arch/um/kernel/exitcode.c

   1 /*
   2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/kernel.h"
   7 #include "linux/init.h"
   8 #include "linux/ctype.h"
   9 #include "linux/proc_fs.h"
  10 #include "asm/uaccess.h"
  11
  12 /* If read and write race, the read will still atomically read a valid
  13  * value.
  14  */
  15 int uml_exitcode = 0;
  16
  17 static int read_proc_exitcode(char *page, char **start, off_t off,
  18                               int count, int *eof, void *data)
  19 {
  20         int len, val;
  21
  22         /* Save uml_exitcode in a local so that we don't need to guarantee
  23          * that sprintf accesses it atomically.
  24          */
  25         val = uml_exitcode;
  26         len = sprintf(page, "%d\n", val);
  27         len -= off;
  28         if(len <= off+count)
  29                 *eof = 1;
  30         *start = page + off;
  31         if(len > count)
  32                 len = count;
  33         if(len < 0)
  34                 len = 0;
  35         return len;
  36 }
  37
  38 static int write_proc_exitcode(struct file *file, const char __user *buffer,
  39                                unsigned long count, void *data)
  40 {
  41         char *end, buf[sizeof("nnnnn\0")];
  42         int tmp;
  43
  44         if(copy_from_user(buf, buffer, count))
  45                 return -EFAULT;
  46
  47         tmp = simple_strtol(buf, &end, 0);
  48         if((*end != '\0') && !isspace(*end))
  49                 return -EINVAL;
  50
  51         uml_exitcode = tmp;
  52         return count;
  53 }
  54
  55 static int make_proc_exitcode(void)
  56 {
  57         struct proc_dir_entry *ent;
  58
  59         ent = create_proc_entry("exitcode", 0600, &proc_root);
  60         if(ent == NULL){
  61                 printk(KERN_WARNING "make_proc_exitcode : Failed to register "
  62                        "/proc/exitcode\n");
  63                 return 0;
  64         }
  65
  66         ent->read_proc = read_proc_exitcode;
  67         ent->write_proc = write_proc_exitcode;
  68
  69         return 0;
  70 }
  71
  72 __initcall(make_proc_exitcode);