1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/proc/kmsg.c
4 *
5 * Copyright (C) 1992 by Linus Torvalds
6 *
7 */
8
9 #include <linux/types.h>
10 #include <linux/errno.h>
11 #include <linux/time.h>
12 #include <linux/kernel.h>
13 #include <linux/poll.h>
14 #include <linux/proc_fs.h>
15 #include <linux/fs.h>
16 #include <linux/syslog.h>
17
18 #include <asm/io.h>
19
20 static int kmsg_open(struct inode * inode, struct file * file)
21 {
22 return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);
23 }
24
25 static int kmsg_release(struct inode * inode, struct file * file)
26 {
27 (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);
28 return 0;
29 }
30
31 static ssize_t kmsg_read(struct file *file, char __user *buf,
32 size_t count, loff_t *ppos)
33 {
34 if ((file->f_flags & O_NONBLOCK) &&
35 !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
36 return -EAGAIN;
37 return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);
38 }
39
40 static __poll_t kmsg_poll(struct file *file, poll_table *wait)
41 {
42 poll_wait(file, &log_wait, wait);
43 if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
44 return EPOLLIN | EPOLLRDNORM;
45 return 0;
46 }
47
48
49 static const struct proc_ops kmsg_proc_ops = {
50 .proc_flags = PROC_ENTRY_PERMANENT,
51 .proc_read = kmsg_read,
52 .proc_poll = kmsg_poll,
53 .proc_open = kmsg_open,
54 .proc_release = kmsg_release,
55 .proc_lseek = generic_file_llseek,
56 };
57
58 static int __init proc_kmsg_init(void)
59 {
60 proc_create("kmsg", S_IRUSR, NULL, &kmsg_proc_ops);
61 return 0;
62 }
63 fs_initcall(proc_kmsg_init);
64
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