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_u64: - scan a decimal representation of a u64 from
 193  *                  a substring_t
 194  * @s: substring_t to be scanned
 195  * @result: resulting unsigned long long on success
 196  *
 197  * Description: Attempts to parse the &substring_t @s as a long decimal
 198  * integer. On success, sets @result to the integer represented by the
 199  * string and returns 0.
 200  * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
 201  */
 202 int match_u64(substring_t *s, u64 *result)
 203 {
 204         return match_u64int(s, result, 0);
 205 }
 206 EXPORT_SYMBOL(match_u64);
 207
 208 /**
 209  * match_octal: - scan an octal representation of an integer from a substring_t
 210  * @s: substring_t to be scanned
 211  * @result: resulting integer on success
 212  *
 213  * Description: Attempts to parse the &substring_t @s as an octal integer. On
 214  * success, sets @result to the integer represented by the string and returns
 215  * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
 216  */
 217 int match_octal(substring_t *s, int *result)
 218 {
 219         return match_number(s, result, 8);
 220 }
 221 EXPORT_SYMBOL(match_octal);
 222
 223 /**
 224  * match_hex: - scan a hex representation of an integer from a substring_t
 225  * @s: substring_t to be scanned
 226  * @result: resulting integer on success
 227  *
 228  * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
 229  * On success, sets @result to the integer represented by the string and
 230  * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
 231  */
 232 int match_hex(substring_t *s, int *result)
 233 {
 234         return match_number(s, result, 16);
 235 }
 236 EXPORT_SYMBOL(match_hex);
 237
 238 /**
 239  * match_wildcard: - parse if a string matches given wildcard pattern
 240  * @pattern: wildcard pattern
 241  * @str: the string to be parsed
 242  *
 243  * Description: Parse the string @str to check if matches wildcard
 244  * pattern @pattern. The pattern may contain two type wildcardes:
 245  *   '*' - matches zero or more characters
 246  *   '?' - matches one character
 247  * If it's matched, return true, else return false.
 248  */
 249 bool match_wildcard(const char *pattern, const char *str)
 250 {
 251         const char *s = str;
 252         const char *p = pattern;
 253         bool star = false;
 254
 255         while (*s) {
 256                 switch (*p) {
 257                 case '?':
 258                         s++;
 259                         p++;
 260                         break;
 261                 case '*':
 262                         star = true;
 263                         str = s;
 264                         if (!*++p)
 265                                 return true;
 266                         pattern = p;
 267                         break;
 268                 default:
 269                         if (*s == *p) {
 270                                 s++;
 271                                 p++;
 272                         } else {
 273                                 if (!star)
 274                                         return false;
 275                                 str++;
 276                                 s = str;
 277                                 p = pattern;
 278                         }
 279                         break;
 280                 }
 281         }
 282
 283         if (*p == '*')
 284                 ++p;
 285         return !*p;
 286 }
 287 EXPORT_SYMBOL(match_wildcard);
 288
 289 /**
 290  * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
 291  * @dest: where to copy to
 292  * @src: &substring_t to copy
 293  * @size: size of destination buffer
 294  *
 295  * Description: Copy the characters in &substring_t @src to the
 296  * c-style string @dest.  Copy no more than @size - 1 characters, plus
 297  * the terminating NUL.  Return length of @src.
 298  */
 299 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
 300 {
 301         size_t ret = src->to - src->from;
 302
 303         if (size) {
 304                 size_t len = ret >= size ? size - 1 : ret;
 305                 memcpy(dest, src->from, len);
 306                 dest[len] = '\0';
 307         }
 308         return ret;
 309 }
 310 EXPORT_SYMBOL(match_strlcpy);
 311
 312 /**
 313  * match_strdup: - allocate a new string with the contents of a substring_t
 314  * @s: &substring_t to copy
 315  *
 316  * Description: Allocates and returns a string filled with the contents of
 317  * the &substring_t @s. The caller is responsible for freeing the returned
 318  * string with kfree().
 319  */
 320 char *match_strdup(const substring_t *s)
 321 {
 322         return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
 323 }
 324 EXPORT_SYMBOL(match_strdup);