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/parser.h>
10 #include <linux/slab.h>
11 #include <linux/string.h>
12
13 /**
14 * match_one: - Determines if a string matches a simple pattern
15 * @s: the string to examine for presence of the pattern
16 * @p: the string containing the pattern
17 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
18 * locations.
19 *
20 * Description: Determines if the pattern @p is present in string @s. Can only
21 * match extremely simple token=arg style patterns. If the pattern is found,
22 * the location(s) of the arguments will be returned in the @args array.
23 */
24 static int match_one(char *s, const char *p, substring_t args[])
25 {
26 char *meta;
27 int argc = 0;
28
29 if (!p)
30 return 1;
31
32 while(1) {
33 int len = -1;
34 meta = strchr(p, '%');
35 if (!meta)
36 return strcmp(p, s) == 0;
37
38 if (strncmp(p, s, meta-p))
39 return 0;
40
41 s += meta - p;
42 p = meta + 1;
43
44 if (isdigit(*p))
45 len = simple_strtoul(p, (char **) &p, 10);
46 else if (*p == '%') {
47 if (*s++ != '%')
48 return 0;
49 p++;
50 continue;
51 }
52
53 if (argc >= MAX_OPT_ARGS)
54 return 0;
55
56 args[argc].from = s;
57 switch (*p++) {
58 case 's': {
59 size_t str_len = strlen(s);
60
61 if (str_len == 0)
62 return 0;
63 if (len == -1 || len > str_len)
64 len = str_len;
65 args[argc].to = s + len;
66 break;
67 }
68 case 'd':
69 simple_strtol(s, &args[argc].to, 0);
70 goto num;
71 case 'u':
72 simple_strtoul(s, &args[argc].to, 0);
73 goto num;
74 case 'o':
75 simple_strtoul(s, &args[argc].to, 8);
76 goto num;
77 case 'x':
78 simple_strtoul(s, &args[argc].to, 16);
79 num:
80 if (args[argc].to == args[argc].from)
81 return 0;
82 break;
83 default:
84 return 0;
85 }
86 s = args[argc].to;
87 argc++;
88 }
89 }
90
91 /**
92 * match_token: - Find a token (and optional args) in a string
93 * @s: the string to examine for token/argument pairs
94 * @table: match_table_t describing the set of allowed option tokens and the
95 * arguments that may be associated with them. Must be terminated with a
96 * &struct match_token whose pattern is set to the NULL pointer.
97 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
98 * locations.
99 *
100 * Description: Detects which if any of a set of token strings has been passed
101 * to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
102 * format identifiers which will be taken into account when matching the
103 * tokens, and whose locations will be returned in the @args array.
104 */
105 int match_token(char *s, const match_table_t table, substring_t args[])
106 {
107 const struct match_token *p;
108
109 for (p = table; !match_one(s, p->pattern, args) ; p++)
110 ;
111
112 return p->token;
113 }
114 EXPORT_SYMBOL(match_token);
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 -ENOMEM, -EINVAL, or -ERANGE on failure.
125 */
126 static int match_number(substring_t *s, int *result, int base)
127 {
128 char *endp;
129 char *buf;
130 int ret;
131 long val;
132
133 buf = match_strdup(s);
134 if (!buf)
135 return -ENOMEM;
136
137 ret = 0;
138 val = simple_strtol(buf, &endp, base);
139 if (endp == buf)
140 ret = -EINVAL;
141 else if (val < (long)INT_MIN || val > (long)INT_MAX)
142 ret = -ERANGE;
143 else
144 *result = (int) val;
145 kfree(buf);
146 return ret;
147 }
148
149 /**
150 * match_u64int: scan a number in the given base from a substring_t
151 * @s: substring to be scanned
152 * @result: resulting u64 on success
153 * @base: base to use when converting string
154 *
155 * Description: Given a &substring_t and a base, attempts to parse the substring
156 * as a number in that base. On success, sets @result to the integer represented
157 * by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
158 */
159 static int match_u64int(substring_t *s, u64 *result, int base)
160 {
161 char *buf;
162 int ret;
163 u64 val;
164
165 buf = match_strdup(s);
166 if (!buf)
167 return -ENOMEM;
168
169 ret = kstrtoull(buf, base, &val);
170 if (!ret)
171 *result = val;
172 kfree(buf);
173 return ret;
174 }
175
176 /**
177 * match_int: - scan a decimal representation of an integer from a substring_t
178 * @s: substring_t to be scanned
179 * @result: resulting integer on success
180 *
181 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
182 * success, sets @result to the integer represented by the string and returns 0.
183 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
184 */
185 int match_int(substring_t *s, int *result)
186 {
187 return match_number(s, result, 0);
188 }
189 EXPORT_SYMBOL(match_int);
190
191 /**
192 * match_u64: - scan a decimal representation of a u64 from
193 * a substring_t
194 * @s: substring_t to be scanned
195 * @result: resulting unsigned long long on success
196 *
197 * Description: Attempts to parse the &substring_t @s as a long decimal
198 * integer. On success, sets @result to the integer represented by the
199 * string and returns 0.
200 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
201 */
202 int match_u64(substring_t *s, u64 *result)
203 {
204 return match_u64int(s, result, 0);
205 }
206 EXPORT_SYMBOL(match_u64);
207
208 /**
209 * match_octal: - scan an octal representation of an integer from a substring_t
210 * @s: substring_t to be scanned
211 * @result: resulting integer on success
212 *
213 * Description: Attempts to parse the &substring_t @s as an octal integer. On
214 * success, sets @result to the integer represented by the string and returns
215 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
216 */
217 int match_octal(substring_t *s, int *result)
218 {
219 return match_number(s, result, 8);
220 }
221 EXPORT_SYMBOL(match_octal);
222
223 /**
224 * match_hex: - scan a hex representation of an integer from a substring_t
225 * @s: substring_t to be scanned
226 * @result: resulting integer on success
227 *
228 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
229 * On success, sets @result to the integer represented by the string and
230 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
231 */
232 int match_hex(substring_t *s, int *result)
233 {
234 return match_number(s, result, 16);
235 }
236 EXPORT_SYMBOL(match_hex);
237
238 /**
239 * match_wildcard: - parse if a string matches given wildcard pattern
240 * @pattern: wildcard pattern
241 * @str: the string to be parsed
242 *
243 * Description: Parse the string @str to check if matches wildcard
244 * pattern @pattern. The pattern may contain two type wildcardes:
245 * '*' - matches zero or more characters
246 * '?' - matches one character
247 * If it's matched, return true, else return false.
248 */
249 bool match_wildcard(const char *pattern, const char *str)
250 {
251 const char *s = str;
252 const char *p = pattern;
253 bool star = false;
254
255 while (*s) {
256 switch (*p) {
257 case '?':
258 s++;
259 p++;
260 break;
261 case '*':
262 star = true;
263 str = s;
264 if (!*++p)
265 return true;
266 pattern = p;
267 break;
268 default:
269 if (*s == *p) {
270 s++;
271 p++;
272 } else {
273 if (!star)
274 return false;
275 str++;
276 s = str;
277 p = pattern;
278 }
279 break;
280 }
281 }
282
283 if (*p == '*')
284 ++p;
285 return !*p;
286 }
287 EXPORT_SYMBOL(match_wildcard);
288
289 /**
290 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
291 * @dest: where to copy to
292 * @src: &substring_t to copy
293 * @size: size of destination buffer
294 *
295 * Description: Copy the characters in &substring_t @src to the
296 * c-style string @dest. Copy no more than @size - 1 characters, plus
297 * the terminating NUL. Return length of @src.
298 */
299 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
300 {
301 size_t ret = src->to - src->from;
302
303 if (size) {
304 size_t len = ret >= size ? size - 1 : ret;
305 memcpy(dest, src->from, len);
306 dest[len] = '\0';
307 }
308 return ret;
309 }
310 EXPORT_SYMBOL(match_strlcpy);
311
312 /**
313 * match_strdup: - allocate a new string with the contents of a substring_t
314 * @s: &substring_t to copy
315 *
316 * Description: Allocates and returns a string filled with the contents of
317 * the &substring_t @s. The caller is responsible for freeing the returned
318 * string with kfree().
319 */
320 char *match_strdup(const substring_t *s)
321 {
322 return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
323 }
324 EXPORT_SYMBOL(match_strdup);