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exitcode.c

/*
 * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include "linux/kernel.h"
#include "linux/init.h"
#include "linux/ctype.h"
#include "linux/proc_fs.h"
#include "asm/uaccess.h"

/* If read and write race, the read will still atomically read a valid
 * value.
 */
int uml_exitcode = 0;

static int read_proc_exitcode(char *page, char **start, off_t off,
                        int count, int *eof, void *data)
{
      int len, val;

      /* Save uml_exitcode in a local so that we don't need to guarantee
       * that sprintf accesses it atomically.
       */
      val = uml_exitcode;
      len = sprintf(page, "%d\n", val);
      len -= off;
      if(len <= off+count)
            *eof = 1;
      *start = page + off;
      if(len > count)
            len = count;
      if(len < 0)
            len = 0;
      return len;
}

static int write_proc_exitcode(struct file *file, const char __user *buffer,
                         unsigned long count, void *data)
{
      char *end, buf[sizeof("nnnnn\0")];
      int tmp;

      if(copy_from_user(buf, buffer, count))
            return -EFAULT;

      tmp = simple_strtol(buf, &end, 0);
      if((*end != '\0') && !isspace(*end))
            return -EINVAL;

      uml_exitcode = tmp;
      return count;
}

static int make_proc_exitcode(void)
{
      struct proc_dir_entry *ent;

      ent = create_proc_entry("exitcode", 0600, &proc_root);
      if(ent == NULL){
            printk(KERN_WARNING "make_proc_exitcode : Failed to register "
                   "/proc/exitcode\n");
            return 0;
      }

      ent->read_proc = read_proc_exitcode;
      ent->write_proc = write_proc_exitcode;

      return 0;
}

__initcall(make_proc_exitcode);

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