arch/um/kernel/exitcode.c

   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 proc_ops exitcode_proc_ops = {
  59         .proc_open      = exitcode_proc_open,
  60         .proc_read      = seq_read,
  61         .proc_lseek     = seq_lseek,
  62         .proc_release   = single_release,
  63         .proc_write     = exitcode_proc_write,
  64 };
  65
  66 static int make_proc_exitcode(void)
  67 {
  68         struct proc_dir_entry *ent;
  69
  70         ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_ops);
  71         if (ent == NULL) {
  72                 printk(KERN_WARNING "make_proc_exitcode : Failed to register "
  73                        "/proc/exitcode\n");
  74                 return 0;
  75         }
  76         return 0;
  77 }
  78
  79 __initcall(make_proc_exitcode);