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/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 -ENOMEM, -EINVAL, or -ERANGE 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    long val;
133    size_t len = s->to - s->from;
134
135    buf = kmalloc(len + 1, GFP_KERNEL);
136    if (!buf)
137        return -ENOMEM;
138    memcpy(buf, s->from, len);
139    buf[len] = '\0';
140
141    ret = 0;
142    val = simple_strtol(buf, &endp, base);
143    if (endp == buf)
144        ret = -EINVAL;
145    else if (val < (long)INT_MIN || val > (long)INT_MAX)
146        ret = -ERANGE;
147    else
148        *result = (int) val;
149    kfree(buf);
150    return ret;
151}
152
153/**
154 * match_int: - scan a decimal representation of an integer from a substring_t
155 * @s: substring_t to be scanned
156 * @result: resulting integer on success
157 *
158 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
159 * success, sets @result to the integer represented by the string and returns 0.
160 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
161 */
162int match_int(substring_t *s, int *result)
163{
164    return match_number(s, result, 0);
165}
166
167/**
168 * match_octal: - scan an octal representation of an integer from a substring_t
169 * @s: substring_t to be scanned
170 * @result: resulting integer on success
171 *
172 * Description: Attempts to parse the &substring_t @s as an octal integer. On
173 * success, sets @result to the integer represented by the string and returns
174 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
175 */
176int match_octal(substring_t *s, int *result)
177{
178    return match_number(s, result, 8);
179}
180
181/**
182 * match_hex: - scan a hex representation of an integer from a substring_t
183 * @s: substring_t to be scanned
184 * @result: resulting integer on success
185 *
186 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
187 * On success, sets @result to the integer represented by the string and
188 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
189 */
190int match_hex(substring_t *s, int *result)
191{
192    return match_number(s, result, 16);
193}
194
195/**
196 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
197 * @dest: where to copy to
198 * @src: &substring_t to copy
199 * @size: size of destination buffer
200 *
201 * Description: Copy the characters in &substring_t @src to the
202 * c-style string @dest. Copy no more than @size - 1 characters, plus
203 * the terminating NUL. Return length of @src.
204 */
205size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
206{
207    size_t ret = src->to - src->from;
208
209    if (size) {
210        size_t len = ret >= size ? size - 1 : ret;
211        memcpy(dest, src->from, len);
212        dest[len] = '\0';
213    }
214    return ret;
215}
216
217/**
218 * match_strdup: - allocate a new string with the contents of a substring_t
219 * @s: &substring_t to copy
220 *
221 * Description: Allocates and returns a string filled with the contents of
222 * the &substring_t @s. The caller is responsible for freeing the returned
223 * string with kfree().
224 */
225char *match_strdup(const substring_t *s)
226{
227    size_t sz = s->to - s->from + 1;
228    char *p = kmalloc(sz, GFP_KERNEL);
229    if (p)
230        match_strlcpy(p, s, sz);
231    return p;
232}
233
234EXPORT_SYMBOL(match_token);
235EXPORT_SYMBOL(match_int);
236EXPORT_SYMBOL(match_octal);
237EXPORT_SYMBOL(match_hex);
238EXPORT_SYMBOL(match_strlcpy);
239EXPORT_SYMBOL(match_strdup);
240

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