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 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         bool internal = ctx->internal;
 124
 125         UCI_HANDLE_ERR(ctx);
 126         UCI_ASSERT(ctx, str && package && section && option);
 127
 128         last = strchr(str, '=');
 129         if (last) {
 130                 *last = 0;
 131                 last++;
 132         }
 133
 134         *package = strsep(&str, ".");
 135         if (!*package || !uci_validate_str(*package, false))
 136                 goto error;
 137
 138         *section = strsep(&str, ".");
 139         *option = NULL;
 140         if (value)
 141                 *value = NULL;
 142         if (!*section)
 143                 goto lastval;
 144
 145         *option = strsep(&str, ".");
 146         if (!*option)
 147                 goto lastval;
 148
 149 lastval:
 150         if (last) {
 151                 if (!value)
 152                         goto error;
 153
 154                 if (!*last)
 155                         goto error;
 156                 *value = last;
 157         }
 158
 159         if (*section && *section[0] && !internal && !uci_validate_name(*section))
 160                 goto error;
 161         if (*option && !uci_validate_name(*option))
 162                 goto error;
 163         if (value && *value && !uci_validate_text(*value))
 164                 goto error;
 165
 166         goto done;
 167
 168 error:
 169         UCI_THROW(ctx, UCI_ERR_PARSE);
 170
 171 done:
 172         return 0;
 173 }
 174
 175
 176 static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
 177 {
 178         struct uci_parse_context *pctx = ctx->pctx;
 179
 180         pctx->reason = reason;
 181         pctx->byte = pos - pctx->buf;
 182         UCI_THROW(ctx, UCI_ERR_PARSE);
 183 }
 184
 185
 186 /*
 187  * Fetch a new line from the input stream and resize buffer if necessary
 188  */
 189 static void uci_getln(struct uci_context *ctx, int offset)
 190 {
 191         struct uci_parse_context *pctx = ctx->pctx;
 192         char *p;
 193         int ofs;
 194
 195         if (pctx->buf == NULL) {
 196                 pctx->buf = uci_malloc(ctx, LINEBUF);
 197                 pctx->bufsz = LINEBUF;
 198         }
 199
 200         ofs = offset;
 201         do {
 202                 p = &pctx->buf[ofs];
 203                 p[ofs] = 0;
 204
 205                 p = fgets(p, pctx->bufsz - ofs, pctx->file);
 206                 if (!p || !*p)
 207                         return;
 208
 209                 ofs += strlen(p);
 210                 if (pctx->buf[ofs - 1] == '\n') {
 211                         pctx->line++;
 212                         pctx->buf[ofs - 1] = 0;
 213                         return;
 214                 }
 215
 216                 if (pctx->bufsz > LINEBUF_MAX/2)
 217                         uci_parse_error(ctx, p, "line too long");
 218
 219                 pctx->bufsz *= 2;
 220                 pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
 221         } while (1);
 222 }
 223
 224 /*
 225  * parse a character escaped by '\'
 226  * returns true if the escaped character is to be parsed
 227  * returns false if the escaped character is to be ignored
 228  */
 229 static inline bool parse_backslash(struct uci_context *ctx, char **str)
 230 {
 231         /* skip backslash */
 232         *str += 1;
 233
 234         /* undecoded backslash at the end of line, fetch the next line */
 235         if (!**str) {
 236                 *str += 1;
 237                 uci_getln(ctx, *str - ctx->pctx->buf);
 238                 return false;
 239         }
 240
 241         /* FIXME: decode escaped char, necessary? */
 242         return true;
 243 }
 244
 245 /*
 246  * move the string pointer forward until a non-whitespace character or
 247  * EOL is reached
 248  */
 249 static void skip_whitespace(struct uci_context *ctx, char **str)
 250 {
 251 restart:
 252         while (**str && isspace(**str))
 253                 *str += 1;
 254
 255         if (**str == '\\') {
 256                 if (!parse_backslash(ctx, str))
 257                         goto restart;
 258         }
 259 }
 260
 261 static inline void addc(char **dest, char **src)
 262 {
 263         **dest = **src;
 264         *dest += 1;
 265         *src += 1;
 266 }
 267
 268 /*
 269  * parse a double quoted string argument from the command line
 270  */
 271 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 272 {
 273         char c;
 274
 275         /* skip quote character */
 276         *str += 1;
 277
 278         while ((c = **str)) {
 279                 switch(c) {
 280                 case '"':
 281                         **target = 0;
 282                         *str += 1;
 283                         return;
 284                 case '\\':
 285                         if (!parse_backslash(ctx, str))
 286                                 continue;
 287                         /* fall through */
 288                 default:
 289                         addc(target, str);
 290                         break;
 291                 }
 292         }
 293         uci_parse_error(ctx, *str, "unterminated \"");
 294 }
 295
 296 /*
 297  * parse a single quoted string argument from the command line
 298  */
 299 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 300 {
 301         char c;
 302         /* skip quote character */
 303         *str += 1;
 304
 305         while ((c = **str)) {
 306                 switch(c) {
 307                 case '\'':
 308                         **target = 0;
 309                         *str += 1;
 310                         return;
 311                 default:
 312                         addc(target, str);
 313                 }
 314         }
 315         uci_parse_error(ctx, *str, "unterminated '");
 316 }
 317
 318 /*
 319  * parse a string from the command line and detect the quoting style
 320  */
 321 static void parse_str(struct uci_context *ctx, char **str, char **target)
 322 {
 323         bool next = true;
 324         do {
 325                 switch(**str) {
 326                 case '\'':
 327                         parse_single_quote(ctx, str, target);
 328                         break;
 329                 case '"':
 330                         parse_double_quote(ctx, str, target);
 331                         break;
 332                 case '#':
 333                         **str = 0;
 334                         /* fall through */
 335                 case 0:
 336                         goto done;
 337                 case ';':
 338                         next = false;
 339                         goto done;
 340                 case '\\':
 341                         if (!parse_backslash(ctx, str))
 342                                 continue;
 343                         /* fall through */
 344                 default:
 345                         addc(target, str);
 346                         break;
 347                 }
 348         } while (**str && !isspace(**str));
 349 done:
 350
 351         /*
 352          * if the string was unquoted and we've stopped at a whitespace
 353          * character, skip to the next one, because the whitespace will
 354          * be overwritten by a null byte here
 355          */
 356         if (**str && next)
 357                 *str += 1;
 358
 359         /* terminate the parsed string */
 360         **target = 0;
 361 }
 362
 363 /*
 364  * extract the next argument from the command line
 365  */
 366 static char *next_arg(struct uci_context *ctx, char **str, bool required, bool name)
 367 {
 368         char *val;
 369         char *ptr;
 370
 371         val = ptr = *str;
 372         skip_whitespace(ctx, str);
 373         if(*str[0] == ';') {
 374                 *str[0] = 0;
 375                 *str += 1;
 376         } else {
 377                 parse_str(ctx, str, &ptr);
 378         }
 379         if (!*val) {
 380                 if (required)
 381                         uci_parse_error(ctx, *str, "insufficient arguments");
 382                 goto done;
 383         }
 384
 385         if (name && !uci_validate_name(val))
 386                 uci_parse_error(ctx, val, "invalid character in field");
 387
 388 done:
 389         return val;
 390 }
 391
 392 int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result)
 393 {
 394         UCI_HANDLE_ERR(ctx);
 395         UCI_ASSERT(ctx, str != NULL);
 396         UCI_ASSERT(ctx, result != NULL);
 397
 398         if (ctx->pctx) {
 399                 if (ctx->pctx->file != stream) {
 400                         uci_cleanup(ctx);
 401                 }
 402         } else {
 403                 uci_alloc_parse_context(ctx);
 404                 ctx->pctx->file = stream;
 405         }
 406         if (!*str) {
 407                 uci_getln(ctx, 0);
 408                 *str = ctx->pctx->buf;
 409         }
 410
 411         *result = next_arg(ctx, str, false, false);
 412
 413         return 0;
 414 }
 415
 416
 417 /*
 418  * open a stream and go to the right position
 419  *
 420  * note: when opening for write and seeking to the beginning of
 421  * the stream, truncate the file
 422  */
 423 static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
 424 {
 425         struct stat statbuf;
 426         FILE *file = NULL;
 427         int fd, ret;
 428         int mode = (write ? O_RDWR : O_RDONLY);
 429
 430         if (create)
 431                 mode |= O_CREAT;
 432
 433         if (!write && ((stat(filename, &statbuf) < 0) ||
 434                 ((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
 435                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 436         }
 437
 438         fd = open(filename, mode, UCI_FILEMODE);
 439         if (fd < 0)
 440                 goto error;
 441
 442         if (flock(fd, (write ? LOCK_EX : LOCK_SH)) < 0)
 443                 goto error;
 444
 445         ret = lseek(fd, 0, pos);
 446
 447         if (ret < 0)
 448                 goto error;
 449
 450         file = fdopen(fd, (write ? "w+" : "r"));
 451         if (file)
 452                 goto done;
 453
 454 error:
 455         UCI_THROW(ctx, UCI_ERR_IO);
 456 done:
 457         return file;
 458 }
 459
 460 static void uci_close_stream(FILE *stream)
 461 {
 462         int fd;
 463
 464         if (!stream)
 465                 return;
 466
 467         fd = fileno(stream);
 468         flock(fd, LOCK_UN);
 469         fclose(stream);
 470 }
 471
 472