arch/um/kernel/exitcode.c

   1 /*
   2  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <linux/ctype.h>
   7 #include <linux/init.h>
   8 #include <linux/kernel.h>
   9 #include <linux/proc_fs.h>
  10 #include <linux/types.h>
  11 #include <asm/uaccess.h>
  12
  13 /*
  14  * If read and write race, the read will still atomically read a valid
  15  * value.
  16  */
  17 int uml_exitcode = 0;
  18
  19 static int read_proc_exitcode(char *page, char **start, off_t off,
  20                               int count, int *eof, void *data)
  21 {
  22         int len, val;
  23
  24         /*
  25          * Save uml_exitcode in a local so that we don't need to guarantee
  26          * that sprintf accesses it atomically.
  27          */
  28         val = uml_exitcode;
  29         len = sprintf(page, "%d\n", val);
  30         len -= off;
  31         if (len <= off+count)
  32                 *eof = 1;
  33         *start = page + off;
  34         if (len > count)
  35                 len = count;
  36         if (len < 0)
  37                 len = 0;
  38         return len;
  39 }
  40
  41 static int write_proc_exitcode(struct file *file, const char __user *buffer,
  42                                unsigned long count, void *data)
  43 {
  44         char *end, buf[sizeof("nnnnn\0")];
  45         int tmp;
  46
  47         if (copy_from_user(buf, buffer, count))
  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 int make_proc_exitcode(void)
  59 {
  60         struct proc_dir_entry *ent;
  61
  62         ent = create_proc_entry("exitcode", 0600, &proc_root);
  63         if (ent == NULL) {
  64                 printk(KERN_WARNING "make_proc_exitcode : Failed to register "
  65                        "/proc/exitcode\n");
  66                 return 0;
  67         }
  68
  69         ent->read_proc = read_proc_exitcode;
  70         ent->write_proc = write_proc_exitcode;
  71
  72         return 0;
  73 }
  74
  75 __initcall(make_proc_exitcode);