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1da177e4 LT |
1 | /* |
2 | * procfs_example.c: an example proc interface | |
3 | * | |
758222f8 | 4 | * Copyright (C) 2001, Erik Mouw (mouw@nl.linux.org) |
1da177e4 LT |
5 | * |
6 | * This file accompanies the procfs-guide in the Linux kernel | |
7 | * source. Its main use is to demonstrate the concepts and | |
8 | * functions described in the guide. | |
9 | * | |
10 | * This software has been developed while working on the LART | |
758222f8 RD |
11 | * computing board (http://www.lartmaker.nl), which was sponsored |
12 | * by the Delt University of Technology projects Mobile Multi-media | |
13 | * Communications and Ubiquitous Communications. | |
1da177e4 LT |
14 | * |
15 | * This program is free software; you can redistribute | |
16 | * it and/or modify it under the terms of the GNU General | |
17 | * Public License as published by the Free Software | |
18 | * Foundation; either version 2 of the License, or (at your | |
19 | * option) any later version. | |
20 | * | |
21 | * This program is distributed in the hope that it will be | |
22 | * useful, but WITHOUT ANY WARRANTY; without even the implied | |
23 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR | |
24 | * PURPOSE. See the GNU General Public License for more | |
25 | * details. | |
26 | * | |
27 | * You should have received a copy of the GNU General Public | |
28 | * License along with this program; if not, write to the | |
29 | * Free Software Foundation, Inc., 59 Temple Place, | |
30 | * Suite 330, Boston, MA 02111-1307 USA | |
31 | * | |
32 | */ | |
33 | ||
34 | #include <linux/module.h> | |
35 | #include <linux/kernel.h> | |
36 | #include <linux/init.h> | |
37 | #include <linux/proc_fs.h> | |
38 | #include <linux/jiffies.h> | |
39 | #include <asm/uaccess.h> | |
40 | ||
41 | ||
42 | #define MODULE_VERS "1.0" | |
43 | #define MODULE_NAME "procfs_example" | |
44 | ||
45 | #define FOOBAR_LEN 8 | |
46 | ||
47 | struct fb_data_t { | |
48 | char name[FOOBAR_LEN + 1]; | |
49 | char value[FOOBAR_LEN + 1]; | |
50 | }; | |
51 | ||
52 | ||
53 | static struct proc_dir_entry *example_dir, *foo_file, | |
54 | *bar_file, *jiffies_file, *symlink; | |
55 | ||
56 | ||
57 | struct fb_data_t foo_data, bar_data; | |
58 | ||
59 | ||
60 | static int proc_read_jiffies(char *page, char **start, | |
61 | off_t off, int count, | |
62 | int *eof, void *data) | |
63 | { | |
64 | int len; | |
65 | ||
66 | len = sprintf(page, "jiffies = %ld\n", | |
67 | jiffies); | |
68 | ||
69 | return len; | |
70 | } | |
71 | ||
72 | ||
73 | static int proc_read_foobar(char *page, char **start, | |
74 | off_t off, int count, | |
75 | int *eof, void *data) | |
76 | { | |
77 | int len; | |
78 | struct fb_data_t *fb_data = (struct fb_data_t *)data; | |
79 | ||
80 | /* DON'T DO THAT - buffer overruns are bad */ | |
81 | len = sprintf(page, "%s = '%s'\n", | |
82 | fb_data->name, fb_data->value); | |
83 | ||
84 | return len; | |
85 | } | |
86 | ||
87 | ||
88 | static int proc_write_foobar(struct file *file, | |
89 | const char *buffer, | |
90 | unsigned long count, | |
91 | void *data) | |
92 | { | |
93 | int len; | |
94 | struct fb_data_t *fb_data = (struct fb_data_t *)data; | |
95 | ||
96 | if(count > FOOBAR_LEN) | |
97 | len = FOOBAR_LEN; | |
98 | else | |
99 | len = count; | |
100 | ||
101 | if(copy_from_user(fb_data->value, buffer, len)) | |
102 | return -EFAULT; | |
103 | ||
104 | fb_data->value[len] = '\0'; | |
105 | ||
106 | return len; | |
107 | } | |
108 | ||
109 | ||
110 | static int __init init_procfs_example(void) | |
111 | { | |
112 | int rv = 0; | |
113 | ||
114 | /* create directory */ | |
115 | example_dir = proc_mkdir(MODULE_NAME, NULL); | |
116 | if(example_dir == NULL) { | |
117 | rv = -ENOMEM; | |
118 | goto out; | |
119 | } | |
1da177e4 LT |
120 | /* create jiffies using convenience function */ |
121 | jiffies_file = create_proc_read_entry("jiffies", | |
122 | 0444, example_dir, | |
123 | proc_read_jiffies, | |
124 | NULL); | |
125 | if(jiffies_file == NULL) { | |
126 | rv = -ENOMEM; | |
127 | goto no_jiffies; | |
128 | } | |
129 | ||
1da177e4 LT |
130 | /* create foo and bar files using same callback |
131 | * functions | |
132 | */ | |
133 | foo_file = create_proc_entry("foo", 0644, example_dir); | |
134 | if(foo_file == NULL) { | |
135 | rv = -ENOMEM; | |
136 | goto no_foo; | |
137 | } | |
138 | ||
139 | strcpy(foo_data.name, "foo"); | |
140 | strcpy(foo_data.value, "foo"); | |
141 | foo_file->data = &foo_data; | |
142 | foo_file->read_proc = proc_read_foobar; | |
143 | foo_file->write_proc = proc_write_foobar; | |
1da177e4 LT |
144 | |
145 | bar_file = create_proc_entry("bar", 0644, example_dir); | |
146 | if(bar_file == NULL) { | |
147 | rv = -ENOMEM; | |
148 | goto no_bar; | |
149 | } | |
150 | ||
151 | strcpy(bar_data.name, "bar"); | |
152 | strcpy(bar_data.value, "bar"); | |
153 | bar_file->data = &bar_data; | |
154 | bar_file->read_proc = proc_read_foobar; | |
155 | bar_file->write_proc = proc_write_foobar; | |
1da177e4 LT |
156 | |
157 | /* create symlink */ | |
158 | symlink = proc_symlink("jiffies_too", example_dir, | |
159 | "jiffies"); | |
160 | if(symlink == NULL) { | |
161 | rv = -ENOMEM; | |
162 | goto no_symlink; | |
163 | } | |
164 | ||
1da177e4 LT |
165 | /* everything OK */ |
166 | printk(KERN_INFO "%s %s initialised\n", | |
167 | MODULE_NAME, MODULE_VERS); | |
168 | return 0; | |
169 | ||
170 | no_symlink: | |
1da177e4 LT |
171 | remove_proc_entry("bar", example_dir); |
172 | no_bar: | |
173 | remove_proc_entry("foo", example_dir); | |
174 | no_foo: | |
175 | remove_proc_entry("jiffies", example_dir); | |
176 | no_jiffies: | |
177 | remove_proc_entry(MODULE_NAME, NULL); | |
178 | out: | |
179 | return rv; | |
180 | } | |
181 | ||
182 | ||
183 | static void __exit cleanup_procfs_example(void) | |
184 | { | |
185 | remove_proc_entry("jiffies_too", example_dir); | |
1da177e4 LT |
186 | remove_proc_entry("bar", example_dir); |
187 | remove_proc_entry("foo", example_dir); | |
188 | remove_proc_entry("jiffies", example_dir); | |
189 | remove_proc_entry(MODULE_NAME, NULL); | |
190 | ||
191 | printk(KERN_INFO "%s %s removed\n", | |
192 | MODULE_NAME, MODULE_VERS); | |
193 | } | |
194 | ||
195 | ||
196 | module_init(init_procfs_example); | |
197 | module_exit(cleanup_procfs_example); | |
198 | ||
199 | MODULE_AUTHOR("Erik Mouw"); | |
200 | MODULE_DESCRIPTION("procfs examples"); | |
5d39d944 | 201 | MODULE_LICENSE("GPL"); |