parser.c

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/*
 * 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/types.h>
#include <linux/export.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/string.h>

static int match_one(char *s, const 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, (char **) &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': {
            size_t str_len = strlen(s);

            if (str_len == 0)
                return 0;
            if (len == -1 || len > str_len)
                len = str_len;
            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++;
    }
}

int match_token(char *s, const match_table_t table, substring_t args[])
{
    const struct match_token *p;

    for (p = table; !match_one(s, p->pattern, args) ; p++)
        ;

    return p->token;
}

static int match_number(substring_t *s, int *result, int base)
{
    char *endp;
    char *buf;
    int ret;
    long val;
    size_t len = s->to - s->from;

    buf = kmalloc(len + 1, GFP_KERNEL);
    if (!buf)
        return -ENOMEM;
    memcpy(buf, s->from, len);
    buf[len] = '\0';

    ret = 0;
    val = simple_strtol(buf, &endp, base);
    if (endp == buf)
        ret = -EINVAL;
    else if (val < (long)INT_MIN || val > (long)INT_MAX)
        ret = -ERANGE;
    else
        *result = (int) val;
    kfree(buf);
    return ret;
}

int match_int(substring_t *s, int *result)
{
    return match_number(s, result, 0);
}

int match_octal(substring_t *s, int *result)
{
    return match_number(s, result, 8);
}

int match_hex(substring_t *s, int *result)
{
    return match_number(s, result, 16);
}

size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
{
    size_t ret = src->to - src->from;

    if (size) {
        size_t len = ret >= size ? size - 1 : ret;
        memcpy(dest, src->from, len);
        dest[len] = '\0';
    }
    return ret;
}

char *match_strdup(const substring_t *s)
{
    size_t sz = s->to - s->from + 1;
    char *p = kmalloc(sz, GFP_KERNEL);
    if (p)
        match_strlcpy(p, s, sz);
    return p;
}

EXPORT_SYMBOL(match_token);
EXPORT_SYMBOL(match_int);
EXPORT_SYMBOL(match_octal);
EXPORT_SYMBOL(match_hex);
EXPORT_SYMBOL(match_strlcpy);
EXPORT_SYMBOL(match_strdup);