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
135 buf = match_strdup(s);
136 if (!buf)
137 return -ENOMEM;
138
139 ret = 0;
140 val = simple_strtol(buf, &endp, base);
141 if (endp == buf)
142 ret = -EINVAL;
143 else if (val < (long)INT_MIN || val > (long)INT_MAX)
144 ret = -ERANGE;
145 else
146 *result = (int) val;
147 kfree(buf);
148 return ret;
149}
150
151/**
152 * match_u64int: scan a number in the given base from a substring_t
153 * @s: substring to be scanned
154 * @result: resulting u64 on success
155 * @base: base to use when converting string
156 *
157 * Description: Given a &substring_t and a base, attempts to parse the substring
158 * as a number in that base. On success, sets @result to the integer represented
159 * by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
160 */
161static int match_u64int(substring_t *s, u64 *result, int base)
162{
163 char *buf;
164 int ret;
165 u64 val;
166
167 buf = match_strdup(s);
168 if (!buf)
169 return -ENOMEM;
170
171 ret = kstrtoull(buf, base, &val);
172 if (!ret)
173 *result = val;
174 kfree(buf);
175 return ret;
176}
177
178/**
179 * match_int: - scan a decimal representation of an integer from a substring_t
180 * @s: substring_t to be scanned
181 * @result: resulting integer on success
182 *
183 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
184 * success, sets @result to the integer represented by the string and returns 0.
185 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
186 */
187int match_int(substring_t *s, int *result)
188{
189 return match_number(s, result, 0);
190}
191EXPORT_SYMBOL(match_int);
192
193/**
194 * match_u64: - scan a decimal representation of a u64 from
195 * a substring_t
196 * @s: substring_t to be scanned
197 * @result: resulting unsigned long long on success
198 *
199 * Description: Attempts to parse the &substring_t @s as a long decimal
200 * integer. On success, sets @result to the integer represented by the
201 * string and returns 0.
202 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
203 */
204int match_u64(substring_t *s, u64 *result)
205{
206 return match_u64int(s, result, 0);
207}
208EXPORT_SYMBOL(match_u64);
209
210/**
211 * match_octal: - scan an octal representation of an integer from a substring_t
212 * @s: substring_t to be scanned
213 * @result: resulting integer on success
214 *
215 * Description: Attempts to parse the &substring_t @s as an octal integer. On
216 * success, sets @result to the integer represented by the string and returns
217 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
218 */
219int match_octal(substring_t *s, int *result)
220{
221 return match_number(s, result, 8);
222}
223EXPORT_SYMBOL(match_octal);
224
225/**
226 * match_hex: - scan a hex representation of an integer from a substring_t
227 * @s: substring_t to be scanned
228 * @result: resulting integer on success
229 *
230 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
231 * On success, sets @result to the integer represented by the string and
232 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
233 */
234int match_hex(substring_t *s, int *result)
235{
236 return match_number(s, result, 16);
237}
238EXPORT_SYMBOL(match_hex);
239
240/**
241 * match_wildcard: - parse if a string matches given wildcard pattern
242 * @pattern: wildcard pattern
243 * @str: the string to be parsed
244 *
245 * Description: Parse the string @str to check if matches wildcard
246 * pattern @pattern. The pattern may contain two type wildcardes:
247 * '*' - matches zero or more characters
248 * '?' - matches one character
249 * If it's matched, return true, else return false.
250 */
251bool match_wildcard(const char *pattern, const char *str)
252{
253 const char *s = str;
254 const char *p = pattern;
255 bool star = false;
256
257 while (*s) {
258 switch (*p) {
259 case '?':
260 s++;
261 p++;
262 break;
263 case '*':
264 star = true;
265 str = s;
266 if (!*++p)
267 return true;
268 pattern = p;
269 break;
270 default:
271 if (*s == *p) {
272 s++;
273 p++;
274 } else {
275 if (!star)
276 return false;
277 str++;
278 s = str;
279 p = pattern;
280 }
281 break;
282 }
283 }
284
285 if (*p == '*')
286 ++p;
287 return !*p;
288}
289EXPORT_SYMBOL(match_wildcard);
290
291/**
292 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
293 * @dest: where to copy to
294 * @src: &substring_t to copy
295 * @size: size of destination buffer
296 *
297 * Description: Copy the characters in &substring_t @src to the
298 * c-style string @dest. Copy no more than @size - 1 characters, plus
299 * the terminating NUL. Return length of @src.
300 */
301size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
302{
303 size_t ret = src->to - src->from;
304
305 if (size) {
306 size_t len = ret >= size ? size - 1 : ret;
307 memcpy(dest, src->from, len);
308 dest[len] = '\0';
309 }
310 return ret;
311}
312EXPORT_SYMBOL(match_strlcpy);
313
314/**
315 * match_strdup: - allocate a new string with the contents of a substring_t
316 * @s: &substring_t to copy
317 *
318 * Description: Allocates and returns a string filled with the contents of
319 * the &substring_t @s. The caller is responsible for freeing the returned
320 * string with kfree().
321 */
322char *match_strdup(const substring_t *s)
323{
324 return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
325}
326EXPORT_SYMBOL(match_strdup);
327