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 * match_one: - Determines if a string matches a simple pattern
16 * @s: the string to examine for presence of the pattern
17 * @p: the string containing the pattern
18 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
19 * locations.
20 *
21 * Description: Determines if the pattern @p is present in string @s. Can only
22 * match extremely simple token=arg style patterns. If the pattern is found,
23 * the location(s) of the arguments will be returned in the @args array.
24 */
match_one(char * s,const char * p,substring_t args[])25 static int match_one(char *s, const char *p, substring_t args[])
26 {
27 char *meta;
28 int argc = 0;
29
30 if (!p)
31 return 1;
32
33 while(1) {
34 int len = -1;
35 meta = strchr(p, '%');
36 if (!meta)
37 return strcmp(p, s) == 0;
38
39 if (strncmp(p, s, meta-p))
40 return 0;
41
42 s += meta - p;
43 p = meta + 1;
44
45 if (isdigit(*p))
46 len = simple_strtoul(p, (char **) &p, 10);
47 else if (*p == '%') {
48 if (*s++ != '%')
49 return 0;
50 p++;
51 continue;
52 }
53
54 if (argc >= MAX_OPT_ARGS)
55 return 0;
56
57 args[argc].from = s;
58 switch (*p++) {
59 case 's': {
60 size_t str_len = strlen(s);
61
62 if (str_len == 0)
63 return 0;
64 if (len == -1 || len > str_len)
65 len = str_len;
66 args[argc].to = s + len;
67 break;
68 }
69 case 'd':
70 simple_strtol(s, &args[argc].to, 0);
71 goto num;
72 case 'u':
73 simple_strtoul(s, &args[argc].to, 0);
74 goto num;
75 case 'o':
76 simple_strtoul(s, &args[argc].to, 8);
77 goto num;
78 case 'x':
79 simple_strtoul(s, &args[argc].to, 16);
80 num:
81 if (args[argc].to == args[argc].from)
82 return 0;
83 break;
84 default:
85 return 0;
86 }
87 s = args[argc].to;
88 argc++;
89 }
90 }
91
92 /**
93 * match_token: - Find a token (and optional args) in a string
94 * @s: the string to examine for token/argument pairs
95 * @table: match_table_t describing the set of allowed option tokens and the
96 * arguments that may be associated with them. Must be terminated with a
97 * &struct match_token whose pattern is set to the NULL pointer.
98 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
99 * locations.
100 *
101 * Description: Detects which if any of a set of token strings has been passed
102 * to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
103 * format identifiers which will be taken into account when matching the
104 * tokens, and whose locations will be returned in the @args array.
105 */
match_token(char * s,const match_table_t table,substring_t args[])106 int match_token(char *s, const match_table_t table, substring_t args[])
107 {
108 const struct match_token *p;
109
110 for (p = table; !match_one(s, p->pattern, args) ; p++)
111 ;
112
113 return p->token;
114 }
115 EXPORT_SYMBOL(match_token);
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 */
match_number(substring_t * s,int * result,int base)127 static int match_number(substring_t *s, int *result, int base)
128 {
129 char *endp;
130 char *buf;
131 int ret;
132 long val;
133
134 buf = match_strdup(s);
135 if (!buf)
136 return -ENOMEM;
137
138 ret = 0;
139 val = simple_strtol(buf, &endp, base);
140 if (endp == buf)
141 ret = -EINVAL;
142 else if (val < (long)INT_MIN || val > (long)INT_MAX)
143 ret = -ERANGE;
144 else
145 *result = (int) val;
146 kfree(buf);
147 return ret;
148 }
149
150 /**
151 * match_u64int: scan a number in the given base from a substring_t
152 * @s: substring to be scanned
153 * @result: resulting u64 on success
154 * @base: base to use when converting string
155 *
156 * Description: Given a &substring_t and a base, attempts to parse the substring
157 * as a number in that base. On success, sets @result to the integer represented
158 * by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
159 */
match_u64int(substring_t * s,u64 * result,int base)160 static int match_u64int(substring_t *s, u64 *result, int base)
161 {
162 char *buf;
163 int ret;
164 u64 val;
165
166 buf = match_strdup(s);
167 if (!buf)
168 return -ENOMEM;
169
170 ret = kstrtoull(buf, base, &val);
171 if (!ret)
172 *result = val;
173 kfree(buf);
174 return ret;
175 }
176
177 /**
178 * match_int: - scan a decimal representation of an integer from a substring_t
179 * @s: substring_t to be scanned
180 * @result: resulting integer on success
181 *
182 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
183 * success, sets @result to the integer represented by the string and returns 0.
184 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
185 */
match_int(substring_t * s,int * result)186 int match_int(substring_t *s, int *result)
187 {
188 return match_number(s, result, 0);
189 }
190 EXPORT_SYMBOL(match_int);
191
192 /**
193 * match_u64: - scan a decimal representation of a u64 from
194 * a substring_t
195 * @s: substring_t to be scanned
196 * @result: resulting unsigned long long on success
197 *
198 * Description: Attempts to parse the &substring_t @s as a long decimal
199 * integer. On success, sets @result to the integer represented by the
200 * string and returns 0.
201 * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
202 */
match_u64(substring_t * s,u64 * result)203 int match_u64(substring_t *s, u64 *result)
204 {
205 return match_u64int(s, result, 0);
206 }
207 EXPORT_SYMBOL(match_u64);
208
209 /**
210 * match_octal: - scan an octal representation of an integer from a substring_t
211 * @s: substring_t to be scanned
212 * @result: resulting integer on success
213 *
214 * Description: Attempts to parse the &substring_t @s as an octal integer. On
215 * success, sets @result to the integer represented by the string and returns
216 * 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
217 */
match_octal(substring_t * s,int * result)218 int match_octal(substring_t *s, int *result)
219 {
220 return match_number(s, result, 8);
221 }
222 EXPORT_SYMBOL(match_octal);
223
224 /**
225 * match_hex: - scan a hex representation of an integer from a substring_t
226 * @s: substring_t to be scanned
227 * @result: resulting integer on success
228 *
229 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
230 * On success, sets @result to the integer represented by the string and
231 * returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
232 */
match_hex(substring_t * s,int * result)233 int match_hex(substring_t *s, int *result)
234 {
235 return match_number(s, result, 16);
236 }
237 EXPORT_SYMBOL(match_hex);
238
239 /**
240 * match_wildcard: - parse if a string matches given wildcard pattern
241 * @pattern: wildcard pattern
242 * @str: the string to be parsed
243 *
244 * Description: Parse the string @str to check if matches wildcard
245 * pattern @pattern. The pattern may contain two type wildcardes:
246 * '*' - matches zero or more characters
247 * '?' - matches one character
248 * If it's matched, return true, else return false.
249 */
match_wildcard(const char * pattern,const char * str)250 bool match_wildcard(const char *pattern, const char *str)
251 {
252 const char *s = str;
253 const char *p = pattern;
254 bool star = false;
255
256 while (*s) {
257 switch (*p) {
258 case '?':
259 s++;
260 p++;
261 break;
262 case '*':
263 star = true;
264 str = s;
265 if (!*++p)
266 return true;
267 pattern = p;
268 break;
269 default:
270 if (*s == *p) {
271 s++;
272 p++;
273 } else {
274 if (!star)
275 return false;
276 str++;
277 s = str;
278 p = pattern;
279 }
280 break;
281 }
282 }
283
284 if (*p == '*')
285 ++p;
286 return !*p;
287 }
288 EXPORT_SYMBOL(match_wildcard);
289
290 /**
291 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
292 * @dest: where to copy to
293 * @src: &substring_t to copy
294 * @size: size of destination buffer
295 *
296 * Description: Copy the characters in &substring_t @src to the
297 * c-style string @dest. Copy no more than @size - 1 characters, plus
298 * the terminating NUL. Return length of @src.
299 */
match_strlcpy(char * dest,const substring_t * src,size_t size)300 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
301 {
302 size_t ret = src->to - src->from;
303
304 if (size) {
305 size_t len = ret >= size ? size - 1 : ret;
306 memcpy(dest, src->from, len);
307 dest[len] = '\0';
308 }
309 return ret;
310 }
311 EXPORT_SYMBOL(match_strlcpy);
312
313 /**
314 * match_strdup: - allocate a new string with the contents of a substring_t
315 * @s: &substring_t to copy
316 *
317 * Description: Allocates and returns a string filled with the contents of
318 * the &substring_t @s. The caller is responsible for freeing the returned
319 * string with kfree().
320 */
match_strdup(const substring_t * s)321 char *match_strdup(const substring_t *s)
322 {
323 return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
324 }
325 EXPORT_SYMBOL(match_strdup);
326