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Linux/lib/parser.c

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  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);
325 

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