#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/proc_fs.h>

#define procfs_name		"helloworld"

struct proc_dir_entry* Our_Proc_File;
struct proc_dir_entry proc_root;

int procfile_read(char* buf, char** buf_loc, off_t off, int buf_len, int* eof, void* data)
{
	int ret;

	printk(KERN_INFO "procfile_read (/proc/%s) called\n", procfs_name);

	if (off > 0)
		ret = 0;
	else
		ret = sprintf(buf, "HelloWorld!\n");

	return ret;
}

int init_module(void)
{
	Our_Proc_File = create_proc_entry(procfs_name, 0644, NULL);

	if (Our_Proc_File == NULL) {
		remove_proc_entry(procfs_name, NULL);
		//remove_proc_entry(procfs_name, &proc_root);
		printk(KERN_ALERT "Error: Could not initialize /proc/%s\n", procfs_name);
		return -ENOMEM;
	}

	Our_Proc_File->read_proc = procfile_read;
	Our_Proc_File->mode = S_IFREG | S_IRUGO;
	Our_Proc_File->uid = 0;
	Our_Proc_File->gid = 0;
	Our_Proc_File->size = 37;

	printk(KERN_INFO "/proc/%s created\n", procfs_name);
	return 0;
}

void cleanup_module(void)
{
	remove_proc_entry(procfs_name, NULL);
	//remove_proc_entry(procfs_name, &proc_root);
	printk(KERN_INFO "/proc/%s removed\n", procfs_name);
}