file.c

   1 /*
   2  * libuci - Library for the Unified Configuration Interface
   3  * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   4  *
   5  * this program is free software; you can redistribute it and/or modify
   6  * it under the terms of the gnu lesser general public license version 2.1
   7  * as published by the free software foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 /*
  16  * This file contains the code for parsing uci config files
  17  */
  18
  19 #include <sys/types.h>
  20 #include <sys/stat.h>
  21 #include <stdbool.h>
  22 #include <stdio.h>
  23 #include <ctype.h>
  24
  25 #define LINEBUF 32
  26 #define LINEBUF_MAX     4096
  27
  28 /*
  29  * Fetch a new line from the input stream and resize buffer if necessary
  30  */
  31 static void uci_getln(struct uci_context *ctx, int offset)
  32 {
  33         struct uci_parse_context *pctx = ctx->pctx;
  34         char *p;
  35         int ofs;
  36
  37         if (pctx->buf == NULL) {
  38                 pctx->buf = uci_malloc(ctx, LINEBUF);
  39                 pctx->bufsz = LINEBUF;
  40         }
  41
  42         ofs = offset;
  43         do {
  44                 p = &pctx->buf[ofs];
  45                 p[ofs] = 0;
  46
  47                 p = fgets(p, pctx->bufsz - ofs, pctx->file);
  48                 if (!p || !p[ofs])
  49                         return;
  50
  51                 ofs += strlen(p);
  52                 if (pctx->buf[ofs - 1] == '\n') {
  53                         pctx->line++;
  54                         pctx->buf[ofs - 1] = 0;
  55                         return;
  56                 }
  57
  58                 if (pctx->bufsz > LINEBUF_MAX/2) {
  59                         pctx->reason = "line too long";
  60                         pctx->byte = LINEBUF_MAX;
  61                         UCI_THROW(ctx, UCI_ERR_PARSE);
  62                 }
  63
  64                 pctx->bufsz *= 2;
  65                 pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
  66         } while (1);
  67 }
  68
  69 /*
  70  * Clean up all extra memory used by the parser
  71  */
  72 static void uci_parse_cleanup(struct uci_context *ctx)
  73 {
  74         struct uci_parse_context *pctx;
  75
  76         pctx = ctx->pctx;
  77         if (!pctx)
  78                 return;
  79
  80         ctx->pctx = NULL;
  81         if (pctx->cfg) {
  82                 uci_list_del(&pctx->cfg->list);
  83                 uci_drop_config(pctx->cfg);
  84         }
  85         if (pctx->buf)
  86                 free(pctx->buf);
  87         if (pctx->file)
  88                 fclose(pctx->file);
  89
  90         free(pctx);
  91 }
  92
  93 /*
  94  * parse a character escaped by '\'
  95  * returns true if the escaped character is to be parsed
  96  * returns false if the escaped character is to be ignored
  97  */
  98 static inline bool parse_backslash(struct uci_context *ctx, char **str)
  99 {
 100         /* skip backslash */
 101         *str += 1;
 102
 103         /* undecoded backslash at the end of line, fetch the next line */
 104         if (!**str) {
 105                 *str += 1;
 106                 uci_getln(ctx, *str - ctx->pctx->buf);
 107                 return false;
 108         }
 109
 110         /* FIXME: decode escaped char, necessary? */
 111         return true;
 112 }
 113
 114 /*
 115  * move the string pointer forward until a non-whitespace character or
 116  * EOL is reached
 117  */
 118 static void skip_whitespace(struct uci_context *ctx, char **str)
 119 {
 120 restart:
 121         while (**str && isspace(**str))
 122                 *str += 1;
 123
 124         if (**str == '\\') {
 125                 if (!parse_backslash(ctx, str))
 126                         goto restart;
 127         }
 128 }
 129
 130 static inline void addc(char **dest, char **src)
 131 {
 132         **dest = **src;
 133         *dest += 1;
 134         *src += 1;
 135 }
 136
 137 /*
 138  * parse a double quoted string argument from the command line
 139  */
 140 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 141 {
 142         char c;
 143
 144         /* skip quote character */
 145         *str += 1;
 146
 147         while ((c = **str)) {
 148                 switch(c) {
 149                 case '"':
 150                         **target = 0;
 151                         *str += 1;
 152                         return;
 153                 case '\\':
 154                         if (!parse_backslash(ctx, str))
 155                                 continue;
 156                         /* fall through */
 157                 default:
 158                         addc(target, str);
 159                         break;
 160                 }
 161         }
 162         ctx->pctx->reason = "unterminated \"";
 163         ctx->pctx->byte = *str - ctx->pctx->buf;
 164         UCI_THROW(ctx, UCI_ERR_PARSE);
 165 }
 166
 167 /*
 168  * parse a single quoted string argument from the command line
 169  */
 170 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 171 {
 172         char c;
 173         /* skip quote character */
 174         *str += 1;
 175
 176         while ((c = **str)) {
 177                 switch(c) {
 178                 case '\'':
 179                         **target = 0;
 180                         *str += 1;
 181                         return;
 182                 default:
 183                         addc(target, str);
 184                 }
 185         }
 186         ctx->pctx->reason = "unterminated '";
 187         ctx->pctx->byte = *str - ctx->pctx->buf;
 188         UCI_THROW(ctx, UCI_ERR_PARSE);
 189 }
 190
 191 /*
 192  * parse a string from the command line and detect the quoting style
 193  */
 194 static void parse_str(struct uci_context *ctx, char **str, char **target)
 195 {
 196         do {
 197                 switch(**str) {
 198                 case '\'':
 199                         parse_single_quote(ctx, str, target);
 200                         break;
 201                 case '"':
 202                         parse_double_quote(ctx, str, target);
 203                         break;
 204                 case 0:
 205                         goto done;
 206                 case '\\':
 207                         if (!parse_backslash(ctx, str))
 208                                 continue;
 209                         /* fall through */
 210                 default:
 211                         addc(target, str);
 212                         break;
 213                 }
 214         } while (**str && !isspace(**str));
 215 done:
 216
 217         /*
 218          * if the string was unquoted and we've stopped at a whitespace
 219          * character, skip to the next one, because the whitespace will
 220          * be overwritten by a null byte here
 221          */
 222         if (**str)
 223                 *str += 1;
 224
 225         /* terminate the parsed string */
 226         **target = 0;
 227 }
 228
 229 /*
 230  * extract the next argument from the command line
 231  */
 232 static char *next_arg(struct uci_context *ctx, char **str, bool required)
 233 {
 234         char *val;
 235         char *ptr;
 236
 237         val = ptr = *str;
 238         skip_whitespace(ctx, str);
 239         parse_str(ctx, str, &ptr);
 240         if (required && !*val) {
 241                 ctx->pctx->reason = "insufficient arguments";
 242                 ctx->pctx->byte = *str - ctx->pctx->buf;
 243                 UCI_THROW(ctx, UCI_ERR_PARSE);
 244         }
 245
 246         return uci_strdup(ctx, val);
 247 }
 248
 249 /*
 250  * verify that the end of the line or command is reached.
 251  * throw an error if extra arguments are given on the command line
 252  */
 253 static void assert_eol(struct uci_context *ctx, char **str)
 254 {
 255         char *tmp;
 256
 257         tmp = next_arg(ctx, str, false);
 258         if (tmp && *tmp) {
 259                 ctx->pctx->reason = "too many arguments";
 260                 ctx->pctx->byte = tmp - ctx->pctx->buf;
 261                 UCI_THROW(ctx, UCI_ERR_PARSE);
 262         }
 263 }
 264
 265 /*
 266  * switch to a different config, either triggered by uci_load, or by a
 267  * 'package <...>' statement in the import file
 268  */
 269 static void uci_switch_config(struct uci_context *ctx)
 270 {
 271         struct uci_parse_context *pctx;
 272         const char *name;
 273
 274         pctx = ctx->pctx;
 275         name = pctx->name;
 276
 277         /* add the last config to main config file list */
 278         if (pctx->cfg) {
 279                 uci_list_add(&ctx->root, &pctx->cfg->list);
 280
 281                 pctx->cfg = NULL;
 282                 pctx->section = NULL;
 283         }
 284
 285         if (!name)
 286                 return;
 287
 288         /*
 289          * if an older config under the same name exists, unload it
 290          * ignore errors here, e.g. if the config was not found
 291          */
 292         UCI_TRAP_SAVE(ctx, ignore);
 293         uci_unload(ctx, name);
 294         UCI_TRAP_RESTORE(ctx);
 295 ignore:
 296         ctx->errno = 0;
 297
 298         pctx->cfg = uci_alloc_config(ctx, name);
 299 }
 300
 301 /*
 302  * parse the 'package' uci command (next config package)
 303  */
 304 static void uci_parse_package(struct uci_context *ctx, char **str)
 305 {
 306         char *name = NULL;
 307
 308         /* command string null-terminated by strtok */
 309         *str += strlen(*str) + 1;
 310
 311         UCI_TRAP_SAVE(ctx, error);
 312         name = next_arg(ctx, str, true);
 313         assert_eol(ctx, str);
 314         ctx->pctx->name = name;
 315         uci_switch_config(ctx);
 316         UCI_TRAP_RESTORE(ctx);
 317         return;
 318
 319 error:
 320         if (name)
 321                 free(name);
 322         UCI_THROW(ctx, ctx->errno);
 323 }
 324
 325 /*
 326  * parse the 'config' uci command (open a section)
 327  */
 328 static void uci_parse_config(struct uci_context *ctx, char **str)
 329 {
 330         char *name = NULL;
 331         char *type = NULL;
 332
 333         if (!ctx->pctx->cfg) {
 334                 if (!ctx->pctx->name) {
 335                         ctx->pctx->byte = *str - ctx->pctx->buf;
 336                         ctx->pctx->reason = "attempting to import a file without a package name";
 337                         UCI_THROW(ctx, UCI_ERR_PARSE);
 338                 }
 339                 uci_switch_config(ctx);
 340         }
 341
 342         /* command string null-terminated by strtok */
 343         *str += strlen(*str) + 1;
 344
 345         UCI_TRAP_SAVE(ctx, error);
 346         type = next_arg(ctx, str, true);
 347         name = next_arg(ctx, str, false);
 348         assert_eol(ctx, str);
 349         ctx->pctx->section = uci_add_section(ctx->pctx->cfg, type, name);
 350         UCI_TRAP_RESTORE(ctx);
 351         return;
 352
 353 error:
 354         if (name)
 355                 free(name);
 356         if (type)
 357                 free(type);
 358         UCI_THROW(ctx, ctx->errno);
 359 }
 360
 361 /*
 362  * parse the 'option' uci command (open a value)
 363  */
 364 static void uci_parse_option(struct uci_context *ctx, char **str)
 365 {
 366         char *name = NULL;
 367         char *value = NULL;
 368
 369         if (!ctx->pctx->section) {
 370                 ctx->pctx->byte = *str - ctx->pctx->buf;
 371                 ctx->pctx->reason = "option command found before the first section";
 372                 UCI_THROW(ctx, UCI_ERR_PARSE);
 373         }
 374         /* command string null-terminated by strtok */
 375         *str += strlen(*str) + 1;
 376
 377         UCI_TRAP_SAVE(ctx, error);
 378         name = next_arg(ctx, str, true);
 379         value = next_arg(ctx, str, true);
 380         assert_eol(ctx, str);
 381         uci_add_option(ctx->pctx->section, name, value);
 382         UCI_TRAP_RESTORE(ctx);
 383         return;
 384
 385 error:
 386         if (name)
 387                 free(name);
 388         if (value)
 389                 free(value);
 390         UCI_THROW(ctx, ctx->errno);
 391 }
 392
 393
 394 /*
 395  * parse a complete input line, split up combined commands by ';'
 396  */
 397 static void uci_parse_line(struct uci_context *ctx)
 398 {
 399         struct uci_parse_context *pctx = ctx->pctx;
 400         char *word, *brk;
 401
 402         for (word = strtok_r(pctx->buf, ";", &brk);
 403                  word;
 404                  word = strtok_r(NULL, ";", &brk)) {
 405
 406                 char *pbrk;
 407                 word = strtok_r(word, " \t", &pbrk);
 408
 409                 switch(word[0]) {
 410                         case 'p':
 411                                 if ((word[1] == 0) || !strcmp(word + 1, "ackage"))
 412                                         uci_parse_package(ctx, &word);
 413                                 break;
 414                         case 'c':
 415                                 if ((word[1] == 0) || !strcmp(word + 1, "onfig"))
 416                                         uci_parse_config(ctx, &word);
 417                                 break;
 418                         case 'o':
 419                                 if ((word[1] == 0) || !strcmp(word + 1, "ption"))
 420                                         uci_parse_option(ctx, &word);
 421                                 break;
 422                         default:
 423                                 pctx->reason = "unterminated command";
 424                                 pctx->byte = word - pctx->buf;
 425                                 UCI_THROW(ctx, UCI_ERR_PARSE);
 426                                 break;
 427                 }
 428         }
 429 }
 430
 431 int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_config **cfg)
 432 {
 433         struct uci_parse_context *pctx;
 434
 435         /* make sure no memory from previous parse attempts is leaked */
 436         uci_parse_cleanup(ctx);
 437
 438         pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
 439         ctx->pctx = pctx;
 440         pctx->file = stream;
 441
 442         /*
 443          * If 'name' was supplied, assume that the supplied stream does not contain
 444          * the appropriate 'package <name>' string to specify the config name
 445          * NB: the config file can still override the package name
 446          */
 447         if (name)
 448                 pctx->name = name;
 449
 450         while (!feof(pctx->file)) {
 451                 uci_getln(ctx, 0);
 452                 if (pctx->buf[0])
 453                         uci_parse_line(ctx);
 454         }
 455
 456         if (cfg)
 457                 *cfg = pctx->cfg;
 458
 459         pctx->name = NULL;
 460         uci_switch_config(ctx);
 461
 462         /* no error happened, we can get rid of the parser context now */
 463         uci_parse_cleanup(ctx);
 464
 465         return 0;
 466 }
 467
 468 int uci_load(struct uci_context *ctx, const char *name, struct uci_config **cfg)
 469 {
 470         struct stat statbuf;
 471         char *filename;
 472         bool confpath;
 473         FILE *file;
 474
 475         UCI_HANDLE_ERR(ctx);
 476         UCI_ASSERT(ctx, name != NULL);
 477
 478 ignore:
 479         ctx->errno = 0;
 480
 481         switch (name[0]) {
 482         case '.':
 483         case '/':
 484                 /* absolute/relative path outside of /etc/config */
 485                 filename = (char *) name;
 486                 confpath = false;
 487                 break;
 488         default:
 489                 filename = uci_malloc(ctx, strlen(name) + sizeof(UCI_CONFDIR) + 2);
 490                 sprintf(filename, UCI_CONFDIR "/%s", name);
 491                 confpath = true;
 492                 break;
 493         }
 494
 495         if ((stat(filename, &statbuf) < 0) ||
 496                 ((statbuf.st_mode &  S_IFMT) != S_IFREG)) {
 497                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 498         }
 499
 500         file = fopen(filename, "r");
 501         if (filename != name)
 502                 free(filename);
 503
 504         if (!file)
 505                 UCI_THROW(ctx, UCI_ERR_IO);
 506
 507         return uci_import(ctx, file, name, cfg);
 508 }
 509