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, 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                         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         const 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_strlcpy: - Copy the characters from a substring_t to a sized buffer
 186  * @dest: where to copy to
 187  * @src: &substring_t to copy
 188  * @size: size of destination buffer
 189  *
 190  * Description: Copy the characters in &substring_t @src to the
 191  * c-style string @dest.  Copy no more than @size - 1 characters, plus
 192  * the terminating NUL.  Return length of @src.
 193  */
 194 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
 195 {
 196         size_t ret = src->to - src->from;
 197
 198         if (size) {
 199                 size_t len = ret >= size ? size - 1 : ret;
 200                 memcpy(dest, src->from, len);
 201                 dest[len] = '\0';
 202         }
 203         return ret;
 204 }
 205
 206 /**
 207  * match_strdup: - allocate a new string with the contents of a substring_t
 208  * @s: &substring_t to copy
 209  *
 210  * Description: Allocates and returns a string filled with the contents of
 211  * the &substring_t @s. The caller is responsible for freeing the returned
 212  * string with kfree().
 213  */
 214 char *match_strdup(const substring_t *s)
 215 {
 216         size_t sz = s->to - s->from + 1;
 217         char *p = kmalloc(sz, GFP_KERNEL);
 218         if (p)
 219                 match_strlcpy(p, s, sz);
 220         return p;
 221 }
 222
 223 EXPORT_SYMBOL(match_token);
 224 EXPORT_SYMBOL(match_int);
 225 EXPORT_SYMBOL(match_octal);
 226 EXPORT_SYMBOL(match_hex);
 227 EXPORT_SYMBOL(match_strlcpy);
 228 EXPORT_SYMBOL(match_strdup);