#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>

#define PROC_FILE_NAME "remember_file"
#define BUFSIZE (1024*1024)

unsigned char *buffer;
size_t buffer_contents = 0;
ssize_t read_simple(struct file *filp,char *buf,size_t count,loff_t *offp ) 
{
	size_t copysize = count;
	size_t potential_copy = buffer_contents - *offp;
	printk("READ:  buf = %lx, count = %lu, *loff_t = %llu\n", (long unsigned int)buf, count, *offp);
	if(*offp >= buffer_contents)
		return 0;
	if(potential_copy < count)
		copysize = potential_copy;
	memcpy(buf, buffer + *offp, copysize);
	*offp += copysize;
	return copysize;
}

unsigned int call_count = 0;
ssize_t write_simple(struct file *filp,const char *buf,size_t count,loff_t *offp)
{
	size_t copysize = count;
	printk("WRITE:  content = %s\n, buf = %lx, count = %lu, *loff_t = %llu\n", buf, (long unsigned int)buf, count, *offp);
	if(count + buffer_contents > BUFSIZE)
		copysize = BUFSIZE - buffer_contents;
	memcpy(buffer + buffer_contents, buf, copysize);
	*offp += copysize;
	buffer_contents += copysize;
	return copysize;
}

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

int proc_init (void) {
	printk("We're in the kernel!\n");
	buffer = kmalloc(BUFSIZE, GFP_KERNEL);
	proc_create(PROC_FILE_NAME,0,NULL,&proc_fops);
	return 0;
}

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

MODULE_LICENSE("GPL"); 
module_init(proc_init);
module_exit(proc_cleanup);