lib/parser.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * lib/parser.c - simple parser for mount, etc. options.
   4  */
   5
   6 #include <linux/ctype.h>
   7 #include <linux/types.h>
   8 #include <linux/export.h>
   9 #include <linux/kstrtox.h>
  10 #include <linux/parser.h>
  11 #include <linux/slab.h>
  12 #include <linux/string.h>
  13
  14 /*
  15  * max size needed by different bases to express U64
  16  * HEX: "0xFFFFFFFFFFFFFFFF" --> 18
  17  * DEC: "18446744073709551615" --> 20
  18  * OCT: "01777777777777777777777" --> 23
  19  * pick the max one to define NUMBER_BUF_LEN
  20  */
  21 #define NUMBER_BUF_LEN 24
  22
  23 /**
  24  * match_one - Determines if a string matches a simple pattern
  25  * @s: the string to examine for presence of the pattern
  26  * @p: the string containing the pattern
  27  * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
  28  * locations.
  29  *
  30  * Description: Determines if the pattern @p is present in string @s. Can only
  31  * match extremely simple token=arg style patterns. If the pattern is found,
  32  * the location(s) of the arguments will be returned in the @args array.
  33  */
  34 static int match_one(char *s, const char *p, substring_t args[])
  35 {
  36         char *meta;
  37         int argc = 0;
  38
  39         if (!p)
  40                 return 1;
  41
  42         while(1) {
  43                 int len = -1;
  44                 meta = strchr(p, '%');
  45                 if (!meta)
  46                         return strcmp(p, s) == 0;
  47
  48                 if (strncmp(p, s, meta-p))
  49                         return 0;
  50
  51                 s += meta - p;
  52                 p = meta + 1;
  53
  54                 if (isdigit(*p))
  55                         len = simple_strtoul(p, (char **) &p, 10);
  56                 else if (*p == '%') {
  57                         if (*s++ != '%')
  58                                 return 0;
  59                         p++;
  60                         continue;
  61                 }
  62
  63                 if (argc >= MAX_OPT_ARGS)
  64                         return 0;
  65
  66                 args[argc].from = s;
  67                 switch (*p++) {
  68                 case 's': {
  69                         size_t str_len = strlen(s);
  70
  71                         if (str_len == 0)
  72                                 return 0;
  73                         if (len == -1 || len > str_len)
  74                                 len = str_len;
  75                         args[argc].to = s + len;
  76                         break;
  77                 }
  78                 case 'd':
  79                         simple_strtol(s, &args[argc].to, 0);
  80                         goto num;
  81                 case 'u':
  82                         simple_strtoul(s, &args[argc].to, 0);
  83                         goto num;
  84                 case 'o':
  85                         simple_strtoul(s, &args[argc].to, 8);
  86                         goto num;
  87                 case 'x':
  88                         simple_strtoul(s, &args[argc].to, 16);
  89                 num:
  90                         if (args[argc].to == args[argc].from)
  91                                 return 0;
  92                         break;
  93                 default:
  94                         return 0;
  95                 }
  96                 s = args[argc].to;
  97                 argc++;
  98         }
  99 }
 100
 101 /**
 102  * match_token - Find a token (and optional args) in a string
 103  * @s: the string to examine for token/argument pairs
 104  * @table: match_table_t describing the set of allowed option tokens and the
 105  * arguments that may be associated with them. Must be terminated with a
 106  * &struct match_token whose pattern is set to the NULL pointer.
 107  * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
 108  * locations.
 109  *
 110  * Description: Detects which if any of a set of token strings has been passed
 111  * to it. Tokens can include up to %MAX_OPT_ARGS instances of basic c-style
 112  * format identifiers which will be taken into account when matching the
 113  * tokens, and whose locations will be returned in the @args array.
 114  */
 115 int match_token(char *s, const match_table_t table, substring_t args[])
 116 {
 117         const struct match_token *p;
 118
 119         for (p = table; !match_one(s, p->pattern, args) ; p++)
 120                 ;
 121
 122         return p->token;
 123 }
 124 EXPORT_SYMBOL(match_token);
 125
 126 /**
 127  * match_number - scan a number in the given base from a substring_t
 128  * @s: substring to be scanned
 129  * @result: resulting integer on success
 130  * @base: base to use when converting string
 131  *
 132  * Description: Given a &substring_t and a base, attempts to parse the substring
 133  * as a number in that base.
 134  *
 135  * Return: On success, sets @result to the integer represented by the
 136  * string and returns 0. Returns -EINVAL or -ERANGE on failure.
 137  */
 138 static int match_number(substring_t *s, int *result, int base)
 139 {
 140         char *endp;
 141         char buf[NUMBER_BUF_LEN];
 142         int ret;
 143         long val;
 144
 145         if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
 146                 return -ERANGE;
 147         ret = 0;
 148         val = simple_strtol(buf, &endp, base);
 149         if (endp == buf)
 150                 ret = -EINVAL;
 151         else if (val < (long)INT_MIN || val > (long)INT_MAX)
 152                 ret = -ERANGE;
 153         else
 154                 *result = (int) val;
 155         return ret;
 156 }
 157
 158 /**
 159  * match_u64int - scan a number in the given base from a substring_t
 160  * @s: substring to be scanned
 161  * @result: resulting u64 on success
 162  * @base: base to use when converting string
 163  *
 164  * Description: Given a &substring_t and a base, attempts to parse the substring
 165  * as a number in that base.
 166  *
 167  * Return: On success, sets @result to the integer represented by the
 168  * string and returns 0. Returns -EINVAL or -ERANGE on failure.
 169  */
 170 static int match_u64int(substring_t *s, u64 *result, int base)
 171 {
 172         char buf[NUMBER_BUF_LEN];
 173         int ret;
 174         u64 val;
 175
 176         if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
 177                 return -ERANGE;
 178         ret = kstrtoull(buf, base, &val);
 179         if (!ret)
 180                 *result = val;
 181         return ret;
 182 }
 183
 184 /**
 185  * match_int - scan a decimal representation of an integer from a substring_t
 186  * @s: substring_t to be scanned
 187  * @result: resulting integer on success
 188  *
 189  * Description: Attempts to parse the &substring_t @s as a decimal integer.
 190  *
 191  * Return: On success, sets @result to the integer represented by the string
 192  * and returns 0. Returns -EINVAL or -ERANGE on failure.
 193  */
 194 int match_int(substring_t *s, int *result)
 195 {
 196         return match_number(s, result, 0);
 197 }
 198 EXPORT_SYMBOL(match_int);
 199
 200 /**
 201  * match_uint - scan a decimal representation of an integer from a substring_t
 202  * @s: substring_t to be scanned
 203  * @result: resulting integer on success
 204  *
 205  * Description: Attempts to parse the &substring_t @s as a decimal integer.
 206  *
 207  * Return: On success, sets @result to the integer represented by the string
 208  * and returns 0. Returns -EINVAL or -ERANGE on failure.
 209  */
 210 int match_uint(substring_t *s, unsigned int *result)
 211 {
 212         char buf[NUMBER_BUF_LEN];
 213
 214         if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
 215                 return -ERANGE;
 216
 217         return kstrtouint(buf, 10, result);
 218 }
 219 EXPORT_SYMBOL(match_uint);
 220
 221 /**
 222  * match_u64 - scan a decimal representation of a u64 from
 223  *                  a substring_t
 224  * @s: substring_t to be scanned
 225  * @result: resulting unsigned long long on success
 226  *
 227  * Description: Attempts to parse the &substring_t @s as a long decimal
 228  * integer.
 229  *
 230  * Return: On success, sets @result to the integer represented by the string
 231  * and returns 0. Returns -EINVAL or -ERANGE on failure.
 232  */
 233 int match_u64(substring_t *s, u64 *result)
 234 {
 235         return match_u64int(s, result, 0);
 236 }
 237 EXPORT_SYMBOL(match_u64);
 238
 239 /**
 240  * match_octal - scan an octal representation of an integer from a substring_t
 241  * @s: substring_t to be scanned
 242  * @result: resulting integer on success
 243  *
 244  * Description: Attempts to parse the &substring_t @s as an octal integer.
 245  *
 246  * Return: On success, sets @result to the integer represented by the string
 247  * and returns 0. Returns -EINVAL or -ERANGE on failure.
 248  */
 249 int match_octal(substring_t *s, int *result)
 250 {
 251         return match_number(s, result, 8);
 252 }
 253 EXPORT_SYMBOL(match_octal);
 254
 255 /**
 256  * match_hex - scan a hex representation of an integer from a substring_t
 257  * @s: substring_t to be scanned
 258  * @result: resulting integer on success
 259  *
 260  * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
 261  *
 262  * Return: On success, sets @result to the integer represented by the string
 263  * and returns 0. Returns -EINVAL or -ERANGE on failure.
 264  */
 265 int match_hex(substring_t *s, int *result)
 266 {
 267         return match_number(s, result, 16);
 268 }
 269 EXPORT_SYMBOL(match_hex);
 270
 271 /**
 272  * match_wildcard - parse if a string matches given wildcard pattern
 273  * @pattern: wildcard pattern
 274  * @str: the string to be parsed
 275  *
 276  * Description: Parse the string @str to check if matches wildcard
 277  * pattern @pattern. The pattern may contain two types of wildcards:
 278  *   '*' - matches zero or more characters
 279  *   '?' - matches one character
 280  *
 281  * Return: If the @str matches the @pattern, return true, else return false.
 282  */
 283 bool match_wildcard(const char *pattern, const char *str)
 284 {
 285         const char *s = str;
 286         const char *p = pattern;
 287         bool star = false;
 288
 289         while (*s) {
 290                 switch (*p) {
 291                 case '?':
 292                         s++;
 293                         p++;
 294                         break;
 295                 case '*':
 296                         star = true;
 297                         str = s;
 298                         if (!*++p)
 299                                 return true;
 300                         pattern = p;
 301                         break;
 302                 default:
 303                         if (*s == *p) {
 304                                 s++;
 305                                 p++;
 306                         } else {
 307                                 if (!star)
 308                                         return false;
 309                                 str++;
 310                                 s = str;
 311                                 p = pattern;
 312                         }
 313                         break;
 314                 }
 315         }
 316
 317         if (*p == '*')
 318                 ++p;
 319         return !*p;
 320 }
 321 EXPORT_SYMBOL(match_wildcard);
 322
 323 /**
 324  * match_strlcpy - Copy the characters from a substring_t to a sized buffer
 325  * @dest: where to copy to
 326  * @src: &substring_t to copy
 327  * @size: size of destination buffer
 328  *
 329  * Description: Copy the characters in &substring_t @src to the
 330  * c-style string @dest.  Copy no more than @size - 1 characters, plus
 331  * the terminating NUL.
 332  *
 333  * Return: length of @src.
 334  */
 335 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
 336 {
 337         size_t ret = src->to - src->from;
 338
 339         if (size) {
 340                 size_t len = ret >= size ? size - 1 : ret;
 341                 memcpy(dest, src->from, len);
 342                 dest[len] = '\0';
 343         }
 344         return ret;
 345 }
 346 EXPORT_SYMBOL(match_strlcpy);
 347
 348 /**
 349  * match_strdup - allocate a new string with the contents of a substring_t
 350  * @s: &substring_t to copy
 351  *
 352  * Description: Allocates and returns a string filled with the contents of
 353  * the &substring_t @s. The caller is responsible for freeing the returned
 354  * string with kfree().
 355  *
 356  * Return: the address of the newly allocated NUL-terminated string or
 357  * %NULL on error.
 358  */
 359 char *match_strdup(const substring_t *s)
 360 {
 361         return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
 362 }
 363 EXPORT_SYMBOL(match_strdup);