lib/parser.c

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