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