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/module.h> 10 #include <linux/parser.h> 11 #include <linux/slab.h> 12 #include <linux/string.h> 13 14 /** 15 * match_one: - Determines if a string matches a simple pattern 16 * @s: the string to examine for presense of the pattern 17 * @p: the string containing the pattern 18 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match 19 * locations. 20 * 21 * Description: Determines if the pattern @p is present in string @s. Can only 22 * match extremely simple token=arg style patterns. If the pattern is found, 23 * the location(s) of the arguments will be returned in the @args array. 24 */ 25 static int match_one(char *s, char *p, substring_t args[]) 26 { 27 char *meta; 28 int argc = 0; 29 30 if (!p) 31 return 1; 32 33 while(1) { 34 int len = -1; 35 meta = strchr(p, '%'); 36 if (!meta) 37 return strcmp(p, s) == 0; 38 39 if (strncmp(p, s, meta-p)) 40 return 0; 41 42 s += meta - p; 43 p = meta + 1; 44 45 if (isdigit(*p)) 46 len = simple_strtoul(p, &p, 10); 47 else if (*p == '%') { 48 if (*s++ != '%') 49 return 0; 50 p++; 51 continue; 52 } 53 54 if (argc >= MAX_OPT_ARGS) 55 return 0; 56 57 args[argc].from = s; 58 switch (*p++) { 59 case 's': 60 if (strlen(s) == 0) 61 return 0; 62 else if (len == -1 || len > strlen(s)) 63 len = strlen(s); 64 args[argc].to = s + len; 65 break; 66 case 'd': 67 simple_strtol(s, &args[argc].to, 0); 68 goto num; 69 case 'u': 70 simple_strtoul(s, &args[argc].to, 0); 71 goto num; 72 case 'o': 73 simple_strtoul(s, &args[argc].to, 8); 74 goto num; 75 case 'x': 76 simple_strtoul(s, &args[argc].to, 16); 77 num: 78 if (args[argc].to == args[argc].from) 79 return 0; 80 break; 81 default: 82 return 0; 83 } 84 s = args[argc].to; 85 argc++; 86 } 87 } 88 89 /** 90 * match_token: - Find a token (and optional args) in a string 91 * @s: the string to examine for token/argument pairs 92 * @table: match_table_t describing the set of allowed option tokens and the 93 * arguments that may be associated with them. Must be terminated with a 94 * &struct match_token whose pattern is set to the NULL pointer. 95 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match 96 * locations. 97 * 98 * Description: Detects which if any of a set of token strings has been passed 99 * to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style 100 * format identifiers which will be taken into account when matching the 101 * tokens, and whose locations will be returned in the @args array. 102 */ 103 int match_token(char *s, match_table_t table, substring_t args[]) 104 { 105 struct match_token *p; 106 107 for (p = table; !match_one(s, p->pattern, args) ; p++) 108 ; 109 110 return p->token; 111 } 112 113 /** 114 * match_number: scan a number in the given base from a substring_t 115 * @s: substring to be scanned 116 * @result: resulting integer on success 117 * @base: base to use when converting string 118 * 119 * Description: Given a &substring_t and a base, attempts to parse the substring 120 * as a number in that base. On success, sets @result to the integer represented 121 * by the string and returns 0. Returns either -ENOMEM or -EINVAL on failure. 122 */ 123 static int match_number(substring_t *s, int *result, int base) 124 { 125 char *endp; 126 char *buf; 127 int ret; 128 129 buf = kmalloc(s->to - s->from + 1, GFP_KERNEL); 130 if (!buf) 131 return -ENOMEM; 132 memcpy(buf, s->from, s->to - s->from); 133 buf[s->to - s->from] = '\0'; 134 *result = simple_strtol(buf, &endp, base); 135 ret = 0; 136 if (endp == buf) 137 ret = -EINVAL; 138 kfree(buf); 139 return ret; 140 } 141 142 /** 143 * match_int: - scan a decimal representation of an integer from a substring_t 144 * @s: substring_t to be scanned 145 * @result: resulting integer on success 146 * 147 * Description: Attempts to parse the &substring_t @s as a decimal integer. On 148 * success, sets @result to the integer represented by the string and returns 0. 149 * Returns either -ENOMEM or -EINVAL on failure. 150 */ 151 int match_int(substring_t *s, int *result) 152 { 153 return match_number(s, result, 0); 154 } 155 156 /** 157 * match_octal: - scan an octal representation of an integer from a substring_t 158 * @s: substring_t to be scanned 159 * @result: resulting integer on success 160 * 161 * Description: Attempts to parse the &substring_t @s as an octal integer. On 162 * success, sets @result to the integer represented by the string and returns 163 * 0. Returns either -ENOMEM or -EINVAL on failure. 164 */ 165 int match_octal(substring_t *s, int *result) 166 { 167 return match_number(s, result, 8); 168 } 169 170 /** 171 * match_hex: - scan a hex representation of an integer from a substring_t 172 * @s: substring_t to be scanned 173 * @result: resulting integer on success 174 * 175 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer. 176 * On success, sets @result to the integer represented by the string and 177 * returns 0. Returns either -ENOMEM or -EINVAL on failure. 178 */ 179 int match_hex(substring_t *s, int *result) 180 { 181 return match_number(s, result, 16); 182 } 183 184 /** 185 * match_strcpy: - copies the characters from a substring_t to a string 186 * @to: string to copy characters to. 187 * @s: &substring_t to copy 188 * 189 * Description: Copies the set of characters represented by the given 190 * &substring_t @s to the c-style string @to. Caller guarantees that @to is 191 * large enough to hold the characters of @s. 192 */ 193 void match_strcpy(char *to, substring_t *s) 194 { 195 memcpy(to, s->from, s->to - s->from); 196 to[s->to - s->from] = '\0'; 197 } 198 199 /** 200 * match_strdup: - allocate a new string with the contents of a substring_t 201 * @s: &substring_t to copy 202 * 203 * Description: Allocates and returns a string filled with the contents of 204 * the &substring_t @s. The caller is responsible for freeing the returned 205 * string with kfree(). 206 */ 207 char *match_strdup(substring_t *s) 208 { 209 char *p = kmalloc(s->to - s->from + 1, GFP_KERNEL); 210 if (p) 211 match_strcpy(p, s); 212 return p; 213 } 214 215 EXPORT_SYMBOL(match_token); 216 EXPORT_SYMBOL(match_int); 217 EXPORT_SYMBOL(match_octal); 218 EXPORT_SYMBOL(match_hex); 219 EXPORT_SYMBOL(match_strcpy); 220 EXPORT_SYMBOL(match_strdup); 221