lib/parser.c

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