/*
* lib/parser.c - simple parser for mount, etc. options.
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/string.h>
/**
* match_one: - Determines if a string matches a simple pattern
* @s: the string to examine for presense of the pattern
* @p: the string containing the pattern
* @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
* locations.
*
* Description: Determines if the pattern @p is present in string @s. Can only
* match extremely simple token=arg style patterns. If the pattern is found,
* the location(s) of the arguments will be returned in the @args array.
*/
static int match_one(char *s, char *p, substring_t args[])
{
char *meta;
int argc = 0;
if (!p)
return 1;
while(1) {
int len = -1;
meta = strchr(p, '%');
if (!meta)
return strcmp(p, s) == 0;
if (strncmp(p, s, meta-p))
return 0;
s += meta - p;
p = meta + 1;
if (isdigit(*p))
len = simple_strtoul(p, &p, 10);
else if (*p == '%') {
if (*s++ != '%')
return 0;
p++;
continue;
}
if (argc >= MAX_OPT_ARGS)
return 0;
args[argc].from = s;
switch (*p++) {
case 's':
if (strlen(s) == 0)
return 0;
else if (len == -1 || len > strlen(s))
len = strlen(s);
args[argc].to = s + len;
break;
case 'd':
simple_strtol(s, &args[argc].to, 0);
goto num;
case 'u':
simple_strtoul(s, &args[argc].to, 0);
goto num;
case 'o':
simple_strtoul(s, &args[argc].to, 8);
goto num;
case 'x':
simple_strtoul(s, &args[argc].to, 16);
num:
if (args[argc].to == args[argc].from)
return 0;
break;
default:
return 0;
}
s = args[argc].to;
argc++;
}
}
/**
* match_token: - Find a token (and optional args) in a string
* @s: the string to examine for token/argument pairs
* @table: match_table_t describing the set of allowed option tokens and the
* arguments that may be associated with them. Must be terminated with a
* &struct match_token whose pattern is set to the NULL pointer.
* @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
* locations.
*
* Description: Detects which if any of a set of token strings has been passed
* to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
* format identifiers which will be taken into account when matching the
* tokens, and whose locations will be returned in the @args array.
*/
int match_token(char *s, match_table_t table, substring_t args[])
{
struct match_token *p;
for (p = table; !match_one(s, p->pattern, args) ; p++)
;
return p->token;
}
/**
* match_number: scan a number in the given base from a substring_t
* @s: substring to be scanned
* @result: resulting integer on success
* @base: base to use when converting string
*
* Description: Given a &substring_t and a base, attempts to parse the substring
* as a number in that base. On success, sets @result to the integer represented
* by the string and returns 0. Returns either -ENOMEM or -EINVAL on failure.
*/
static int match_number(substring_t *s, int *result, int base)
{
char *endp;
char *buf;
int ret;
buf = kmalloc(s->to - s->from + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
memcpy(buf, s->from, s->to - s->from);
buf[s->to - s->from] = '\0';
*result = simple_strtol(buf, &endp, base);
ret = 0;
if (endp == buf)
ret = -EINVAL;
kfree(buf);
return ret;
}
/**
* match_int: - scan a decimal representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as a decimal integer. On
* success, sets @result to the integer represented by the string and returns 0.
* Returns either -ENOMEM or -EINVAL on failure.
*/
int match_int(substring_t *s, int *result)
{
return match_number(s, result, 0);
}
/**
* match_octal: - scan an octal representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as an octal integer. On
* success, sets @result to the integer represented by the string and returns
* 0. Returns either -ENOMEM or -EINVAL on failure.
*/
int match_octal(substring_t *s, int *result)
{
return match_number(s, result, 8);
}
/**
* match_hex: - scan a hex representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
* On success, sets @result to the integer represented by the string and
* returns 0. Returns either -ENOMEM or -EINVAL on failure.
*/
int match_hex(substring_t *s, int *result)
{
return match_number(s, result, 16);
}
/**
* match_strcpy: - copies the characters from a substring_t to a string
* @to: string to copy characters to.
* @s: &substring_t to copy
*
* Description: Copies the set of characters represented by the given
* &substring_t @s to the c-style string @to. Caller guarantees that @to is
* large enough to hold the characters of @s.
*/
void match_strcpy(char *to, substring_t *s)
{
memcpy(to, s->from, s->to - s->from);
to[s->to - s->from] = '\0';
}
/**
* match_strdup: - allocate a new string with the contents of a substring_t
* @s: &substring_t to copy
*
* Description: Allocates and returns a string filled with the contents of
* the &substring_t @s. The caller is responsible for freeing the returned
* string with kfree().
*/
char *match_strdup(substring_t *s)
{
char *p = kmalloc(s->to - s->from + 1, GFP_KERNEL);
if (p)
match_strcpy(p, s);
return p;
}
EXPORT_SYMBOL(match_token);
EXPORT_SYMBOL(match_int);
EXPORT_SYMBOL(match_octal);
EXPORT_SYMBOL(match_hex);
EXPORT_SYMBOL(match_strcpy);
EXPORT_SYMBOL(match_strdup);
