#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include<linux/sched.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/slab.h>
#include <linux/random.h>


#define PROC_FILE_NAME "extra_iparrot"

#define LENMAX 1024
char message[LENMAX] = "I have two cats in my garage, named Zeke and Tabby\n";
size_t mlen;

ssize_t read_simple(struct file *filp, char *buf, size_t count, loff_t *offp ) {
	if(*offp < mlen) { // If we have data to deliver
		size_t quantity = mlen - *offp;
		if(count < quantity)
			quantity = count;
		memcpy(buf, message + *offp, quantity);
		*offp += quantity;
		return quantity;
	} else {
		return 0;
	}
}

ssize_t change_message(struct file *filp, const char* buf, size_t count, loff_t *offp){
	size_t copy_size = count;
	char *i;
	if(copy_size > LENMAX - 1)
		copy_size = LENMAX - 1;
	mlen = copy_size;
	memcpy(message, buf, copy_size);

	for(i = message; *i; i++){
		if(get_random_long() % 8 == 0){
			*i += 1;
		}	
	}

	return count;
}

struct file_operations proc_fops = {
read: read_simple,
      write: change_message,
};

int init_module (void) {
	mlen = strlen(message);
	message[LENMAX - 1] = 0;
	proc_create(PROC_FILE_NAME,0,NULL,&proc_fops);
	return 0;
}

void cleanup_module(void) {
	remove_proc_entry(PROC_FILE_NAME,NULL);
}

MODULE_LICENSE("GPL");