kmsg.c

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/*
 *  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 <asm/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_FILE);
}

static int kmsg_release(struct inode * inode, struct file * file)
{
    (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_FILE);
    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_FILE))
        return -EAGAIN;
    return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_FILE);
}

static unsigned int 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_FILE))
        return POLLIN | POLLRDNORM;
    return 0;
}


static const struct file_operations proc_kmsg_operations = {
    .read       = kmsg_read,
    .poll       = kmsg_poll,
    .open       = kmsg_open,
    .release    = kmsg_release,
    .llseek     = generic_file_llseek,
};

static int __init proc_kmsg_init(void)
{
    proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
    return 0;
}
module_init(proc_kmsg_init);