#include <linux/module.h>	// Needed by all modules
#include <linux/kernel.h>	// KERN_INFO
#include <linux/sched.h>	// for_each_process, pr_info
#include <linux/uaccess.h>	// For copy_to_user
#include <linux/slab.h>		// kmalloc, apparantly
#include <linux/fs.h>		// file_operations
#include <linux/proc_fs.h>	// proc_create

#define PROC_FILE_NAME "prinfo"
#define INITIAL_REPORT_SIZE (1024*8)

char* query;
size_t qlen = 1024;
char* report;
size_t reportlen;
size_t read_spot;
ssize_t returnresults(struct file *filp,char *buf,size_t count,loff_t *offp ) 
{
	// User has space for count
	// We want to give them reportlen - read_spot
	size_t len = (count > reportlen - read_spot)? (reportlen - read_spot):count;
	if(read_spot == reportlen){
		read_spot = 0;
		return 0;
	}
	copy_to_user(buf, report + read_spot, len);
	read_spot += len;
	return len;
}

unsigned int call_count = 0;
ssize_t doquery(struct file *filp,const char *buf,size_t count,loff_t *offp)
{
	struct task_struct* task_list;
	unsigned int task_count = 0;
	
	int len = (qlen > count)? count:qlen;
	copy_from_user(query, buf, len);
	if(query[len-1] == '\n' || query[len-1] == ' ')
		query[len-1] = 0;
	else
		query[len] = 0;
	printk("Received Query: %s\n", query);
	
	report = kmalloc(INITIAL_REPORT_SIZE, 0);
	reportlen = 0;
	for_each_process(task_list) {
		if(strstr(task_list->comm, query)){
			// This kind of thing:  "Result 0:  name_of_process\n"
			// Virtual Memory Areas:  
			//   Starting Address:  task_list->mm->vm_start, vm_next is the next one!
			struct vm_area_struct *curr = task_list->mm->mmap;
			reportlen += snprintf(report + reportlen, INITIAL_REPORT_SIZE - reportlen, 
				"Result %d [%d]: %s\n", task_count, task_list->pid, task_list->comm);
			while(curr){
				if(curr->vm_file)
					reportlen += snprintf(report + reportlen, INITIAL_REPORT_SIZE - reportlen, 
						"VMA:  %lx (%s)\n", curr->vm_start, curr->vm_file->f_path.dentry->d_iname);
				else
					reportlen += snprintf(report + reportlen, INITIAL_REPORT_SIZE - reportlen, 
						"VMA:  %lx ()\n", curr->vm_start);
				// The filename:  curr->vm_file.path->dentry->d_iname

				curr = curr->vm_next;
			}
			task_count++;
		}
	}
	read_spot = 0;
	return len;
}

struct file_operations proc_fops = {
	read: returnresults,
	write: doquery
};

int init_module(void){
	query = kmalloc(qlen, 0);
	proc_create(PROC_FILE_NAME,0,NULL,&proc_fops);
	return 0;
}

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


MODULE_LICENSE("GPL");