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_int: - scan a decimal representation of an integer from a substring_t 156 * @s: substring_t to be scanned 157 * @result: resulting integer on success 158 * 159 * Description: Attempts to parse the &substring_t @s as a decimal integer. On 160 * success, sets @result to the integer represented by the string and returns 0. 161 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 162 */ 163 int match_int(substring_t *s, int *result) 164 { 165 return match_number(s, result, 0); 166 } 167 EXPORT_SYMBOL(match_int); 168 169 /** 170 * match_octal: - scan an octal representation of an integer from a substring_t 171 * @s: substring_t to be scanned 172 * @result: resulting integer on success 173 * 174 * Description: Attempts to parse the &substring_t @s as an octal integer. On 175 * success, sets @result to the integer represented by the string and returns 176 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 177 */ 178 int match_octal(substring_t *s, int *result) 179 { 180 return match_number(s, result, 8); 181 } 182 EXPORT_SYMBOL(match_octal); 183 184 /** 185 * match_hex: - scan a hex 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 hexadecimal integer. 190 * On success, sets @result to the integer represented by the string and 191 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure. 192 */ 193 int match_hex(substring_t *s, int *result) 194 { 195 return match_number(s, result, 16); 196 } 197 EXPORT_SYMBOL(match_hex); 198 199 /** 200 * match_wildcard: - parse if a string matches given wildcard pattern 201 * @pattern: wildcard pattern 202 * @str: the string to be parsed 203 * 204 * Description: Parse the string @str to check if matches wildcard 205 * pattern @pattern. The pattern may contain two type wildcardes: 206 * '*' - matches zero or more characters 207 * '?' - matches one character 208 * If it's matched, return true, else return false. 209 */ 210 bool match_wildcard(const char *pattern, const char *str) 211 { 212 const char *s = str; 213 const char *p = pattern; 214 bool star = false; 215 216 while (*s) { 217 switch (*p) { 218 case '?': 219 s++; 220 p++; 221 break; 222 case '*': 223 star = true; 224 str = s; 225 if (!*++p) 226 return true; 227 pattern = p; 228 break; 229 default: 230 if (*s == *p) { 231 s++; 232 p++; 233 } else { 234 if (!star) 235 return false; 236 str++; 237 s = str; 238 p = pattern; 239 } 240 break; 241 } 242 } 243 244 if (*p == '*') 245 ++p; 246 return !*p; 247 } 248 EXPORT_SYMBOL(match_wildcard); 249 250 /** 251 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer 252 * @dest: where to copy to 253 * @src: &substring_t to copy 254 * @size: size of destination buffer 255 * 256 * Description: Copy the characters in &substring_t @src to the 257 * c-style string @dest. Copy no more than @size - 1 characters, plus 258 * the terminating NUL. Return length of @src. 259 */ 260 size_t match_strlcpy(char *dest, const substring_t *src, size_t size) 261 { 262 size_t ret = src->to - src->from; 263 264 if (size) { 265 size_t len = ret >= size ? size - 1 : ret; 266 memcpy(dest, src->from, len); 267 dest[len] = '\0'; 268 } 269 return ret; 270 } 271 EXPORT_SYMBOL(match_strlcpy); 272 273 /** 274 * match_strdup: - allocate a new string with the contents of a substring_t 275 * @s: &substring_t to copy 276 * 277 * Description: Allocates and returns a string filled with the contents of 278 * the &substring_t @s. The caller is responsible for freeing the returned 279 * string with kfree(). 280 */ 281 char *match_strdup(const substring_t *s) 282 { 283 size_t sz = s->to - s->from + 1; 284 char *p = kmalloc(sz, GFP_KERNEL); 285 if (p) 286 match_strlcpy(p, s, sz); 287 return p; 288 } 289 EXPORT_SYMBOL(match_strdup); 290