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

#define TIMER_DELAY HZ/5 // Should be 200ms
struct timer_list my_timer;
bool disable = 1;

#define BUFLEN 128 // We should probably find the maximum length of a process name
char process_to_stop[BUFLEN] = "kpat";

static void send_signal(int sig_num, struct task_struct* task)
{
	int ret;
	struct kernel_siginfo info;
	memset(&info, 0, sizeof(struct kernel_siginfo));
	info.si_signo = sig_num;
	info.si_code = 0;
	info.si_int = 1234;
	ret = send_sig_info(sig_num, &info, task);
	if (ret < 0) {
		printk("error sending signal\n");
	}
}

void stop_specified_process(void)
{
	if(disable){
		struct task_struct* task_list;
		for_each_process(task_list) {
			printk("Looking for process \"%s\"", process_to_stop);
			if(strstr(task_list->comm, process_to_stop)) {
				printk("Found process %s\n", task_list->comm);
				send_signal(9, task_list);
			}
		}
	}
}

static void my_timer_func(struct timer_list *timers)
{
	stop_specified_process();
	my_timer.expires = jiffies + TIMER_DELAY;
	add_timer(&my_timer);
}

ssize_t write_handler(struct file *filp, const char *buf, size_t count, loff_t *offp){
	if(count >= 4 && !strncmp(buf, "stop", 4))
		disable = 1;
	if(count >= 5 && !strncmp(buf, "start", 5))
		disable = 0;
	if(count >= 5 && !strncmp(buf, "name ", 5)){
		char* i = process_to_stop;
		printk("Setting name to %s", buf + 5);
		strncpy(process_to_stop, buf + 5, BUFLEN - 1);
		process_to_stop[BUFLEN - 1] = 0;
		for(; *i; i++)
			if(*i == '\n')
				*i = 0;
	}
	return count;
}

struct proc_ops proc_fops = {
	proc_write: write_handler
};

int init_module(void)
{
	timer_setup(&my_timer, my_timer_func, 0);
	my_timer.expires = jiffies + TIMER_DELAY;
	add_timer(&my_timer);

	proc_create("solstop", 0, NULL, &proc_fops);
	return 0;
}

void cleanup_module(void)
{
	del_timer(&my_timer);
	remove_proc_entry("solstop", NULL);
}

MODULE_LICENSE("MIT");