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 } 116 117 /** 118 * match_number: scan a number in the given base from a substring_t 119 * @s: substring to be scanned 120 * @result: resulting integer on success 121 * @base: base to use when converting string 122 * 123 * Description: Given a &substring_t and a base, attempts to parse the substring 124 * as a number in that base. On success, sets @result to the integer represented 125 * by the string and returns 0. Returns either -ENOMEM or -EINVAL on failure. 126 */ 127 static int match_number(substring_t *s, int *result, int base) 128 { 129 char *endp; 130 char *buf; 131 int ret; 132 size_t len = s->to - s->from; 133 134 buf = kmalloc(len + 1, GFP_KERNEL); 135 if (!buf) 136 return -ENOMEM; 137 memcpy(buf, s->from, len); 138 buf[len] = '\0'; 139 *result = simple_strtol(buf, &endp, base); 140 ret = 0; 141 if (endp == buf) 142 ret = -EINVAL; 143 kfree(buf); 144 return ret; 145 } 146 147 /** 148 * match_int: - scan a decimal representation of an integer from a substring_t 149 * @s: substring_t to be scanned 150 * @result: resulting integer on success 151 * 152 * Description: Attempts to parse the &substring_t @s as a decimal integer. On 153 * success, sets @result to the integer represented by the string and returns 0. 154 * Returns either -ENOMEM or -EINVAL on failure. 155 */ 156 int match_int(substring_t *s, int *result) 157 { 158 return match_number(s, result, 0); 159 } 160 161 /** 162 * match_octal: - scan an octal representation of an integer from a substring_t 163 * @s: substring_t to be scanned 164 * @result: resulting integer on success 165 * 166 * Description: Attempts to parse the &substring_t @s as an octal integer. On 167 * success, sets @result to the integer represented by the string and returns 168 * 0. Returns either -ENOMEM or -EINVAL on failure. 169 */ 170 int match_octal(substring_t *s, int *result) 171 { 172 return match_number(s, result, 8); 173 } 174 175 /** 176 * match_hex: - scan a hex representation of an integer from a substring_t 177 * @s: substring_t to be scanned 178 * @result: resulting integer on success 179 * 180 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer. 181 * On success, sets @result to the integer represented by the string and 182 * returns 0. Returns either -ENOMEM or -EINVAL on failure. 183 */ 184 int match_hex(substring_t *s, int *result) 185 { 186 return match_number(s, result, 16); 187 } 188 189 /** 190 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer 191 * @dest: where to copy to 192 * @src: &substring_t to copy 193 * @size: size of destination buffer 194 * 195 * Description: Copy the characters in &substring_t @src to the 196 * c-style string @dest. Copy no more than @size - 1 characters, plus 197 * the terminating NUL. Return length of @src. 198 */ 199 size_t match_strlcpy(char *dest, const substring_t *src, size_t size) 200 { 201 size_t ret = src->to - src->from; 202 203 if (size) { 204 size_t len = ret >= size ? size - 1 : ret; 205 memcpy(dest, src->from, len); 206 dest[len] = '\0'; 207 } 208 return ret; 209 } 210 211 /** 212 * match_strdup: - allocate a new string with the contents of a substring_t 213 * @s: &substring_t to copy 214 * 215 * Description: Allocates and returns a string filled with the contents of 216 * the &substring_t @s. The caller is responsible for freeing the returned 217 * string with kfree(). 218 */ 219 char *match_strdup(const substring_t *s) 220 { 221 size_t sz = s->to - s->from + 1; 222 char *p = kmalloc(sz, GFP_KERNEL); 223 if (p) 224 match_strlcpy(p, s, sz); 225 return p; 226 } 227 228 EXPORT_SYMBOL(match_token); 229 EXPORT_SYMBOL(match_int); 230 EXPORT_SYMBOL(match_octal); 231 EXPORT_SYMBOL(match_hex); 232 EXPORT_SYMBOL(match_strlcpy); 233 EXPORT_SYMBOL(match_strdup); 234