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 
exitcode_proc_show(struct seq_file * m,void * v)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 
exitcode_proc_open(struct inode * inode,struct file * file)34 static int exitcode_proc_open(struct inode *inode, struct file *file)
35 {
36 	return single_open(file, exitcode_proc_show, NULL);
37 }
38 
exitcode_proc_write(struct file * file,const char __user * buffer,size_t count,loff_t * pos)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 
make_proc_exitcode(void)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);
80