linux/kernel/configs.c
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   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/**************************************************/
  58/* globals and useful constants                   */
  59
  60static ssize_t
  61ikconfig_read_current(struct file *file, char __user *buf,
  62                      size_t len, loff_t * offset)
  63{
  64        loff_t pos = *offset;
  65        ssize_t count;
  66
  67        if (pos >= kernel_config_data_size)
  68                return 0;
  69
  70        count = min(len, (size_t)(kernel_config_data_size - pos));
  71        if (copy_to_user(buf, kernel_config_data + MAGIC_SIZE + pos, count))
  72                return -EFAULT;
  73
  74        *offset += count;
  75        return count;
  76}
  77
  78static struct file_operations ikconfig_file_ops = {
  79        .owner = THIS_MODULE,
  80        .read = ikconfig_read_current,
  81};
  82
  83/***************************************************/
  84/* ikconfig_init: start up everything we need to */
  85
  86static int __init ikconfig_init(void)
  87{
  88        struct proc_dir_entry *entry;
  89
  90        /* create the current config file */
  91        entry = create_proc_entry("config.gz", S_IFREG | S_IRUGO,
  92                                  &proc_root);
  93        if (!entry)
  94                return -ENOMEM;
  95
  96        entry->proc_fops = &ikconfig_file_ops;
  97        entry->size = kernel_config_data_size;
  98
  99        return 0;
 100}
 101
 102/***************************************************/
 103/* ikconfig_cleanup: clean up our mess           */
 104
 105static void __exit ikconfig_cleanup(void)
 106{
 107        remove_proc_entry("config.gz", &proc_root);
 108}
 109
 110module_init(ikconfig_init);
 111module_exit(ikconfig_cleanup);
 112
 113MODULE_LICENSE("GPL");
 114MODULE_AUTHOR("Randy Dunlap");
 115MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");
 116
 117#endif /* CONFIG_IKCONFIG_PROC */
 118