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, NULL);
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);
76
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