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 void uci_alloc_parse_context(struct uci_context *ctx)
 105 {
 106         ctx->pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
 107 }
 108
 109 int uci_parse_tuple(struct uci_context *ctx, char *str, char **package, char **section, char **option, char **value)
 110 {
 111         char *last = NULL;
 112
 113         UCI_HANDLE_ERR(ctx);
 114         UCI_ASSERT(ctx, str && package && section && option);
 115
 116         last = strchr(str, '=');
 117         if (last) {
 118                 *last = 0;
 119                 last++;
 120         }
 121
 122         *package = strsep(&str, ".");
 123         if (!*package || !uci_validate_name(*package))
 124                 goto error;
 125
 126         *section = strsep(&str, ".");
 127         if (!*section)
 128                 goto lastval;
 129
 130         *option = strsep(&str, ".");
 131         if (!*option)
 132                 goto lastval;
 133
 134 lastval:
 135         if (last) {
 136                 if (!value)
 137                         goto error;
 138
 139                 if (!*last)
 140                         goto error;
 141                 *value = last;
 142         }
 143
 144         if (*section && *section[0] && !uci_validate_name(*section))
 145                 goto error;
 146         if (*option && !uci_validate_name(*option))
 147                 goto error;
 148
 149         goto done;
 150
 151 error:
 152         UCI_THROW(ctx, UCI_ERR_PARSE);
 153
 154 done:
 155         return 0;
 156 }
 157
 158
 159 static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
 160 {
 161         struct uci_parse_context *pctx = ctx->pctx;
 162
 163         pctx->reason = reason;
 164         pctx->byte = pos - pctx->buf;
 165         UCI_THROW(ctx, UCI_ERR_PARSE);
 166 }
 167
 168
 169 /*
 170  * Fetch a new line from the input stream and resize buffer if necessary
 171  */
 172 static void uci_getln(struct uci_context *ctx, int offset)
 173 {
 174         struct uci_parse_context *pctx = ctx->pctx;
 175         char *p;
 176         int ofs;
 177
 178         if (pctx->buf == NULL) {
 179                 pctx->buf = uci_malloc(ctx, LINEBUF);
 180                 pctx->bufsz = LINEBUF;
 181         }
 182
 183         ofs = offset;
 184         do {
 185                 p = &pctx->buf[ofs];
 186                 p[ofs] = 0;
 187
 188                 p = fgets(p, pctx->bufsz - ofs, pctx->file);
 189                 if (!p || !*p)
 190                         return;
 191
 192                 ofs += strlen(p);
 193                 if (pctx->buf[ofs - 1] == '\n') {
 194                         pctx->line++;
 195                         pctx->buf[ofs - 1] = 0;
 196                         return;
 197                 }
 198
 199                 if (pctx->bufsz > LINEBUF_MAX/2)
 200                         uci_parse_error(ctx, p, "line too long");
 201
 202                 pctx->bufsz *= 2;
 203                 pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
 204         } while (1);
 205 }
 206
 207 /*
 208  * parse a character escaped by '\'
 209  * returns true if the escaped character is to be parsed
 210  * returns false if the escaped character is to be ignored
 211  */
 212 static inline bool parse_backslash(struct uci_context *ctx, char **str)
 213 {
 214         /* skip backslash */
 215         *str += 1;
 216
 217         /* undecoded backslash at the end of line, fetch the next line */
 218         if (!**str) {
 219                 *str += 1;
 220                 uci_getln(ctx, *str - ctx->pctx->buf);
 221                 return false;
 222         }
 223
 224         /* FIXME: decode escaped char, necessary? */
 225         return true;
 226 }
 227
 228 /*
 229  * move the string pointer forward until a non-whitespace character or
 230  * EOL is reached
 231  */
 232 static void skip_whitespace(struct uci_context *ctx, char **str)
 233 {
 234 restart:
 235         while (**str && isspace(**str))
 236                 *str += 1;
 237
 238         if (**str == '\\') {
 239                 if (!parse_backslash(ctx, str))
 240                         goto restart;
 241         }
 242 }
 243
 244 static inline void addc(char **dest, char **src)
 245 {
 246         **dest = **src;
 247         *dest += 1;
 248         *src += 1;
 249 }
 250
 251 /*
 252  * parse a double quoted string argument from the command line
 253  */
 254 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 255 {
 256         char c;
 257
 258         /* skip quote character */
 259         *str += 1;
 260
 261         while ((c = **str)) {
 262                 switch(c) {
 263                 case '"':
 264                         **target = 0;
 265                         *str += 1;
 266                         return;
 267                 case '\\':
 268                         if (!parse_backslash(ctx, str))
 269                                 continue;
 270                         /* fall through */
 271                 default:
 272                         addc(target, str);
 273                         break;
 274                 }
 275         }
 276         uci_parse_error(ctx, *str, "unterminated \"");
 277 }
 278
 279 /*
 280  * parse a single quoted string argument from the command line
 281  */
 282 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 283 {
 284         char c;
 285         /* skip quote character */
 286         *str += 1;
 287
 288         while ((c = **str)) {
 289                 switch(c) {
 290                 case '\'':
 291                         **target = 0;
 292                         *str += 1;
 293                         return;
 294                 default:
 295                         addc(target, str);
 296                 }
 297         }
 298         uci_parse_error(ctx, *str, "unterminated '");
 299 }
 300
 301 /*
 302  * parse a string from the command line and detect the quoting style
 303  */
 304 static void parse_str(struct uci_context *ctx, char **str, char **target)
 305 {
 306         do {
 307                 switch(**str) {
 308                 case '\'':
 309                         parse_single_quote(ctx, str, target);
 310                         break;
 311                 case '"':
 312                         parse_double_quote(ctx, str, target);
 313                         break;
 314                 case '#':
 315                         **str = 0;
 316                         /* fall through */
 317                 case 0:
 318                         goto done;
 319                 case '\\':
 320                         if (!parse_backslash(ctx, str))
 321                                 continue;
 322                         /* fall through */
 323                 default:
 324                         addc(target, str);
 325                         break;
 326                 }
 327         } while (**str && !isspace(**str));
 328 done:
 329
 330         /*
 331          * if the string was unquoted and we've stopped at a whitespace
 332          * character, skip to the next one, because the whitespace will
 333          * be overwritten by a null byte here
 334          */
 335         if (**str)
 336                 *str += 1;
 337
 338         /* terminate the parsed string */
 339         **target = 0;
 340 }
 341
 342 /*
 343  * extract the next argument from the command line
 344  */
 345 static char *next_arg(struct uci_context *ctx, char **str, bool required, bool name)
 346 {
 347         char *val;
 348         char *ptr;
 349
 350         val = ptr = *str;
 351         skip_whitespace(ctx, str);
 352         parse_str(ctx, str, &ptr);
 353         if (!*val) {
 354                 if (required)
 355                         uci_parse_error(ctx, *str, "insufficient arguments");
 356                 goto done;
 357         }
 358
 359         if (name && !uci_validate_name(val))
 360                 uci_parse_error(ctx, val, "invalid character in field");
 361
 362 done:
 363         return val;
 364 }
 365
 366 int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result)
 367 {
 368         UCI_HANDLE_ERR(ctx);
 369         UCI_ASSERT(ctx, str != NULL);
 370         UCI_ASSERT(ctx, result != NULL);
 371
 372         if (ctx->pctx) {
 373                 if (ctx->pctx->file != stream) {
 374                         uci_cleanup(ctx);
 375                 }
 376         } else {
 377                 uci_alloc_parse_context(ctx);
 378                 ctx->pctx->file = stream;
 379         }
 380         if (!*str) {
 381                 uci_getln(ctx, 0);
 382                 *str = ctx->pctx->buf;
 383         }
 384
 385         *result = next_arg(ctx, str, false, false);
 386
 387         return 0;
 388 }
 389
 390
 391 /*
 392  * open a stream and go to the right position
 393  *
 394  * note: when opening for write and seeking to the beginning of
 395  * the stream, truncate the file
 396  */
 397 static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
 398 {
 399         struct stat statbuf;
 400         FILE *file = NULL;
 401         int fd, ret;
 402         int mode = (write ? O_RDWR : O_RDONLY);
 403
 404         if (create)
 405                 mode |= O_CREAT;
 406
 407         if (!write && ((stat(filename, &statbuf) < 0) ||
 408                 ((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
 409                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 410         }
 411
 412         fd = open(filename, mode, UCI_FILEMODE);
 413         if (fd < 0)
 414                 goto error;
 415
 416         if (flock(fd, (write ? LOCK_EX : LOCK_SH)) < 0)
 417                 goto error;
 418
 419         ret = lseek(fd, 0, pos);
 420
 421         if (ret < 0)
 422                 goto error;
 423
 424         file = fdopen(fd, (write ? "w+" : "r"));
 425         if (file)
 426                 goto done;
 427
 428 error:
 429         UCI_THROW(ctx, UCI_ERR_IO);
 430 done:
 431         return file;
 432 }
 433
 434 static void uci_close_stream(FILE *stream)
 435 {
 436         int fd;
 437
 438         if (!stream)
 439                 return;
 440
 441         fd = fileno(stream);
 442         flock(fd, LOCK_UN);
 443         fclose(stream);
 444 }
 445
 446