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/module.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 presense 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 */
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 if (strlen(s) == 0)
61 return 0;
62 else if (len == -1 || len > strlen(s))
63 len = strlen(s);
64 args[argc].to = s + len;
65 break;
66 case 'd':
67 simple_strtol(s, &args[argc].to, 0);
68 goto num;
69 case 'u':
70 simple_strtoul(s, &args[argc].to, 0);
71 goto num;
72 case 'o':
73 simple_strtoul(s, &args[argc].to, 8);
74 goto num;
75 case 'x':
76 simple_strtoul(s, &args[argc].to, 16);
77 num:
78 if (args[argc].to == args[argc].from)
79 return 0;
80 break;
81 default:
82 return 0;
83 }
84 s = args[argc].to;
85 argc++;
86 }
87 }
88
89 /**
90 * match_token: - Find a token (and optional args) in a string
91 * @s: the string to examine for token/argument pairs
92 * @table: match_table_t describing the set of allowed option tokens and the
93 * arguments that may be associated with them. Must be terminated with a
94 * &struct match_token whose pattern is set to the NULL pointer.
95 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
96 * locations.
97 *
98 * Description: Detects which if any of a set of token strings has been passed
99 * to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
100 * format identifiers which will be taken into account when matching the
101 * tokens, and whose locations will be returned in the @args array.
102 */
103 int match_token(char *s, const match_table_t table, substring_t args[])
104 {
105 const struct match_token *p;
106
107 for (p = table; !match_one(s, p->pattern, args) ; p++)
108 ;
109
110 return p->token;
111 }
112
113 /**
114 * match_number: scan a number in the given base from a substring_t
115 * @s: substring to be scanned
116 * @result: resulting integer on success
117 * @base: base to use when converting string
118 *
119 * Description: Given a &substring_t and a base, attempts to parse the substring
120 * as a number in that base. On success, sets @result to the integer represented
121 * by the string and returns 0. Returns either -ENOMEM or -EINVAL on failure.
122 */
123 static int match_number(substring_t *s, int *result, int base)
124 {
125 char *endp;
126 char *buf;
127 int ret;
128
129 buf = kmalloc(s->to - s->from + 1, GFP_KERNEL);
130 if (!buf)
131 return -ENOMEM;
132 memcpy(buf, s->from, s->to - s->from);
133 buf[s->to - s->from] = '\0';
134 *result = simple_strtol(buf, &endp, base);
135 ret = 0;
136 if (endp == buf)
137 ret = -EINVAL;
138 kfree(buf);
139 return ret;
140 }
141
142 /**
143 * match_int: - scan a decimal representation of an integer from a substring_t
144 * @s: substring_t to be scanned
145 * @result: resulting integer on success
146 *
147 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
148 * success, sets @result to the integer represented by the string and returns 0.
149 * Returns either -ENOMEM or -EINVAL on failure.
150 */
151 int match_int(substring_t *s, int *result)
152 {
153 return match_number(s, result, 0);
154 }
155
156 /**
157 * match_octal: - scan an octal representation of an integer from a substring_t
158 * @s: substring_t to be scanned
159 * @result: resulting integer on success
160 *
161 * Description: Attempts to parse the &substring_t @s as an octal integer. On
162 * success, sets @result to the integer represented by the string and returns
163 * 0. Returns either -ENOMEM or -EINVAL on failure.
164 */
165 int match_octal(substring_t *s, int *result)
166 {
167 return match_number(s, result, 8);
168 }
169
170 /**
171 * match_hex: - scan a hex representation of an integer from a substring_t
172 * @s: substring_t to be scanned
173 * @result: resulting integer on success
174 *
175 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
176 * On success, sets @result to the integer represented by the string and
177 * returns 0. Returns either -ENOMEM or -EINVAL on failure.
178 */
179 int match_hex(substring_t *s, int *result)
180 {
181 return match_number(s, result, 16);
182 }
183
184 /**
185 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
186 * @dest: where to copy to
187 * @src: &substring_t to copy
188 * @size: size of destination buffer
189 *
190 * Description: Copy the characters in &substring_t @src to the
191 * c-style string @dest. Copy no more than @size - 1 characters, plus
192 * the terminating NUL. Return length of @src.
193 */
194 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
195 {
196 size_t ret = src->to - src->from;
197
198 if (size) {
199 size_t len = ret >= size ? size - 1 : ret;
200 memcpy(dest, src->from, len);
201 dest[len] = '\0';
202 }
203 return ret;
204 }
205
206 /**
207 * match_strdup: - allocate a new string with the contents of a substring_t
208 * @s: &substring_t to copy
209 *
210 * Description: Allocates and returns a string filled with the contents of
211 * the &substring_t @s. The caller is responsible for freeing the returned
212 * string with kfree().
213 */
214 char *match_strdup(const substring_t *s)
215 {
216 size_t sz = s->to - s->from + 1;
217 char *p = kmalloc(sz, GFP_KERNEL);
218 if (p)
219 match_strlcpy(p, s, sz);
220 return p;
221 }
222
223 EXPORT_SYMBOL(match_token);
224 EXPORT_SYMBOL(match_int);
225 EXPORT_SYMBOL(match_octal);
226 EXPORT_SYMBOL(match_hex);
227 EXPORT_SYMBOL(match_strlcpy);
228 EXPORT_SYMBOL(match_strdup);
229
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