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 */ match_one(char * s,const char * p,substring_t args[])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 */ match_token(char * s,const match_table_t table,substring_t args[])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 */ match_number(substring_t * s,int * result,int base)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 */ match_u64int(substring_t * s,u64 * result,int base)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 */ match_int(substring_t * s,int * result)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 */ match_u64(substring_t * s,u64 * result)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 */ match_octal(substring_t * s,int * result)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 */ match_hex(substring_t * s,int * result)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 */ match_wildcard(const char * pattern,const char * str)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 */ match_strlcpy(char * dest,const substring_t * src,size_t size)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 */ match_strdup(const substring_t * s)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); 325