag_negate@ is set, then the flag bit will be cleared if a
 *              matching negated long option is found.  The value 0 is
 *              returned.
 *
 *              If @flag@ is zero, the value in @val@ is returned by mdwopt,
 *              possibly with bit 8 set if the option was negated.
 *
 *              Arguments for long options are stored in @data->arg@, as
 *              before.
 *
 *              Numeric options, if enabled, cause the value `%|#|%' to be
 *              returned, and the numeric value to be stored in @data->opt@.
 *
 *              If the flag @gFlag_envVar@ is set on entry, options will be
 *              extracted from an environment variable whose name is built by
 *              capitalising all the letters of the program's name.  (This
 *              allows a user to have different default settings for a
 *              program, by calling it through different symbolic links.)  */

int mdwopt(int argc, char *const *argv,
           const char *shortopt,
           const struct option *longopts, int *longind,
           mdwopt_data *data, int flags)
{
  /* --- Local variables --- */

  char *p, *q, *r;                      /* Some useful things to have */
  char *prefix;                         /* Prefix from this option */
  int i;                                /* Always useful */
  char noarg = '?';                     /* Standard missing-arg char */

  /* --- Sort out our data --- */

  if (!data)                            /* If default data requested */
    data = &mdwopt_global;              /* Then use the global stuff */

  /* --- See if this is the first time --- */

  if (data->ind == 0 || (data->ind == 1 && ~flags & gFlag_noProgName)) {

    /* --- Sort out default returning order --- */

    if (getenv("_POSIX_OPTION_ORDER") || /* Examine environment for opts */
        getenv("POSIXLY_CORRECT"))      /* To see if we disable features */
      data->order = ord__posix;         /* If set, use POSIX ordering */
    else
      data->order = ord__permute;       /* Otherwise mangle the options */

    /* --- Now see what the caller actually wants --- */

    switch (shortopt[0]) {              /* Look at the first character */
      case '-':                         /* `%|-|%' turns on in-orderness */
        data->order = ord__return;
        break;
      case '+':                         /* `%|+|%' turns on POSIXness */
        data->order = ord__posix;
        break;
      case '!':                         /* `%|!|%' ignores POSIXness */
        data->order = ord__permute;
        break;
    }

    /* --- Now decide on the program's name --- */

    if (~flags & gFlag_noProgName) {
      p = q = (char *)argv[0];
      while (*p) {
        if (*p++ == PATHSEP)
          q = p;
      }
      data->prog = q;

      data->ind = data->next = 1;
      data->list = 0;

      /* --- See about environment variables --- *
       *
       * Be careful.  The program may be setuid, and an attacker might have
       * given us a long name in @argv[0]@.  If the name is very long, don't
       * support this option.
       */

      if (flags & gFlag_envVar && strlen(data->prog) < 48) {

        char buf[64];

        /* --- For RISC OS, support a different format --- *
         *
         * Acorn's RISC OS tends to put settings in variables named
         * `App$Options' rather than `APP'.  Under RISC OS, I'll support
         * both methods, just to avoid confuddlement.
         */

#ifdef __riscos
        sprintf(buf, "%s$Options", data->prog);
        p = getenv(buf);
        if (!p) {
#endif

          p = buf;                      /* Point to a buffer */
          q = data->prog;               /* Point to program name */
          while (*q)                    /* While characters left here */
            *p++ = toupper(*q++);       /* Copy and uppercase */
          *p++ = 0;                     /* Terminate my copy of this */
          p = getenv(buf);              /* Get the value of the variable */

#ifdef __riscos
        }
#endif

        /* --- Copy the options string into a buffer --- */

        if (p) {                        /* If it is defined */
          q = malloc(strlen(p) + 1);    /* Allocate space for a copy */
          if (!q) {                     /* If that failed */
            fprintf(stderr,             /* Report a nice error */
                    "%s: Not enough memory to read settings in "
                    "environment variable\n",
                    data->prog);
          } else {                      /* Otherwise */
            strcpy(q, p);               /* Copy the text over */
            data->ind = -1;             /* Mark that we're parsing envvar */
            data->env = data->estart = q; /* And store the pointer away */
          }
        }

      }
    }
    else
      data->ind = data->next = 0;
  }

  /* --- Do some initial bodgery --- *
   *
   * The @shortopt@ string can have some interesting characters at the
   * beginning.  We'll skip past them.
   */

  switch (shortopt[0]) {
    case '+':
    case '-':
    case '!':
      shortopt++;
      break;
  }

  if (shortopt[0] == ':') {
    noarg = shortopt[0];
    shortopt++;
  }

  if (longind)                          /* Allow longind to be null */
    *longind = -1;                      /* Clear this to avoid confusion */
  data->opt = -1;                       /* And this too */
  data->arg = 0;                        /* No option set up here */

  /* --- Now go off and search for an option --- */

  if (!data->list || !*data->list) {
    data->order &= 3;                   /* Clear negation flag */

    /* --- Now we need to find the next option --- *
     *
     * Exactly how we do this depends on the settings of the order variable.
     * We identify options as being things starting with `%|-|%', and which
     * aren't equal to `%|-|%' or `%|--|%'.  We'll look for options until:
     *
     *   * We find something which isn't an option AND @order == ord__posix@
     *   * We find a `%|--|%'
     *   * We reach the end of the list
     *
     * There are some added little wrinkles, which we'll meet as we go.
     */

    for (;;) {                          /* Keep looping for a while */
      p = mo__nextWord(argc, argv, data); /* Get the next word out */
      if (!p)                           /* If there's no next word */
        return (EOF);                   /* There's no more now */

      /* --- See if we've found an option --- */

      if ((p[0] == '-' || (p[0] == '+' && flags & gFlag_negation)) &&
          p[1] != 0) {
        if (strcmp(p, "--") == 0) {     /* If this is the magic marker */
          mo__permute(argv, data);      /* Stow the magic marker item */
          return (EOF);                 /* There's nothing else to do */
        }
        break;                          /* We've found something! */
      }

      /* --- Figure out how to proceed --- */

      switch (data->order & 3) {
        case ord__posix:                /* POSIX option order */
          return (EOF);                 /* This is easy */
          break;
        case ord__permute:              /* Permute the option order */
          break;
        case ord__return:               /* Return each argument */
          mo__permute(argv, data);      /* Insert word in same place */
          data->arg = p;                /* Point to the argument */
          return (0);                   /* Return the value */
      }
    }

    /* --- We found an option --- */

    mo__permute(argv, data);            /* Do any permuting necessary */

    /* --- Check for a numeric option --- *
     *
     * We only check the first character (or the second if the first is a
     * sign).  This ought to be enough.
     */

    if (flags & gFlag_numbers && (p[0] == '-' || flags & gFlag_negNumber)) {
      if (((p[1] == '+' || p[1] == '-') && isdigit((unsigned char)p[2])) ||
          isdigit((unsigned char)p[1])) {
        data->opt = strtol(p + 1, &data->arg, 10);
        while (isspace((unsigned char)data->arg[0]))
          data->arg++;
        if (!data->arg[0])
          data->arg = 0;
        return (p[0] == '-' ? '#' : '#' | gFlag_negated);
      }
    }

    /* --- Check for a long option --- */

    if (p[0] == '+')
      data->order |= ord__negate;

    if (((p[0] == '-' && p[1] == '-') ||
         (flags & gFlag_noShorts && !mo__findOpt(p[1], shortopt, data))) &&
        (~flags & gFlag_noLongs))       /* Is this a long option? */
    {
      int match = -1;                   /* Count matches as we go */

      if (p[0] == '+') {                /* If it's negated */
        data->order |= ord__negate;     /* Set the negate flag */
        p++;                            /* Point to the main text */
        prefix = "+";                   /* Set the prefix string up */
      } else if (p[1] == '-') {         /* If this is a `%|--|%' option */
        if ((flags & gFlag_negation) && strncmp(p + 2, "no-", 3) == 0) {
          p += 5;                       /* Point to main text */
          prefix = "--no-";             /* And set the prefix */
          data->order |= ord__negate;   /* Set the negatedness flag */
        } else {
          p += 2;                       /* Point to the main text */
          prefix = "--";                /* Remember the prefix string */
        }
      } else {
        if ((flags & gFlag_negation) && strncmp(p + 1, "no-", 3) == 0) {
          p += 4;                       /* Find the text */
          prefix = "-no-";              /* Set the prefix */
          data->order |= ord__negate;   /* Set negatedness flag */
        } else {
          p++;                          /* Otherwise find the text */
          prefix = "-";                 /* And remember the prefix */
        }
      }

      for (i = 0; longopts[i].name; i++) { /* Loop through the options */
        if ((data->order & ord__negate) &&
            (~longopts[i].has_arg & gFlag_negate))
          continue;                     /* If neg and opt doesn't allow */

        r = (char *) longopts[i].name;  /* Point to the name string */
        q = p;                          /* Point to the string start */
        for (;;) {                      /* Do a loop here */
          if (*q == 0 || *q == '=') {   /* End of the option string? */
            if (*r == 0) {              /* If end of other string */
              match = i;                /* This is the match */
              goto botched;             /* And exit the loop now */
            }
            if (match == -1) {          /* If no match currently */
              match = i;                /* Then this is it, here */
              break;                    /* Stop looking now */
            } else {
              match = -1;               /* Else it's ambiguous */
              goto botched;             /* So give up right now */
            }
          }
          else if (*q != *r)            /* Otherwise if mismatch */
            break;                      /* Abort this loop */
          q++, r++;                     /* Increment the counters */
        }
      }

    botched:
      if (match == -1) {                /* If we couldn't find a match */
        if (data->err) {
          fprintf(stderr, "%s: unrecognised option `%s%s'\n",
                  data->prog,
                  prefix, p);
        }
        return ('?');
      }

      if (longind)                      /* Allow longind to be null */
        *longind = match;               /* Store the match away */

      /* --- Handle argument behaviour --- */

      while (*p != 0 && *p != '=')      /* Find the argument string */
        p++;
      p = (*p ? p + 1 : 0);             /* Sort out argument presence */
      q = (char *) longopts[match].name; /* Remember the name here */

      switch (longopts[match].has_arg & 3) {
        case no_argument:
          if (p) {
            if (data->err) {
              fprintf(stderr,
                      "%s: option `%s%s' does not accept arguments\n",
                      data->prog,
                      prefix, q);
            }
            return ('?');
          }
          break;

        case required_argument:
          if (!p) {                     /* If no argument given */
            p = mo__nextWord(argc, argv, data);

            if (!p) {                   /* If no more arguments */
              if (data->err) {
                fprintf(stderr, "%s: option `%s%s' requires an argument\n",
                        data->prog,
                        prefix, q);
              }
              return (noarg);
            }

            mo__permute(argv, data);
          }
          break;

        case optional_argument:
          /* Who cares? */
          break;
      }
      data->arg = p;

      /* --- Do correct things now we have a match --- */

      if (longopts[match].flag) {       /* If he has a @flag@ argument */
        if (longopts[match].has_arg & gFlag_switch) {
          if (data->order & ord__negate)
            *longopts[match].flag &= ~longopts[match].val;
          else
            *longopts[match].flag |= longopts[match].val;
        } else {
          if (data->order & ord__negate)
            *longopts[match].flag = 0;
          else
            *longopts[match].flag = longopts[match].val;
        }
        return (0);                     /* And return something */
      } else {
        if (data->order & ord__negate)
          return (longopts[match].val | gFlag_negated);
        else
          return (longopts[match].val);
      }
    }

    /* --- Do short options things --- */

    else {
      if (p[0] == '+')                  /* If starts with a `%|+|%' */
        data->order |= ord__negate;
      data->list = p + 1;               /* Omit leading `%|-|%'/`%|+|%' */
    }
  }

  /* --- Now process the short options --- */

  i = *data->list++;                    /* Get the next option letter */
  data->opt = i;                        /* Store this away nicely */

  p = (char *) mo__findOpt(i, shortopt, data);
  if (!p) {                             /* No more options left */
    if (data->err) {
      fprintf(stderr, "%s: unknown option `%c%c'\n",
              data->prog,
              data->order & ord__negate ? '+' : '-',
              i);
    }
    return ('?');
  }

  data->opt = i;                        /* Store this for the caller */

  /* --- Sort out an argument, if we expect one --- */

  if (p[0] == ':') {                    /* If we expect an option */
    q = (data->list[0] ? data->list : 0); /* If argument expected, use it */
    data->list = 0;                     /* Kill the remaining options */
    if (p[1] != ':' && !q) {            /* If no arg, and not optional */

      /* --- Same code as before --- */

      q = mo__nextWord(argc, argv, data); /* Read the next word */
      if (!q) {                         /* If no more arguments */
        if (data->err) {
          fprintf(stderr, "%s: option `%c%c' requires an argument\n",
                  data->prog,
                  data->order & ord__negate ? '+' : '-',
                  i);
        }
        return (noarg);
      }
      mo__permute(argv, data);
    }

    data->arg = q;
  }
  return ((data->order & ord__negate) ? i | gFlag_negated : i);
}

/*----- That's all, folks -------------------------------------------------*/