chiark - git - mdw - fwd/blob - conf.h

   1 /* -*-c-*-
   2  *
   3  * $Id: conf.h,v 1.9 2004/04/08 01:36:25 mdw Exp $
   4  *
   5  * Configuration parsing
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 #ifndef CONF_H
  30 #define CONF_H
  31
  32 #ifdef __cplusplus
  33   extern "C" {
  34 #endif
  35
  36 /*----- Header files ------------------------------------------------------*/
  37
  38 #include <mLib/dstr.h>
  39
  40 #ifndef SCAN_H
  41 #  include "scan.h"
  42 #endif
  43
  44 /*----- Magic numbers -----------------------------------------------------*/
  45
  46 #define CTOK_EOF (-1)
  47 #define CTOK_WORD 256
  48
  49 /*----- Functions provided ------------------------------------------------*/
  50
  51 /* --- @conf_undelim@ --- *
  52  *
  53  * Arguments:   @scanner *sc@ = pointer to scanner definition
  54  *              @const char *d, *dd@ = pointer to characters to escape
  55  *
  56  * Returns:     ---
  57  *
  58  * Use:         Modifies the tokenizer.  Characters in the first list will
  59  *              always be considered to begin a word.  Characters in the
  60  *              second list will always be allowed to continue a word.
  61  */
  62
  63 extern void conf_undelim(scanner */*sc*/,
  64                          const char */*d*/, const char */*dd*/);
  65
  66 /* --- @token@ --- *
  67  *
  68  * Arguments:   @scanner *sc@ = pointer to scanner definition
  69  *
  70  * Returns:     Type of token scanned.
  71  *
  72  * Use:         Reads the next token from the character scanner.
  73  */
  74
  75 extern int token(scanner */*sc*/);
  76
  77 /* --- @error@ --- *
  78  *
  79  * Arguments:   @scanner *sc@ = pointer to scanner definition
  80  *              @const char *msg@ = message skeleton string
  81  *              @...@ = extra arguments for the skeleton
  82  *
  83  * Returns:     Doesn't
  84  *
  85  * Use:         Reports an error at the current scanner location.
  86  */
  87
  88 extern void error(scanner */*sc*/, const char */*msg*/, ...);
  89
  90 /* --- @pushback@ --- *
  91  *
  92  * Arguments:   @scanner *sc@ = pointer to scanner definition
  93  *
  94  * Returns:     ---
  95  *
  96  * Use:         Pushes the current token back.  This is normally a precursor
  97  *              to pushing a new scanner source.
  98  */
  99
 100 extern void pushback(scanner */*sc*/);
 101
 102 /* --- @conf_enum@ --- *
 103  *
 104  * Arguments:   @scanner *sc@ = pointer to a scanner object
 105  *              @const char *list@ = comma-separated things to allow
 106  *              @unsigned @f = flags for the search
 107  *              @const char *err@ = error message if not found
 108  *
 109  * Returns:     Index into list, zero-based, or @-1@.
 110  *
 111  * Use:         Checks whether the current token is a string which matches
 112  *              one of the comma-separated items given.  The return value is
 113  *              the index (zero-based) of the matched string in the list.
 114  *
 115  *              The flags control the behaviour if no exact match is found.
 116  *              If @ENUM_ABBREV@ is set, and the current token is a left
 117  *              substring of exactly one of the possibilities, then that one
 118  *              is chosen.  If @ENUM_NONE@ is set, the value @-1@ is
 119  *              returned; otherwise an error is reported and the program is
 120  *              terminated.
 121  */
 122
 123 #define ENUM_ABBREV 1u
 124 #define ENUM_NONE 2u
 125
 126 extern int conf_enum(scanner */*sc*/, const char */*list*/,
 127                      unsigned /*flags*/, const char */*err*/);
 128
 129 /* --- @conf_prefix@ --- *
 130  *
 131  * Arguments:   @scanner *sc@ = pointer to a scanner object
 132  *              @const char *p@ = pointer to prefix string to check
 133  *
 134  * Returns:     Nonzero if the prefix matches.
 135  *
 136  * Use:         If the current token is a word matching the given prefix
 137  *              string, then it and an optional `.' character are removed and
 138  *              a nonzero result is returned.  Otherwise the current token is
 139  *              left as it is, and zero is returned.
 140  *
 141  *              Typical options parsing code would remove an expected prefix,
 142  *              scan an option anyway (since qualifying prefixes are
 143  *              optional) and if a match is found, claim the option.  If no
 144  *              match is found, and a prefix was stripped, then an error
 145  *              should be reported.
 146  */
 147
 148 extern int conf_prefix(scanner */*sc*/, const char */*p*/);
 149
 150 /* --- @CONF_BEGIN@, @CONF_END@ --- *
 151  *
 152  * Arguments:   @sc@ = scanner to read from
 153  *              @prefix@ = prefix to scan for
 154  *              @desc@ = description of what we're parsing
 155  *
 156  * Use:         Bracket an options parsing routine.  The current token is
 157  *              checked to see whether it matches the prefix.  If so, it is
 158  *              removed and the following token examined.  If that's a `.'
 159  *              then it's removed.  If it's a `{' then the enclosed
 160  *              option-parsing code is executed in a loop until a matching
 161  *              '}' is found.  If the options parser doesn't accept an
 162  *              option, the behaviour is dependent on whether a prefix was
 163  *              seen: if so, an error is reported; otherwse a zero return is
 164  *              made.
 165  */
 166
 167 #define CS_PLAIN 0
 168 #define CS_PREFIX 1
 169 #define CS_BRACE 2
 170 #define CS_UNKNOWN 3
 171
 172 #define CONF_BEGIN(sc, prefix, desc) do {                               \
 173   scanner *_conf_sc = (sc);                                             \
 174   const char *_conf_desc = (desc);                                      \
 175   int _conf_state = CS_PLAIN;                                           \
 176                                                                         \
 177   /* --- Read the initial prefix --- */                                 \
 178                                                                         \
 179   if (_conf_sc->t == CTOK_WORD &&                                       \
 180       strcmp(_conf_sc->d.buf, (prefix)) == 0) {                         \
 181     token(_conf_sc);                                                    \
 182     _conf_state = CS_PREFIX;                                            \
 183     if (_conf_sc->t == '.')                                             \
 184       token(_conf_sc);                                                  \
 185     else if (_conf_sc->t == '{') {                                      \
 186       token(_conf_sc);                                                  \
 187       _conf_state = CS_BRACE;                                           \
 188     }                                                                   \
 189   }                                                                     \
 190                                                                         \
 191   /* --- Ensure the next token is a word --- */                         \
 192                                                                         \
 193   if (_conf_sc->t != CTOK_WORD)                                         \
 194     error(_conf_sc, "parse error, expected option keyword");            \
 195   do {
 196
 197 #define CONF_END                                                        \
 198                                                                         \
 199     /* --- Reject an option --- *                                       \
 200      *                                                                  \
 201      * We could get here as a result of an explicit @CONF_REJECT@ or    \
 202      * because the option wasn't accepted.                              \
 203      */                                                                 \
 204                                                                         \
 205     goto _conf_reject;                                                  \
 206   _conf_reject:                                                         \
 207     if (_conf_state == CS_PLAIN)                                        \
 208       _conf_state = CS_UNKNOWN;                                         \
 209     else {                                                              \
 210       error(_conf_sc, "unknown %s option `%s'",                         \
 211             _conf_desc, _conf_sc->d.buf);                               \
 212     }                                                                   \
 213                                                                         \
 214     /* --- Accept an option --- *                                       \
 215      *                                                                  \
 216      * It's safe to drop through from above.  Either an error will have \
 217      * been reported, or the state is not @CS_BRACE@.                   \
 218      */                                                                 \
 219                                                                         \
 220   _conf_accept:                                                         \
 221     if (_conf_state == CS_BRACE && _conf_sc->t == ';')                  \
 222       token(_conf_sc);                                                  \
 223   } while (_conf_state == CS_BRACE && _conf_sc->t == CTOK_WORD);        \
 224                                                                         \
 225   /* --- Check for a closing brace --- */                               \
 226                                                                         \
 227   if (_conf_state == CS_BRACE) {                                        \
 228     if (_conf_sc->t == '}')                                             \
 229       token(_conf_sc);                                                  \
 230     else                                                                \
 231       error(_conf_sc, "parse error, expected `}'");                     \
 232   }                                                                     \
 233                                                                         \
 234   /* --- Return an appropriate value --- */                             \
 235                                                                         \
 236   return (_conf_state != CS_UNKNOWN);                                   \
 237 } while (0)
 238
 239 /* --- @CONF_ACCEPT@, @CONF_REJECT@ --- *
 240  *
 241  * Arguments:   ---
 242  *
 243  * Use:         Within an options parser (between @CONF_BEGIN@ and
 244  *              @CONF_END@), accept or reject an option.
 245  */
 246
 247 #define CONF_ACCEPT goto _conf_accept
 248 #define CONF_REJECT goto _conf_reject
 249
 250 /* --- @CONF_QUAL@ --- *
 251  *
 252  * Arguments:   ---
 253  *
 254  * Use:         Evaluates to a nonzero value if the current option is
 255  *              qualified.  This can be used to decide whether abbreviations
 256  *              for options should be accepted.
 257  */
 258
 259 #define CONF_QUAL (_conf_state != CS_PLAIN)
 260
 261 /* --- @conf_name@ --- *
 262  *
 263  * Arguments:   @scanner *sc@ = pointer to scanner
 264  *              @char delim@ = delimiter character to look for
 265  *              @dstr *d@ = pointer to dynamic string for output
 266  *
 267  * Returns:     ---
 268  *
 269  * Use:         Reads in a compound name consisting of words separated by
 270  *              delimiters.  Leading and trailing delimiters are permitted,
 271  *              although they'll probably cause confusion if used.  The name
 272  *              may be enclosed in square brackets if that helps at all.
 273  *
 274  *              Examples of compound names are filenames (delimited by `/')
 275  *              and IP addresses (delimited by `.').
 276  */
 277
 278 extern void conf_name(scanner */*sc*/, char /*delim*/, dstr */*d*/);
 279
 280 /*----- That's all, folks -------------------------------------------------*/
 281
 282 #ifdef __cplusplus
 283   }
 284 #endif
 285
 286 #endif