#include <linux/module.h>	// Needed by all modules
#include <linux/kernel.h>	// KERN_INFO
#include <linux/sched/signal.h>	// for_each_process, pr_info
#include <linux/init.h>
#include <linux/vt.h>
#include <linux/proc_fs.h>	// For proc filesystem

#define BUFLEN 1024
char report_buffer[BUFLEN];
void make_process_report(const char* process_name)
{
	struct task_struct* task_list;
	size_t process_counter = 0;
	int sofar = 0;
	printk("Running make_process_report, looking for %s (%lu characters)\n", process_name, strlen(process_name));
	for_each_process(task_list) {
		++process_counter;
		if(strstr(task_list->comm, process_name)){
			printk("Found process %s\n", task_list->comm);
			sofar += snprintf(report_buffer+sofar, BUFLEN-sofar, "%s (%d)\n", task_list->comm, task_list->pid);
//			sofar += snprintf(report_buffer+sofar, BUFLEN-sofar, "state: %ld\n", task_list->state);
			sofar += snprintf(report_buffer+sofar, BUFLEN-sofar, "prio: %d\n", task_list->prio);	
			sofar += snprintf(report_buffer+sofar, BUFLEN-sofar, "utime, stime, gtime: %llu, %llu, %llu\n", task_list->utime, task_list->stime, task_list->gtime);	
		}
	}
}

ssize_t read_handler(struct file *filp, char *buf, size_t count, loff_t *offp)
{
	register size_t len = strlen(report_buffer);
	size_t copylen = len - *offp;
	printk("len = %lu\n", len);
	printk("report_buffer contains %s\n", report_buffer);
	if(copylen > count)
		copylen = count;
	if(*offp == len)
		return 0;
	memcpy(buf, report_buffer + *offp, copylen);
	*offp += copylen;
	return copylen;
}

ssize_t write_handler(struct file *filp, const char *buf, size_t count, loff_t *offp)
{
	char process_name[128];
	memcpy(process_name, buf, count);
	process_name[count] = 0;
	if(process_name[count - 1] == '\n')
		process_name[count - 1] = 0;
	make_process_report(process_name);
	return count;
}

struct proc_ops proc_fops = {
	proc_write: write_handler,
	proc_read: read_handler		 
};

int init_module(void)
{
	proc_create("process_report", 0, NULL, &proc_fops);
	return 0;
}

void cleanup_module(void)
{
	remove_proc_entry("process_report", NULL);
}

MODULE_LICENSE("MIT");