Version bump.

[fwd] / conf.h

/* -*-c-*-
 *
 * $Id: conf.h,v 1.7 2002/02/22 23:42:56 mdw Exp $
 *
 * Configuration parsing
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the `fw' port forwarder.
 *
 * `fw' 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 2 of the License, or
 * (at your option) any later version.
 * 
 * `fw' 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 `fw'; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: conf.h,v $
 * Revision 1.7  2002/02/22 23:42:56  mdw
 * `fw'-specific configuration code moved out.  This file might become part
 * of a library some day.
 *
 * Revision 1.6  2002/01/13 14:48:16  mdw
 * Make delimiters be a property of a scanner.  Change the delimiter-
 * changing functions' names.
 *
 * Revision 1.5  1999/10/22 22:46:44  mdw
 * Improve documentation for conf_enum.
 *
 * Revision 1.4  1999/08/19 18:32:48  mdw
 * Improve lexical analysis.  In particular, `chmod' patterns don't have to
 * be quoted any more.
 *
 * Revision 1.3  1999/07/27 18:30:14  mdw
 * Improve documentation and layout for @CONF_BEGIN@ and friends.  Remove
 * irritating warning about unused label by introducing a spurious `goto'.
 *
 * Revision 1.2  1999/07/26 23:28:39  mdw
 * Major reconstruction work for new design.
 *
 * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
 * Initial revision.
 *
 */

#ifndef CONF_H
#define CONF_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#include <mLib/dstr.h>

#ifndef SCAN_H
#  include "scan.h"
#endif

/*----- Magic numbers -----------------------------------------------------*/

#define CTOK_EOF (-1)
#define CTOK_WORD 256

/*----- Functions provided ------------------------------------------------*/

/* --- @conf_undelim@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to scanner definition
 *              @const char *d, *dd@ = pointer to characters to escape
 *
 * Returns:     ---
 *
 * Use:         Modifies the tokenizer.  Characters in the first list will
 *              always be considered to begin a word.  Characters in the
 *              second list will always be allowed to continue a word.
 */

extern void conf_undelim(scanner */*sc*/,
                         const char */*d*/, const char */*dd*/);

/* --- @token@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to scanner definition
 *
 * Returns:     Type of token scanned.
 *
 * Use:         Reads the next token from the character scanner.
 */

extern int token(scanner */*sc*/);

/* --- @error@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to scanner definition
 *              @const char *msg@ = message skeleton string
 *              @...@ = extra arguments for the skeleton
 *
 * Returns:     Doesn't
 *
 * Use:         Reports an error at the current scanner location.
 */

extern void error(scanner */*sc*/, const char */*msg*/, ...);

/* --- @pushback@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to scanner definition
 *
 * Returns:     ---
 *
 * Use:         Pushes the current token back.  This is normally a precursor
 *              to pushing a new scanner source.
 */

extern void pushback(scanner */*sc*/);

/* --- @conf_enum@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to a scanner object
 *              @const char *list@ = comma-separated things to allow
 *              @unsigned @f = flags for the search
 *              @const char *err@ = error message if not found
 *
 * Returns:     Index into list, zero-based, or @-1@.
 *
 * Use:         Checks whether the current token is a string which matches
 *              one of the comma-separated items given.  The return value is
 *              the index (zero-based) of the matched string in the list.
 *
 *              The flags control the behaviour if no exact match is found.
 *              If @ENUM_ABBREV@ is set, and the current token is a left
 *              substring of exactly one of the possibilities, then that one
 *              is chosen.  If @ENUM_NONE@ is set, the value @-1@ is
 *              returned; otherwise an error is reported and the program is
 *              terminated.
 */

#define ENUM_ABBREV 1u
#define ENUM_NONE 2u

extern int conf_enum(scanner */*sc*/, const char */*list*/,
                     unsigned /*flags*/, const char */*err*/);

/* --- @conf_prefix@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to a scanner object
 *              @const char *p@ = pointer to prefix string to check
 *
 * Returns:     Nonzero if the prefix matches.
 *
 * Use:         If the current token is a word matching the given prefix
 *              string, then it and an optional `.' character are removed and
 *              a nonzero result is returned.  Otherwise the current token is
 *              left as it is, and zero is returned.
 *
 *              Typical options parsing code would remove an expected prefix,
 *              scan an option anyway (since qualifying prefixes are
 *              optional) and if a match is found, claim the option.  If no
 *              match is found, and a prefix was stripped, then an error
 *              should be reported.
 */

extern int conf_prefix(scanner */*sc*/, const char */*p*/);

/* --- @CONF_BEGIN@, @CONF_END@ --- *
 *
 * Arguments:   @sc@ = scanner to read from
 *              @prefix@ = prefix to scan for
 *              @desc@ = description of what we're parsing
 *
 * Use:         Bracket an options parsing routine.  The current token is
 *              checked to see whether it matches the prefix.  If so, it is
 *              removed and the following token examined.  If that's a `.'
 *              then it's removed.  If it's a `{' then the enclosed
 *              option-parsing code is executed in a loop until a matching
 *              '}' is found.  If the options parser doesn't accept an
 *              option, the behaviour is dependent on whether a prefix was
 *              seen: if so, an error is reported; otherwse a zero return is
 *              made.
 */

#define CS_PLAIN 0
#define CS_PREFIX 1
#define CS_BRACE 2
#define CS_UNKNOWN 3

#define CONF_BEGIN(sc, prefix, desc) do {                               \
  scanner *_conf_sc = (sc);                                             \
  const char *_conf_desc = (desc);                                      \
  int _conf_state = CS_PLAIN;                                           \
                                                                        \
  /* --- Read the initial prefix --- */                                 \
                                                                        \
  if (_conf_sc->t == CTOK_WORD &&                                       \
      strcmp(_conf_sc->d.buf, (prefix)) == 0) {                         \
    token(_conf_sc);                                                    \
    _conf_state = CS_PREFIX;                                            \
    if (_conf_sc->t == '.')                                             \
      token(_conf_sc);                                                  \
    else if (_conf_sc->t == '{') {                                      \
      token(_conf_sc);                                                  \
      _conf_state = CS_BRACE;                                           \
    }                                                                   \
  }                                                                     \
                                                                        \
  /* --- Ensure the next token is a word --- */                         \
                                                                        \
  if (_conf_sc->t != CTOK_WORD)                                         \
    error(_conf_sc, "parse error, expected option keyword");            \
  do {

#define CONF_END                                                        \
                                                                        \
    /* --- Reject an option --- *                                       \
     *                                                                  \
     * We could get here as a result of an explicit @CONF_REJECT@ or    \
     * because the option wasn't accepted.                              \
     */                                                                 \
                                                                        \
     goto _conf_reject;                                                 \
  _conf_reject:                                                         \
    if (_conf_state == CS_PLAIN)                                        \
      _conf_state = CS_UNKNOWN;                                         \
    else {                                                              \
      error(_conf_sc, "unknown %s option `%s'",                         \
            _conf_desc, _conf_sc->d.buf);                               \
    }                                                                   \
                                                                        \
    /* --- Accept an option --- *                                       \
     *                                                                  \
     * It's safe to drop through from above.  Either an error will have \
     * been reported, or the state is not @CS_BRACE@.                   \
     */                                                                 \
                                                                        \
  _conf_accept:                                                         \
    if (_conf_state == CS_BRACE && _conf_sc->t == ';')                  \
      token(_conf_sc);                                                  \
  } while (_conf_state == CS_BRACE && _conf_sc->t == CTOK_WORD);        \
                                                                        \
  /* --- Check for a closing brace --- */                               \
                                                                        \
  if (_conf_state == CS_BRACE) {                                        \
    if (_conf_sc->t == '}')                                             \
      token(_conf_sc);                                                  \
    else                                                                \
      error(_conf_sc, "parse error, expected `}'");                     \
  }                                                                     \
                                                                        \
  /* --- Return an appropriate value --- */                             \
                                                                        \
  return (_conf_state != CS_UNKNOWN);                                   \
} while (0)

/* --- @CONF_ACCEPT@, @CONF_REJECT@ --- *
 *
 * Arguments:   ---
 *
 * Use:         Within an options parser (between @CONF_BEGIN@ and
 *              @CONF_END@), accept or reject an option.
 */

#define CONF_ACCEPT goto _conf_accept
#define CONF_REJECT goto _conf_reject

/* --- @CONF_QUAL@ --- *
 *
 * Arguments:   ---
 *
 * Use:         Evaluates to a nonzero value if the current option is
 *              qualified.  This can be used to decide whether abbreviations
 *              for options should be accepted.
 */

#define CONF_QUAL (_conf_state != CS_PLAIN)

/* --- @conf_name@ --- *
 *
 * Arguments:   @scanner *sc@ = pointer to scanner
 *              @char delim@ = delimiter character to look for
 *              @dstr *d@ = pointer to dynamic string for output
 *
 * Returns:     ---
 *
 * Use:         Reads in a compound name consisting of words separated by
 *              delimiters.  Leading and trailing delimiters are permitted,
 *              although they'll probably cause confusion if used.  The name
 *              may be enclosed in square brackets if that helps at all.
 *
 *              Examples of compound names are filenames (delimited by `/')
 *              and IP addresses (delimited by `.').
 */

extern void conf_name(scanner */*sc*/, char /*delim*/, dstr */*d*/);

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

#ifdef __cplusplus
  }
#endif

#endif