1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1992 by Linus Torvalds
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>
16 #include <linux/syslog.h>
18 #include <linux/uaccess.h>
21 extern wait_queue_head_t log_wait;
23 static int kmsg_open(struct inode * inode, struct file * file)
25 return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);
28 static int kmsg_release(struct inode * inode, struct file * file)
30 (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);
34 static ssize_t kmsg_read(struct file *file, char __user *buf,
35 size_t count, loff_t *ppos)
37 if ((file->f_flags & O_NONBLOCK) &&
38 !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
40 return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);
43 static __poll_t kmsg_poll(struct file *file, poll_table *wait)
45 poll_wait(file, &log_wait, wait);
46 if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
47 return EPOLLIN | EPOLLRDNORM;
52 static const struct proc_ops kmsg_proc_ops = {
53 .proc_flags = PROC_ENTRY_PERMANENT,
54 .proc_read = kmsg_read,
55 .proc_poll = kmsg_poll,
56 .proc_open = kmsg_open,
57 .proc_release = kmsg_release,
58 .proc_lseek = generic_file_llseek,
61 static int __init proc_kmsg_init(void)
63 proc_create("kmsg", S_IRUSR, NULL, &kmsg_proc_ops);
66 fs_initcall(proc_kmsg_init);