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 */
19int uml_exitcode = 0;
20
21static 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
34static int exitcode_proc_open(struct inode *inode, struct file *file)
35{
36	return single_open(file, exitcode_proc_show, NULL);
37}
38
39static 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
58static 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
66static 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);
80