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

   1 /* -*-c-*-
   2  *
   3  * Configuration parsing
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the `fwd' port forwarder.
  11  *
  12  * `fwd' is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * `fwd' is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with `fwd'; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 #include "fwd.h"
  28
  29 /*----- Main code ---------------------------------------------------------*/
  30
  31 /* --- @conf_undelim@ --- *
  32  *
  33  * Arguments:   @scanner *sc@ = pointer to scanner definition
  34  *              @const char *d, *dd@ = pointer to characters to escape
  35  *
  36  * Returns:     ---
  37  *
  38  * Use:         Modifies the tokenizer.  Characters in the first list will
  39  *              always be considered to begin a word.  Characters in the
  40  *              second list will always be allowed to continue a word.
  41  */
  42
  43 void conf_undelim(scanner *sc, const char *d, const char *dd)
  44 {
  45   sc->wbegin = d;
  46   sc->wcont = dd;
  47 }
  48
  49 /* --- @token@ --- *
  50  *
  51  * Arguments:   @scanner *sc@ = pointer to scanner definition
  52  *
  53  * Returns:     Type of token scanned.
  54  *
  55  * Use:         Reads the next token from the character scanner.
  56  */
  57
  58 int token(scanner *sc)
  59 {
  60 #define SELFDELIM \
  61   '{': case '}': case '/': case ',': \
  62   case '=': case ':': case ';': \
  63   case '.': case '[': case ']'
  64
  65   int ch;
  66
  67   DRESET(&sc->d);
  68
  69   /* --- Main tokenization --- */
  70
  71   for (;;) {
  72     ch = scan(sc);
  73
  74     /* --- Deal with pushed-back tokens --- */
  75
  76     if (sc->head->tok) {
  77       dstr_puts(&sc->d, sc->head->tok);
  78       xfree(sc->head->tok);
  79       sc->head->tok = 0;
  80       sc->t = sc->head->t;
  81       goto done;
  82     }
  83
  84     else if (isspace(ch))
  85       ;
  86     else switch (ch) {
  87
  88       /* --- End of file --- */
  89
  90       case EOF:
  91         sc->t = CTOK_EOF;
  92         goto done;
  93
  94       /* --- Comment character --- */
  95
  96       case '#':
  97         do ch = scan(sc); while (ch != EOF && ch != '\n');
  98         break;
  99
 100       /* --- Various self-delimiting characters --- */
 101
 102       case SELFDELIM:
 103         if (!sc->wbegin || strchr(sc->wbegin, ch) == 0) {
 104           dstr_putc(&sc->d, ch);
 105           dstr_putz(&sc->d);
 106           sc->t = ch;
 107           goto done;
 108         }
 109
 110       /* --- Bare words --- *
 111        *
 112        * These aren't as bare any more.  You can now backslash-escape
 113        * individual characters, and enclose sections in double-quotes.
 114        */
 115
 116       default: {
 117         int q = 0;
 118
 119         for (;;) {
 120           switch (ch) {
 121             case EOF:
 122               goto word;
 123             case '\\':
 124               ch = scan(sc);
 125               if (ch == EOF)
 126                 goto word;
 127               DPUTC(&sc->d, ch);
 128               break;
 129             case '\"':
 130               q = !q;
 131               break;
 132             case SELFDELIM:
 133               if (q || (sc->wcont && strchr(sc->wcont, ch)))
 134                 goto insert;
 135               goto word;
 136             default:
 137               if (!q && isspace(ch))
 138                 goto word;
 139             insert:
 140               DPUTC(&sc->d, ch);
 141               break;
 142           }
 143           ch = scan(sc);
 144         }
 145       word:
 146         unscan(sc, ch);
 147         DPUTZ(&sc->d);
 148         sc->t = CTOK_WORD;
 149         goto done;
 150       }
 151     }
 152   }
 153
 154 done:
 155   return (sc->t);
 156 }
 157
 158 /* --- @pushback@ --- *
 159  *
 160  * Arguments:   @scanner *sc@ = pointer to scanner definition
 161  *
 162  * Returns:     ---
 163  *
 164  * Use:         Pushes the current token back.  This is normally a precursor
 165  *              to pushing a new scanner source.
 166  */
 167
 168 void pushback(scanner *sc)
 169 {
 170   sc->head->tok = xstrdup(sc->d.buf);
 171   sc->head->t = sc->t;
 172 }
 173
 174 /* --- @error@ --- *
 175  *
 176  * Arguments:   @scanner *sc@ = pointer to scanner definition
 177  *              @const char *msg@ = message skeleton string
 178  *              @...@ = extra arguments for the skeleton
 179  *
 180  * Returns:     Doesn't
 181  *
 182  * Use:         Reports an error at the current scanner location.
 183  */
 184
 185 void error(scanner *sc, const char *msg, ...)
 186 {
 187   va_list ap;
 188   va_start(ap, msg);
 189   fprintf(stderr, "%s: %s:%i: ", QUIS, sc->head->src, sc->head->line);
 190   vfprintf(stderr, msg, ap);
 191   fputc('\n', stderr);
 192   exit(1);
 193 }
 194
 195 /* --- @conf_enum@ --- *
 196  *
 197  * Arguments:   @scanner *sc@ = pointer to a scanner object
 198  *              @const char *list@ = comma-separated things to allow
 199  *              @unsigned f@ = flags for the search
 200  *              @const char *err@ = error message if not found
 201  *
 202  * Returns:     Index into list, zero-based, or @-1@.
 203  *
 204  * Use:         Checks whether the current token is a string which matches
 205  *              one of the comma-separated items given.  The return value is
 206  *              the index (zero-based) of the matched string in the list.
 207  *
 208  *              The flags control the behaviour if no exact match is found.
 209  *              If @ENUM_ABBREV@ is set, and the current token is a left
 210  *              substring of exactly one of the possibilities, then that one
 211  *              is chosen.  If @ENUM_NONE@ is set, the value @-1@ is
 212  *              returned; otherwise an error is reported and the program is
 213  *              terminated.
 214  */
 215
 216 int conf_enum(scanner *sc, const char *list, unsigned f, const char *err)
 217 {
 218   const char *p, *q;
 219   int chosen = -1;
 220   int ok;
 221   int index;
 222
 223   /* --- Make sure it's a string --- */
 224
 225   if (sc->t != CTOK_WORD)
 226     error(sc, "parse error, expected %s", err);
 227
 228   /* --- Grind through the list --- */
 229
 230   q = sc->d.buf;
 231   ok = 1;
 232   index = 0;
 233   p = list;
 234   for (;;) {
 235     switch (*p) {
 236       case 0:
 237         if (ok && !*q) {
 238           token(sc);
 239           return (index);
 240         } else if (chosen != -1) {
 241           token(sc);
 242           return (chosen);
 243         }
 244         else if (f & ENUM_NONE)
 245           return (-1);
 246         else
 247           error(sc, "unknown %s `%s'", err, sc->d.buf);
 248         break;
 249       case ',':
 250         if (ok && !*q) {
 251           token(sc);
 252           return (index);
 253         }
 254         ok = 1;
 255         q = sc->d.buf;
 256         index++;
 257         break;
 258       default:
 259         if (!ok)
 260           break;
 261         if ((f & ENUM_ABBREV) && !*q) {
 262           if (chosen != -1)
 263             error(sc, "ambiguous %s `%s'", err, sc->d.buf);
 264           chosen = index;
 265           ok = 0;
 266         }
 267         if (*p == *q)
 268           q++;
 269         else
 270           ok = 0;
 271         break;
 272     }
 273     p++;
 274   }
 275 }
 276
 277 /* --- @conf_prefix@ --- *
 278  *
 279  * Arguments:   @scanner *sc@ = pointer to a scanner object
 280  *              @const char *p@ = pointer to prefix string to check
 281  *
 282  * Returns:     Nonzero if the prefix matches.
 283  *
 284  * Use:         If the current token is a word matching the given prefix
 285  *              string, then it and an optional `.' character are removed and
 286  *              a nonzero result is returned.  Otherwise the current token is
 287  *              left as it is, and zero is returned.
 288  *
 289  *              Typical options parsing code would remove an expected prefix,
 290  *              scan an option anyway (since qualifying prefixes are
 291  *              optional) and if a match is found, claim the option.  If no
 292  *              match is found, and a prefix was stripped, then an error
 293  *              should be reported.
 294  */
 295
 296 int conf_prefix(scanner *sc, const char *p)
 297 {
 298   if (sc->t == CTOK_WORD && strcmp(p, sc->d.buf) == 0) {
 299     token(sc);
 300     if (sc->t == '.')
 301       token(sc);
 302     return (1);
 303   }
 304   return (0);
 305 }
 306
 307 /* --- @conf_name@ --- *
 308  *
 309  * Arguments:   @scanner *sc@ = pointer to scanner
 310  *              @char delim@ = delimiter character to look for
 311  *              @dstr *d@ = pointer to dynamic string for output
 312  *
 313  * Returns:     ---
 314  *
 315  * Use:         Reads in a compound name consisting of words separated by
 316  *              delimiters.  Leading and trailing delimiters are permitted,
 317  *              although they'll probably cause confusion if used.  The name
 318  *              may be enclosed in square brackets if that helps at all.
 319  *
 320  *              Examples of compound names are filenames (delimited by `/')
 321  *              and IP addresses (delimited by `.').
 322  */
 323
 324 void conf_name(scanner *sc, char delim, dstr *d)
 325 {
 326   unsigned f = 0;
 327
 328 #define f_ok 1u
 329 #define f_bra 2u
 330
 331   /* --- Read an optional opening bracket --- */
 332
 333   if (sc->t == '[') {
 334     token(sc);
 335     f |= f_bra | f_ok;
 336   }
 337
 338   /* --- Do the main reading sequence --- */
 339
 340   do {
 341     if (sc->t == delim) {
 342       DPUTC(d, delim);
 343       f |= f_ok;
 344       token(sc);
 345     }
 346     if (sc->t == CTOK_WORD) {
 347       DPUTD(d, &sc->d);
 348       f |= f_ok;
 349       token(sc);
 350     }
 351   } while (sc->t == delim);
 352
 353   /* --- Check that the string was OK --- */
 354
 355   if (!(f & f_ok))
 356     error(sc, "parse error, name expected");
 357
 358   /* --- Read a closing bracket --- */
 359
 360   if (f & f_bra) {
 361     if (sc->t == ']')
 362       token(sc);
 363     else
 364       error(sc, "parse error, missing `]'");
 365   }
 366   DPUTZ(d);
 367
 368 #undef f_ok
 369 #undef f_bra
 370 }
 371
 372 /* --- @conf_fname@ --- *
 373  *
 374  * Arguments:   @scanner *sc@ = pointer to scanner
 375  *              @dstr *d@ = pointer to dynamic string for output
 376  *
 377  * Returns:     ---
 378  *
 379  * Use:         Reads a file name from the input and stores it in @d@.
 380  */
 381
 382 void conf_fname(scanner *sc, dstr *d)
 383 {
 384   const char fnchars[] = ".-+";
 385   conf_undelim(sc, fnchars, fnchars);
 386   conf_name(sc, '/', d);
 387   conf_undelim(sc, 0, 0);
 388 }
 389
 390 /*----- That's all, folks -------------------------------------------------*/