Question about keyboard hack?

[qiang zeng <zengqianghit@gmail.com>]

Dear all,
Currently, i am trying to write a program that can hack into keyboard
input and record whatever the  key input into one file.

I got two questions here.
one is that i am trying to hack the put_queue() function, because it
says that the character that is tranlated from scancode is sent to
this function. Is that correct choice or i shall try other function??
_put_queue(int ch)
{
   loging (ch);
   put_queue(int ch);
}

second is that how i can write these character into a file from kernel space. 
i use sys_write(logfile, &ch , strlen(ch)); 
always my pc hungs when executing.

thanks in advance,
ZQ