// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/proc/kmsg.c * * Copyright (C) 1992 by Linus Torvalds * */ #include <linux/types.h> #include <linux/errno.h> #include <linux/time.h> #include <linux/kernel.h> #include <linux/poll.h> #include <linux/proc_fs.h> #include <linux/fs.h> #include <linux/syslog.h> #include <linux/uaccess.h> #include <asm/io.h> extern wait_queue_head_t log_wait; static int kmsg_open(struct inode * inode, struct file * file) { return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC); } static int kmsg_release(struct inode * inode, struct file * file) { (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC); return 0; } static ssize_t kmsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { if ((file->f_flags & O_NONBLOCK) && !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC)) return -EAGAIN; return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC); } static __poll_t kmsg_poll(struct file *file, poll_table *wait) { poll_wait(file, &log_wait, wait); if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC)) return EPOLLIN | EPOLLRDNORM; return 0; } static const struct proc_ops kmsg_proc_ops = { .proc_flags = PROC_ENTRY_PERMANENT, .proc_read = kmsg_read, .proc_poll = kmsg_poll, .proc_open = kmsg_open, .proc_release = kmsg_release, .proc_lseek = generic_file_llseek, }; static int __init proc_kmsg_init(void) { proc_create("kmsg", S_IRUSR, NULL, &kmsg_proc_ops); return 0; } fs_initcall(proc_kmsg_init);