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 */ 25static int match_one(char *s, const 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, (char **) &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 size_t str_len = strlen(s); 61 62 if (str_len == 0) 63 return 0; 64 if (len == -1 || len > str_len) 65 len = str_len; 66 args[argc].to = s + len; 67 break; 68 } 69 case 'd': 70 simple_strtol(s, &args[argc].to, 0); 71 goto num; 72 case 'u': 73 simple_strtoul(s, &args[argc].to, 0); 74 goto num; 75 case 'o': 76 simple_strtoul(s, &args[argc].to, 8); 77 goto num; 78 case 'x': 79 simple_strtoul(s, &args[argc].to, 16); 80 num: 81 if (args[argc].to == args[argc].from) 82 return 0; 83 break; 84 default: 85 return 0; 86 } 87 s = args[argc].to; 88 argc++; 89 } 90} 91 92/** 93 * match_token: - Find a token (and optional args) in a string 94 * @s: the string to examine for token/argument pairs 95 * @table: match_table_t describing the set of allowed option tokens and the 96 * arguments that may be associated with them. Must be terminated with a 97 * &struct match_token whose pattern is set to the NULL pointer. 98 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match 99 * locations. 100 * 101 * Description: Detects which if any of a set of token strings has been passed 102 * to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style 103 * format identifiers which will be taken into account when matching the 104 * tokens, and whose locations will be returned in the @args array. 105 */ 106int match_token(char *s, const match_table_t table, substring_t args[]) 107{ 108 const struct match_token *p; 109 110 for (p = table; !match_one(s, p->pattern, args) ; p++) 111 ; 112 113 return p->token; 114} 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 either -ENOMEM or -EINVAL on failure. 125 */ 126static int match_number(substring_t *s, int *result, int base) 127{ 128 char *endp; 129 char *buf; 130 int ret; 131 132 buf = kmalloc(s->to - s->from + 1, GFP_KERNEL); 133 if (!buf) 134 return -ENOMEM; 135 memcpy(buf, s->from, s->to - s->from); 136 buf[s->to - s->from] = '\0'; 137 *result = simple_strtol(buf, &endp, base); 138 ret = 0; 139 if (endp == buf) 140 ret = -EINVAL; 141 kfree(buf); 142 return ret; 143} 144 145/** 146 * match_int: - scan a decimal representation of an integer from a substring_t 147 * @s: substring_t to be scanned 148 * @result: resulting integer on success 149 * 150 * Description: Attempts to parse the &substring_t @s as a decimal integer. On 151 * success, sets @result to the integer represented by the string and returns 0. 152 * Returns either -ENOMEM or -EINVAL on failure. 153 */ 154int match_int(substring_t *s, int *result) 155{ 156 return match_number(s, result, 0); 157} 158 159/** 160 * match_octal: - scan an octal representation of an integer from a substring_t 161 * @s: substring_t to be scanned 162 * @result: resulting integer on success 163 * 164 * Description: Attempts to parse the &substring_t @s as an octal integer. On 165 * success, sets @result to the integer represented by the string and returns 166 * 0. Returns either -ENOMEM or -EINVAL on failure. 167 */ 168int match_octal(substring_t *s, int *result) 169{ 170 return match_number(s, result, 8); 171} 172 173/** 174 * match_hex: - scan a hex representation of an integer from a substring_t 175 * @s: substring_t to be scanned 176 * @result: resulting integer on success 177 * 178 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer. 179 * On success, sets @result to the integer represented by the string and 180 * returns 0. Returns either -ENOMEM or -EINVAL on failure. 181 */ 182int match_hex(substring_t *s, int *result) 183{ 184 return match_number(s, result, 16); 185} 186 187/** 188 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer 189 * @dest: where to copy to 190 * @src: &substring_t to copy 191 * @size: size of destination buffer 192 * 193 * Description: Copy the characters in &substring_t @src to the 194 * c-style string @dest. Copy no more than @size - 1 characters, plus 195 * the terminating NUL. Return length of @src. 196 */ 197size_t match_strlcpy(char *dest, const substring_t *src, size_t size) 198{ 199 size_t ret = src->to - src->from; 200 201 if (size) { 202 size_t len = ret >= size ? size - 1 : ret; 203 memcpy(dest, src->from, len); 204 dest[len] = '\0'; 205 } 206 return ret; 207} 208 209/** 210 * match_strdup: - allocate a new string with the contents of a substring_t 211 * @s: &substring_t to copy 212 * 213 * Description: Allocates and returns a string filled with the contents of 214 * the &substring_t @s. The caller is responsible for freeing the returned 215 * string with kfree(). 216 */ 217char *match_strdup(const substring_t *s) 218{ 219 size_t sz = s->to - s->from + 1; 220 char *p = kmalloc(sz, GFP_KERNEL); 221 if (p) 222 match_strlcpy(p, s, sz); 223 return p; 224} 225 226EXPORT_SYMBOL(match_token); 227EXPORT_SYMBOL(match_int); 228EXPORT_SYMBOL(match_octal); 229EXPORT_SYMBOL(match_hex); 230EXPORT_SYMBOL(match_strlcpy); 231EXPORT_SYMBOL(match_strdup); 232