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 /**************************************************/
  58 /* globals and useful constants                   */
  59
  60 static ssize_t
  61 ikconfig_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
  78 static const 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
  86 static 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
 105 static void __exit ikconfig_cleanup(void)
 106 {
 107         remove_proc_entry("config.gz", &proc_root);
 108 }
 109
 110 module_init(ikconfig_init);
 111 module_exit(ikconfig_cleanup);
 112
 113 MODULE_LICENSE("GPL");
 114 MODULE_AUTHOR("Randy Dunlap");
 115 MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");
 116
 117 #endif /* CONFIG_IKCONFIG_PROC */