parse.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 128
  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)
  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 = 0;
  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  * move the string pointer forward until a non-whitespace character or
  95  * EOL is reached
  96  */
  97 static void skip_whitespace(char **str)
  98 {
  99         while (**str && isspace(**str))
 100                 *str += 1;
 101 }
 102
 103 static inline void addc(char **dest, char **src)
 104 {
 105         **dest = **src;
 106         *dest += 1;
 107         *src += 1;
 108 }
 109
 110 static inline void parse_backslash(char **str, char **target)
 111 {
 112         /* skip backslash */
 113         *str += 1;
 114         /* FIXME: decode escaped characters? */
 115         addc(target, str);
 116 }
 117
 118 /*
 119  * parse a double quoted string argument from the command line
 120  */
 121 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 122 {
 123         char c;
 124
 125         /* skip quote character */
 126         *str += 1;
 127
 128         while ((c = **str)) {
 129                 switch(c) {
 130                 case '\\':
 131                         parse_backslash(str, target);
 132                         continue;
 133                 case '"':
 134                         **target = 0;
 135                         *str += 1;
 136                         return;
 137                 default:
 138                         addc(target, str);
 139                         break;
 140                 }
 141         }
 142         ctx->pctx->reason = "unterminated \"";
 143         ctx->pctx->byte = *str - ctx->pctx->buf;
 144         UCI_THROW(ctx, UCI_ERR_PARSE);
 145 }
 146
 147 /*
 148  * parse a single quoted string argument from the command line
 149  */
 150 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 151 {
 152         char c;
 153         /* skip quote character */
 154         *str += 1;
 155
 156         while ((c = **str)) {
 157                 switch(c) {
 158                 case '\'':
 159                         **target = 0;
 160                         *str += 1;
 161                         return;
 162                 default:
 163                         addc(target, str);
 164                 }
 165         }
 166         ctx->pctx->reason = "unterminated '";
 167         ctx->pctx->byte = *str - ctx->pctx->buf;
 168         UCI_THROW(ctx, UCI_ERR_PARSE);
 169 }
 170
 171 /*
 172  * parse a string from the command line and detect the quoting style
 173  */
 174 static void parse_str(struct uci_context *ctx, char **str, char **target)
 175 {
 176         do {
 177                 switch(**str) {
 178                 case '\\':
 179                         parse_backslash(str, target);
 180                         continue;
 181                 case '\'':
 182                         parse_single_quote(ctx, str, target);
 183                         break;
 184                 case '"':
 185                         parse_double_quote(ctx, str, target);
 186                         break;
 187                 case 0:
 188                         goto done;
 189                 default:
 190                         addc(target, str);
 191                         break;
 192                 }
 193         } while (**str && !isspace(**str));
 194 done:
 195
 196         /*
 197          * if the string was unquoted and we've stopped at a whitespace
 198          * character, skip to the next one, because the whitespace will
 199          * be overwritten by a null byte here
 200          */
 201         if (**str)
 202                 *str += 1;
 203
 204         /* terminate the parsed string */
 205         **target = 0;
 206 }
 207
 208 /*
 209  * extract the next argument from the command line
 210  */
 211 static char *next_arg(struct uci_context *ctx, char **str, bool required)
 212 {
 213         char *val;
 214         char *ptr;
 215
 216         val = ptr = *str;
 217         skip_whitespace(str);
 218         parse_str(ctx, str, &ptr);
 219         if (required && !*val) {
 220                 ctx->pctx->reason = "insufficient arguments";
 221                 ctx->pctx->byte = *str - ctx->pctx->buf;
 222                 UCI_THROW(ctx, UCI_ERR_PARSE);
 223         }
 224
 225         return uci_strdup(ctx, val);
 226 }
 227
 228 /*
 229  * verify that the end of the line or command is reached.
 230  * throw an error if extra arguments are given on the command line
 231  */
 232 static void assert_eol(struct uci_context *ctx, char **str)
 233 {
 234         char *tmp;
 235
 236         tmp = next_arg(ctx, str, false);
 237         if (tmp && *tmp) {
 238                 ctx->pctx->reason = "too many arguments";
 239                 ctx->pctx->byte = tmp - ctx->pctx->buf;
 240                 UCI_THROW(ctx, UCI_ERR_PARSE);
 241         }
 242 }
 243
 244 /*
 245  * parse the 'config' uci command (open a section)
 246  */
 247 static void uci_parse_config(struct uci_context *ctx, char **str)
 248 {
 249         char *name = NULL;
 250         char *type = NULL;
 251
 252         /* command string null-terminated by strtok */
 253         *str += strlen(*str) + 1;
 254
 255         UCI_TRAP_SAVE(ctx, error);
 256         type = next_arg(ctx, str, true);
 257         name = next_arg(ctx, str, false);
 258         assert_eol(ctx, str);
 259         ctx->pctx->section = uci_add_section(ctx->pctx->cfg, type, name);
 260         UCI_TRAP_RESTORE(ctx);
 261         return;
 262
 263 error:
 264         if (name)
 265                 free(name);
 266         if (type)
 267                 free(type);
 268         UCI_THROW(ctx, ctx->errno);
 269 }
 270
 271 /*
 272  * parse the 'option' uci command (open a value)
 273  */
 274 static void uci_parse_option(struct uci_context *ctx, char **str)
 275 {
 276         char *name = NULL;
 277         char *value = NULL;
 278
 279         if (!ctx->pctx->section) {
 280                 ctx->pctx->byte = *str - ctx->pctx->buf;
 281                 ctx->pctx->reason = "option command found before the first section";
 282                 UCI_THROW(ctx, UCI_ERR_PARSE);
 283         }
 284         /* command string null-terminated by strtok */
 285         *str += strlen(*str) + 1;
 286
 287         UCI_TRAP_SAVE(ctx, error);
 288         name = next_arg(ctx, str, true);
 289         value = next_arg(ctx, str, true);
 290         assert_eol(ctx, str);
 291         uci_add_option(ctx->pctx->section, name, value);
 292         UCI_TRAP_RESTORE(ctx);
 293         return;
 294
 295 error:
 296         if (name)
 297                 free(name);
 298         if (value)
 299                 free(value);
 300         UCI_THROW(ctx, ctx->errno);
 301 }
 302
 303 /*
 304  * parse a complete input line, split up combined commands by ';'
 305  */
 306 static void uci_parse_line(struct uci_context *ctx)
 307 {
 308         struct uci_parse_context *pctx = ctx->pctx;
 309         char *word, *brk;
 310
 311         for (word = strtok_r(pctx->buf, ";", &brk);
 312                  word;
 313                  word = strtok_r(NULL, ";", &brk)) {
 314
 315                 char *pbrk;
 316                 word = strtok_r(word, " \t", &pbrk);
 317
 318                 switch(word[0]) {
 319                         case 'c':
 320                                 if ((word[1] == 0) || !strcmp(word + 1, "onfig"))
 321                                         uci_parse_config(ctx, &word);
 322                                 break;
 323                         case 'o':
 324                                 if ((word[1] == 0) || !strcmp(word + 1, "ption"))
 325                                         uci_parse_option(ctx, &word);
 326                                 break;
 327                         default:
 328                                 pctx->reason = "unterminated command";
 329                                 pctx->byte = word - pctx->buf;
 330                                 UCI_THROW(ctx, UCI_ERR_PARSE);
 331                                 break;
 332                 }
 333         }
 334 }
 335
 336 int uci_load(struct uci_context *ctx, const char *name, struct uci_config **cfg)
 337 {
 338         struct uci_parse_context *pctx;
 339         struct stat statbuf;
 340         char *filename;
 341         bool confpath;
 342
 343         UCI_HANDLE_ERR(ctx);
 344         UCI_ASSERT(ctx, name != NULL);
 345
 346         UCI_TRAP_SAVE(ctx, ignore);
 347         uci_unload(ctx, name);
 348         UCI_TRAP_RESTORE(ctx);
 349
 350 ignore:
 351         ctx->errno = 0;
 352
 353         /* make sure no memory from previous parse attempts is leaked */
 354         uci_parse_cleanup(ctx);
 355
 356         pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
 357         ctx->pctx = pctx;
 358
 359         switch (name[0]) {
 360         case '.':
 361         case '/':
 362                 /* absolute/relative path outside of /etc/config */
 363                 filename = (char *) name;
 364                 confpath = false;
 365                 break;
 366         default:
 367                 filename = uci_malloc(ctx, strlen(name) + sizeof(UCI_CONFDIR) + 2);
 368                 sprintf(filename, UCI_CONFDIR "/%s", name);
 369                 confpath = true;
 370                 break;
 371         }
 372
 373         if ((stat(filename, &statbuf) < 0) ||
 374                 ((statbuf.st_mode &  S_IFMT) != S_IFREG)) {
 375                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 376         }
 377
 378         pctx->file = fopen(filename, "r");
 379         if (filename != name)
 380                 free(filename);
 381
 382         if (!pctx->file)
 383                 UCI_THROW(ctx, UCI_ERR_IO);
 384
 385         pctx->cfg = uci_alloc_config(ctx, name);
 386
 387         while (!feof(pctx->file)) {
 388                 uci_getln(ctx);
 389                 if (pctx->buf[0])
 390                         uci_parse_line(ctx);
 391         }
 392
 393         /* add to main config file list */
 394         uci_list_add(&ctx->root, &pctx->cfg->list);
 395         if (cfg)
 396                 *cfg = pctx->cfg;
 397
 398         pctx->cfg = NULL;
 399
 400         /* no error happened, we can get rid of the parser context now */
 401         uci_parse_cleanup(ctx);
 402
 403         return 0;
 404 }
 405