build: Actually compile the `blast' helper program.

[fwd] / conf.h

/* -*-c-*-
 *
 * 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.
 */

#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