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   1 /* -*-c-*-
   2  *
   3  * $Id: conf.h,v 1.3 1999/07/27 18:30:14 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 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: conf.h,v $
  32  * Revision 1.3  1999/07/27 18:30:14  mdw
  33  * Improve documentation and layout for @CONF_BEGIN@ and friends.  Remove
  34  * irritating warning about unused label by introducing a spurious `goto'.
  35  *
  36  * Revision 1.2  1999/07/26 23:28:39  mdw
  37  * Major reconstruction work for new design.
  38  *
  39  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  40  * Initial revision.
  41  *
  42  */
  43
  44 #ifndef CONF_H
  45 #define CONF_H
  46
  47 #ifdef __cplusplus
  48   extern "C" {
  49 #endif
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #include <mLib/dstr.h>
  54
  55 #ifndef SCAN_H
  56 #  include "scan.h"
  57 #endif
  58
  59 /*----- Magic numbers -----------------------------------------------------*/
  60
  61 #define CTOK_EOF (-1)
  62 #define CTOK_WORD 256
  63
  64 /*----- Functions provided ------------------------------------------------*/
  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 /* --- @conf_enum@ --- *
  91  *
  92  * Arguments:   @scanner *sc@ = pointer to a scanner object
  93  *              @const char *list@ = comma-separated things to allow
  94  *              @unsigned @f = flags for the search
  95  *              @const char *err@ = error message if not found
  96  *
  97  * Returns:     Index into list, zero-based, or @-1@.
  98  *
  99  * Use:         Checks whether the current token is a string which matches
 100  *              one of the comma-separated items given.  If not, an error is
 101  *              reported; otherwise the index of the matched item is
 102  *              returned.
 103  */
 104
 105 #define ENUM_ABBREV 1u
 106 #define ENUM_NONE 2u
 107
 108 extern int conf_enum(scanner */*sc*/, const char */*list*/,
 109                      unsigned /*flags*/, const char */*err*/);
 110
 111 /* --- @conf_prefix@ --- *
 112  *
 113  * Arguments:   @scanner *sc@ = pointer to a scanner object
 114  *              @const char *p@ = pointer to prefix string to check
 115  *
 116  * Returns:     Nonzero if the prefix matches.
 117  *
 118  * Use:         If the current token is a word matching the given prefix
 119  *              string, then it and an optional `.' character are removed and
 120  *              a nonzero result is returned.  Otherwise the current token is
 121  *              left as it is, and zero is returned.
 122  *
 123  *              Typical options parsing code would remove an expected prefix,
 124  *              scan an option anyway (since qualifying prefixes are
 125  *              optional) and if a match is found, claim the option.  If no
 126  *              match is found, and a prefix was stripped, then an error
 127  *              should be reported.
 128  */
 129
 130 extern int conf_prefix(scanner */*sc*/, const char */*p*/);
 131
 132 /* --- @CONF_BEGIN@, @CONF_END@ --- *
 133  *
 134  * Arguments:   @sc@ = scanner to read from
 135  *              @prefix@ = prefix to scan for
 136  *              @desc@ = description of what we're parsing
 137  *
 138  * Use:         Bracket an options parsing routine.  The current token is
 139  *              checked to see whether it matches the prefix.  If so, it is
 140  *              removed and the following token examined.  If that's a `.'
 141  *              then it's removed.  If it's a `{' then the enclosed
 142  *              option-parsing code is executed in a loop until a matching
 143  *              '}' is found.  If the options parser doesn't accept an
 144  *              option, the behaviour is dependent on whether a prefix was
 145  *              seen: if so, an error is reported; otherwse a zero return is
 146  *              made.
 147  */
 148
 149 #define CS_PLAIN 0
 150 #define CS_PREFIX 1
 151 #define CS_BRACE 2
 152 #define CS_UNKNOWN 3
 153
 154 #define CONF_BEGIN(sc, prefix, desc) do {                               \
 155   scanner *_conf_sc = (sc);                                             \
 156   const char *_conf_desc = (desc);                                      \
 157   int _conf_state = CS_PLAIN;                                           \
 158                                                                         \
 159   /* --- Read the initial prefix --- */                                 \
 160                                                                         \
 161   if (_conf_sc->t == CTOK_WORD &&                                       \
 162       strcmp(_conf_sc->d.buf, (prefix)) == 0) {                         \
 163     token(_conf_sc);                                                    \
 164     _conf_state = CS_PREFIX;                                            \
 165     if (_conf_sc->t == '.')                                             \
 166       token(_conf_sc);                                                  \
 167     else if (_conf_sc->t == '{') {                                      \
 168       token(_conf_sc);                                                  \
 169       _conf_state = CS_BRACE;                                           \
 170     }                                                                   \
 171   }                                                                     \
 172                                                                         \
 173   /* --- Ensure the next token is a word --- */                         \
 174                                                                         \
 175   if (_conf_sc->t != CTOK_WORD)                                         \
 176     error(_conf_sc, "parse error, expected option keyword");            \
 177   do {
 178
 179 #define CONF_END                                                        \
 180                                                                         \
 181     /* --- Reject an option --- *                                       \
 182      *                                                                  \
 183      * We could get here as a result of an explicit @CONF_REJECT@ or    \
 184      * because the option wasn't accepted.                              \
 185      */                                                                 \
 186                                                                         \
 187      goto _conf_reject;                                                 \
 188   _conf_reject:                                                         \
 189     if (_conf_state == CS_PLAIN)                                        \
 190       _conf_state = CS_UNKNOWN;                                         \
 191     else {                                                              \
 192       error(_conf_sc, "unknown %s option `%s'",                         \
 193             _conf_desc, _conf_sc->d.buf);                               \
 194     }                                                                   \
 195                                                                         \
 196     /* --- Accept an option --- *                                       \
 197      *                                                                  \
 198      * It's safe to drop through from above.  Either an error will have \
 199      * been reported, or the state is not @CS_BRACE@.                   \
 200      */                                                                 \
 201                                                                         \
 202   _conf_accept:                                                         \
 203     if (_conf_state == CS_BRACE && _conf_sc->t == ';')                  \
 204       token(_conf_sc);                                                  \
 205   } while (_conf_state == CS_BRACE && _conf_sc->t == CTOK_WORD);        \
 206                                                                         \
 207   /* --- Check for a closing brace --- */                               \
 208                                                                         \
 209   if (_conf_state == CS_BRACE) {                                        \
 210     if (_conf_sc->t == '}')                                             \
 211       token(_conf_sc);                                                  \
 212     else                                                                \
 213       error(_conf_sc, "parse error, expected `}'");                     \
 214   }                                                                     \
 215                                                                         \
 216   /* --- Return an appropriate value --- */                             \
 217                                                                         \
 218   return (_conf_state != CS_UNKNOWN);                                   \
 219 } while (0)
 220
 221 /* --- @CONF_ACCEPT@, @CONF_REJECT@ --- *
 222  *
 223  * Arguments:   ---
 224  *
 225  * Use:         Within an options parser (between @CONF_BEGIN@ and
 226  *              @CONF_END@), accept or reject an option.
 227  */
 228
 229 #define CONF_ACCEPT goto _conf_accept
 230 #define CONF_REJECT goto _conf_reject
 231
 232 /* --- @CONF_QUAL@ --- *
 233  *
 234  * Arguments:   ---
 235  *
 236  * Use:         Evaluates to a nonzero value if the current option is
 237  *              qualified.  This can be used to decide whether abbreviations
 238  *              for options should be accepted.
 239  */
 240
 241 #define CONF_QUAL (_conf_state != CS_PLAIN)
 242
 243 /* --- @conf_name@ --- *
 244  *
 245  * Arguments:   @scanner *sc@ = pointer to scanner
 246  *              @char delim@ = delimiter character to look for
 247  *              @dstr *d@ = pointer to dynamic string for output
 248  *
 249  * Returns:     ---
 250  *
 251  * Use:         Reads in a compound name consisting of words separated by
 252  *              delimiters.  Leading and trailing delimiters are permitted,
 253  *              although they'll probably cause confusion if used.  The name
 254  *              may be enclosed in square brackets if that helps at all.
 255  *
 256  *              Examples of compound names are filenames (delimited by `/')
 257  *              and IP addresses (delimited by `.').
 258  */
 259
 260 extern void conf_name(scanner */*sc*/, char /*delim*/, dstr */*d*/);
 261
 262 /* --- @conf_parse@ --- *
 263  *
 264  * Arguments:   @scanner *sc@ = pointer to a scanner structure
 265  *
 266  * Returns:     ---
 267  *
 268  * Use:         Parses a configuration file fragment from the scanner
 269  */
 270
 271 extern void conf_parse(scanner *sc);
 272
 273 /*----- That's all, folks -------------------------------------------------*/
 274
 275 #ifdef __cplusplus
 276   }
 277 #endif
 278
 279 #endif