kernel/configs.c

   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 <rddunlap@osdl.org>
   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 */