fs/proc/kmsg.c

   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
  20 extern wait_queue_head_t log_wait;
  21
  22 static int kmsg_open(struct inode * inode, struct file * file)
  23 {
  24         return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);
  25 }
  26
  27 static int kmsg_release(struct inode * inode, struct file * file)
  28 {
  29         (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);
  30         return 0;
  31 }
  32
  33 static 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_PROC))
  38                 return -EAGAIN;
  39         return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);
  40 }
  41
  42 static 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_PROC))
  46                 return POLLIN | POLLRDNORM;
  47         return 0;
  48 }
  49
  50
  51 static 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
  59 static int __init proc_kmsg_init(void)
  60 {
  61         proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
  62         return 0;
  63 }
  64 fs_initcall(proc_kmsg_init);