root/arch/um/kernel/exitcode.c

DEFINITIONS

1. exitcode_proc_show
2. exitcode_proc_open
3. exitcode_proc_write
4. make_proc_exitcode

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  */
   5 
   6 #include <linux/ctype.h>
   7 #include <linux/init.h>
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/proc_fs.h>
  11 #include <linux/seq_file.h>
  12 #include <linux/types.h>
  13 #include <linux/uaccess.h>
  14 
  15 /*
  16  * If read and write race, the read will still atomically read a valid
  17  * value.
  18  */
  19 int uml_exitcode = 0;
  20 
  21 static int exitcode_proc_show(struct seq_file *m, void *v)
  22 {
  23         int val;
  24 
  25         /*
  26          * Save uml_exitcode in a local so that we don't need to guarantee
  27          * that sprintf accesses it atomically.
  28          */
  29         val = uml_exitcode;
  30         seq_printf(m, "%d\n", val);
  31         return 0;
  32 }
  33 
  34 static int exitcode_proc_open(struct inode *inode, struct file *file)
  35 {
  36         return single_open(file, exitcode_proc_show, NULL);
  37 }
  38 
  39 static ssize_t exitcode_proc_write(struct file *file,
  40                 const char __user *buffer, size_t count, loff_t *pos)
  41 {
  42         char *end, buf[sizeof("nnnnn\0")];
  43         size_t size;
  44         int tmp;
  45 
  46         size = min(count, sizeof(buf));
  47         if (copy_from_user(buf, buffer, size))
  48                 return -EFAULT;
  49 
  50         tmp = simple_strtol(buf, &end, 0);
  51         if ((*end != '\0') && !isspace(*end))
  52                 return -EINVAL;
  53 
  54         uml_exitcode = tmp;
  55         return count;
  56 }
  57 
  58 static const struct file_operations exitcode_proc_fops = {
  59         .owner          = THIS_MODULE,
  60         .open           = exitcode_proc_open,
  61         .read           = seq_read,
  62         .llseek         = seq_lseek,
  63         .release        = single_release,
  64         .write          = exitcode_proc_write,
  65 };
  66 
  67 static int make_proc_exitcode(void)
  68 {
  69         struct proc_dir_entry *ent;
  70 
  71         ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_fops);
  72         if (ent == NULL) {
  73                 printk(KERN_WARNING "make_proc_exitcode : Failed to register "
  74                        "/proc/exitcode\n");
  75                 return 0;
  76         }
  77         return 0;
  78 }
  79 
  80 __initcall(make_proc_exitcode);