release/src/router/nfs-utils/utils/mount/parse_opt.c

   1 /*
   2  * parse_opt.c -- mount option string parsing helpers
   3  *
   4  * Copyright (C) 2007 Oracle.  All rights reserved.
   5  * Copyright (C) 2007 Chuck Lever <chuck.lever@oracle.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public
  18  * License along with this program; if not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 021110-1307, USA.
  21  *
  22  */
  23
  24 /*
  25  * Converting a C string containing mount options to a data object
  26  * and manipulating that object is cleaner in C than manipulating
  27  * the C string itself.  This is similar to the way Python handles
  28  * string manipulation.
  29  *
  30  * The current implementation uses a linked list as the data object
  31  * since lists are simple, and we don't need to worry about more
  32  * than ten or twenty options at a time.
  33  *
  34  * Hopefully the interface is abstract enough that the underlying
  35  * data structure can be replaced if needed without changing the API.
  36  */
  37
  38
  39 #ifdef HAVE_CONFIG_H
  40 #include <config.h>
  41 #endif
  42
  43 #include <ctype.h>
  44 #include <unistd.h>
  45 #include <stdio.h>
  46 #include <string.h>
  47 #include <stdlib.h>
  48 #include <errno.h>
  49
  50 #include "parse_opt.h"
  51 #include "token.h"
  52
  53
  54 struct mount_option {
  55         struct mount_option *next, *prev;
  56         char *keyword;
  57         char *value;
  58 };
  59
  60 struct mount_options {
  61         struct mount_option *head, *tail;
  62         unsigned int count;
  63 };
  64
  65 static struct mount_option *option_create(char *str)
  66 {
  67         struct mount_option *option;
  68         char *opteq;
  69
  70         if (!str)
  71                 return NULL;
  72
  73         option = malloc(sizeof(*option));
  74         if (!option)
  75                 return NULL;
  76
  77         option->next = NULL;
  78         option->prev = NULL;
  79
  80         opteq = strchr(str, '=');
  81         if (opteq) {
  82                 option->keyword = strndup(str, opteq - str);
  83                 if (!option->keyword)
  84                         goto fail;
  85                 option->value = strdup(opteq + 1);
  86                 if (!option->value) {
  87                         free(option->keyword);
  88                         goto fail;
  89                 }
  90         } else {
  91                 option->keyword = strdup(str);
  92                 if (!option->keyword)
  93                         goto fail;
  94                 option->value = NULL;
  95         }
  96
  97         return option;
  98
  99 fail:
 100         free(option);
 101         return NULL;
 102 }
 103
 104 static void option_destroy(struct mount_option *option)
 105 {
 106         free(option->keyword);
 107         free(option->value);
 108         free(option);
 109 }
 110
 111 static void options_init(struct mount_options *options)
 112 {
 113         options->head = options->tail = NULL;
 114         options->count = 0;
 115 }
 116
 117 static struct mount_options *options_create(void)
 118 {
 119         struct mount_options *options;
 120
 121         options = malloc(sizeof(*options));
 122         if (options)
 123                 options_init(options);
 124
 125         return options;
 126 }
 127
 128 static int options_empty(struct mount_options *options)
 129 {
 130         return options->count == 0;
 131 }
 132
 133 static void options_tail_insert(struct mount_options *options,
 134                                 struct mount_option *option)
 135 {
 136         struct mount_option *prev = options->tail;
 137
 138         option->next = NULL;
 139         option->prev = prev;
 140
 141         if (prev)
 142                 prev->next = option;
 143         else
 144                 options->head = option;
 145         options->tail = option;
 146
 147         options->count++;
 148 }
 149
 150 static void options_delete(struct mount_options *options,
 151                            struct mount_option *option)
 152 {
 153         struct mount_option *prev = option->prev;
 154         struct mount_option *next = option->next;
 155
 156         if (!options_empty(options)) {
 157                 if (prev)
 158                         prev->next = option->next;
 159                 if (next)
 160                         next->prev = option->prev;
 161
 162                 if (options->head == option)
 163                         options->head = option->next;
 164                 if (options->tail == option)
 165                         options->tail = prev;
 166
 167                 options->count--;
 168
 169                 option_destroy(option);
 170         }
 171 }
 172
 173
 174 /**
 175  * po_destroy - deallocate a group of mount options
 176  * @options: pointer to mount options to free
 177  *
 178  */
 179 void po_destroy(struct mount_options *options)
 180 {
 181         if (options) {
 182                 while (!options_empty(options))
 183                         options_delete(options, options->head);
 184                 free(options);
 185         }
 186 }
 187
 188 /**
 189  * po_split - split options string into group of options
 190  * @options: pointer to C string containing zero or more comma-delimited options
 191  *
 192  * Convert our mount options string to a list to make it easier
 193  * to adjust the options as we go.  This is just an exercise in
 194  * lexical parsing -- this function doesn't pay attention to the
 195  * meaning of the options themselves.
 196  *
 197  * Returns a new group of mount options if successful; otherwise NULL
 198  * is returned if some failure occurred.
 199  */
 200 struct mount_options *po_split(char *str)
 201 {
 202         struct mount_options *options;
 203         struct tokenizer_state *tstate;
 204         char *opt;
 205
 206         if (!str)
 207                 return options_create();
 208
 209         options = options_create();
 210         if (options) {
 211                 tstate = init_tokenizer(str, ',');
 212                 for (opt = next_token(tstate); opt; opt = next_token(tstate)) {
 213                         struct mount_option *option = option_create(opt);
 214                         free(opt);
 215                         if (!option)
 216                                 goto fail;
 217                         options_tail_insert(options, option);
 218                 }
 219                 if (tokenizer_error(tstate))
 220                         goto fail;
 221                 end_tokenizer(tstate);
 222         }
 223         return options;
 224
 225 fail:
 226         end_tokenizer(tstate);
 227         po_destroy(options);
 228         return NULL;
 229 }
 230
 231 /**
 232  * po_replace - replace mount options in one mount_options object with another
 233  * @target: pointer to previously instantiated object to replace
 234  * @source: pointer to object containing source mount options
 235  *
 236  * Side effect: the object referred to by source is emptied.
 237  */
 238 void po_replace(struct mount_options *target, struct mount_options *source)
 239 {
 240         if (target) {
 241                 while (!options_empty(target))
 242                         options_delete(target, target->head);
 243
 244                 if (source) {
 245                         target->head = source->head;
 246                         target->tail = source->tail;
 247                         target->count = source->count;
 248
 249                         options_init(source);
 250                 }
 251         }
 252 }
 253
 254 /**
 255  * po_join - recombine group of mount options into a C string
 256  * @options: pointer to mount options to recombine
 257  * @str: handle on string to replace (input and output)
 258  *
 259  * Convert our mount options object back into a string that the
 260  * rest of the world can use.
 261  *
 262  * Upon return, @string contains the address of a replacement
 263  * C string containing a comma-delimited list of mount options
 264  * and values; or the passed-in string is freed and NULL is
 265  * returned if some failure occurred.
 266  */
 267 po_return_t po_join(struct mount_options *options, char **str)
 268 {
 269         size_t len = 0;
 270         struct mount_option *option;
 271
 272         if (!str || !options)
 273                 return PO_FAILED;
 274
 275         free(*str);
 276         *str = NULL;
 277
 278         if (options_empty(options)) {
 279                 *str = strdup("");
 280                 return *str ? PO_SUCCEEDED : PO_FAILED;
 281         }
 282
 283         for (option = options->head; option; option = option->next) {
 284                 len += strlen(option->keyword);
 285                 if (option->value)
 286                         len +=strlen(option->value) + 1;  /* equals sign */
 287                 if (option->next)
 288                         len++;  /* comma */
 289         }
 290
 291         len++;  /* NULL on the end */
 292
 293         *str = malloc(len);
 294         if (!*str)
 295                 return PO_FAILED;
 296         *str[0] = '\0';
 297
 298         for (option = options->head; option; option = option->next) {
 299                 strcat(*str, option->keyword);
 300                 if (option->value) {
 301                         strcat(*str, "=");
 302                         strcat(*str, option->value);
 303                 }
 304                 if (option->next)
 305                         strcat(*str, ",");
 306         }
 307
 308         return PO_SUCCEEDED;
 309 }
 310
 311 /**
 312  * po_append - concatenate an option onto a group of options
 313  * @options: pointer to mount options
 314  * @option: pointer to a C string containing the option to add
 315  *
 316  */
 317 po_return_t po_append(struct mount_options *options, char *str)
 318 {
 319         struct mount_option *option = option_create(str);
 320
 321         if (option) {
 322                 options_tail_insert(options, option);
 323                 return PO_SUCCEEDED;
 324         }
 325         return PO_FAILED;
 326 }
 327
 328 /**
 329  * po_contains - check for presense of an option in a group
 330  * @options: pointer to mount options
 331  * @keyword: pointer to a C string containing option keyword for which to search
 332  *
 333  */
 334 po_found_t po_contains(struct mount_options *options, char *keyword)
 335 {
 336         struct mount_option *option;
 337
 338         if (options && keyword) {
 339                 for (option = options->head; option; option = option->next)
 340                         if (strcmp(option->keyword, keyword) == 0)
 341                                 return PO_FOUND;
 342         }
 343
 344         return PO_NOT_FOUND;
 345 }
 346
 347 /**
 348  * po_get - return the value of the rightmost instance of an option
 349  * @options: pointer to mount options
 350  * @keyword: pointer to a C string containing option keyword for which to search
 351  *
 352  * If multiple instances of the same option are present in a mount option
 353  * list, the rightmost instance is always the effective one.
 354  *
 355  * Returns pointer to C string containing the value of the option.
 356  * Returns NULL if the option isn't found, or if the option doesn't
 357  * have a value.
 358  */
 359 char *po_get(struct mount_options *options, char *keyword)
 360 {
 361         struct mount_option *option;
 362
 363         if (options && keyword) {
 364                 for (option = options->tail; option; option = option->prev)
 365                         if (strcmp(option->keyword, keyword) == 0)
 366                                 return option->value;
 367         }
 368
 369         return NULL;
 370 }
 371
 372 /**
 373  * po_get_numeric - return numeric value of rightmost instance of keyword option
 374  * @options: pointer to mount options
 375  * @keyword: pointer to a C string containing option keyword for which to search
 376  * @value: OUT: set to the value of the keyword
 377  *
 378  * This is specifically for parsing keyword options that take only a numeric
 379  * value.  If multiple instances of the same option are present in a mount
 380  * option list, the rightmost instance is always the effective one.
 381  *
 382  * Returns:
 383  *      * PO_FOUND if the keyword was found and the value is numeric; @value is
 384  *        set to the keyword's value
 385  *      * PO_NOT_FOUND if the keyword was not found
 386  *      * PO_BAD_VALUE if the keyword was found, but the value is not numeric
 387  *
 388  * These last two are separate in case the caller wants to warn about bad mount
 389  * options instead of silently using a default.
 390  */
 391 #ifdef HAVE_STRTOL
 392 po_found_t po_get_numeric(struct mount_options *options, char *keyword, long *value)
 393 {
 394         char *option, *endptr;
 395         long tmp;
 396
 397         option = po_get(options, keyword);
 398         if (option == NULL)
 399                 return PO_NOT_FOUND;
 400
 401         errno = 0;
 402         tmp = strtol(option, &endptr, 10);
 403         if (errno == 0 && endptr != option) {
 404                 *value = tmp;
 405                 return PO_FOUND;
 406         }
 407         return PO_BAD_VALUE;
 408 }
 409 #else   /* HAVE_STRTOL */
 410 po_found_t po_get_numeric(struct mount_options *options, char *keyword, long *value)
 411 {
 412         char *option;
 413
 414         option = po_get(options, keyword);
 415         if (option == NULL)
 416                 return PO_NOT_FOUND;
 417
 418         *value = atoi(option);
 419         return PO_FOUND;
 420 }
 421 #endif  /* HAVE_STRTOL */
 422
 423 /**
 424  * po_rightmost - determine the relative position of several options
 425  * @options: pointer to mount options
 426  * @keys: pointer to an array of C strings containing option keywords
 427  *
 428  * This function can be used to determine which of several similar
 429  * options will be the one to take effect.
 430  *
 431  * The kernel parses the mount option string from left to right.
 432  * If an option is specified more than once (for example, "intr"
 433  * and "nointr", the rightmost option is the last to be parsed,
 434  * and it therefore takes precedence over previous similar options.
 435  *
 436  * This can also distinguish among multiple synonymous options, such
 437  * as "proto=," "udp" and "tcp."
 438  *
 439  * Returns the index into @keys of the option that is rightmost.
 440  * If none of the options listed in @keys is present in @options, or
 441  * if @options is NULL, returns -1.
 442  */
 443 int po_rightmost(struct mount_options *options, const char *keys[])
 444 {
 445         struct mount_option *option;
 446         unsigned int i;
 447
 448         if (options) {
 449                 for (option = options->tail; option; option = option->prev) {
 450                         for (i = 0; keys[i] != NULL; i++)
 451                                 if (strcmp(option->keyword, keys[i]) == 0)
 452                                         return i;
 453                 }
 454         }
 455
 456         return -1;
 457 }
 458
 459 /**
 460  * po_remove_all - remove instances of an option from a group
 461  * @options: pointer to mount options
 462  * @keyword: pointer to a C string containing an option keyword to remove
 463  *
 464  * Side-effect: the passed-in list is truncated on success.
 465  */
 466 po_found_t po_remove_all(struct mount_options *options, char *keyword)
 467 {
 468         struct mount_option *option, *next;
 469         int found = PO_NOT_FOUND;
 470
 471         if (options && keyword) {
 472                 for (option = options->head; option; option = next) {
 473                         next = option->next;
 474                         if (strcmp(option->keyword, keyword) == 0) {
 475                                 options_delete(options, option);
 476                                 found = PO_FOUND;
 477                         }
 478                 }
 479         }
 480
 481         return found;
 482 }