/*
 * ps_showallprocs functionality fix for FreeBSD 4.x.
 *
 * (c) 2003 Pawel Jakub Dawidek <nick@garage.freebsd.pl>
 *
 * $Id: showprocs.c,v 1.2 2003/04/20 14:55:20 jules Exp $
 */

#include <sys/param.h>

#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/libkern.h>
#include <sys/kernel.h>
#include <sys/syslog.h>


#define FSP_CATCH	0
#define FSP_ORIG	1


extern int	ps_showallprocs;
int	(*vsp_sysctl_kern_proc)(SYSCTL_HANDLER_ARGS);

static int
fsp_sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
{
	struct proc	*p;
	int	*name = (int *)arg1;
        u_int	namelen = arg2;

	if (oidp->oid_number == KERN_PROC_PID) {
		if (namelen != 1)
			return (EINVAL);
		p = pfind((pid_t)name[0]);
		if (p == NULL)
			return (0);
		/*
		 * Show a user only their processes.
		 */
		if (!ps_showallprocs && p_trespass(curproc, p))
			return (0);
	}
	/* That's it, rest original sysctl_kern_proc will do. */

	return (vsp_sysctl_kern_proc(oidp, arg1, arg2, req));
}

static int
fsp_sysctl_switch(int what)
{
	struct sysctl_oid	*oid;
	struct sysctl_req	req;
	int	name[3] = { CTL_KERN, KERN_PROC, KERN_PROC_PID };
	int	error;

	/* kern.proc.pid */
	error = sysctl_find_oid(name, 3, &oid, NULL, &req);
	if (error != 0) {
		printf("showprocs: Unexpected error while looking for "
		    "kern.proc.pid sysctl.\n");
		return (error);
	}
	if (what == FSP_ORIG)
		oid->oid_handler = vsp_sysctl_kern_proc;
	else /* if (what == FSP_CATCH) */ {
		vsp_sysctl_kern_proc = oid->oid_handler;
		oid->oid_handler = fsp_sysctl_kern_proc;
	}

	return (0);
}

static int
mod(struct module *module, int cmd, void *arg)
{
	int error;

	error = 0;

	switch (cmd) {
	case MOD_LOAD:
		error = fsp_sysctl_switch(FSP_CATCH);
		if (error != 0)
			break;
		log(LOG_INFO, "ps_showallprocs fix loaded.\n");
		break;
	case MOD_UNLOAD:
		fsp_sysctl_switch(FSP_ORIG);
		log(LOG_INFO, "ps_showallprocs fix unloaded.\n");
		break;
	default:
		error = EINVAL;
		break;
	}

	return (error);
}

static moduledata_t showprocs_mod = {
	"showprocs",
	mod,
	NULL
};

DECLARE_MODULE(showprocs, showprocs_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);