/* Copyright 2006 Varun Marupadi
 * varun [dot] marupadi [at] gmail [dot] com
 * Unless mentioned otherwise below, this and 
 * all programs I write are distributed under the
 * terms of the GNU General Public License version
 * 2 only
 */

/*
 * force_printk: routine to push output directly to 
 * the screen: useful for quick debugging of kernel hacks.
 * Originally written for use in the CPS196 Systems and 
 * Networks class in the Computer Science Department at Duke 
 * University, Durham, NC in the Spring of 2006. 
 * This file is released by the author into the PUBLIC DOMAIN
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/tty.h>

/* 
 * Get as input the same parameters as printk(), write the
 * formatted output directly to the console of the current
 * process. String length limited to 1Kbytes. Return -1 on
 * error.
 */
int force_printk(char *format, ...)
{
    struct tty_struct *current_tty;
    va_list args;
    char out_string[1024];

    va_start(args, format);
    vsnprintf(out_string, sizeof(out_string), format, args);
    va_end(args);

    current_tty = current->signal->tty;

    if (current_tty == NULL)
	return -1;
    ((current_tty->driver)->write) (current_tty, out_string,
				    strlen(out_string));
    ((current_tty->driver)->write) (current_tty, "\r\n", 2);

    return 0;
}