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