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/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 */
  26static 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 */
 107int 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 */
 127static 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 */
 156int 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 */
 170int 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 */
 184int 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 */
 199size_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 */
 219char *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
 228EXPORT_SYMBOL(match_token);
 229EXPORT_SYMBOL(match_int);
 230EXPORT_SYMBOL(match_octal);
 231EXPORT_SYMBOL(match_hex);
 232EXPORT_SYMBOL(match_strlcpy);
 233EXPORT_SYMBOL(match_strdup);
 234
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