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 <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/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/init.h>
  31 #include <asm/uaccess.h>
  32
  33 /**************************************************/
  34 /* the actual current config file                 */
  35
  36 /*
  37  * Define kernel_config_data and kernel_config_data_size, which contains the
  38  * wrapped and compressed configuration file.  The file is first compressed
  39  * with gzip and then bounded by two eight byte magic numbers to allow
  40  * extraction from a binary kernel image:
  41  *
  42  *   IKCFG_ST
  43  *   <image>
  44  *   IKCFG_ED
  45  */
  46 #define MAGIC_START     "IKCFG_ST"
  47 #define MAGIC_END       "IKCFG_ED"
  48 #include "config_data.h"
  49
  50
  51 #define MAGIC_SIZE (sizeof(MAGIC_START) - 1)
  52 #define kernel_config_data_size \
  53         (sizeof(kernel_config_data) - 1 - MAGIC_SIZE * 2)
  54
  55 #ifdef CONFIG_IKCONFIG_PROC
  56
  57 static ssize_t
  58 ikconfig_read_current(struct file *file, char __user *buf,
  59                       size_t len, loff_t * offset)
  60 {
  61         return simple_read_from_buffer(buf, len, offset,
  62                                        kernel_config_data + MAGIC_SIZE,
  63                                        kernel_config_data_size);
  64 }
  65
  66 static const struct file_operations ikconfig_file_ops = {
  67         .owner = THIS_MODULE,
  68         .read = ikconfig_read_current,
  69         .llseek = default_llseek,
  70 };
  71
  72 static int __init ikconfig_init(void)
  73 {
  74         struct proc_dir_entry *entry;
  75
  76         /* create the current config file */
  77         entry = proc_create("config.gz", S_IFREG | S_IRUGO, NULL,
  78                             &ikconfig_file_ops);
  79         if (!entry)
  80                 return -ENOMEM;
  81
  82         proc_set_size(entry, kernel_config_data_size);
  83
  84         return 0;
  85 }
  86
  87 static void __exit ikconfig_cleanup(void)
  88 {
  89         remove_proc_entry("config.gz", NULL);
  90 }
  91
  92 module_init(ikconfig_init);
  93 module_exit(ikconfig_cleanup);
  94
  95 #endif /* CONFIG_IKCONFIG_PROC */
  96
  97 MODULE_LICENSE("GPL");
  98 MODULE_AUTHOR("Randy Dunlap");
  99 MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");