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 */
match_one(char * s,const char * p,substring_t args[])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 */
match_token(char * s,const match_table_t table,substring_t args[])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
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 either -ENOMEM or -EINVAL 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 size_t len = s->to - s->from;
133
134 buf = kmalloc(len + 1, GFP_KERNEL);
135 if (!buf)
136 return -ENOMEM;
137 memcpy(buf, s->from, len);
138 buf[len] = '\0';
139 *result = simple_strtol(buf, &endp, base);
140 ret = 0;
141 if (endp == buf)
142 ret = -EINVAL;
143 kfree(buf);
144 return ret;
145 }
146
147 /**
148 * match_int: - scan a decimal representation of an integer from a substring_t
149 * @s: substring_t to be scanned
150 * @result: resulting integer on success
151 *
152 * Description: Attempts to parse the &substring_t @s as a decimal integer. On
153 * success, sets @result to the integer represented by the string and returns 0.
154 * Returns either -ENOMEM or -EINVAL on failure.
155 */
match_int(substring_t * s,int * result)156 int match_int(substring_t *s, int *result)
157 {
158 return match_number(s, result, 0);
159 }
160
161 /**
162 * match_octal: - scan an octal representation of an integer from a substring_t
163 * @s: substring_t to be scanned
164 * @result: resulting integer on success
165 *
166 * Description: Attempts to parse the &substring_t @s as an octal integer. On
167 * success, sets @result to the integer represented by the string and returns
168 * 0. Returns either -ENOMEM or -EINVAL on failure.
169 */
match_octal(substring_t * s,int * result)170 int match_octal(substring_t *s, int *result)
171 {
172 return match_number(s, result, 8);
173 }
174
175 /**
176 * match_hex: - scan a hex representation of an integer from a substring_t
177 * @s: substring_t to be scanned
178 * @result: resulting integer on success
179 *
180 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
181 * On success, sets @result to the integer represented by the string and
182 * returns 0. Returns either -ENOMEM or -EINVAL on failure.
183 */
match_hex(substring_t * s,int * result)184 int match_hex(substring_t *s, int *result)
185 {
186 return match_number(s, result, 16);
187 }
188
189 /**
190 * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
191 * @dest: where to copy to
192 * @src: &substring_t to copy
193 * @size: size of destination buffer
194 *
195 * Description: Copy the characters in &substring_t @src to the
196 * c-style string @dest. Copy no more than @size - 1 characters, plus
197 * the terminating NUL. Return length of @src.
198 */
match_strlcpy(char * dest,const substring_t * src,size_t size)199 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
200 {
201 size_t ret = src->to - src->from;
202
203 if (size) {
204 size_t len = ret >= size ? size - 1 : ret;
205 memcpy(dest, src->from, len);
206 dest[len] = '\0';
207 }
208 return ret;
209 }
210
211 /**
212 * match_strdup: - allocate a new string with the contents of a substring_t
213 * @s: &substring_t to copy
214 *
215 * Description: Allocates and returns a string filled with the contents of
216 * the &substring_t @s. The caller is responsible for freeing the returned
217 * string with kfree().
218 */
match_strdup(const substring_t * s)219 char *match_strdup(const substring_t *s)
220 {
221 size_t sz = s->to - s->from + 1;
222 char *p = kmalloc(sz, GFP_KERNEL);
223 if (p)
224 match_strlcpy(p, s, sz);
225 return p;
226 }
227
228 EXPORT_SYMBOL(match_token);
229 EXPORT_SYMBOL(match_int);
230 EXPORT_SYMBOL(match_octal);
231 EXPORT_SYMBOL(match_hex);
232 EXPORT_SYMBOL(match_strlcpy);
233 EXPORT_SYMBOL(match_strdup);
234