mdw@git.distorted.org.uk Git - fwd/blob - conf.c

   1 /* -*-c-*-
   2  *
   3  * $Id: conf.c,v 1.10 2002/02/22 23:42:56 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.c,v $
  32  * Revision 1.10  2002/02/22 23:42:56  mdw
  33  * `fw'-specific configuration code moved out.  This file might become part
  34  * of a library some day.
  35  *
  36  * Revision 1.9  2002/01/13 14:48:16  mdw
  37  * Make delimiters be a property of a scanner.  Change the delimiter-
  38  * changing functions' names.
  39  *
  40  * Revision 1.8  2001/02/03 20:33:26  mdw
  41  * Fix flags to be unsigned.
  42  *
  43  * Revision 1.7  2000/08/01 17:58:10  mdw
  44  * Fix subtleties with <ctype.h> functions.
  45  *
  46  * Revision 1.6  2000/02/12 18:13:20  mdw
  47  * Terminate tables of sources and targets.
  48  *
  49  * Revision 1.5  1999/10/22 22:46:44  mdw
  50  * Improve documentation for conf_enum.
  51  *
  52  * Revision 1.4  1999/10/15 21:12:36  mdw
  53  * Remove redundant debugging code.
  54  *
  55  * Revision 1.3  1999/08/19 18:32:48  mdw
  56  * Improve lexical analysis.  In particular, `chmod' patterns don't have to
  57  * be quoted any more.
  58  *
  59  * Revision 1.2  1999/07/26 23:28:39  mdw
  60  * Major reconstruction work for new design.
  61  *
  62  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  63  * Initial revision.
  64  *
  65  */
  66
  67 /*----- Header files ------------------------------------------------------*/
  68
  69 #include <ctype.h>
  70 #include <errno.h>
  71 #include <stdarg.h>
  72 #include <stdio.h>
  73 #include <stdlib.h>
  74 #include <string.h>
  75
  76 #include <mLib/dstr.h>
  77 #include <mLib/quis.h>
  78 #include <mLib/report.h>
  79
  80 #include "conf.h"
  81 #include "scan.h"
  82
  83 /*----- Main code ---------------------------------------------------------*/
  84
  85 /* --- @conf_undelim@ --- *
  86  *
  87  * Arguments:   @scanner *sc@ = pointer to scanner definition
  88  *              @const char *d, *dd@ = pointer to characters to escape
  89  *
  90  * Returns:     ---
  91  *
  92  * Use:         Modifies the tokenizer.  Characters in the first list will
  93  *              always be considered to begin a word.  Characters in the
  94  *              second list will always be allowed to continue a word.
  95  */
  96
  97 void conf_undelim(scanner *sc, const char *d, const char *dd)
  98 {
  99   sc->wbegin = d;
 100   sc->wcont = dd;
 101 }
 102
 103 /* --- @token@ --- *
 104  *
 105  * Arguments:   @scanner *sc@ = pointer to scanner definition
 106  *
 107  * Returns:     Type of token scanned.
 108  *
 109  * Use:         Reads the next token from the character scanner.
 110  */
 111
 112 int token(scanner *sc)
 113 {
 114 #define SELFDELIM \
 115   '{': case '}': case '/': case ',': \
 116   case '=': case ':': case ';': \
 117   case '.': case '[': case ']'
 118
 119   int ch;
 120
 121   DRESET(&sc->d);
 122
 123   /* --- Main tokenization --- */
 124
 125   for (;;) {
 126     ch = scan(sc);
 127
 128     /* --- Deal with pushed-back tokens --- */
 129
 130     if (sc->head->tok) {
 131       dstr_puts(&sc->d, sc->head->tok);
 132       xfree(sc->head->tok);
 133       sc->head->tok = 0;
 134       sc->t = sc->head->t;
 135       goto done;
 136     }
 137
 138     else if (isspace(ch))
 139       ;
 140     else switch (ch) {
 141
 142       /* --- End of file --- */
 143
 144       case EOF:
 145         sc->t = CTOK_EOF;
 146         goto done;
 147
 148       /* --- Comment character --- */
 149
 150       case '#':
 151         do ch = scan(sc); while (ch != EOF && ch != '\n');
 152         break;
 153
 154       /* --- Various self-delimiting characters --- */
 155
 156       case SELFDELIM:
 157         if (!sc->wbegin || strchr(sc->wbegin, ch) == 0) {
 158           dstr_putc(&sc->d, ch);
 159           dstr_putz(&sc->d);
 160           sc->t = ch;
 161           goto done;
 162         }
 163
 164       /* --- Bare words --- *
 165        *
 166        * These aren't as bare any more.  You can now backslash-escape
 167        * individual characters, and enclose sections in double-quotes.
 168        */
 169
 170       default: {
 171         int q = 0;
 172
 173         for (;;) {
 174           switch (ch) {
 175             case EOF:
 176               goto word;
 177             case '\\':
 178               ch = scan(sc);
 179               if (ch == EOF)
 180                 goto word;
 181               DPUTC(&sc->d, ch);
 182               break;
 183             case '\"':
 184               q = !q;
 185               break;
 186             case SELFDELIM:
 187               if (q || (sc->wcont && strchr(sc->wcont, ch)))
 188                 goto insert;
 189               goto word;
 190             default:
 191               if (!q && isspace(ch))
 192                 goto word;
 193             insert:
 194               DPUTC(&sc->d, ch);
 195               break;
 196           }
 197           ch = scan(sc);
 198         }
 199       word:
 200         unscan(sc, ch);
 201         DPUTZ(&sc->d);
 202         sc->t = CTOK_WORD;
 203         goto done;
 204       }
 205     }
 206   }
 207
 208 done:
 209   return (sc->t);
 210 }
 211
 212 /* --- @pushback@ --- *
 213  *
 214  * Arguments:   @scanner *sc@ = pointer to scanner definition
 215  *
 216  * Returns:     ---
 217  *
 218  * Use:         Pushes the current token back.  This is normally a precursor
 219  *              to pushing a new scanner source.
 220  */
 221
 222 void pushback(scanner *sc)
 223 {
 224   sc->head->tok = xstrdup(sc->d.buf);
 225   sc->head->t = sc->t;
 226 }
 227
 228 /* --- @error@ --- *
 229  *
 230  * Arguments:   @scanner *sc@ = pointer to scanner definition
 231  *              @const char *msg@ = message skeleton string
 232  *              @...@ = extra arguments for the skeleton
 233  *
 234  * Returns:     Doesn't
 235  *
 236  * Use:         Reports an error at the current scanner location.
 237  */
 238
 239 void error(scanner *sc, const char *msg, ...)
 240 {
 241   va_list ap;
 242   va_start(ap, msg);
 243   fprintf(stderr, "%s: %s:%i: ", QUIS, sc->head->src, sc->head->line);
 244   vfprintf(stderr, msg, ap);
 245   fputc('\n', stderr);
 246   exit(1);
 247 }
 248
 249 /* --- @conf_enum@ --- *
 250  *
 251  * Arguments:   @scanner *sc@ = pointer to a scanner object
 252  *              @const char *list@ = comma-separated things to allow
 253  *              @unsigned f@ = flags for the search
 254  *              @const char *err@ = error message if not found
 255  *
 256  * Returns:     Index into list, zero-based, or @-1@.
 257  *
 258  * Use:         Checks whether the current token is a string which matches
 259  *              one of the comma-separated items given.  The return value is
 260  *              the index (zero-based) of the matched string in the list.
 261  *
 262  *              The flags control the behaviour if no exact match is found.
 263  *              If @ENUM_ABBREV@ is set, and the current token is a left
 264  *              substring of exactly one of the possibilities, then that one
 265  *              is chosen.  If @ENUM_NONE@ is set, the value @-1@ is
 266  *              returned; otherwise an error is reported and the program is
 267  *              terminated.
 268  */
 269
 270 int conf_enum(scanner *sc, const char *list, unsigned f, const char *err)
 271 {
 272   const char *p, *q;
 273   int chosen = -1;
 274   int ok;
 275   int index;
 276
 277   /* --- Make sure it's a string --- */
 278
 279   if (sc->t != CTOK_WORD)
 280     error(sc, "parse error, expected %s", err);
 281
 282   /* --- Grind through the list --- */
 283
 284   q = sc->d.buf;
 285   ok = 1;
 286   index = 0;
 287   p = list;
 288   for (;;) {
 289     switch (*p) {
 290       case 0:
 291         if (ok && !*q) {
 292           token(sc);
 293           return (index);
 294         } else if (chosen != -1) {
 295           token(sc);
 296           return (chosen);
 297         }
 298         else if (f & ENUM_NONE)
 299           return (-1);
 300         else
 301           error(sc, "unknown %s `%s'", err, sc->d.buf);
 302         break;
 303       case ',':
 304         if (ok && !*q) {
 305           token(sc);
 306           return (index);
 307         }
 308         ok = 1;
 309         q = sc->d.buf;
 310         index++;
 311         break;
 312       default:
 313         if (!ok)
 314           break;
 315         if ((f & ENUM_ABBREV) && !*q) {
 316           if (chosen != -1)
 317             error(sc, "ambiguous %s `%s'", err, sc->d.buf);
 318           chosen = index;
 319           ok = 0;
 320         }
 321         if (*p == *q)
 322           q++;
 323         else
 324           ok = 0;
 325         break;
 326     }
 327     p++;
 328   }
 329 }
 330
 331 /* --- @conf_prefix@ --- *
 332  *
 333  * Arguments:   @scanner *sc@ = pointer to a scanner object
 334  *              @const char *p@ = pointer to prefix string to check
 335  *
 336  * Returns:     Nonzero if the prefix matches.
 337  *
 338  * Use:         If the current token is a word matching the given prefix
 339  *              string, then it and an optional `.' character are removed and
 340  *              a nonzero result is returned.  Otherwise the current token is
 341  *              left as it is, and zero is returned.
 342  *
 343  *              Typical options parsing code would remove an expected prefix,
 344  *              scan an option anyway (since qualifying prefixes are
 345  *              optional) and if a match is found, claim the option.  If no
 346  *              match is found, and a prefix was stripped, then an error
 347  *              should be reported.
 348  */
 349
 350 int conf_prefix(scanner *sc, const char *p)
 351 {
 352   if (sc->t == CTOK_WORD && strcmp(p, sc->d.buf) == 0) {
 353     token(sc);
 354     if (sc->t == '.')
 355       token(sc);
 356     return (1);
 357   }
 358   return (0);
 359 }
 360
 361 /* --- @conf_name@ --- *
 362  *
 363  * Arguments:   @scanner *sc@ = pointer to scanner
 364  *              @char delim@ = delimiter character to look for
 365  *              @dstr *d@ = pointer to dynamic string for output
 366  *
 367  * Returns:     ---
 368  *
 369  * Use:         Reads in a compound name consisting of words separated by
 370  *              delimiters.  Leading and trailing delimiters are permitted,
 371  *              although they'll probably cause confusion if used.  The name
 372  *              may be enclosed in square brackets if that helps at all.
 373  *
 374  *              Examples of compound names are filenames (delimited by `/')
 375  *              and IP addresses (delimited by `.').
 376  */
 377
 378 void conf_name(scanner *sc, char delim, dstr *d)
 379 {
 380   unsigned f = 0;
 381
 382 #define f_ok 1u
 383 #define f_bra 2u
 384
 385   /* --- Read an optional opening bracket --- */
 386
 387   if (sc->t == '[') {
 388     token(sc);
 389     f |= f_bra | f_ok;
 390   }
 391
 392   /* --- Do the main reading sequence --- */
 393
 394   do {
 395     if (sc->t == delim) {
 396       DPUTC(d, delim);
 397       f |= f_ok;
 398       token(sc);
 399     }
 400     if (sc->t == CTOK_WORD) {
 401       DPUTD(d, &sc->d);
 402       f |= f_ok;
 403       token(sc);
 404     }
 405   } while (sc->t == delim);
 406
 407   /* --- Check that the string was OK --- */
 408
 409   if (!(f & f_ok))
 410     error(sc, "parse error, name expected");
 411
 412   /* --- Read a closing bracket --- */
 413
 414   if (f & f_bra) {
 415     if (sc->t == ']')
 416       token(sc);
 417     else
 418       error(sc, "parse error, missing `]'");
 419   }
 420   DPUTZ(d);
 421
 422 #undef f_ok
 423 #undef f_bra
 424 }
 425
 426 /*----- That's all, folks -------------------------------------------------*/