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}
116EXPORT_SYMBOL(match_token);
117
118/**
119 * match_number: scan a number in the given base from a substring_t
120 * @s: substring to be scanned
121 * @result: resulting integer on success
122 * @base: base to use when converting string
123 *
124 * Description: Given a &substring_t and a base, attempts to parse the substring
125 * as a number in that base. On success, sets @result to the integer represented
126 * by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
127 */
128static int match_number(substring_t *s, int *result, int base)
129{
130	char *endp;
131	char *buf;
132	int ret;
133	long val;
134	size_t len = s->to - s->from;
135
136	buf = kmalloc(len + 1, GFP_KERNEL);
137	if (!buf)
138		return -ENOMEM;
139	memcpy(buf, s->from, len);
140	buf[len] = '\0';
141
142	ret = 0;
143	val = simple_strtol(buf, &endp, base);
144	if (endp == buf)
145		ret = -EINVAL;
146	else if (val < (long)INT_MIN || val > (long)INT_MAX)
147		ret = -ERANGE;
148	else
149		*result = (int) val;
150	kfree(buf);
151	return ret;
152}
153
154/**
155 * match_int: - scan a decimal representation of an integer from a substring_t
156 * @s: substring_t to be scanned
157 * @result: resulting integer on success
158 *
159 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
160 * success, sets @result to the integer represented by the string and returns 0.
161 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
162 */
163int match_int(substring_t *s, int *result)
164{
165	return match_number(s, result, 0);
166}
167EXPORT_SYMBOL(match_int);
168
169/**
170 * match_octal: - scan an octal representation of an integer from a substring_t
171 * @s: substring_t to be scanned
172 * @result: resulting integer on success
173 *
174 * Description: Attempts to parse the &substring_t @s as an octal integer. On
175 * success, sets @result to the integer represented by the string and returns
176 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
177 */
178int match_octal(substring_t *s, int *result)
179{
180	return match_number(s, result, 8);
181}
182EXPORT_SYMBOL(match_octal);
183
184/**
185 * match_hex: - scan a hex representation of an integer from a substring_t
186 * @s: substring_t to be scanned
187 * @result: resulting integer on success
188 *
189 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
190 * On success, sets @result to the integer represented by the string and
191 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
192 */
193int match_hex(substring_t *s, int *result)
194{
195	return match_number(s, result, 16);
196}
197EXPORT_SYMBOL(match_hex);
198
199/**
200 * match_wildcard: - parse if a string matches given wildcard pattern
201 * @pattern: wildcard pattern
202 * @str: the string to be parsed
203 *
204 * Description: Parse the string @str to check if matches wildcard
205 * pattern @pattern. The pattern may contain two type wildcardes:
206 *   '*' - matches zero or more characters
207 *   '?' - matches one character
208 * If it's matched, return true, else return false.
209 */
210bool match_wildcard(const char *pattern, const char *str)
211{
212	const char *s = str;
213	const char *p = pattern;
214	bool star = false;
215
216	while (*s) {
217		switch (*p) {
218		case '?':
219			s++;
220			p++;
221			break;
222		case '*':
223			star = true;
224			str = s;
225			if (!*++p)
226				return true;
227			pattern = p;
228			break;
229		default:
230			if (*s == *p) {
231				s++;
232				p++;
233			} else {
234				if (!star)
235					return false;
236				str++;
237				s = str;
238				p = pattern;
239			}
240			break;
241		}
242	}
243
244	if (*p == '*')
245		++p;
246	return !*p;
247}
248EXPORT_SYMBOL(match_wildcard);
249
250/**
251 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
252 * @dest: where to copy to
253 * @src: &substring_t to copy
254 * @size: size of destination buffer
255 *
256 * Description: Copy the characters in &substring_t @src to the
257 * c-style string @dest.  Copy no more than @size - 1 characters, plus
258 * the terminating NUL.  Return length of @src.
259 */
260size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
261{
262	size_t ret = src->to - src->from;
263
264	if (size) {
265		size_t len = ret >= size ? size - 1 : ret;
266		memcpy(dest, src->from, len);
267		dest[len] = '\0';
268	}
269	return ret;
270}
271EXPORT_SYMBOL(match_strlcpy);
272
273/**
274 * match_strdup: - allocate a new string with the contents of a substring_t
275 * @s: &substring_t to copy
276 *
277 * Description: Allocates and returns a string filled with the contents of
278 * the &substring_t @s. The caller is responsible for freeing the returned
279 * string with kfree().
280 */
281char *match_strdup(const substring_t *s)
282{
283	size_t sz = s->to - s->from + 1;
284	char *p = kmalloc(sz, GFP_KERNEL);
285	if (p)
286		match_strlcpy(p, s, sz);
287	return p;
288}
289EXPORT_SYMBOL(match_strdup);
290