linux/lib/parser.c
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   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 */
  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        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 */
 155int 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 */
 169int 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 */
 183int 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 */
 198size_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 */
 218char *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
 227EXPORT_SYMBOL(match_token);
 228EXPORT_SYMBOL(match_int);
 229EXPORT_SYMBOL(match_octal);
 230EXPORT_SYMBOL(match_hex);
 231EXPORT_SYMBOL(match_strlcpy);
 232EXPORT_SYMBOL(match_strdup);
 233
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