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         if (pctx->cfg) {
  81                 uci_list_del(&pctx->cfg->list);
  82                 uci_drop_file(pctx->cfg);
  83         }
  84         if (pctx->buf)
  85                 free(pctx->buf);
  86         if (pctx->file)
  87                 fclose(pctx->file);
  88
  89         free(pctx);
  90 }
  91
  92 /*
  93  * move the string pointer forward until a non-whitespace character or
  94  * EOL is reached
  95  */
  96 static void skip_whitespace(char **str)
  97 {
  98         while (**str && isspace(**str))
  99                 *str += 1;
 100 }
 101
 102 static inline void addc(char **dest, char **src)
 103 {
 104         **dest = **src;
 105         *dest += 1;
 106         *src += 1;
 107 }
 108
 109 static inline void parse_backslash(char **str, char **target)
 110 {
 111         /* skip backslash */
 112         *str += 1;
 113         /* FIXME: decode escaped characters? */
 114         addc(target, str);
 115 }
 116
 117 /*
 118  * parse a double quoted string argument from the command line
 119  */
 120 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 121 {
 122         char c;
 123
 124         /* skip quote character */
 125         *str += 1;
 126
 127         while ((c = **str)) {
 128                 switch(c) {
 129                 case '\\':
 130                         parse_backslash(str, target);
 131                         continue;
 132                 case '"':
 133                         **target = 0;
 134                         *str += 1;
 135                         return;
 136                 default:
 137                         addc(target, str);
 138                         break;
 139                 }
 140         }
 141         ctx->pctx->reason = "unterminated \"";
 142         ctx->pctx->byte = *str - ctx->pctx->buf;
 143         UCI_THROW(ctx, UCI_ERR_PARSE);
 144 }
 145
 146 /*
 147  * parse a single quoted string argument from the command line
 148  */
 149 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 150 {
 151         char c;
 152         /* skip quote character */
 153         *str += 1;
 154
 155         while ((c = **str)) {
 156                 switch(c) {
 157                 case '\'':
 158                         **target = 0;
 159                         *str += 1;
 160                         return;
 161                 default:
 162                         addc(target, str);
 163                 }
 164         }
 165         ctx->pctx->reason = "unterminated '";
 166         ctx->pctx->byte = *str - ctx->pctx->buf;
 167         UCI_THROW(ctx, UCI_ERR_PARSE);
 168 }
 169
 170 /*
 171  * parse a string from the command line and detect the quoting style
 172  */
 173 static void parse_str(struct uci_context *ctx, char **str, char **target)
 174 {
 175         do {
 176                 switch(**str) {
 177                 case '\\':
 178                         parse_backslash(str, target);
 179                         continue;
 180                 case '\'':
 181                         parse_single_quote(ctx, str, target);
 182                         break;
 183                 case '"':
 184                         parse_double_quote(ctx, str, target);
 185                         break;
 186                 case 0:
 187                         goto done;
 188                 default:
 189                         addc(target, str);
 190                         break;
 191                 }
 192         } while (**str && !isspace(**str));
 193 done:
 194
 195         /*
 196          * if the string was unquoted and we've stopped at a whitespace
 197          * character, skip to the next one, because the whitespace will
 198          * be overwritten by a null byte here
 199          */
 200         if (**str)
 201                 *str += 1;
 202
 203         /* terminate the parsed string */
 204         **target = 0;
 205 }
 206
 207 /*
 208  * extract the next argument from the command line
 209  */
 210 static char *next_arg(struct uci_context *ctx, char **str, bool required)
 211 {
 212         char *val;
 213         char *ptr;
 214
 215         val = ptr = *str;
 216         skip_whitespace(str);
 217         parse_str(ctx, str, &ptr);
 218         if (required && !*val) {
 219                 ctx->pctx->reason = "insufficient arguments";
 220                 ctx->pctx->byte = *str - ctx->pctx->buf;
 221                 UCI_THROW(ctx, UCI_ERR_PARSE);
 222         }
 223
 224         return uci_strdup(ctx, val);
 225 }
 226
 227 /*
 228  * verify that the end of the line or command is reached.
 229  * throw an error if extra arguments are given on the command line
 230  */
 231 static void assert_eol(struct uci_context *ctx, char **str)
 232 {
 233         char *tmp;
 234
 235         tmp = next_arg(ctx, str, false);
 236         if (tmp && *tmp) {
 237                 ctx->pctx->reason = "too many arguments";
 238                 ctx->pctx->byte = tmp - ctx->pctx->buf;
 239                 UCI_THROW(ctx, UCI_ERR_PARSE);
 240         }
 241 }
 242
 243 /*
 244  * parse the 'config' uci command (open a section)
 245  */
 246 static void uci_parse_config(struct uci_context *ctx, char **str)
 247 {
 248         char *type, *name;
 249
 250         /* command string null-terminated by strtok */
 251         *str += strlen(*str) + 1;
 252
 253         type = next_arg(ctx, str, true);
 254         name = next_arg(ctx, str, false);
 255         assert_eol(ctx, str);
 256 }
 257
 258 /*
 259  * parse the 'option' uci command (open a value)
 260  */
 261 static void uci_parse_option(struct uci_context *ctx, char **str)
 262 {
 263         char *name, *value;
 264
 265         /* command string null-terminated by strtok */
 266         *str += strlen(*str) + 1;
 267
 268         name = next_arg(ctx, str, true);
 269         value = next_arg(ctx, str, true);
 270         assert_eol(ctx, str);
 271 }
 272
 273 /*
 274  * parse a complete input line, split up combined commands by ';'
 275  */
 276 static void uci_parse_line(struct uci_context *ctx)
 277 {
 278         struct uci_parse_context *pctx = ctx->pctx;
 279         char *word, *brk;
 280
 281         for (word = strtok_r(pctx->buf, ";", &brk);
 282                  word;
 283                  word = strtok_r(NULL, ";", &brk)) {
 284
 285                 char *pbrk;
 286                 word = strtok_r(word, " \t", &pbrk);
 287
 288                 switch(word[0]) {
 289                         case 'c':
 290                                 if ((word[1] == 0) || !strcmp(word + 1, "onfig"))
 291                                         uci_parse_config(ctx, &word);
 292                                 break;
 293                         case 'o':
 294                                 if ((word[1] == 0) || !strcmp(word + 1, "ption"))
 295                                         uci_parse_option(ctx, &word);
 296                                 break;
 297                         default:
 298                                 pctx->reason = "unterminated command";
 299                                 pctx->byte = word - pctx->buf;
 300                                 UCI_THROW(ctx, UCI_ERR_PARSE);
 301                                 break;
 302                 }
 303         }
 304 }
 305
 306 int uci_load(struct uci_context *ctx, const char *name)
 307 {
 308         struct uci_parse_context *pctx;
 309         struct stat statbuf;
 310         char *filename;
 311         bool confpath;
 312
 313         UCI_HANDLE_ERR(ctx);
 314         UCI_ASSERT(ctx, name != NULL);
 315
 316         /* make sure no memory from previous parse attempts is leaked */
 317         uci_parse_cleanup(ctx);
 318
 319         pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
 320         ctx->pctx = pctx;
 321
 322         switch (name[0]) {
 323         case '.':
 324         case '/':
 325                 /* absolute/relative path outside of /etc/config */
 326                 filename = (char *) name;
 327                 confpath = false;
 328                 break;
 329         default:
 330                 filename = uci_malloc(ctx, strlen(name) + sizeof(UCI_CONFDIR) + 2);
 331                 sprintf(filename, UCI_CONFDIR "/%s", name);
 332                 confpath = true;
 333                 break;
 334         }
 335
 336         if ((stat(filename, &statbuf) < 0) ||
 337                 ((statbuf.st_mode &  S_IFMT) != S_IFREG))
 338                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 339
 340         pctx->file = fopen(filename, "r");
 341         if (filename != name)
 342                 free(filename);
 343
 344         if (!pctx->file)
 345                 UCI_THROW(ctx, UCI_ERR_IO);
 346
 347         pctx->cfg = uci_alloc_file(ctx, name);
 348
 349         while (!feof(pctx->file)) {
 350                 uci_getln(ctx);
 351                 if (pctx->buf[0])
 352                         uci_parse_line(ctx);
 353         }
 354
 355         /* add to main config file list */
 356         uci_list_add(&ctx->root, &pctx->cfg->list);
 357         pctx->cfg = NULL;
 358
 359         /* no error happened, we can get rid of the parser context now */
 360         uci_parse_cleanup(ctx);
 361
 362         return 0;
 363 }
 364