util.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 misc utility functions and wrappers to standard
  17  * functions, which throw exceptions upon failure.
  18  */
  19 #include <sys/types.h>
  20 #include <sys/stat.h>
  21 #include <sys/file.h>
  22 #include <stdbool.h>
  23 #include <unistd.h>
  24 #include <ctype.h>
  25 #include <fcntl.h>
  26 #include <errno.h>
  27
  28 #define LINEBUF 32
  29 #define LINEBUF_MAX     4096
  30
  31 __plugin void *uci_malloc(struct uci_context *ctx, size_t size)
  32 {
  33         void *ptr;
  34
  35         ptr = malloc(size);
  36         if (!ptr)
  37                 UCI_THROW(ctx, UCI_ERR_MEM);
  38         memset(ptr, 0, size);
  39
  40         return ptr;
  41 }
  42
  43 __plugin void *uci_realloc(struct uci_context *ctx, void *ptr, size_t size)
  44 {
  45         ptr = realloc(ptr, size);
  46         if (!ptr)
  47                 UCI_THROW(ctx, UCI_ERR_MEM);
  48
  49         return ptr;
  50 }
  51
  52 __plugin char *uci_strdup(struct uci_context *ctx, const char *str)
  53 {
  54         char *ptr;
  55
  56         ptr = strdup(str);
  57         if (!ptr)
  58                 UCI_THROW(ctx, UCI_ERR_MEM);
  59
  60         return ptr;
  61 }
  62
  63 /* Based on an efficient hash function published by D. J. Bernstein */
  64 static unsigned int djbhash(unsigned int hash, char *str)
  65 {
  66         int len = strlen(str);
  67         int i;
  68
  69         /* initial value */
  70         if (hash == ~0)
  71                 hash = 5381;
  72
  73         for(i = 0; i < len; i++) {
  74                 hash = ((hash << 5) + hash) + str[i];
  75         }
  76         return (hash & 0x7FFFFFFF);
  77 }
  78
  79 /*
  80  * validate strings for names and types, reject special characters
  81  * for names, only alphanum and _ is allowed (shell compatibility)
  82  * for types, we allow more characters
  83  */
  84 __plugin bool uci_validate_str(const char *str, bool name)
  85 {
  86         if (!*str)
  87                 return false;
  88
  89         while (*str) {
  90                 unsigned char c = *str;
  91                 if (!isalnum(c) && c != '_') {
  92                         if (name || (c < 33) || (c > 126))
  93                                 return false;
  94                 }
  95                 str++;
  96         }
  97         return true;
  98 }
  99
 100 static inline bool uci_validate_package(const char *str)
 101 {
 102         return uci_validate_str(str, false);
 103 }
 104
 105 static inline bool uci_validate_type(const char *str)
 106 {
 107         return uci_validate_str(str, false);
 108 }
 109
 110 static inline bool uci_validate_name(const char *str)
 111 {
 112         return uci_validate_str(str, true);
 113 }
 114
 115 bool uci_validate_text(const char *str)
 116 {
 117         while (*str) {
 118                 unsigned char c = *str;
 119                 if ((c == '\r') || (c == '\n') ||
 120                         ((c < 32) && (c != '\t')))
 121                         return false;
 122                 str++;
 123         }
 124         return true;
 125 }
 126
 127 static void uci_alloc_parse_context(struct uci_context *ctx)
 128 {
 129         ctx->pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
 130 }
 131
 132 int uci_parse_ptr(struct uci_context *ctx, struct uci_ptr *ptr, char *str)
 133 {
 134         char *last = NULL;
 135         char *tmp;
 136
 137         UCI_HANDLE_ERR(ctx);
 138         UCI_ASSERT(ctx, str);
 139         UCI_ASSERT(ctx, ptr);
 140
 141         memset(ptr, 0, sizeof(struct uci_ptr));
 142
 143         /* value */
 144         last = strchr(str, '=');
 145         if (last) {
 146                 *last = 0;
 147                 last++;
 148                 ptr->value = last;
 149         }
 150
 151         ptr->package = strsep(&str, ".");
 152         if (!ptr->package)
 153                 goto error;
 154
 155         ptr->section = strsep(&str, ".");
 156         if (!ptr->section) {
 157                 ptr->target = UCI_TYPE_PACKAGE;
 158                 goto lastval;
 159         }
 160
 161         ptr->option = strsep(&str, ".");
 162         if (!ptr->option) {
 163                 ptr->target = UCI_TYPE_SECTION;
 164                 goto lastval;
 165         } else {
 166                 ptr->target = UCI_TYPE_OPTION;
 167         }
 168
 169         tmp = strsep(&str, ".");
 170         if (tmp)
 171                 goto error;
 172
 173 lastval:
 174         if (ptr->package && !uci_validate_package(ptr->package))
 175                 goto error;
 176         if (ptr->section && !uci_validate_name(ptr->section))
 177                 ptr->flags |= UCI_LOOKUP_EXTENDED;
 178         if (ptr->option && !uci_validate_name(ptr->option))
 179                 goto error;
 180         if (ptr->value && !uci_validate_text(ptr->value))
 181                 goto error;
 182
 183         return 0;
 184
 185 error:
 186         memset(ptr, 0, sizeof(struct uci_ptr));
 187         UCI_THROW(ctx, UCI_ERR_PARSE);
 188 }
 189
 190
 191 static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
 192 {
 193         struct uci_parse_context *pctx = ctx->pctx;
 194
 195         pctx->reason = reason;
 196         pctx->byte = pos - pctx->buf;
 197         UCI_THROW(ctx, UCI_ERR_PARSE);
 198 }
 199
 200
 201 /*
 202  * Fetch a new line from the input stream and resize buffer if necessary
 203  */
 204 static void uci_getln(struct uci_context *ctx, int offset)
 205 {
 206         struct uci_parse_context *pctx = ctx->pctx;
 207         char *p;
 208         int ofs;
 209
 210         if (pctx->buf == NULL) {
 211                 pctx->buf = uci_malloc(ctx, LINEBUF);
 212                 pctx->bufsz = LINEBUF;
 213         }
 214
 215         ofs = offset;
 216         do {
 217                 p = &pctx->buf[ofs];
 218                 p[ofs] = 0;
 219
 220                 p = fgets(p, pctx->bufsz - ofs, pctx->file);
 221                 if (!p || !*p)
 222                         return;
 223
 224                 ofs += strlen(p);
 225                 if (pctx->buf[ofs - 1] == '\n') {
 226                         pctx->line++;
 227                         pctx->buf[ofs - 1] = 0;
 228                         return;
 229                 }
 230
 231                 if (pctx->bufsz > LINEBUF_MAX/2)
 232                         uci_parse_error(ctx, p, "line too long");
 233
 234                 pctx->bufsz *= 2;
 235                 pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
 236         } while (1);
 237 }
 238
 239 /*
 240  * parse a character escaped by '\'
 241  * returns true if the escaped character is to be parsed
 242  * returns false if the escaped character is to be ignored
 243  */
 244 static inline bool parse_backslash(struct uci_context *ctx, char **str)
 245 {
 246         /* skip backslash */
 247         *str += 1;
 248
 249         /* undecoded backslash at the end of line, fetch the next line */
 250         if (!**str) {
 251                 *str += 1;
 252                 uci_getln(ctx, *str - ctx->pctx->buf);
 253                 return false;
 254         }
 255
 256         /* FIXME: decode escaped char, necessary? */
 257         return true;
 258 }
 259
 260 /*
 261  * move the string pointer forward until a non-whitespace character or
 262  * EOL is reached
 263  */
 264 static void skip_whitespace(struct uci_context *ctx, char **str)
 265 {
 266 restart:
 267         while (**str && isspace(**str))
 268                 *str += 1;
 269
 270         if (**str == '\\') {
 271                 if (!parse_backslash(ctx, str))
 272                         goto restart;
 273         }
 274 }
 275
 276 static inline void addc(char **dest, char **src)
 277 {
 278         **dest = **src;
 279         *dest += 1;
 280         *src += 1;
 281 }
 282
 283 /*
 284  * parse a double quoted string argument from the command line
 285  */
 286 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 287 {
 288         char c;
 289
 290         /* skip quote character */
 291         *str += 1;
 292
 293         while ((c = **str)) {
 294                 switch(c) {
 295                 case '"':
 296                         **target = 0;
 297                         *str += 1;
 298                         return;
 299                 case '\\':
 300                         if (!parse_backslash(ctx, str))
 301                                 continue;
 302                         /* fall through */
 303                 default:
 304                         addc(target, str);
 305                         break;
 306                 }
 307         }
 308         uci_parse_error(ctx, *str, "unterminated \"");
 309 }
 310
 311 /*
 312  * parse a single quoted string argument from the command line
 313  */
 314 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 315 {
 316         char c;
 317         /* skip quote character */
 318         *str += 1;
 319
 320         while ((c = **str)) {
 321                 switch(c) {
 322                 case '\'':
 323                         **target = 0;
 324                         *str += 1;
 325                         return;
 326                 default:
 327                         addc(target, str);
 328                 }
 329         }
 330         uci_parse_error(ctx, *str, "unterminated '");
 331 }
 332
 333 /*
 334  * parse a string from the command line and detect the quoting style
 335  */
 336 static void parse_str(struct uci_context *ctx, char **str, char **target)
 337 {
 338         bool next = true;
 339         do {
 340                 switch(**str) {
 341                 case '\'':
 342                         parse_single_quote(ctx, str, target);
 343                         break;
 344                 case '"':
 345                         parse_double_quote(ctx, str, target);
 346                         break;
 347                 case '#':
 348                         **str = 0;
 349                         /* fall through */
 350                 case 0:
 351                         goto done;
 352                 case ';':
 353                         next = false;
 354                         goto done;
 355                 case '\\':
 356                         if (!parse_backslash(ctx, str))
 357                                 continue;
 358                         /* fall through */
 359                 default:
 360                         addc(target, str);
 361                         break;
 362                 }
 363         } while (**str && !isspace(**str));
 364 done:
 365
 366         /*
 367          * if the string was unquoted and we've stopped at a whitespace
 368          * character, skip to the next one, because the whitespace will
 369          * be overwritten by a null byte here
 370          */
 371         if (**str && next)
 372                 *str += 1;
 373
 374         /* terminate the parsed string */
 375         **target = 0;
 376 }
 377
 378 /*
 379  * extract the next argument from the command line
 380  */
 381 static char *next_arg(struct uci_context *ctx, char **str, bool required, bool name)
 382 {
 383         char *val;
 384         char *ptr;
 385
 386         val = ptr = *str;
 387         skip_whitespace(ctx, str);
 388         if(*str[0] == ';') {
 389                 *str[0] = 0;
 390                 *str += 1;
 391         } else {
 392                 parse_str(ctx, str, &ptr);
 393         }
 394         if (!*val) {
 395                 if (required)
 396                         uci_parse_error(ctx, *str, "insufficient arguments");
 397                 goto done;
 398         }
 399
 400         if (name && !uci_validate_name(val))
 401                 uci_parse_error(ctx, val, "invalid character in field");
 402
 403 done:
 404         return val;
 405 }
 406
 407 int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result)
 408 {
 409         UCI_HANDLE_ERR(ctx);
 410         UCI_ASSERT(ctx, str != NULL);
 411         UCI_ASSERT(ctx, result != NULL);
 412
 413         if (ctx->pctx && (ctx->pctx->file != stream))
 414                 uci_cleanup(ctx);
 415
 416         if (!ctx->pctx)
 417                 uci_alloc_parse_context(ctx);
 418
 419         ctx->pctx->file = stream;
 420
 421         if (!*str) {
 422                 uci_getln(ctx, 0);
 423                 *str = ctx->pctx->buf;
 424         }
 425
 426         *result = next_arg(ctx, str, false, false);
 427
 428         return 0;
 429 }
 430
 431
 432 /*
 433  * open a stream and go to the right position
 434  *
 435  * note: when opening for write and seeking to the beginning of
 436  * the stream, truncate the file
 437  */
 438 static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
 439 {
 440         struct stat statbuf;
 441         FILE *file = NULL;
 442         int fd, ret;
 443         int mode = (write ? O_RDWR : O_RDONLY);
 444
 445         if (create)
 446                 mode |= O_CREAT;
 447
 448         if (!write && ((stat(filename, &statbuf) < 0) ||
 449                 ((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
 450                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 451         }
 452
 453         fd = open(filename, mode, UCI_FILEMODE);
 454         if (fd < 0)
 455                 goto error;
 456
 457         ret = flock(fd, (write ? LOCK_EX : LOCK_SH));
 458         if ((ret < 0) && (errno != ENOSYS))
 459                 goto error;
 460
 461         ret = lseek(fd, 0, pos);
 462
 463         if (ret < 0)
 464                 goto error;
 465
 466         file = fdopen(fd, (write ? "w+" : "r"));
 467         if (file)
 468                 goto done;
 469
 470 error:
 471         UCI_THROW(ctx, UCI_ERR_IO);
 472 done:
 473         return file;
 474 }
 475
 476 static void uci_close_stream(FILE *stream)
 477 {
 478         int fd;
 479
 480         if (!stream)
 481                 return;
 482
 483         fflush(stream);
 484         fd = fileno(stream);
 485         flock(fd, LOCK_UN);
 486         fclose(stream);
 487 }
 488
 489