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[cfd] / mdwopt.c

/* -*-c-*-
 *
 * Options parsing, similar to GNU @getopt_long@
 *
 * (c) 1996 Straylight/Edgeware
 */

/*----- 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.
 */

/*----- 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 */
};

/*----- Word splitting ----------------------------------------------------*/

#ifdef BUILDING_MLIB
#  include "str.h"
#  define qword str_qword
#else

/* --- @qword@ --- *
 *
 * Arguments:   @char **pp@ = address of pointer into string
 *              @unsigned f@ = various flags
 *
 * Returns:     Pointer to the next space-separated possibly-quoted word from
 *              the string, or null.
 *
 * Use:         Fetches the next word from a string.  If the flag
 *              @STRF_QUOTE@ is set, the `\' character acts as an escape, and
 *              single and double quotes protect whitespace.
 */

#define STRF_QUOTE 1u

static char *qword(char **pp, unsigned f)
{
  char *p = *pp, *q, *qq;
  int st = 0, pst = 0;

  /* --- Preliminaries --- */

  if (!p)
    return (0);
  while (isspace((unsigned char)*p))
    p++;
  if (!*p) {
    *pp = 0;
    return (0);
  }

  /* --- Main work --- */

  for (q = qq = p; *q; q++) {
    switch (st) {
      case '\\':
        *qq++ = *q;
        st = pst;
        break;
      case '\'':
      case '\"':
        if (*q == st)
          st = pst = 0;
        else if (*q == '\\')
          st = '\\';
        else
          *qq++ = *q;
        break;
      default:
        if (isspace((unsigned char)*q)) {
          do q++; while (*q && isspace((unsigned char)*q));
          goto done;
        } else if (!(f & STRF_QUOTE))
          goto stdchar;
        switch (*q) {
          case '\\':
            st = '\\';
            break;
          case '\'':
          case '\"':
            st = pst = *q;
            break;
          default:
          stdchar:
            *qq++ = *q;
            break;
        }
    }
  }

  /* --- Finished --- */

done:
  *pp = *q ? q : 0;
  *qq++ = 0;
  return (p);
}

#endif

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

/* --- @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 *nextword(int argc, char *const *argv, mdwopt_data *data)
{
  if (data->ind == -1) {
    char *p;
    if ((p = qword(&data->env, STRF_QUOTE)) != 0)
      return (p);
    data->ind = 1;
  }

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

/* --- @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 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++;
  }
}

/* --- @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 *findOpt(int o, const char *shortopt,
                               mdwopt_data *data)
{
  const char *p = shortopt;
  for (;;) {
    if (!*p)
      return (0);

    if (o != *p || (p[1] != '+' && data->order & ORD_NEGATE)) {
      p++;
      while (*p == '+')
        p++;
      while (*p == ':')
        p++;
    }
    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 popularized 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 @OPTF_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
 *              @OPTF_SWITCH@ is set, however, the value is combined with
 *              the existing value of the flags using a bitwise OR.  If
 *              @OPTF_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 @OPTF_ENVVAR@ is set on entry, options will be
 *              extracted from an environment variable whose name is built by
 *              capitalizing 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;
  char *prefix;
  int i;
  char noarg = '?';

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

  if (!data)
    data = &mdwopt_global;

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

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

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

    if (getenv("_POSIX_OPTION_ORDER") ||
        getenv("POSIXLY_CORRECT"))
      data->order = ORD_POSIX;
    else
      data->order = ORD_PERMUTE;

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

    switch (shortopt[0]) {
      case '-':
        data->order = ORD_RETURN;
        break;
      case '+':
        data->order = ORD_POSIX;
        break;
      case '!':
        data->order = ORD_PERMUTE;
        break;
    }

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

    if (~flags & OPTF_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 & OPTF_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;
          q = data->prog;
          while (*q)
            *p++ = toupper(*q++);
          *p++ = 0;
          p = getenv(buf);

#ifdef __riscos
        }
#endif

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

        if (p) {
          q = malloc(strlen(p) + 1);
          if (!q) {
            fprintf(stderr,
                    "%s: Not enough memory to read settings in "
                    "environment variable\n",
                    data->prog);
          } else {
            strcpy(q, p);
            data->ind = -1;
            data->env = data->estart = q;
          }
        }

      }
    }
    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)
    *longind = -1;
  data->opt = -1;
  data->arg = 0;

  /* --- 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 (;;) {
      p = nextword(argc, argv, data);
      if (!p)
        return (EOF);

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

      if ((p[0] == '-' || (p[0] == '+' && flags & OPTF_NEGATION)) &&
          p[1] != 0) {
        if (strcmp(p, "--") == 0) {
          permute(argv, data);
          return (EOF);
        }
        break;
      }

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

      switch (data->order & 3) {
        case ORD_POSIX:
          return (EOF);
          break;
        case ORD_PERMUTE:
          break;
        case ORD_RETURN:
          permute(argv, data);
          data->arg = p;
          return (0);
      }
    }

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

    permute(argv, data);

    /* --- 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 & OPTF_NUMBERS && (p[0] == '-' || flags & OPTF_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] == '-' ? '#' : '#' | OPTF_NEGATED);
      }
    }

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

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

    if (((p[0] == '-' && p[1] == '-') ||
         (flags & OPTF_NOSHORTS && !findOpt(p[1], shortopt, data))) &&
        (~flags & OPTF_NOLONGS))
    {
      int match = -1;

      if (p[0] == '+') {
        data->order |= ORD_NEGATE;
        p++;
        prefix = "+";
      } else if (p[1] == '-') {
        if ((flags & OPTF_NEGATION) && strncmp(p + 2, "no-", 3) == 0) {
          p += 5;
          prefix = "--no-";
          data->order |= ORD_NEGATE;
        } else {
          p += 2;
          prefix = "--";
        }
      } else {
        if ((flags & OPTF_NEGATION) && strncmp(p + 1, "no-", 3) == 0) {
          p += 4;
          prefix = "-no-";
          data->order |= ORD_NEGATE;
        } else {
          p++;
          prefix = "-";
        }
      }

      for (i = 0; longopts[i].name; i++) {
        if ((data->order & ORD_NEGATE) &&
            (~longopts[i].has_arg & OPTF_NEGATE))
          continue;

        r = (char *) longopts[i].name;
        q = p;
        for (;;) {
          if (*q == 0 || *q == '=') {
            if (*r == 0) {
              match = i;
              goto botched;
            }
            if (match == -1) {
              match = i;
              break;
            } else {
              match = -1;
              goto botched;
            }
          }
          else if (*q != *r)
            break;
          q++, r++;
        }
      }

    botched:
      if (match == -1) {
        if (data->err) {
          fprintf(stderr, "%s: unrecognized option `%s%s'\n",
                  data->prog,
                  prefix, p);
        }
        return ('?');
      }

      if (longind)
        *longind = match;

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

      while (*p != 0 && *p != '=')
        p++;
      p = (*p ? p + 1 : 0);
      q = (char *) longopts[match].name;

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

        case OPTF_ARGREQ:
          if (!p) {
            p = nextword(argc, argv, data);

            if (!p) {
              if (data->err) {
                fprintf(stderr, "%s: option `%s%s' requires an argument\n",
                        data->prog,
                        prefix, q);
              }
              return (noarg);
            }

            permute(argv, data);
          }
          break;

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

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

      if (longopts[match].flag) {
        if (longopts[match].has_arg & OPTF_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);
      } else {
        if (data->order & ORD_NEGATE)
          return (longopts[match].val | OPTF_NEGATED);
        else
          return (longopts[match].val);
      }
    }

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

    else {
      if (p[0] == '+')
        data->order |= ORD_NEGATE;
      data->list = p + 1;
    }
  }

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

  i = *data->list++;
  data->opt = i;

  p = (char *) findOpt(i, shortopt, data);
  if (!p) {
    if (data->err) {
      fprintf(stderr, "%s: unknown option `%c%c'\n",
              data->prog,
              data->order & ORD_NEGATE ? '+' : '-',
              i);
    }
    return ('?');
  }

  data->opt = i;

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

  if (p[0] == ':') {
    q = (data->list[0] ? data->list : 0);
    data->list = 0;
    if (p[1] != ':' && !q) {

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

      q = nextword(argc, argv, data);
      if (!q) {
        if (data->err) {
          fprintf(stderr, "%s: option `%c%c' requires an argument\n",
                  data->prog,
                  data->order & ORD_NEGATE ? '+' : '-',
                  i);
        }
        return (noarg);
      }
      permute(argv, data);
    }

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

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