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 size_t len = s->to - s->from; 135 136 buf = kmalloc(len + 1, GFP_KERNEL); 137 if (!buf) 138 return -ENOMEM; 139 memcpy(buf, s->from, len); 140 buf[len] = '\0'; 141 142 ret = 0; 143 val = simple_strtol(buf, &endp, base); 144 if (endp == buf) 145 ret = -EINVAL; 146 else if (val < (long)INT_MIN || val > (long)INT_MAX) 147 ret = -ERANGE; 148 else 149 *result = (int) val; 150 kfree(buf); 151 return ret; 152 } 153 154 /** 155 * match_u64int: scan a number in the given base from a substring_t 156 * @s: substring to be scanned 157 * @result: resulting u64 on success 158 * @base: base to use when converting string 159 * 160 * Description: Given a &substring_t and a base, attempts to parse the substring 161 * as a number in that base. On success, sets @result to the integer represented 162 * by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 163 */ 164 static int match_u64int(substring_t *s, u64 *result, int base) 165 { 166 char *buf; 167 int ret; 168 u64 val; 169 170 buf = match_strdup(s); 171 if (!buf) 172 return -ENOMEM; 173 174 ret = kstrtoull(buf, base, &val); 175 if (!ret) 176 *result = val; 177 kfree(buf); 178 return ret; 179 } 180 181 /** 182 * match_int: - scan a decimal representation of an integer from a substring_t 183 * @s: substring_t to be scanned 184 * @result: resulting integer on success 185 * 186 * Description: Attempts to parse the &substring_t @s as a decimal integer. On 187 * success, sets @result to the integer represented by the string and returns 0. 188 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 189 */ 190 int match_int(substring_t *s, int *result) 191 { 192 return match_number(s, result, 0); 193 } 194 EXPORT_SYMBOL(match_int); 195 196 /** 197 * match_u64: - scan a decimal representation of a u64 from 198 * a substring_t 199 * @s: substring_t to be scanned 200 * @result: resulting unsigned long long on success 201 * 202 * Description: Attempts to parse the &substring_t @s as a long decimal 203 * integer. On success, sets @result to the integer represented by the 204 * string and returns 0. 205 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 206 */ 207 int match_u64(substring_t *s, u64 *result) 208 { 209 return match_u64int(s, result, 0); 210 } 211 EXPORT_SYMBOL(match_u64); 212 213 /** 214 * match_octal: - scan an octal representation of an integer from a substring_t 215 * @s: substring_t to be scanned 216 * @result: resulting integer on success 217 * 218 * Description: Attempts to parse the &substring_t @s as an octal integer. On 219 * success, sets @result to the integer represented by the string and returns 220 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 221 */ 222 int match_octal(substring_t *s, int *result) 223 { 224 return match_number(s, result, 8); 225 } 226 EXPORT_SYMBOL(match_octal); 227 228 /** 229 * match_hex: - scan a hex representation of an integer from a substring_t 230 * @s: substring_t to be scanned 231 * @result: resulting integer on success 232 * 233 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer. 234 * On success, sets @result to the integer represented by the string and 235 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 236 */ 237 int match_hex(substring_t *s, int *result) 238 { 239 return match_number(s, result, 16); 240 } 241 EXPORT_SYMBOL(match_hex); 242 243 /** 244 * match_wildcard: - parse if a string matches given wildcard pattern 245 * @pattern: wildcard pattern 246 * @str: the string to be parsed 247 * 248 * Description: Parse the string @str to check if matches wildcard 249 * pattern @pattern. The pattern may contain two type wildcardes: 250 * '*' - matches zero or more characters 251 * '?' - matches one character 252 * If it's matched, return true, else return false. 253 */ 254 bool match_wildcard(const char *pattern, const char *str) 255 { 256 const char *s = str; 257 const char *p = pattern; 258 bool star = false; 259 260 while (*s) { 261 switch (*p) { 262 case '?': 263 s++; 264 p++; 265 break; 266 case '*': 267 star = true; 268 str = s; 269 if (!*++p) 270 return true; 271 pattern = p; 272 break; 273 default: 274 if (*s == *p) { 275 s++; 276 p++; 277 } else { 278 if (!star) 279 return false; 280 str++; 281 s = str; 282 p = pattern; 283 } 284 break; 285 } 286 } 287 288 if (*p == '*') 289 ++p; 290 return !*p; 291 } 292 EXPORT_SYMBOL(match_wildcard); 293 294 /** 295 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer 296 * @dest: where to copy to 297 * @src: &substring_t to copy 298 * @size: size of destination buffer 299 * 300 * Description: Copy the characters in &substring_t @src to the 301 * c-style string @dest. Copy no more than @size - 1 characters, plus 302 * the terminating NUL. Return length of @src. 303 */ 304 size_t match_strlcpy(char *dest, const substring_t *src, size_t size) 305 { 306 size_t ret = src->to - src->from; 307 308 if (size) { 309 size_t len = ret >= size ? size - 1 : ret; 310 memcpy(dest, src->from, len); 311 dest[len] = '\0'; 312 } 313 return ret; 314 } 315 EXPORT_SYMBOL(match_strlcpy); 316 317 /** 318 * match_strdup: - allocate a new string with the contents of a substring_t 319 * @s: &substring_t to copy 320 * 321 * Description: Allocates and returns a string filled with the contents of 322 * the &substring_t @s. The caller is responsible for freeing the returned 323 * string with kfree(). 324 */ 325 char *match_strdup(const substring_t *s) 326 { 327 return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL); 328 } 329 EXPORT_SYMBOL(match_strdup); 330