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