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