1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * lib/parser.c - simple parser for mount, etc. options.
4 */
5
6 #include <linux/ctype.h>
7 #include <linux/types.h>
8 #include <linux/export.h>
9 #include <linux/kstrtox.h>
10 #include <linux/parser.h>
11 #include <linux/slab.h>
12 #include <linux/string.h>
13
14 /*
15 * max size needed by different bases to express U64
16 * HEX: "0xFFFFFFFFFFFFFFFF" --> 18
17 * DEC: "18446744073709551615" --> 20
18 * OCT: "01777777777777777777777" --> 23
19 * pick the max one to define NUMBER_BUF_LEN
20 */
21 #define NUMBER_BUF_LEN 24
22
23 /**
24 * match_one - Determines if a string matches a simple pattern
25 * @s: the string to examine for presence of the pattern
26 * @p: the string containing the pattern
27 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
28 * locations.
29 *
30 * Description: Determines if the pattern @p is present in string @s. Can only
31 * match extremely simple token=arg style patterns. If the pattern is found,
32 * the location(s) of the arguments will be returned in the @args array.
33 */
34 static int match_one(char *s, const char *p, substring_t args[])
35 {
36 char *meta;
37 int argc = 0;
38
39 if (!p)
40 return 1;
41
42 while(1) {
43 int len = -1;
44 meta = strchr(p, '%');
45 if (!meta)
46 return strcmp(p, s) == 0;
47
48 if (strncmp(p, s, meta-p))
49 return 0;
50
51 s += meta - p;
52 p = meta + 1;
53
54 if (isdigit(*p))
55 len = simple_strtoul(p, (char **) &p, 10);
56 else if (*p == '%') {
57 if (*s++ != '%')
58 return 0;
59 p++;
60 continue;
61 }
62
63 if (argc >= MAX_OPT_ARGS)
64 return 0;
65
66 args[argc].from = s;
67 switch (*p++) {
68 case 's': {
69 size_t str_len = strlen(s);
70
71 if (str_len == 0)
72 return 0;
73 if (len == -1 || len > str_len)
74 len = str_len;
75 args[argc].to = s + len;
76 break;
77 }
78 case 'd':
79 simple_strtol(s, &args[argc].to, 0);
80 goto num;
81 case 'u':
82 simple_strtoul(s, &args[argc].to, 0);
83 goto num;
84 case 'o':
85 simple_strtoul(s, &args[argc].to, 8);
86 goto num;
87 case 'x':
88 simple_strtoul(s, &args[argc].to, 16);
89 num:
90 if (args[argc].to == args[argc].from)
91 return 0;
92 break;
93 default:
94 return 0;
95 }
96 s = args[argc].to;
97 argc++;
98 }
99 }
100
101 /**
102 * match_token - Find a token (and optional args) in a string
103 * @s: the string to examine for token/argument pairs
104 * @table: match_table_t describing the set of allowed option tokens and the
105 * arguments that may be associated with them. Must be terminated with a
106 * &struct match_token whose pattern is set to the NULL pointer.
107 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
108 * locations.
109 *
110 * Description: Detects which if any of a set of token strings has been passed
111 * to it. Tokens can include up to %MAX_OPT_ARGS instances of basic c-style
112 * format identifiers which will be taken into account when matching the
113 * tokens, and whose locations will be returned in the @args array.
114 */
115 int match_token(char *s, const match_table_t table, substring_t args[])
116 {
117 const struct match_token *p;
118
119 for (p = table; !match_one(s, p->pattern, args) ; p++)
120 ;
121
122 return p->token;
123 }
124 EXPORT_SYMBOL(match_token);
125
126 /**
127 * match_number - scan a number in the given base from a substring_t
128 * @s: substring to be scanned
129 * @result: resulting integer on success
130 * @base: base to use when converting string
131 *
132 * Description: Given a &substring_t and a base, attempts to parse the substring
133 * as a number in that base.
134 *
135 * Return: On success, sets @result to the integer represented by the
136 * string and returns 0. Returns -EINVAL or -ERANGE on failure.
137 */
138 static int match_number(substring_t *s, int *result, int base)
139 {
140 char *endp;
141 char buf[NUMBER_BUF_LEN];
142 int ret;
143 long val;
144
145 if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
146 return -ERANGE;
147 ret = 0;
148 val = simple_strtol(buf, &endp, base);
149 if (endp == buf)
150 ret = -EINVAL;
151 else if (val < (long)INT_MIN || val > (long)INT_MAX)
152 ret = -ERANGE;
153 else
154 *result = (int) val;
155 return ret;
156 }
157
158 /**
159 * match_u64int - scan a number in the given base from a substring_t
160 * @s: substring to be scanned
161 * @result: resulting u64 on success
162 * @base: base to use when converting string
163 *
164 * Description: Given a &substring_t and a base, attempts to parse the substring
165 * as a number in that base.
166 *
167 * Return: On success, sets @result to the integer represented by the
168 * string and returns 0. Returns -EINVAL or -ERANGE on failure.
169 */
170 static int match_u64int(substring_t *s, u64 *result, int base)
171 {
172 char buf[NUMBER_BUF_LEN];
173 int ret;
174 u64 val;
175
176 if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
177 return -ERANGE;
178 ret = kstrtoull(buf, base, &val);
179 if (!ret)
180 *result = val;
181 return ret;
182 }
183
184 /**
185 * match_int - scan a decimal 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 decimal integer.
190 *
191 * Return: On success, sets @result to the integer represented by the string
192 * and returns 0. Returns -EINVAL or -ERANGE on failure.
193 */
194 int match_int(substring_t *s, int *result)
195 {
196 return match_number(s, result, 0);
197 }
198 EXPORT_SYMBOL(match_int);
199
200 /**
201 * match_uint - scan a decimal representation of an integer from a substring_t
202 * @s: substring_t to be scanned
203 * @result: resulting integer on success
204 *
205 * Description: Attempts to parse the &substring_t @s as a decimal integer.
206 *
207 * Return: On success, sets @result to the integer represented by the string
208 * and returns 0. Returns -EINVAL or -ERANGE on failure.
209 */
210 int match_uint(substring_t *s, unsigned int *result)
211 {
212 char buf[NUMBER_BUF_LEN];
213
214 if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
215 return -ERANGE;
216
217 return kstrtouint(buf, 10, result);
218 }
219 EXPORT_SYMBOL(match_uint);
220
221 /**
222 * match_u64 - scan a decimal representation of a u64 from
223 * a substring_t
224 * @s: substring_t to be scanned
225 * @result: resulting unsigned long long on success
226 *
227 * Description: Attempts to parse the &substring_t @s as a long decimal
228 * integer.
229 *
230 * Return: On success, sets @result to the integer represented by the string
231 * and returns 0. Returns -EINVAL or -ERANGE on failure.
232 */
233 int match_u64(substring_t *s, u64 *result)
234 {
235 return match_u64int(s, result, 0);
236 }
237 EXPORT_SYMBOL(match_u64);
238
239 /**
240 * match_octal - scan an octal representation of an integer from a substring_t
241 * @s: substring_t to be scanned
242 * @result: resulting integer on success
243 *
244 * Description: Attempts to parse the &substring_t @s as an octal integer.
245 *
246 * Return: On success, sets @result to the integer represented by the string
247 * and returns 0. Returns -EINVAL or -ERANGE on failure.
248 */
249 int match_octal(substring_t *s, int *result)
250 {
251 return match_number(s, result, 8);
252 }
253 EXPORT_SYMBOL(match_octal);
254
255 /**
256 * match_hex - scan a hex representation of an integer from a substring_t
257 * @s: substring_t to be scanned
258 * @result: resulting integer on success
259 *
260 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
261 *
262 * Return: On success, sets @result to the integer represented by the string
263 * and returns 0. Returns -EINVAL or -ERANGE on failure.
264 */
265 int match_hex(substring_t *s, int *result)
266 {
267 return match_number(s, result, 16);
268 }
269 EXPORT_SYMBOL(match_hex);
270
271 /**
272 * match_wildcard - parse if a string matches given wildcard pattern
273 * @pattern: wildcard pattern
274 * @str: the string to be parsed
275 *
276 * Description: Parse the string @str to check if matches wildcard
277 * pattern @pattern. The pattern may contain two types of wildcards:
278 * '*' - matches zero or more characters
279 * '?' - matches one character
280 *
281 * Return: If the @str matches the @pattern, return true, else return false.
282 */
283 bool match_wildcard(const char *pattern, const char *str)
284 {
285 const char *s = str;
286 const char *p = pattern;
287 bool star = false;
288
289 while (*s) {
290 switch (*p) {
291 case '?':
292 s++;
293 p++;
294 break;
295 case '*':
296 star = true;
297 str = s;
298 if (!*++p)
299 return true;
300 pattern = p;
301 break;
302 default:
303 if (*s == *p) {
304 s++;
305 p++;
306 } else {
307 if (!star)
308 return false;
309 str++;
310 s = str;
311 p = pattern;
312 }
313 break;
314 }
315 }
316
317 if (*p == '*')
318 ++p;
319 return !*p;
320 }
321 EXPORT_SYMBOL(match_wildcard);
322
323 /**
324 * match_strlcpy - Copy the characters from a substring_t to a sized buffer
325 * @dest: where to copy to
326 * @src: &substring_t to copy
327 * @size: size of destination buffer
328 *
329 * Description: Copy the characters in &substring_t @src to the
330 * c-style string @dest. Copy no more than @size - 1 characters, plus
331 * the terminating NUL.
332 *
333 * Return: length of @src.
334 */
335 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
336 {
337 size_t ret = src->to - src->from;
338
339 if (size) {
340 size_t len = ret >= size ? size - 1 : ret;
341 memcpy(dest, src->from, len);
342 dest[len] = '\0';
343 }
344 return ret;
345 }
346 EXPORT_SYMBOL(match_strlcpy);
347
348 /**
349 * match_strdup - allocate a new string with the contents of a substring_t
350 * @s: &substring_t to copy
351 *
352 * Description: Allocates and returns a string filled with the contents of
353 * the &substring_t @s. The caller is responsible for freeing the returned
354 * string with kfree().
355 *
356 * Return: the address of the newly allocated NUL-terminated string or
357 * %NULL on error.
358 */
359 char *match_strdup(const substring_t *s)
360 {
361 return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
362 }
363 EXPORT_SYMBOL(match_strdup);
364
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