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_ptr(struct uci_context *ctx, struct uci_ptr *ptr, char *str)
 121 {
 122         char *last = NULL;
 123
 124         UCI_HANDLE_ERR(ctx);
 125         UCI_ASSERT(ctx, str);
 126         UCI_ASSERT(ctx, ptr);
 127
 128         memset(ptr, 0, sizeof(struct uci_ptr));
 129
 130         /* value */
 131         last = strchr(str, '=');
 132         if (last) {
 133                 *last = 0;
 134                 last++;
 135                 ptr->value = last;
 136         }
 137
 138         ptr->package = strsep(&str, ".");
 139         if (!ptr->package)
 140                 goto error;
 141
 142         ptr->section = strsep(&str, ".");
 143         if (!ptr->section) {
 144                 ptr->target = UCI_TYPE_PACKAGE;
 145                 goto lastval;
 146         }
 147
 148         ptr->option = strsep(&str, ".");
 149         if (!ptr->option) {
 150                 ptr->target = UCI_TYPE_SECTION;
 151                 goto lastval;
 152         } else {
 153                 ptr->target = UCI_TYPE_OPTION;
 154         }
 155
 156 lastval:
 157         if (ptr->package && !uci_validate_str(ptr->package, false))
 158                 goto error;
 159         if (ptr->section && !uci_validate_name(ptr->section))
 160                 ptr->flags |= UCI_LOOKUP_EXTENDED;
 161         if (ptr->option && !uci_validate_name(ptr->option))
 162                 goto error;
 163         if (ptr->value && !uci_validate_text(ptr->value))
 164                 goto error;
 165
 166         return 0;
 167
 168 error:
 169         memset(ptr, 0, sizeof(struct uci_ptr));
 170         UCI_THROW(ctx, UCI_ERR_PARSE);
 171 }
 172
 173
 174 static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
 175 {
 176         struct uci_parse_context *pctx = ctx->pctx;
 177
 178         pctx->reason = reason;
 179         pctx->byte = pos - pctx->buf;
 180         UCI_THROW(ctx, UCI_ERR_PARSE);
 181 }
 182
 183
 184 /*
 185  * Fetch a new line from the input stream and resize buffer if necessary
 186  */
 187 static void uci_getln(struct uci_context *ctx, int offset)
 188 {
 189         struct uci_parse_context *pctx = ctx->pctx;
 190         char *p;
 191         int ofs;
 192
 193         if (pctx->buf == NULL) {
 194                 pctx->buf = uci_malloc(ctx, LINEBUF);
 195                 pctx->bufsz = LINEBUF;
 196         }
 197
 198         ofs = offset;
 199         do {
 200                 p = &pctx->buf[ofs];
 201                 p[ofs] = 0;
 202
 203                 p = fgets(p, pctx->bufsz - ofs, pctx->file);
 204                 if (!p || !*p)
 205                         return;
 206
 207                 ofs += strlen(p);
 208                 if (pctx->buf[ofs - 1] == '\n') {
 209                         pctx->line++;
 210                         pctx->buf[ofs - 1] = 0;
 211                         return;
 212                 }
 213
 214                 if (pctx->bufsz > LINEBUF_MAX/2)
 215                         uci_parse_error(ctx, p, "line too long");
 216
 217                 pctx->bufsz *= 2;
 218                 pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
 219         } while (1);
 220 }
 221
 222 /*
 223  * parse a character escaped by '\'
 224  * returns true if the escaped character is to be parsed
 225  * returns false if the escaped character is to be ignored
 226  */
 227 static inline bool parse_backslash(struct uci_context *ctx, char **str)
 228 {
 229         /* skip backslash */
 230         *str += 1;
 231
 232         /* undecoded backslash at the end of line, fetch the next line */
 233         if (!**str) {
 234                 *str += 1;
 235                 uci_getln(ctx, *str - ctx->pctx->buf);
 236                 return false;
 237         }
 238
 239         /* FIXME: decode escaped char, necessary? */
 240         return true;
 241 }
 242
 243 /*
 244  * move the string pointer forward until a non-whitespace character or
 245  * EOL is reached
 246  */
 247 static void skip_whitespace(struct uci_context *ctx, char **str)
 248 {
 249 restart:
 250         while (**str && isspace(**str))
 251                 *str += 1;
 252
 253         if (**str == '\\') {
 254                 if (!parse_backslash(ctx, str))
 255                         goto restart;
 256         }
 257 }
 258
 259 static inline void addc(char **dest, char **src)
 260 {
 261         **dest = **src;
 262         *dest += 1;
 263         *src += 1;
 264 }
 265
 266 /*
 267  * parse a double quoted string argument from the command line
 268  */
 269 static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
 270 {
 271         char c;
 272
 273         /* skip quote character */
 274         *str += 1;
 275
 276         while ((c = **str)) {
 277                 switch(c) {
 278                 case '"':
 279                         **target = 0;
 280                         *str += 1;
 281                         return;
 282                 case '\\':
 283                         if (!parse_backslash(ctx, str))
 284                                 continue;
 285                         /* fall through */
 286                 default:
 287                         addc(target, str);
 288                         break;
 289                 }
 290         }
 291         uci_parse_error(ctx, *str, "unterminated \"");
 292 }
 293
 294 /*
 295  * parse a single quoted string argument from the command line
 296  */
 297 static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
 298 {
 299         char c;
 300         /* skip quote character */
 301         *str += 1;
 302
 303         while ((c = **str)) {
 304                 switch(c) {
 305                 case '\'':
 306                         **target = 0;
 307                         *str += 1;
 308                         return;
 309                 default:
 310                         addc(target, str);
 311                 }
 312         }
 313         uci_parse_error(ctx, *str, "unterminated '");
 314 }
 315
 316 /*
 317  * parse a string from the command line and detect the quoting style
 318  */
 319 static void parse_str(struct uci_context *ctx, char **str, char **target)
 320 {
 321         bool next = true;
 322         do {
 323                 switch(**str) {
 324                 case '\'':
 325                         parse_single_quote(ctx, str, target);
 326                         break;
 327                 case '"':
 328                         parse_double_quote(ctx, str, target);
 329                         break;
 330                 case '#':
 331                         **str = 0;
 332                         /* fall through */
 333                 case 0:
 334                         goto done;
 335                 case ';':
 336                         next = false;
 337                         goto done;
 338                 case '\\':
 339                         if (!parse_backslash(ctx, str))
 340                                 continue;
 341                         /* fall through */
 342                 default:
 343                         addc(target, str);
 344                         break;
 345                 }
 346         } while (**str && !isspace(**str));
 347 done:
 348
 349         /*
 350          * if the string was unquoted and we've stopped at a whitespace
 351          * character, skip to the next one, because the whitespace will
 352          * be overwritten by a null byte here
 353          */
 354         if (**str && next)
 355                 *str += 1;
 356
 357         /* terminate the parsed string */
 358         **target = 0;
 359 }
 360
 361 /*
 362  * extract the next argument from the command line
 363  */
 364 static char *next_arg(struct uci_context *ctx, char **str, bool required, bool name)
 365 {
 366         char *val;
 367         char *ptr;
 368
 369         val = ptr = *str;
 370         skip_whitespace(ctx, str);
 371         if(*str[0] == ';') {
 372                 *str[0] = 0;
 373                 *str += 1;
 374         } else {
 375                 parse_str(ctx, str, &ptr);
 376         }
 377         if (!*val) {
 378                 if (required)
 379                         uci_parse_error(ctx, *str, "insufficient arguments");
 380                 goto done;
 381         }
 382
 383         if (name && !uci_validate_name(val))
 384                 uci_parse_error(ctx, val, "invalid character in field");
 385
 386 done:
 387         return val;
 388 }
 389
 390 int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result)
 391 {
 392         UCI_HANDLE_ERR(ctx);
 393         UCI_ASSERT(ctx, str != NULL);
 394         UCI_ASSERT(ctx, result != NULL);
 395
 396         if (ctx->pctx) {
 397                 if (ctx->pctx->file != stream) {
 398                         uci_cleanup(ctx);
 399                 }
 400         } else {
 401                 uci_alloc_parse_context(ctx);
 402                 ctx->pctx->file = stream;
 403         }
 404         if (!*str) {
 405                 uci_getln(ctx, 0);
 406                 *str = ctx->pctx->buf;
 407         }
 408
 409         *result = next_arg(ctx, str, false, false);
 410
 411         return 0;
 412 }
 413
 414
 415 /*
 416  * open a stream and go to the right position
 417  *
 418  * note: when opening for write and seeking to the beginning of
 419  * the stream, truncate the file
 420  */
 421 static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
 422 {
 423         struct stat statbuf;
 424         FILE *file = NULL;
 425         int fd, ret;
 426         int mode = (write ? O_RDWR : O_RDONLY);
 427
 428         if (create)
 429                 mode |= O_CREAT;
 430
 431         if (!write && ((stat(filename, &statbuf) < 0) ||
 432                 ((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
 433                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 434         }
 435
 436         fd = open(filename, mode, UCI_FILEMODE);
 437         if (fd < 0)
 438                 goto error;
 439
 440         if (flock(fd, (write ? LOCK_EX : LOCK_SH)) < 0)
 441                 goto error;
 442
 443         ret = lseek(fd, 0, pos);
 444
 445         if (ret < 0)
 446                 goto error;
 447
 448         file = fdopen(fd, (write ? "w+" : "r"));
 449         if (file)
 450                 goto done;
 451
 452 error:
 453         UCI_THROW(ctx, UCI_ERR_IO);
 454 done:
 455         return file;
 456 }
 457
 458 static void uci_close_stream(FILE *stream)
 459 {
 460         int fd;
 461
 462         if (!stream)
 463                 return;
 464
 465         fd = fileno(stream);
 466         flock(fd, LOCK_UN);
 467         fclose(stream);
 468 }
 469
 470