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Linux/lib/parser.c

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

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