Linux kernel mirror (for testing)
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linux
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
20extern wait_queue_head_t log_wait;
21
22static int kmsg_open(struct inode * inode, struct file * file)
23{
24 return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);
25}
26
27static int kmsg_release(struct inode * inode, struct file * file)
28{
29 (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);
30 return 0;
31}
32
33static ssize_t kmsg_read(struct file *file, char __user *buf,
34 size_t count, loff_t *ppos)
35{
36 if ((file->f_flags & O_NONBLOCK) &&
37 !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
38 return -EAGAIN;
39 return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);
40}
41
42static __poll_t kmsg_poll(struct file *file, poll_table *wait)
43{
44 poll_wait(file, &log_wait, wait);
45 if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
46 return EPOLLIN | EPOLLRDNORM;
47 return 0;
48}
49
50
51static const struct proc_ops kmsg_proc_ops = {
52 .proc_flags = PROC_ENTRY_PERMANENT,
53 .proc_read = kmsg_read,
54 .proc_poll = kmsg_poll,
55 .proc_open = kmsg_open,
56 .proc_release = kmsg_release,
57 .proc_lseek = generic_file_llseek,
58};
59
60static int __init proc_kmsg_init(void)
61{
62 proc_create("kmsg", S_IRUSR, NULL, &kmsg_proc_ops);
63 return 0;
64}
65fs_initcall(proc_kmsg_init);