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/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);