linux/fs/proc/kmsg.c
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   1/*
   2 *  linux/fs/proc/kmsg.c
   3 *
   4 *  Copyright (C) 1992  by Linus Torvalds
   5 *
   6 */
   7
   8#include <linux/types.h>
   9#include <linux/errno.h>
  10#include <linux/time.h>
  11#include <linux/kernel.h>
  12#include <linux/poll.h>
  13#include <linux/proc_fs.h>
  14#include <linux/fs.h>
  15#include <linux/syslog.h>
  16
  17#include <asm/uaccess.h>
  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_FILE);
  25}
  26
  27static int kmsg_release(struct inode * inode, struct file * file)
  28{
  29        (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_FILE);
  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_FILE))
  38                return -EAGAIN;
  39        return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_FILE);
  40}
  41
  42static unsigned int 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_FILE))
  46                return POLLIN | POLLRDNORM;
  47        return 0;
  48}
  49
  50
  51static const struct file_operations proc_kmsg_operations = {
  52        .read           = kmsg_read,
  53        .poll           = kmsg_poll,
  54        .open           = kmsg_open,
  55        .release        = kmsg_release,
  56        .llseek         = generic_file_llseek,
  57};
  58
  59static int __init proc_kmsg_init(void)
  60{
  61        proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
  62        return 0;
  63}
  64module_init(proc_kmsg_init);
  65