/*
 * Sample syscall module
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/module.h>
#include <sys/sysent.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>

/* Our new System calls + their args structs (syscalls take only a void*) */

struct setDummy_args
{
	int pid;
	int dummy;
};


static int
setDummy(struct thread *td, struct setDummy_args *arg)
{
	struct proc *proc_res = NULL;
	int prev_dummy = 0;

	printf("setDummy args = %d %d\n", arg->pid, arg->dummy);

	proc_res = pfind(arg->pid);
	if (proc_res == NULL)
	{
		curthread->td_retval[0] = -1;
	}
	else
	{
		prev_dummy = proc_res->dummy;
		proc_res->dummy = arg->dummy;

		curthread->td_retval[0] = arg->dummy;

		PROC_UNLOCK(proc_res);
		printf("setDummy() - pid %d, prev. dummy %d\n", arg->pid, prev_dummy);
	}

	return 0;
}

struct getDummy_args
{
	int pid;
};

static int
getDummy(struct thread *td, struct getDummy_args *arg)
{
	int ret_dummy = -1;
	struct proc *proc_res = NULL;

	printf("getDummy args = %d\n", arg->pid);
	proc_res = pfind(arg->pid);
	if (proc_res == NULL)
	{
		curthread->td_retval[0] = -1;
	}
	else
	{
		ret_dummy = proc_res->dummy;
		curthread->td_retval[0] = ret_dummy;
		PROC_UNLOCK(proc_res);

		printf("getDummy() - pid %d, dummy %d\n", arg->pid, ret_dummy);
	}

	return 0;
}

static struct sysent sysent_setDummy =
	{2,	/* number of parameters to syscall */
	setDummy};	/* Function pointer to syscall */
static struct sysent sysent_getDummy = {1, getDummy};

/* Placeholder for offset value of syscall number */
static int syscallnum[2] = {NO_SYSCALL, NO_SYSCALL};

static char str[2][9] = {"setDummy", "getDummy"};

/* Entry & Exit point to the module */
static int
load_handler(struct module *m, int cmd, void *arg)
{
	int err = 0;

	switch (cmd)
	{
	case MOD_LOAD:
		printf("Syscall %s() loaded at offset %d.\n", str[(int)arg], syscallnum[(int)arg]);
		break;
	case MOD_UNLOAD:
		printf("Syscall %s() unloaded at offset %d.\n", str[(int)arg], syscallnum[(int)arg]);
		break;
	default:
		err = EINVAL;
		break;
	}
	return err;
}


/* Macro - Glue to the whole module */
/* Read "man 9 SYSCALL_MODULE" */
SYSCALL_MODULE(setDummy, &syscallnum[0], &sysent_setDummy, load_handler, 0);
SYSCALL_MODULE(getDummy, &syscallnum[1], &sysent_getDummy, load_handler, 1);