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, count: 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, count: 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, count: 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(filp: file, wait_address: &log_wait, p: wait); |
43 | if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, count: 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(name: "kmsg" , S_IRUSR, NULL, proc_ops: &kmsg_proc_ops); |
61 | return 0; |
62 | } |
63 | fs_initcall(proc_kmsg_init); |
64 | |