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

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