/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/refcount.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/time.h>
#include <sys/umtxvar.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_extern.h>

static MALLOC_DEFINE(M_PLIMIT, "plimit", "plimit structures");
static MALLOC_DEFINE(M_UIDINFO, "uidinfo", "uidinfo structures");
#define UIHASH(uid)     (&uihashtbl[(uid) & uihash])
static struct rwlock uihashtbl_lock;
static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash;           /* size of hash table - 1 */

static void     calcru1(struct proc *p, struct rusage_ext *ruxp,
                    struct timeval *up, struct timeval *sp);
static int      donice(struct thread *td, struct proc *chgp, int n);
static struct uidinfo *uilookup(uid_t uid);
static void     ruxagg_ext_locked(struct rusage_ext *rux, struct thread *td);

/*
 * Resource controls and accounting.
 */
#ifndef _SYS_SYSPROTO_H_
struct getpriority_args {
        int     which;
        int     who;
};
#endif
int
sys_getpriority(struct thread *td, struct getpriority_args *uap)
{

        return (kern_getpriority(td, uap->which, uap->who));
}

int
kern_getpriority(struct thread *td, int which, int who)
{
        struct proc *p;
        struct pgrp *pg;
        int error, low;

        error = 0;
        low = PRIO_MAX + 1;
        switch (which) {
        case PRIO_PROCESS:
                if (who == 0)
                        low = td->td_proc->p_nice;
                else {
                        p = pfind(who);
                        if (p == NULL)
                                break;
                        if (p_cansee(td, p) == 0)
                                low = p->p_nice;
                        PROC_UNLOCK(p);
                }
                break;

        case PRIO_PGRP:
                sx_slock(&proctree_lock);
                if (who == 0) {
                        pg = td->td_proc->p_pgrp;
                        PGRP_LOCK(pg);
                } else {
                        pg = pgfind(who);
                        if (pg == NULL) {
                                sx_sunlock(&proctree_lock);
                                break;
                        }
                }
                sx_sunlock(&proctree_lock);
                LIST_FOREACH(p, &pg->pg_members, p_pglist) {
                        PROC_LOCK(p);
                        if (p->p_state == PRS_NORMAL &&
                            p_cansee(td, p) == 0) {
                                if (p->p_nice < low)
                                        low = p->p_nice;
                        }
                        PROC_UNLOCK(p);
                }
                PGRP_UNLOCK(pg);
                break;

        case PRIO_USER:
                if (who == 0)
                        who = td->td_ucred->cr_uid;
                sx_slock(&allproc_lock);
                FOREACH_PROC_IN_SYSTEM(p) {
                        PROC_LOCK(p);
                        if (p->p_state == PRS_NORMAL &&
                            p_cansee(td, p) == 0 &&
                            p->p_ucred->cr_uid == who) {
                                if (p->p_nice < low)
                                        low = p->p_nice;
                        }
                        PROC_UNLOCK(p);
                }
                sx_sunlock(&allproc_lock);
                break;

        default:
                error = EINVAL;
                break;
        }
        if (low == PRIO_MAX + 1 && error == 0)
                error = ESRCH;
        td->td_retval[0] = low;
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct setpriority_args {
        int     which;
        int     who;
        int     prio;
};
#endif
int
sys_setpriority(struct thread *td, struct setpriority_args *uap)
{

        return (kern_setpriority(td, uap->which, uap->who, uap->prio));
}

int
kern_setpriority(struct thread *td, int which, int who, int prio)
{
        struct proc *curp, *p;
        struct pgrp *pg;
        int found = 0, error = 0;

        curp = td->td_proc;
        switch (which) {
        case PRIO_PROCESS:
                if (who == 0) {
                        PROC_LOCK(curp);
                        error = donice(td, curp, prio);
                        PROC_UNLOCK(curp);
                } else {
                        p = pfind(who);
                        if (p == NULL)
                                break;
                        error = p_cansee(td, p);
                        if (error == 0)
                                error = donice(td, p, prio);
                        PROC_UNLOCK(p);
                }
                found++;
                break;

        case PRIO_PGRP:
                sx_slock(&proctree_lock);
                if (who == 0) {
                        pg = curp->p_pgrp;
                        PGRP_LOCK(pg);
                } else {
                        pg = pgfind(who);
                        if (pg == NULL) {
                                sx_sunlock(&proctree_lock);
                                break;
                        }
                }
                sx_sunlock(&proctree_lock);
                LIST_FOREACH(p, &pg->pg_members, p_pglist) {
                        PROC_LOCK(p);
                        if (p->p_state == PRS_NORMAL &&
                            p_cansee(td, p) == 0) {
                                error = donice(td, p, prio);
                                found++;
                        }
                        PROC_UNLOCK(p);
                }
                PGRP_UNLOCK(pg);
                break;

        case PRIO_USER:
                if (who == 0)
                        who = td->td_ucred->cr_uid;
                sx_slock(&allproc_lock);
                FOREACH_PROC_IN_SYSTEM(p) {
                        PROC_LOCK(p);
                        if (p->p_state == PRS_NORMAL &&
                            p->p_ucred->cr_uid == who &&
                            p_cansee(td, p) == 0) {
                                error = donice(td, p, prio);
                                found++;
                        }
                        PROC_UNLOCK(p);
                }
                sx_sunlock(&allproc_lock);
                break;

        default:
                error = EINVAL;
                break;
        }
        if (found == 0 && error == 0)
                error = ESRCH;
        return (error);
}

/*
 * Set "nice" for a (whole) process.
 */
static int
donice(struct thread *td, struct proc *p, int n)
{
        int error;

        PROC_LOCK_ASSERT(p, MA_OWNED);
        if ((error = p_cansched(td, p)))
                return (error);
        if (n > PRIO_MAX)
                n = PRIO_MAX;
        if (n < PRIO_MIN)
                n = PRIO_MIN;
        if (n < p->p_nice && priv_check(td, PRIV_SCHED_SETPRIORITY) != 0)
                return (EACCES);
        sched_nice(p, n);
        return (0);
}

static int unprivileged_idprio;
SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_idprio, CTLFLAG_RW,
    &unprivileged_idprio, 0,
    "Allow non-root users to set an idle priority (deprecated)");

/*
 * Set realtime priority for LWP.
 */
#ifndef _SYS_SYSPROTO_H_
struct rtprio_thread_args {
        int             function;
        lwpid_t         lwpid;
        struct rtprio   *rtp;
};
#endif
int
sys_rtprio_thread(struct thread *td, struct rtprio_thread_args *uap)
{
        struct proc *p;
        struct rtprio rtp;
        struct thread *td1;
        int cierror, error;

        /* Perform copyin before acquiring locks if needed. */
        if (uap->function == RTP_SET)
                cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
        else
                cierror = 0;

        if (uap->lwpid == 0 || uap->lwpid == td->td_tid) {
                p = td->td_proc;
                td1 = td;
                PROC_LOCK(p);
        } else {
                td1 = tdfind(uap->lwpid, -1);
                if (td1 == NULL)
                        return (ESRCH);
                p = td1->td_proc;
        }

        switch (uap->function) {
        case RTP_LOOKUP:
                if ((error = p_cansee(td, p)))
                        break;
                pri_to_rtp(td1, &rtp);
                PROC_UNLOCK(p);
                return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
        case RTP_SET:
                if ((error = p_cansched(td, p)) || (error = cierror))
                        break;

                /* Disallow setting rtprio in most cases if not superuser. */

                /*
                 * Realtime priority has to be restricted for reasons which
                 * should be obvious.  However, for idleprio processes, there is
                 * a potential for system deadlock if an idleprio process gains
                 * a lock on a resource that other processes need (and the
                 * idleprio process can't run due to a CPU-bound normal
                 * process).  Fix me!  XXX
                 *
                 * This problem is not only related to idleprio process.
                 * A user level program can obtain a file lock and hold it
                 * indefinitely.  Additionally, without idleprio processes it is
                 * still conceivable that a program with low priority will never
                 * get to run.  In short, allowing this feature might make it
                 * easier to lock a resource indefinitely, but it is not the
                 * only thing that makes it possible.
                 */
                if (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_REALTIME &&
                    (error = priv_check(td, PRIV_SCHED_RTPRIO)) != 0)
                        break;
                if (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_IDLE &&
                    unprivileged_idprio == 0 &&
                    (error = priv_check(td, PRIV_SCHED_IDPRIO)) != 0)
                        break;
                error = rtp_to_pri(&rtp, td1);
                break;
        default:
                error = EINVAL;
                break;
        }
        PROC_UNLOCK(p);
        return (error);
}

/*
 * Set realtime priority.
 */
#ifndef _SYS_SYSPROTO_H_
struct rtprio_args {
        int             function;
        pid_t           pid;
        struct rtprio   *rtp;
};
#endif
int
sys_rtprio(struct thread *td, struct rtprio_args *uap)
{
        struct proc *p;
        struct thread *tdp;
        struct rtprio rtp;
        int cierror, error;

        /* Perform copyin before acquiring locks if needed. */
        if (uap->function == RTP_SET)
                cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
        else
                cierror = 0;

        if (uap->pid == 0) {
                p = td->td_proc;
                PROC_LOCK(p);
        } else {
                p = pfind(uap->pid);
                if (p == NULL)
                        return (ESRCH);
        }

        switch (uap->function) {
        case RTP_LOOKUP:
                if ((error = p_cansee(td, p)))
                        break;
                /*
                 * Return OUR priority if no pid specified,
                 * or if one is, report the highest priority
                 * in the process.  There isn't much more you can do as
                 * there is only room to return a single priority.
                 * Note: specifying our own pid is not the same
                 * as leaving it zero.
                 */
                if (uap->pid == 0) {
                        pri_to_rtp(td, &rtp);
                } else {
                        struct rtprio rtp2;

                        rtp.type = RTP_PRIO_IDLE;
                        rtp.prio = RTP_PRIO_MAX;
                        FOREACH_THREAD_IN_PROC(p, tdp) {
                                pri_to_rtp(tdp, &rtp2);
                                if (rtp2.type <  rtp.type ||
                                    (rtp2.type == rtp.type &&
                                    rtp2.prio < rtp.prio)) {
                                        rtp.type = rtp2.type;
                                        rtp.prio = rtp2.prio;
                                }
                        }
                }
                PROC_UNLOCK(p);
                return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
        case RTP_SET:
                if ((error = p_cansched(td, p)) || (error = cierror))
                        break;

                /*
                 * Disallow setting rtprio in most cases if not superuser.
                 * See the comment in sys_rtprio_thread about idprio
                 * threads holding a lock.
                 */
                if (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_REALTIME &&
                    (error = priv_check(td, PRIV_SCHED_RTPRIO)) != 0)
                        break;
                if (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_IDLE &&
                    unprivileged_idprio == 0 &&
                    (error = priv_check(td, PRIV_SCHED_IDPRIO)) != 0)
                        break;

                /*
                 * If we are setting our own priority, set just our
                 * thread but if we are doing another process,
                 * do all the threads on that process. If we
                 * specify our own pid we do the latter.
                 */
                if (uap->pid == 0) {
                        error = rtp_to_pri(&rtp, td);
                } else {
                        FOREACH_THREAD_IN_PROC(p, td) {
                                if ((error = rtp_to_pri(&rtp, td)) != 0)
                                        break;
                        }
                }
                break;
        default:
                error = EINVAL;
                break;
        }
        PROC_UNLOCK(p);
        return (error);
}

int
rtp_to_pri(struct rtprio *rtp, struct thread *td)
{
        u_char  newpri, oldclass, oldpri;

        switch (RTP_PRIO_BASE(rtp->type)) {
        case RTP_PRIO_REALTIME:
                if (rtp->prio > RTP_PRIO_MAX)
                        return (EINVAL);
                newpri = PRI_MIN_REALTIME + rtp->prio;
                break;
        case RTP_PRIO_NORMAL:
                if (rtp->prio > (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE))
                        return (EINVAL);
                newpri = PRI_MIN_TIMESHARE + rtp->prio;
                break;
        case RTP_PRIO_IDLE:
                if (rtp->prio > RTP_PRIO_MAX)
                        return (EINVAL);
                newpri = PRI_MIN_IDLE + rtp->prio;
                break;
        default:
                return (EINVAL);
        }

        thread_lock(td);
        oldclass = td->td_pri_class;
        sched_class(td, rtp->type);     /* XXX fix */
        oldpri = td->td_user_pri;
        sched_user_prio(td, newpri);
        if (td->td_user_pri != oldpri && (oldclass != RTP_PRIO_NORMAL ||
            td->td_pri_class != RTP_PRIO_NORMAL))
                sched_prio(td, td->td_user_pri);
        if (TD_ON_UPILOCK(td) && oldpri != newpri) {
                critical_enter();
                thread_unlock(td);
                umtx_pi_adjust(td, oldpri);
                critical_exit();
        } else
                thread_unlock(td);
        return (0);
}

void
pri_to_rtp(struct thread *td, struct rtprio *rtp)
{

        thread_lock(td);
        switch (PRI_BASE(td->td_pri_class)) {
        case PRI_REALTIME:
                rtp->prio = td->td_base_user_pri - PRI_MIN_REALTIME;
                break;
        case PRI_TIMESHARE:
                rtp->prio = td->td_base_user_pri - PRI_MIN_TIMESHARE;
                break;
        case PRI_IDLE:
                rtp->prio = td->td_base_user_pri - PRI_MIN_IDLE;
                break;
        default:
                break;
        }
        rtp->type = td->td_pri_class;
        thread_unlock(td);
}

#if defined(COMPAT_43)
#ifndef _SYS_SYSPROTO_H_
struct osetrlimit_args {
        u_int   which;
        struct  orlimit *rlp;
};
#endif
int
osetrlimit(struct thread *td, struct osetrlimit_args *uap)
{
        struct orlimit olim;
        struct rlimit lim;
        int error;

        if ((error = copyin(uap->rlp, &olim, sizeof(struct orlimit))))
                return (error);
        lim.rlim_cur = olim.rlim_cur;
        lim.rlim_max = olim.rlim_max;
        error = kern_setrlimit(td, uap->which, &lim);
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct ogetrlimit_args {
        u_int   which;
        struct  orlimit *rlp;
};
#endif
int
ogetrlimit(struct thread *td, struct ogetrlimit_args *uap)
{
        struct orlimit olim;
        struct rlimit rl;
        int error;

        if (uap->which >= RLIM_NLIMITS)
                return (EINVAL);
        lim_rlimit(td, uap->which, &rl);

        /*
         * XXX would be more correct to convert only RLIM_INFINITY to the
         * old RLIM_INFINITY and fail with EOVERFLOW for other larger
         * values.  Most 64->32 and 32->16 conversions, including not
         * unimportant ones of uids are even more broken than what we
         * do here (they blindly truncate).  We don't do this correctly
         * here since we have little experience with EOVERFLOW yet.
         * Elsewhere, getuid() can't fail...
         */
        olim.rlim_cur = rl.rlim_cur > 0x7fffffff ? 0x7fffffff : rl.rlim_cur;
        olim.rlim_max = rl.rlim_max > 0x7fffffff ? 0x7fffffff : rl.rlim_max;
        error = copyout(&olim, uap->rlp, sizeof(olim));
        return (error);
}
#endif /* COMPAT_43 */

#ifndef _SYS_SYSPROTO_H_
struct setrlimit_args {
        u_int   which;
        struct  rlimit *rlp;
};
#endif
int
sys_setrlimit(struct thread *td, struct setrlimit_args *uap)
{
        struct rlimit alim;
        int error;

        if ((error = copyin(uap->rlp, &alim, sizeof(struct rlimit))))
                return (error);
        error = kern_setrlimit(td, uap->which, &alim);
        return (error);
}

static void
lim_cb(void *arg)
{
        struct rlimit rlim;
        struct thread *td;
        struct proc *p;

        p = arg;
        PROC_LOCK_ASSERT(p, MA_OWNED);
        /*
         * Check if the process exceeds its cpu resource allocation.  If
         * it reaches the max, arrange to kill the process in ast().
         */
        if (p->p_cpulimit == RLIM_INFINITY)
                return;
        PROC_STATLOCK(p);
        FOREACH_THREAD_IN_PROC(p, td) {
                ruxagg(p, td);
        }
        PROC_STATUNLOCK(p);
        if (p->p_rux.rux_runtime > p->p_cpulimit * cpu_tickrate()) {
                lim_rlimit_proc(p, RLIMIT_CPU, &rlim);
                if (p->p_rux.rux_runtime >= rlim.rlim_max * cpu_tickrate()) {
                        killproc(p, "exceeded maximum CPU limit");
                } else {
                        if (p->p_cpulimit < rlim.rlim_max)
                                p->p_cpulimit += 5;
                        kern_psignal(p, SIGXCPU);
                }
        }
        if ((p->p_flag & P_WEXIT) == 0)
                callout_reset_sbt(&p->p_limco, SBT_1S, 0,
                    lim_cb, p, C_PREL(1));
}

int
kern_setrlimit(struct thread *td, u_int which, struct rlimit *limp)
{

        return (kern_proc_setrlimit(td, td->td_proc, which, limp));
}

int
kern_proc_setrlimit(struct thread *td, struct proc *p, u_int which,
    struct rlimit *limp)
{
        struct plimit *newlim, *oldlim, *oldlim_td;
        struct rlimit *alimp;
        struct rlimit oldssiz;
        int error;

        if (which >= RLIM_NLIMITS)
                return (EINVAL);

        /*
         * Preserve historical bugs by treating negative limits as unsigned.
         */
        if (limp->rlim_cur < 0)
                limp->rlim_cur = RLIM_INFINITY;
        if (limp->rlim_max < 0)
                limp->rlim_max = RLIM_INFINITY;

        oldssiz.rlim_cur = 0;
        newlim = lim_alloc();
        PROC_LOCK(p);
        oldlim = p->p_limit;
        alimp = &oldlim->pl_rlimit[which];
        if (limp->rlim_cur > alimp->rlim_max ||
            limp->rlim_max > alimp->rlim_max)
                if ((error = priv_check(td, PRIV_PROC_SETRLIMIT))) {
                        PROC_UNLOCK(p);
                        lim_free(newlim);
                        return (error);
                }
        if (limp->rlim_cur > limp->rlim_max)
                limp->rlim_cur = limp->rlim_max;
        lim_copy(newlim, oldlim);
        alimp = &newlim->pl_rlimit[which];

        switch (which) {
        case RLIMIT_CPU:
                if (limp->rlim_cur != RLIM_INFINITY &&
                    p->p_cpulimit == RLIM_INFINITY)
                        callout_reset_sbt(&p->p_limco, SBT_1S, 0,
                            lim_cb, p, C_PREL(1));
                p->p_cpulimit = limp->rlim_cur;
                break;
        case RLIMIT_DATA:
                if (limp->rlim_cur > maxdsiz)
                        limp->rlim_cur = maxdsiz;
                if (limp->rlim_max > maxdsiz)
                        limp->rlim_max = maxdsiz;
                break;

        case RLIMIT_STACK:
                if (limp->rlim_cur > maxssiz)
                        limp->rlim_cur = maxssiz;
                if (limp->rlim_max > maxssiz)
                        limp->rlim_max = maxssiz;
                oldssiz = *alimp;
                if (p->p_sysent->sv_fixlimit != NULL)
                        p->p_sysent->sv_fixlimit(&oldssiz,
                            RLIMIT_STACK);
                break;

        case RLIMIT_NOFILE:
                if (limp->rlim_cur > maxfilesperproc)
                        limp->rlim_cur = maxfilesperproc;
                if (limp->rlim_max > maxfilesperproc)
                        limp->rlim_max = maxfilesperproc;
                break;

        case RLIMIT_NPROC:
                if (limp->rlim_cur > maxprocperuid)
                        limp->rlim_cur = maxprocperuid;
                if (limp->rlim_max > maxprocperuid)
                        limp->rlim_max = maxprocperuid;
                if (limp->rlim_cur < 1)
                        limp->rlim_cur = 1;
                if (limp->rlim_max < 1)
                        limp->rlim_max = 1;
                break;
        }
        if (p->p_sysent->sv_fixlimit != NULL)
                p->p_sysent->sv_fixlimit(limp, which);
        *alimp = *limp;
        p->p_limit = newlim;
        PROC_UPDATE_COW(p);
        oldlim_td = NULL;
        if (td == curthread && PROC_COW_CHANGECOUNT(td, p) == 1) {
                oldlim_td = lim_cowsync();
                thread_cow_synced(td);
        }
        PROC_UNLOCK(p);
        if (oldlim_td != NULL) {
                MPASS(oldlim_td == oldlim);
                lim_freen(oldlim, 2);
        } else {
                lim_free(oldlim);
        }

        if (which == RLIMIT_STACK &&
            /*
             * Skip calls from exec_new_vmspace(), done when stack is
             * not mapped yet.
             */
            (td != curthread || (p->p_flag & P_INEXEC) == 0)) {
                /*
                 * Stack is allocated to the max at exec time with only
                 * "rlim_cur" bytes accessible.  If stack limit is going
                 * up make more accessible, if going down make inaccessible.
                 */
                if (limp->rlim_cur != oldssiz.rlim_cur) {
                        vm_offset_t addr;
                        vm_size_t size;
                        vm_prot_t prot;

                        if (limp->rlim_cur > oldssiz.rlim_cur) {
                                prot = p->p_sysent->sv_stackprot;
                                size = limp->rlim_cur - oldssiz.rlim_cur;
                                addr = round_page(p->p_vmspace->vm_stacktop) -
                                    limp->rlim_cur;
                        } else {
                                prot = VM_PROT_NONE;
                                size = oldssiz.rlim_cur - limp->rlim_cur;
                                addr = round_page(p->p_vmspace->vm_stacktop) -
                                    oldssiz.rlim_cur;
                        }
                        addr = trunc_page(addr);
                        size = round_page(size);
                        (void)vm_map_protect(&p->p_vmspace->vm_map,
                            addr, addr + size, prot, 0,
                            VM_MAP_PROTECT_SET_PROT);
                }
        }

        return (0);
}

#ifndef _SYS_SYSPROTO_H_
struct getrlimit_args {
        u_int   which;
        struct  rlimit *rlp;
};
#endif
/* ARGSUSED */
int
sys_getrlimit(struct thread *td, struct getrlimit_args *uap)
{
        struct rlimit rlim;
        int error;

        if (uap->which >= RLIM_NLIMITS)
                return (EINVAL);
        lim_rlimit(td, uap->which, &rlim);
        error = copyout(&rlim, uap->rlp, sizeof(struct rlimit));
        return (error);
}

static int
getrlimitusage_one(struct proc *p, u_int which, int flags, rlim_t *res)
{
        struct thread *td;
        struct uidinfo *ui;
        struct vmspace *vm;
        uid_t uid;
        int error;

        error = 0;
        PROC_LOCK(p);
        uid = (flags & GETRLIMITUSAGE_EUID) == 0 ? p->p_ucred->cr_ruid :
            p->p_ucred->cr_uid;
        PROC_UNLOCK(p);

        ui = uifind(uid);
        vm = vmspace_acquire_ref(p);

        switch (which) {
        case RLIMIT_CPU:
                PROC_LOCK(p);
                PROC_STATLOCK(p);
                FOREACH_THREAD_IN_PROC(p, td)
                        ruxagg(p, td);
                *res = p->p_rux.rux_runtime;
                PROC_STATUNLOCK(p);
                PROC_UNLOCK(p);
                *res /= cpu_tickrate();
                break;
        case RLIMIT_FSIZE:
                error = ENXIO;
                break;
        case RLIMIT_DATA:
                if (vm == NULL)
                        error = ENXIO;
                else
                        *res = vm->vm_dsize * PAGE_SIZE;
                break;
        case RLIMIT_STACK:
                if (vm == NULL)
                        error = ENXIO;
                else
                        *res = vm->vm_ssize * PAGE_SIZE;
                break;
        case RLIMIT_CORE:
                error = ENXIO;
                break;
        case RLIMIT_RSS:
                if (vm == NULL)
                        error = ENXIO;
                else
                        *res = vmspace_resident_count(vm) * PAGE_SIZE;
                break;
        case RLIMIT_MEMLOCK:
                if (vm == NULL)
                        error = ENXIO;
                else
                        *res = pmap_wired_count(vmspace_pmap(vm)) * PAGE_SIZE;
                break;
        case RLIMIT_NPROC:
                *res = ui->ui_proccnt;
                break;
        case RLIMIT_NOFILE:
                *res = proc_nfiles(p);
                break;
        case RLIMIT_SBSIZE:
                *res = ui->ui_sbsize;
                break;
        case RLIMIT_VMEM:
                if (vm == NULL)
                        error = ENXIO;
                else
                        *res = vm->vm_map.size;
                break;
        case RLIMIT_NPTS:
                *res = ui->ui_ptscnt;
                break;
        case RLIMIT_SWAP:
                *res = ui->ui_vmsize;
                break;
        case RLIMIT_KQUEUES:
                *res = ui->ui_kqcnt;
                break;
        case RLIMIT_UMTXP:
                *res = ui->ui_umtxcnt;
                break;
        case RLIMIT_PIPEBUF:
                *res = ui->ui_pipecnt;
                break;
        case RLIMIT_VMM:
                *res = ui->ui_vmmcnt;
                break;
        default:
                error = EINVAL;
                break;
        }

        vmspace_free(vm);
        uifree(ui);
        return (error);
}

int
sys_getrlimitusage(struct thread *td, struct getrlimitusage_args *uap)
{
        rlim_t res;
        int error;

        if ((uap->flags & ~(GETRLIMITUSAGE_EUID)) != 0)
                return (EINVAL);
        error = getrlimitusage_one(curproc, uap->which, uap->flags, &res);
        if (error == 0)
                error = copyout(&res, uap->res, sizeof(res));
        return (error);
}

/*
 * Transform the running time and tick information for children of proc p
 * into user and system time usage.
 */
void
calccru(struct proc *p, struct timeval *up, struct timeval *sp)
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        calcru1(p, &p->p_crux, up, sp);
}

/*
 * Transform the running time and tick information in proc p into user
 * and system time usage.  If appropriate, include the current time slice
 * on this CPU.
 */
void
calcru(struct proc *p, struct timeval *up, struct timeval *sp)
{
        struct thread *td;
        uint64_t runtime, u;

        PROC_LOCK_ASSERT(p, MA_OWNED);
        PROC_STATLOCK_ASSERT(p, MA_OWNED);
        /*
         * If we are getting stats for the current process, then add in the
         * stats that this thread has accumulated in its current time slice.
         * We reset the thread and CPU state as if we had performed a context
         * switch right here.
         */
        td = curthread;
        if (td->td_proc == p) {
                u = cpu_ticks();
                runtime = u - PCPU_GET(switchtime);
                td->td_runtime += runtime;
                td->td_incruntime += runtime;
                PCPU_SET(switchtime, u);
        }
        /* Make sure the per-thread stats are current. */
        FOREACH_THREAD_IN_PROC(p, td) {
                if (td->td_incruntime == 0)
                        continue;
                ruxagg(p, td);
        }
        calcru1(p, &p->p_rux, up, sp);
}

/* Collect resource usage for a single thread. */
void
rufetchtd(struct thread *td, struct rusage *ru)
{
        struct proc *p;
        uint64_t runtime, u;

        p = td->td_proc;
        PROC_STATLOCK_ASSERT(p, MA_OWNED);
        THREAD_LOCK_ASSERT(td, MA_OWNED);
        /*
         * If we are getting stats for the current thread, then add in the
         * stats that this thread has accumulated in its current time slice.
         * We reset the thread and CPU state as if we had performed a context
         * switch right here.
         */
        if (td == curthread) {
                u = cpu_ticks();
                runtime = u - PCPU_GET(switchtime);
                td->td_runtime += runtime;
                td->td_incruntime += runtime;
                PCPU_SET(switchtime, u);
        }
        ruxagg_locked(p, td);
        *ru = td->td_ru;
        calcru1(p, &td->td_rux, &ru->ru_utime, &ru->ru_stime);
}

static uint64_t
mul64_by_fraction(uint64_t a, uint64_t b, uint64_t c)
{
        uint64_t acc, bh, bl;
        int i, s, sa, sb;

        /*
         * Calculate (a * b) / c accurately enough without overflowing.  c
         * must be nonzero, and its top bit must be 0.  a or b must be
         * <= c, and the implementation is tuned for b <= c.
         *
         * The comments about times are for use in calcru1() with units of
         * microseconds for 'a' and stathz ticks at 128 Hz for b and c.
         *
         * Let n be the number of top zero bits in c.  Each iteration
         * either returns, or reduces b by right shifting it by at least n.
         * The number of iterations is at most 1 + 64 / n, and the error is
         * at most the number of iterations.
         *
         * It is very unusual to need even 2 iterations.  Previous
         * implementations overflowed essentially by returning early in the
         * first iteration, with n = 38 giving overflow at 105+ hours and
         * n = 32 giving overlow at at 388+ days despite a more careful
         * calculation.  388 days is a reasonable uptime, and the calculation
         * needs to work for the uptime times the number of CPUs since 'a'
         * is per-process.
         */
        if (a >= (uint64_t)1 << 63)
                return (0);             /* Unsupported arg -- can't happen. */
        acc = 0;
        for (i = 0; i < 128; i++) {
                sa = flsll(a);
                sb = flsll(b);
                if (sa + sb <= 64)
                        /* Up to 105 hours on first iteration. */
                        return (acc + (a * b) / c);
                if (a >= c) {
                        /*
                         * This reduction is based on a = q * c + r, with the
                         * remainder r < c.  'a' may be large to start, and
                         * moving bits from b into 'a' at the end of the loop
                         * sets the top bit of 'a', so the reduction makes
                         * significant progress.
                         */
                        acc += (a / c) * b;
                        a %= c;
                        sa = flsll(a);
                        if (sa + sb <= 64)
                                /* Up to 388 days on first iteration. */
                                return (acc + (a * b) / c);
                }

                /*
                 * This step writes a * b as a * ((bh << s) + bl) =
                 * a * (bh << s) + a * bl = (a << s) * bh + a * bl.  The 2
                 * additive terms are handled separately.  Splitting in
                 * this way is linear except for rounding errors.
                 *
                 * s = 64 - sa is the maximum such that a << s fits in 64
                 * bits.  Since a < c and c has at least 1 zero top bit,
                 * sa < 64 and s > 0.  Thus this step makes progress by
                 * reducing b (it increases 'a', but taking remainders on
                 * the next iteration completes the reduction).
                 *
                 * Finally, the choice for s is just what is needed to keep
                 * a * bl from overflowing, so we don't need complications
                 * like a recursive call mul64_by_fraction(a, bl, c) to
                 * handle the second additive term.
                 */
                s = 64 - sa;
                bh = b >> s;
                bl = b - (bh << s);
                acc += (a * bl) / c;
                a <<= s;
                b = bh;
        }
        return (0);             /* Algorithm failure -- can't happen. */
}

static void
calcru1(struct proc *p, struct rusage_ext *ruxp, struct timeval *up,
    struct timeval *sp)
{
        /* {user, system, interrupt, total} {ticks, usec}: */
        uint64_t ut, uu, st, su, it, tt, tu;

        ut = ruxp->rux_uticks;
        st = ruxp->rux_sticks;
        it = ruxp->rux_iticks;
        tt = ut + st + it;
        if (tt == 0) {
                /* Avoid divide by zero */
                st = 1;
                tt = 1;
        }
        tu = cputick2usec(ruxp->rux_runtime);
        if ((int64_t)tu < 0) {
                /* XXX: this should be an assert /phk */
                printf("calcru: negative runtime of %jd usec for pid %d (%s)\n",
                    (intmax_t)tu, p->p_pid, p->p_comm);
                tu = ruxp->rux_tu;
        }

        /* Subdivide tu.  Avoid overflow in the multiplications. */
        if (__predict_true(tu <= ((uint64_t)1 << 38) && tt <= (1 << 26))) {
                /* Up to 76 hours when stathz is 128. */
                uu = (tu * ut) / tt;
                su = (tu * st) / tt;
        } else {
                uu = mul64_by_fraction(tu, ut, tt);
                su = mul64_by_fraction(tu, st, tt);
        }

        if (tu >= ruxp->rux_tu) {
                /*
                 * The normal case, time increased.
                 * Enforce monotonicity of bucketed numbers.
                 */
                if (uu < ruxp->rux_uu)
                        uu = ruxp->rux_uu;
                if (su < ruxp->rux_su)
                        su = ruxp->rux_su;
        } else if (tu + 3 > ruxp->rux_tu || 101 * tu > 100 * ruxp->rux_tu) {
                /*
                 * When we calibrate the cputicker, it is not uncommon to
                 * see the presumably fixed frequency increase slightly over
                 * time as a result of thermal stabilization and NTP
                 * discipline (of the reference clock).  We therefore ignore
                 * a bit of backwards slop because we  expect to catch up
                 * shortly.  We use a 3 microsecond limit to catch low
                 * counts and a 1% limit for high counts.
                 */
                uu = ruxp->rux_uu;
                su = ruxp->rux_su;
                tu = ruxp->rux_tu;
        } else if (vm_guest == VM_GUEST_NO) {  /* tu < ruxp->rux_tu */
                /*
                 * What happened here was likely that a laptop, which ran at
                 * a reduced clock frequency at boot, kicked into high gear.
                 * The wisdom of spamming this message in that case is
                 * dubious, but it might also be indicative of something
                 * serious, so lets keep it and hope laptops can be made
                 * more truthful about their CPU speed via ACPI.
                 */
                printf("calcru: runtime went backwards from %ju usec "
                    "to %ju usec for pid %d (%s)\n",
                    (uintmax_t)ruxp->rux_tu, (uintmax_t)tu,
                    p->p_pid, p->p_comm);
        }

        ruxp->rux_uu = uu;
        ruxp->rux_su = su;
        ruxp->rux_tu = tu;

        up->tv_sec = uu / 1000000;
        up->tv_usec = uu % 1000000;
        sp->tv_sec = su / 1000000;
        sp->tv_usec = su % 1000000;
}

#ifndef _SYS_SYSPROTO_H_
struct getrusage_args {
        int     who;
        struct  rusage *rusage;
};
#endif
int
sys_getrusage(struct thread *td, struct getrusage_args *uap)
{
        struct rusage ru;
        int error;

        error = kern_getrusage(td, uap->who, &ru);
        if (error == 0)
                error = copyout(&ru, uap->rusage, sizeof(struct rusage));
        return (error);
}

int
kern_getrusage(struct thread *td, int who, struct rusage *rup)
{
        struct proc *p;
        int error;

        error = 0;
        p = td->td_proc;
        PROC_LOCK(p);
        switch (who) {
        case RUSAGE_SELF:
                rufetchcalc(p, rup, &rup->ru_utime,
                    &rup->ru_stime);
                break;

        case RUSAGE_CHILDREN:
                *rup = p->p_stats->p_cru;
                calccru(p, &rup->ru_utime, &rup->ru_stime);
                break;

        case RUSAGE_THREAD:
                PROC_STATLOCK(p);
                thread_lock(td);
                rufetchtd(td, rup);
                thread_unlock(td);
                PROC_STATUNLOCK(p);
                break;

        default:
                error = EINVAL;
        }
        PROC_UNLOCK(p);
        return (error);
}

void
rucollect(struct rusage *ru, struct rusage *ru2)
{
        long *ip, *ip2;
        int i;

        if (ru->ru_maxrss < ru2->ru_maxrss)
                ru->ru_maxrss = ru2->ru_maxrss;
        ip = &ru->ru_first;
        ip2 = &ru2->ru_first;
        for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
                *ip++ += *ip2++;
}

void
ruadd(struct rusage *ru, struct rusage_ext *rux, struct rusage *ru2,
    struct rusage_ext *rux2)
{

        rux->rux_runtime += rux2->rux_runtime;
        rux->rux_uticks += rux2->rux_uticks;
        rux->rux_sticks += rux2->rux_sticks;
        rux->rux_iticks += rux2->rux_iticks;
        rux->rux_uu += rux2->rux_uu;
        rux->rux_su += rux2->rux_su;
        rux->rux_tu += rux2->rux_tu;
        rucollect(ru, ru2);
}

/*
 * Aggregate tick counts into the proc's rusage_ext.
 */
static void
ruxagg_ext_locked(struct rusage_ext *rux, struct thread *td)
{

        rux->rux_runtime += td->td_incruntime;
        rux->rux_uticks += td->td_uticks;
        rux->rux_sticks += td->td_sticks;
        rux->rux_iticks += td->td_iticks;
}

void
ruxagg_locked(struct proc *p, struct thread *td)
{
        THREAD_LOCK_ASSERT(td, MA_OWNED);
        PROC_STATLOCK_ASSERT(td->td_proc, MA_OWNED);

        ruxagg_ext_locked(&p->p_rux, td);
        ruxagg_ext_locked(&td->td_rux, td);
        td->td_incruntime = 0;
        td->td_uticks = 0;
        td->td_iticks = 0;
        td->td_sticks = 0;
}

void
ruxagg(struct proc *p, struct thread *td)
{

        thread_lock(td);
        ruxagg_locked(p, td);
        thread_unlock(td);
}

/*
 * Update the rusage_ext structure and fetch a valid aggregate rusage
 * for proc p if storage for one is supplied.
 */
void
rufetch(struct proc *p, struct rusage *ru)
{
        struct thread *td;

        PROC_STATLOCK_ASSERT(p, MA_OWNED);

        *ru = p->p_ru;
        if (p->p_numthreads > 0)  {
                FOREACH_THREAD_IN_PROC(p, td) {
                        ruxagg(p, td);
                        rucollect(ru, &td->td_ru);
                }
        }
}

/*
 * Atomically perform a rufetch and a calcru together.
 * Consumers, can safely assume the calcru is executed only once
 * rufetch is completed.
 */
void
rufetchcalc(struct proc *p, struct rusage *ru, struct timeval *up,
    struct timeval *sp)
{

        PROC_STATLOCK(p);
        rufetch(p, ru);
        calcru(p, up, sp);
        PROC_STATUNLOCK(p);
}

/*
 * Allocate a new resource limits structure and initialize its
 * reference count and mutex pointer.
 */
struct plimit *
lim_alloc(void)
{
        struct plimit *limp;

        limp = malloc(sizeof(struct plimit), M_PLIMIT, M_WAITOK);
        refcount_init(&limp->pl_refcnt, 1);
        return (limp);
}

struct plimit *
lim_hold(struct plimit *limp)
{

        refcount_acquire(&limp->pl_refcnt);
        return (limp);
}

struct plimit *
lim_cowsync(void)
{
        struct thread *td;
        struct proc *p;
        struct plimit *oldlimit;

        td = curthread;
        p = td->td_proc;
        PROC_LOCK_ASSERT(p, MA_OWNED);

        if (td->td_limit == p->p_limit)
                return (NULL);

        oldlimit = td->td_limit;
        td->td_limit = lim_hold(p->p_limit);

        return (oldlimit);
}

void
lim_fork(struct proc *p1, struct proc *p2)
{

        PROC_LOCK_ASSERT(p1, MA_OWNED);
        PROC_LOCK_ASSERT(p2, MA_OWNED);

        p2->p_limit = lim_hold(p1->p_limit);
        callout_init_mtx(&p2->p_limco, &p2->p_mtx, 0);
        if (p1->p_cpulimit != RLIM_INFINITY)
                callout_reset_sbt(&p2->p_limco, SBT_1S, 0,
                    lim_cb, p2, C_PREL(1));
}

void
lim_free(struct plimit *limp)
{

        if (refcount_release(&limp->pl_refcnt))
                free((void *)limp, M_PLIMIT);
}

void
lim_freen(struct plimit *limp, int n)
{

        if (refcount_releasen(&limp->pl_refcnt, n))
                free((void *)limp, M_PLIMIT);
}

void
limbatch_add(struct limbatch *lb, struct thread *td)
{
        struct plimit *limp;

        MPASS(td->td_limit != NULL);
        limp = td->td_limit;

        if (lb->limp != limp) {
                if (lb->count != 0) {
                        lim_freen(lb->limp, lb->count);
                        lb->count = 0;
                }
                lb->limp = limp;
        }

        lb->count++;
}

void
limbatch_final(struct limbatch *lb)
{

        MPASS(lb->count != 0);
        lim_freen(lb->limp, lb->count);
}

/*
 * Make a copy of the plimit structure.
 * We share these structures copy-on-write after fork.
 */
void
lim_copy(struct plimit *dst, struct plimit *src)
{

        KASSERT(dst->pl_refcnt <= 1, ("lim_copy to shared limit"));
        bcopy(src->pl_rlimit, dst->pl_rlimit, sizeof(src->pl_rlimit));
}

/*
 * Return the hard limit for a particular system resource.  The
 * which parameter specifies the index into the rlimit array.
 */
rlim_t
lim_max(struct thread *td, int which)
{
        struct rlimit rl;

        lim_rlimit(td, which, &rl);
        return (rl.rlim_max);
}

rlim_t
lim_max_proc(struct proc *p, int which)
{
        struct rlimit rl;

        lim_rlimit_proc(p, which, &rl);
        return (rl.rlim_max);
}

/*
 * Return the current (soft) limit for a particular system resource.
 * The which parameter which specifies the index into the rlimit array
 */
rlim_t
(lim_cur)(struct thread *td, int which)
{
        struct rlimit rl;

        lim_rlimit(td, which, &rl);
        return (rl.rlim_cur);
}

rlim_t
lim_cur_proc(struct proc *p, int which)
{
        struct rlimit rl;

        lim_rlimit_proc(p, which, &rl);
        return (rl.rlim_cur);
}

/*
 * Return a copy of the entire rlimit structure for the system limit
 * specified by 'which' in the rlimit structure pointed to by 'rlp'.
 */
void
lim_rlimit(struct thread *td, int which, struct rlimit *rlp)
{
        struct proc *p = td->td_proc;

        MPASS(td == curthread);
        KASSERT(which >= 0 && which < RLIM_NLIMITS,
            ("request for invalid resource limit"));
        *rlp = td->td_limit->pl_rlimit[which];
        if (p->p_sysent->sv_fixlimit != NULL)
                p->p_sysent->sv_fixlimit(rlp, which);
}

void
lim_rlimit_proc(struct proc *p, int which, struct rlimit *rlp)
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        KASSERT(which >= 0 && which < RLIM_NLIMITS,
            ("request for invalid resource limit"));
        *rlp = p->p_limit->pl_rlimit[which];
        if (p->p_sysent->sv_fixlimit != NULL)
                p->p_sysent->sv_fixlimit(rlp, which);
}

void
uihashinit(void)
{

        uihashtbl = hashinit(maxproc / 16, M_UIDINFO, &uihash);
        rw_init(&uihashtbl_lock, "uidinfo hash");
}

/*
 * Look up a uidinfo struct for the parameter uid.
 * uihashtbl_lock must be locked.
 * Increase refcount on uidinfo struct returned.
 */
static struct uidinfo *
uilookup(uid_t uid)
{
        struct uihashhead *uipp;
        struct uidinfo *uip;

        rw_assert(&uihashtbl_lock, RA_LOCKED);
        uipp = UIHASH(uid);
        LIST_FOREACH(uip, uipp, ui_hash)
                if (uip->ui_uid == uid) {
                        uihold(uip);
                        break;
                }

        return (uip);
}

/*
 * Find or allocate a struct uidinfo for a particular uid.
 * Returns with uidinfo struct referenced.
 * uifree() should be called on a struct uidinfo when released.
 */
struct uidinfo *
uifind(uid_t uid)
{
        struct uidinfo *new_uip, *uip;
        struct ucred *cred;

        cred = curthread->td_ucred;
        if (cred->cr_uidinfo->ui_uid == uid) {
                uip = cred->cr_uidinfo;
                uihold(uip);
                return (uip);
        } else if (cred->cr_ruidinfo->ui_uid == uid) {
                uip = cred->cr_ruidinfo;
                uihold(uip);
                return (uip);
        }

        rw_rlock(&uihashtbl_lock);
        uip = uilookup(uid);
        rw_runlock(&uihashtbl_lock);
        if (uip != NULL)
                return (uip);

        new_uip = malloc(sizeof(*new_uip), M_UIDINFO, M_WAITOK | M_ZERO);
        racct_create(&new_uip->ui_racct);
        refcount_init(&new_uip->ui_ref, 1);
        new_uip->ui_uid = uid;

        rw_wlock(&uihashtbl_lock);
        /*
         * There's a chance someone created our uidinfo while we
         * were in malloc and not holding the lock, so we have to
         * make sure we don't insert a duplicate uidinfo.
         */
        if ((uip = uilookup(uid)) == NULL) {
                LIST_INSERT_HEAD(UIHASH(uid), new_uip, ui_hash);
                rw_wunlock(&uihashtbl_lock);
                uip = new_uip;
        } else {
                rw_wunlock(&uihashtbl_lock);
                racct_destroy(&new_uip->ui_racct);
                free(new_uip, M_UIDINFO);
        }
        return (uip);
}

/*
 * Place another refcount on a uidinfo struct.
 */
void
uihold(struct uidinfo *uip)
{

        refcount_acquire(&uip->ui_ref);
}

/*-
 * Since uidinfo structs have a long lifetime, we use an
 * opportunistic refcounting scheme to avoid locking the lookup hash
 * for each release.
 *
 * If the refcount hits 0, we need to free the structure,
 * which means we need to lock the hash.
 * Optimal case:
 *   After locking the struct and lowering the refcount, if we find
 *   that we don't need to free, simply unlock and return.
 * Suboptimal case:
 *   If refcount lowering results in need to free, bump the count
 *   back up, lose the lock and acquire the locks in the proper
 *   order to try again.
 */
void
uifree(struct uidinfo *uip)
{

        if (refcount_release_if_not_last(&uip->ui_ref))
                return;

        rw_wlock(&uihashtbl_lock);
        if (refcount_release(&uip->ui_ref) == 0) {
                rw_wunlock(&uihashtbl_lock);
                return;
        }

        racct_destroy(&uip->ui_racct);
        LIST_REMOVE(uip, ui_hash);
        rw_wunlock(&uihashtbl_lock);

        if (uip->ui_sbsize != 0)
                printf("freeing uidinfo: uid = %d, sbsize = %ld\n",
                    uip->ui_uid, uip->ui_sbsize);
        if (uip->ui_proccnt != 0)
                printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
                    uip->ui_uid, uip->ui_proccnt);
        if (uip->ui_vmsize != 0)
                printf("freeing uidinfo: uid = %d, swapuse = %lld\n",
                    uip->ui_uid, (unsigned long long)uip->ui_vmsize);
        if (uip->ui_ptscnt != 0)
                printf("freeing uidinfo: uid = %d, ptscnt = %ld\n",
                    uip->ui_uid, uip->ui_ptscnt);
        if (uip->ui_kqcnt != 0)
                printf("freeing uidinfo: uid = %d, kqcnt = %ld\n",
                    uip->ui_uid, uip->ui_kqcnt);
        if (uip->ui_umtxcnt != 0)
                printf("freeing uidinfo: uid = %d, umtxcnt = %ld\n",
                    uip->ui_uid, uip->ui_umtxcnt);
        if (uip->ui_pipecnt != 0)
                printf("freeing uidinfo: uid = %d, pipecnt = %ld\n",
                    uip->ui_uid, uip->ui_pipecnt);
        if (uip->ui_inotifycnt != 0)
                printf("freeing uidinfo: uid = %d, inotifycnt = %ld\n",
                    uip->ui_uid, uip->ui_inotifycnt);
        if (uip->ui_inotifywatchcnt != 0)
                printf("freeing uidinfo: uid = %d, inotifywatchcnt = %ld\n",
                    uip->ui_uid, uip->ui_inotifywatchcnt);
        if (uip->ui_vmmcnt != 0)
                printf("freeing vmmcnt: uid = %d, vmmcnt = %ld\n",
                    uip->ui_uid, uip->ui_vmmcnt);
        free(uip, M_UIDINFO);
}

#ifdef RACCT
void
ui_racct_foreach(void (*callback)(struct racct *racct,
    void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
    void *arg2, void *arg3)
{
        struct uidinfo *uip;
        struct uihashhead *uih;

        rw_rlock(&uihashtbl_lock);
        if (pre != NULL)
                (pre)();
        for (uih = &uihashtbl[uihash]; uih >= uihashtbl; uih--) {
                LIST_FOREACH(uip, uih, ui_hash) {
                        (callback)(uip->ui_racct, arg2, arg3);
                }
        }
        if (post != NULL)
                (post)();
        rw_runlock(&uihashtbl_lock);
}
#endif

static inline int
chglimit(struct uidinfo *uip, long *limit, int diff, rlim_t max, const char *name)
{
        long new;

        /* Don't allow them to exceed max, but allow subtraction. */
        new = atomic_fetchadd_long(limit, (long)diff) + diff;
        if (diff > 0 && max != 0) {
                if (new < 0 || new > max) {
                        atomic_subtract_long(limit, (long)diff);
                        return (0);
                }
        } else if (new < 0)
                printf("negative %s for uid = %d\n", name, uip->ui_uid);
        return (1);
}

/*
 * Change the count associated with number of processes
 * a given user is using.  When 'max' is 0, don't enforce a limit
 */
int
chgproccnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_proccnt, diff, max, "proccnt"));
}

/*
 * Change the total socket buffer size a user has used.
 */
int
chgsbsize(struct uidinfo *uip, u_int *hiwat, u_int to, rlim_t max)
{
        int diff, rv;

        diff = to - *hiwat;
        if (diff > 0 && max == 0) {
                rv = 0;
        } else {
                rv = chglimit(uip, &uip->ui_sbsize, diff, max, "sbsize");
                if (rv != 0)
                        *hiwat = to;
        }
        return (rv);
}

/*
 * Change the count associated with number of pseudo-terminals
 * a given user is using.  When 'max' is 0, don't enforce a limit
 */
int
chgptscnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_ptscnt, diff, max, "ptscnt"));
}

int
chgkqcnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_kqcnt, diff, max, "kqcnt"));
}

int
chgumtxcnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_umtxcnt, diff, max, "umtxcnt"));
}

int
chgpipecnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_pipecnt, diff, max, "pipecnt"));
}

int
chginotifycnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_inotifycnt, diff, max, "inotifycnt"));
}

int
chginotifywatchcnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_inotifywatchcnt, diff, max,
            "inotifywatchcnt"));
}

int
chgvmmcnt(struct uidinfo *uip, int diff, rlim_t max)
{

        return (chglimit(uip, &uip->ui_vmmcnt, diff, max, "vmmcnt"));
}

static int
sysctl_kern_proc_rlimit_usage(SYSCTL_HANDLER_ARGS)
{
        rlim_t resval[RLIM_NLIMITS];
        struct proc *p;
        size_t len;
        int error, *name, i;

        name = (int *)arg1;
        if ((u_int)arg2 != 1 && (u_int)arg2 != 2)
                return (EINVAL);
        if (req->newptr != NULL)
                return (EINVAL);

        error = pget((pid_t)name[0], PGET_WANTREAD, &p);
        if (error != 0)
                return (error);

        if ((u_int)arg2 == 1) {
                len = sizeof(resval);
                memset(resval, 0, sizeof(resval));
                for (i = 0; i < RLIM_NLIMITS; i++) {
                        error = getrlimitusage_one(p, (unsigned)i, 0,
                            &resval[i]);
                        if (error == ENXIO) {
                                resval[i] = -1;
                                error = 0;
                        } else if (error != 0) {
                                break;
                        }
                }
        } else {
                len = sizeof(resval[0]);
                error = getrlimitusage_one(p, (unsigned)name[1], 0,
                    &resval[0]);
                if (error == ENXIO) {
                        resval[0] = -1;
                        error = 0;
                }
        }
        if (error == 0)
                error = SYSCTL_OUT(req, resval, len);
        PRELE(p);
        return (error);
}
static SYSCTL_NODE(_kern_proc, KERN_PROC_RLIMIT_USAGE, rlimit_usage,
    CTLFLAG_RD | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE,
    sysctl_kern_proc_rlimit_usage,
    "Process limited resources usage info");