1 /*
2 * kernel/configs.c
3 * Echo the kernel .config file used to build the kernel
4 *
5 * Copyright (C) 2002 Khalid Aziz <khalid_aziz@hp.com>
6 * Copyright (C) 2002 Randy Dunlap <rdunlap@xenotime.net>
7 * Copyright (C) 2002 Al Stone <ahs3@fc.hp.com>
8 * Copyright (C) 2002 Hewlett-Packard Company
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or (at
13 * your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
18 * NON INFRINGEMENT. See the GNU General Public License for more
19 * details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 */
25
26 #include <linux/config.h>
27 #include <linux/kernel.h>
28 #include <linux/module.h>
29 #include <linux/proc_fs.h>
30 #include <linux/seq_file.h>
31 #include <linux/init.h>
32 #include <asm/uaccess.h>
33
34 /**************************************************/
35 /* the actual current config file */
36
37 /*
38 * Define kernel_config_data and kernel_config_data_size, which contains the
39 * wrapped and compressed configuration file. The file is first compressed
40 * with gzip and then bounded by two eight byte magic numbers to allow
41 * extraction from a binary kernel image:
42 *
43 * IKCFG_ST
44 * <image>
45 * IKCFG_ED
46 */
47 #define MAGIC_START "IKCFG_ST"
48 #define MAGIC_END "IKCFG_ED"
49 #include "config_data.h"
50
51
52 #define MAGIC_SIZE (sizeof(MAGIC_START) - 1)
53 #define kernel_config_data_size \
54 (sizeof(kernel_config_data) - 1 - MAGIC_SIZE * 2)
55
56 #ifdef CONFIG_IKCONFIG_PROC
57
58 /**************************************************/
59 /* globals and useful constants */
60
61 static ssize_t
62 ikconfig_read_current(struct file *file, char __user *buf,
63 size_t len, loff_t * offset)
64 {
65 loff_t pos = *offset;
66 ssize_t count;
67
68 if (pos >= kernel_config_data_size)
69 return 0;
70
71 count = min(len, (size_t)(kernel_config_data_size - pos));
72 if (copy_to_user(buf, kernel_config_data + MAGIC_SIZE + pos, count))
73 return -EFAULT;
74
75 *offset += count;
76 return count;
77 }
78
79 static struct file_operations ikconfig_file_ops = {
80 .owner = THIS_MODULE,
81 .read = ikconfig_read_current,
82 };
83
84 /***************************************************/
85 /* ikconfig_init: start up everything we need to */
86
87 static int __init ikconfig_init(void)
88 {
89 struct proc_dir_entry *entry;
90
91 /* create the current config file */
92 entry = create_proc_entry("config.gz", S_IFREG | S_IRUGO,
93 &proc_root);
94 if (!entry)
95 return -ENOMEM;
96
97 entry->proc_fops = &ikconfig_file_ops;
98 entry->size = kernel_config_data_size;
99
100 return 0;
101 }
102
103 /***************************************************/
104 /* ikconfig_cleanup: clean up our mess */
105
106 static void __exit ikconfig_cleanup(void)
107 {
108 remove_proc_entry("config.gz", &proc_root);
109 }
110
111 module_init(ikconfig_init);
112 module_exit(ikconfig_cleanup);
113
114 MODULE_LICENSE("GPL");
115 MODULE_AUTHOR("Randy Dunlap");
116 MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");
117
118 #endif /* CONFIG_IKCONFIG_PROC */
119
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