/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/file.h>
#include <sys/proc.h>
#include <sys/session.h>
#include <sys/debug.h>

/* ARGSUSED */
int
setpgrp(int flag, int pid, int pgid)
{
        proc_t  *p = curproc;
        int     retval = 0;
        int     sid;

        switch (flag) {

        case 1: /* setpgrp() */
                mutex_enter(&pidlock);
                if (p->p_sessp->s_sidp != p->p_pidp && !pgmembers(p->p_pid)) {
                        mutex_exit(&pidlock);
                        sess_create();
                } else
                        mutex_exit(&pidlock);
                mutex_enter(&p->p_splock);
                sid = p->p_sessp->s_sid;
                mutex_exit(&p->p_splock);
                return (sid);

        case 3: /* setsid() */
                mutex_enter(&pidlock);
                if (p->p_pgidp == p->p_pidp || pgmembers(p->p_pid)) {
                        mutex_exit(&pidlock);
                        return (set_errno(EPERM));
                }
                mutex_exit(&pidlock);
                sess_create();
                mutex_enter(&p->p_splock);
                sid = p->p_sessp->s_sid;
                mutex_exit(&p->p_splock);
                return (sid);

        case 5: /* setpgid() */
        {
                mutex_enter(&pidlock);
                if (pid == 0)
                        pid = p->p_pid;
                else if (pid < 0 || pid >= maxpid) {
                        mutex_exit(&pidlock);
                        return (set_errno(EINVAL));
                } else if (pid != p->p_pid) {
                        for (p = p->p_child; /* empty */; p = p->p_sibling) {
                                if (p == NULL) {
                                        mutex_exit(&pidlock);
                                        return (set_errno(ESRCH));
                                }
                                if (p->p_pid == pid)
                                        break;
                        }
                        if (p->p_flag & SEXECED) {
                                mutex_exit(&pidlock);
                                return (set_errno(EACCES));
                        }
                        if (p->p_sessp != ttoproc(curthread)->p_sessp) {
                                mutex_exit(&pidlock);
                                return (set_errno(EPERM));
                        }
                }

                if (p->p_sessp->s_sid == pid) {
                        mutex_exit(&pidlock);
                        return (set_errno(EPERM));
                }

                if (pgid == 0)
                        pgid = p->p_pid;
                else if (pgid < 0 || pgid >= maxpid) {
                        mutex_exit(&pidlock);
                        return (set_errno(EINVAL));
                }

                if (p->p_pgrp == pgid) {
                        mutex_exit(&pidlock);
                        break;
                } else if (p->p_pid == pgid) {
                        /*
                         * We need to protect p_pgidp with p_lock because
                         * /proc looks at it while holding only p_lock.
                         */
                        mutex_enter(&p->p_lock);
                        pgexit(p);
                        pgjoin(p, p->p_pidp);
                        mutex_exit(&p->p_lock);
                } else {
                        register proc_t *q;

                        if ((q = pgfind(pgid)) == NULL ||
                            q->p_sessp != p->p_sessp) {
                                mutex_exit(&pidlock);
                                return (set_errno(EPERM));
                        }
                        /*
                         * See comment above about p_lock and /proc
                         */
                        mutex_enter(&p->p_lock);
                        pgexit(p);
                        pgjoin(p, q->p_pgidp);
                        mutex_exit(&p->p_lock);
                }
                mutex_exit(&pidlock);
                break;
        }

        case 0: /* getpgrp() */
                mutex_enter(&pidlock);
                retval = p->p_pgrp;
                mutex_exit(&pidlock);
                break;

        case 2: /* getsid() */
        case 4: /* getpgid() */
                if (pid < 0 || pid >= maxpid) {
                        return (set_errno(EINVAL));
                }
                mutex_enter(&pidlock);
                if (pid != 0 && p->p_pid != pid &&
                    ((p = prfind(pid)) == NULL || p->p_stat == SIDL)) {
                        mutex_exit(&pidlock);
                        return (set_errno(ESRCH));
                }
                if (flag == 2)
                        retval = p->p_sessp->s_sid;
                else
                        retval = p->p_pgrp;
                mutex_exit(&pidlock);
                break;

        }
        return (retval);
}