xref: /openbmc/linux/lib/parser.c (revision 00140a83)
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