| 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); |