/*      $NetBSD: sysv_sem.c,v 1.105 2025/10/26 16:15:12 christos Exp $  */

/*-
 * Copyright (c) 1999, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center, and by Andrew Doran.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Implementation of SVID semaphores
 *
 * Author: Daniel Boulet
 *
 * This software is provided ``AS IS'' without any warranties of any kind.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.105 2025/10/26 16:15:12 christos Exp $");

#ifdef _KERNEL_OPT
#include "opt_sysv.h"
#endif

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/sem.h>
#include <sys/sysctl.h>
#include <sys/kmem.h>
#include <sys/mount.h>          /* XXX for <sys/syscallargs.h> */
#include <sys/syscallargs.h>
#include <sys/kauth.h>
#include <sys/once.h>

/*
 * Memory areas:
 *  1st: Pool of semaphore identifiers
 *  2nd: Semaphores
 *  3rd: Conditional variables
 *  4th: Undo structures
 */
struct semid_ds *       sema                    __read_mostly;
static struct __sem *   sem                     __read_mostly;
static kcondvar_t *     semcv                   __read_mostly;
static int *            semu                    __read_mostly;

static kmutex_t         semlock                 __cacheline_aligned;
static bool             sem_realloc_state       __read_mostly;
static kcondvar_t       sem_realloc_cv;

/*
 * List of active undo structures, total number of semaphores,
 * and total number of semop waiters.
 */
static struct sem_undo *semu_list               __read_mostly;
static u_int            semtot                  __cacheline_aligned;
static u_int            sem_waiters             __cacheline_aligned;

/* Macro to find a particular sem_undo vector */
#define SEMU(s, ix)     ((struct sem_undo *)(((long)s) + ix * seminfo.semusz))

#ifdef SEM_DEBUG
#define SEM_PRINTF(a) printf a
#else
#define SEM_PRINTF(a)
#endif

void *hook;     /* cookie from exithook_establish() */

extern int kern_has_sysvsem;

SYSCTL_SETUP_PROTO(sysctl_ipc_sem_setup);

struct sem_undo *semu_alloc(struct proc *);
int semundo_adjust(struct proc *, struct sem_undo **, int, int, int);
void semundo_clear(int, int);

static ONCE_DECL(exithook_control);
static int seminit_exithook(void);

int
seminit(void)
{
        int i, sz;
        vaddr_t v;

        mutex_init(&semlock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&sem_realloc_cv, "semrealc");
        sem_realloc_state = false;
        semtot = 0;
        sem_waiters = 0;

        /* Allocate the wired memory for our structures */
        sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
            ALIGN(seminfo.semmns * sizeof(struct __sem)) +
            ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
            ALIGN(seminfo.semmnu * seminfo.semusz);
        sz = round_page(sz);
        v = uvm_km_alloc(kernel_map, sz, 0, UVM_KMF_WIRED|UVM_KMF_ZERO);
        if (v == 0) {
                printf("sysv_sem: cannot allocate memory");
                return ENOMEM;
        }
        sema = (void *)v;
        sem = (void *)((uintptr_t)sema +
            ALIGN(seminfo.semmni * sizeof(struct semid_ds)));
        semcv = (void *)((uintptr_t)sem +
            ALIGN(seminfo.semmns * sizeof(struct __sem)));
        semu = (void *)((uintptr_t)semcv +
            ALIGN(seminfo.semmni * sizeof(kcondvar_t)));

        for (i = 0; i < seminfo.semmni; i++) {
                sema[i]._sem_base = 0;
                sema[i].sem_perm.mode = 0;
                cv_init(&semcv[i], "semwait");
        }
        for (i = 0; i < seminfo.semmnu; i++) {
                struct sem_undo *suptr = SEMU(semu, i);
                suptr->un_proc = NULL;
        }
        semu_list = NULL;

        kern_has_sysvsem = 1;

        return 0;
}

static int
seminit_exithook(void)
{

        hook = exithook_establish(semexit, NULL);
        return 0;
}

int
semfini(void)
{
        int i, sz;
        vaddr_t v = (vaddr_t)sema;

        /* Don't allow module unload if we're busy */
        mutex_enter(&semlock);
        if (semtot) {
                mutex_exit(&semlock);
                return 1;
        }

        /* Remove the exit hook */
        if (hook)
                exithook_disestablish(hook);

        /* Destroy all our condvars */
        for (i = 0; i < seminfo.semmni; i++) {
                cv_destroy(&semcv[i]);
        }

        /* Free the wired memory that we allocated */
        sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
            ALIGN(seminfo.semmns * sizeof(struct __sem)) +
            ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
            ALIGN(seminfo.semmnu * seminfo.semusz);
        sz = round_page(sz);
        uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);

        /* Destroy the last cv and mutex */
        cv_destroy(&sem_realloc_cv);
        mutex_exit(&semlock);
        mutex_destroy(&semlock);

        kern_has_sysvsem = 0;

        return 0;
}

static int
semrealloc(int newsemmni, int newsemmns, int newsemmnu)
{
        struct semid_ds *new_sema, *old_sema;
        struct __sem *new_sem;
        struct sem_undo *new_semu_list, *suptr, *nsuptr;
        int *new_semu;
        kcondvar_t *new_semcv;
        vaddr_t v;
        int i, j, lsemid, nmnus, sz;

        if (newsemmni < 1 || newsemmns < 1 || newsemmnu < 1)
                return EINVAL;

        /* Allocate the wired memory for our structures */
        sz = ALIGN(newsemmni * sizeof(struct semid_ds)) +
            ALIGN(newsemmns * sizeof(struct __sem)) +
            ALIGN(newsemmni * sizeof(kcondvar_t)) +
            ALIGN(newsemmnu * seminfo.semusz);
        sz = round_page(sz);
        v = uvm_km_alloc(kernel_map, sz, 0, UVM_KMF_WIRED|UVM_KMF_ZERO);
        if (v == 0)
                return ENOMEM;

        mutex_enter(&semlock);
        if (sem_realloc_state) {
                mutex_exit(&semlock);
                uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
                return EBUSY;
        }
        sem_realloc_state = true;
        if (sem_waiters) {
                /*
                 * Mark reallocation state, wake-up all waiters,
                 * and wait while they will all exit.
                 */
                for (i = 0; i < seminfo.semmni; i++)
                        cv_broadcast(&semcv[i]);
                while (sem_waiters)
                        cv_wait(&sem_realloc_cv, &semlock);
        }
        old_sema = sema;

        /* Get the number of last slot */
        lsemid = 0;
        for (i = 0; i < seminfo.semmni; i++)
                if (sema[i].sem_perm.mode & SEM_ALLOC)
                        lsemid = i;

        /* Get the number of currently used undo structures */
        nmnus = 0;
        for (i = 0; i < seminfo.semmnu; i++) {
                suptr = SEMU(semu, i);
                if (suptr->un_proc == NULL)
                        continue;
                nmnus++;
        }

        /* We cannot reallocate less memory than we use */
        if (lsemid >= newsemmni || semtot > newsemmns || nmnus > newsemmnu) {
                mutex_exit(&semlock);
                uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
                return EBUSY;
        }

        new_sema = (void *)v;
        new_sem = (void *)((uintptr_t)new_sema +
            ALIGN(newsemmni * sizeof(struct semid_ds)));
        new_semcv = (void *)((uintptr_t)new_sem +
            ALIGN(newsemmns * sizeof(struct __sem)));
        new_semu = (void *)((uintptr_t)new_semcv +
            ALIGN(newsemmni * sizeof(kcondvar_t)));

        /* Initialize all semaphore identifiers and condvars */
        for (i = 0; i < newsemmni; i++) {
                new_sema[i]._sem_base = 0;
                new_sema[i].sem_perm.mode = 0;
                cv_init(&new_semcv[i], "semwait");
        }
        for (i = 0; i < newsemmnu; i++) {
                nsuptr = SEMU(new_semu, i);
                nsuptr->un_proc = NULL;
        }

        /*
         * Copy all identifiers, semaphores and list of the
         * undo structures to the new memory allocation.
         */
        j = 0;
        for (i = 0; i <= lsemid; i++) {
                if ((sema[i].sem_perm.mode & SEM_ALLOC) == 0)
                        continue;
                memcpy(&new_sema[i], &sema[i], sizeof(struct semid_ds));
                new_sema[i]._sem_base = &new_sem[j];
                memcpy(new_sema[i]._sem_base, sema[i]._sem_base,
                    (sizeof(struct __sem) * sema[i].sem_nsems));
                j += sema[i].sem_nsems;
        }
        KASSERT(j == semtot);

        j = 0;
        new_semu_list = NULL;
        for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
                KASSERT(j < newsemmnu);
                nsuptr = SEMU(new_semu, j);
                memcpy(nsuptr, suptr, SEMUSZ);
                nsuptr->un_next = new_semu_list;
                new_semu_list = nsuptr;
                j++;
        }

        for (i = 0; i < seminfo.semmni; i++) {
                KASSERT(cv_has_waiters(&semcv[i]) == false);
                cv_destroy(&semcv[i]);
        }

        sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
            ALIGN(seminfo.semmns * sizeof(struct __sem)) +
            ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
            ALIGN(seminfo.semmnu * seminfo.semusz);
        sz = round_page(sz);

        /* Set the pointers and update the new values */
        sema = new_sema;
        sem = new_sem;
        semcv = new_semcv;
        semu = new_semu;
        semu_list = new_semu_list;

        seminfo.semmni = newsemmni;
        seminfo.semmns = newsemmns;
        seminfo.semmnu = newsemmnu;

        /* Reallocation completed - notify all waiters, if any */
        sem_realloc_state = false;
        cv_broadcast(&sem_realloc_cv);
        mutex_exit(&semlock);

        uvm_km_free(kernel_map, (vaddr_t)old_sema, sz, UVM_KMF_WIRED);
        return 0;
}

/*
 * Placebo.
 */

int
sys_semconfig(struct lwp *l, const struct sys_semconfig_args *uap,
    register_t *retval)
{

        RUN_ONCE(&exithook_control, seminit_exithook);

        *retval = 0;
        return 0;
}

/*
 * Allocate a new sem_undo structure for a process.
 * => Returns NULL on failure.
 */
struct sem_undo *
semu_alloc(struct proc *p)
{
        struct sem_undo *suptr, **supptr;
        bool attempted = false;
        int i;

        KASSERT(mutex_owned(&semlock));
again:
        /* Look for a free structure. */
        for (i = 0; i < seminfo.semmnu; i++) {
                suptr = SEMU(semu, i);
                if (suptr->un_proc == NULL) {
                        /* Found.  Fill it in and return. */
                        suptr->un_next = semu_list;
                        semu_list = suptr;
                        suptr->un_cnt = 0;
                        suptr->un_proc = p;
                        return suptr;
                }
        }

        /* Not found.  Attempt to free some structures. */
        if (!attempted) {
                bool freed = false;

                attempted = true;
                supptr = &semu_list;
                while ((suptr = *supptr) != NULL) {
                        if (suptr->un_cnt == 0)  {
                                suptr->un_proc = NULL;
                                *supptr = suptr->un_next;
                                freed = true;
                        } else {
                                supptr = &suptr->un_next;
                        }
                }
                if (freed) {
                        goto again;
                }
        }
        return NULL;
}

/*
 * Adjust a particular entry for a particular proc
 */

int
semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
    int adjval)
{
        struct sem_undo *suptr;
        struct sem_undo_entry *sunptr;
        int i;

        KASSERT(mutex_owned(&semlock));

        /*
         * Look for and remember the sem_undo if the caller doesn't
         * provide it
         */

        suptr = *supptr;
        if (suptr == NULL) {
                for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
                        if (suptr->un_proc == p)
                                break;

                if (suptr == NULL) {
                        suptr = semu_alloc(p);
                        if (suptr == NULL)
                                return (ENOSPC);
                }
                *supptr = suptr;
        }

        /*
         * Look for the requested entry and adjust it (delete if
         * adjval becomes 0).
         */
        sunptr = &suptr->un_ent[0];
        for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
                if (sunptr->un_id != semid || sunptr->un_num != semnum)
                        continue;
                sunptr->un_adjval += adjval;
                if (sunptr->un_adjval == 0) {
                        suptr->un_cnt--;
                        if (i < suptr->un_cnt)
                                suptr->un_ent[i] =
                                    suptr->un_ent[suptr->un_cnt];
                }
                return (0);
        }

        /* Didn't find the right entry - create it */
        if (suptr->un_cnt == SEMUME)
                return (EINVAL);

        sunptr = &suptr->un_ent[suptr->un_cnt];
        suptr->un_cnt++;
        sunptr->un_adjval = adjval;
        sunptr->un_id = semid;
        sunptr->un_num = semnum;
        return (0);
}

void
semundo_clear(int semid, int semnum)
{
        struct sem_undo *suptr;
        struct sem_undo_entry *sunptr, *sunend;

        KASSERT(mutex_owned(&semlock));

        for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
                for (sunptr = &suptr->un_ent[0],
                    sunend = sunptr + suptr->un_cnt; sunptr < sunend;) {
                        if (sunptr->un_id == semid) {
                                if (semnum == -1 || sunptr->un_num == semnum) {
                                        suptr->un_cnt--;
                                        sunend--;
                                        if (sunptr != sunend)
                                                *sunptr = *sunend;
                                        if (semnum != -1)
                                                break;
                                        else
                                                continue;
                                }
                        }
                        sunptr++;
                }
}

int
sys_____semctl50(struct lwp *l, const struct sys_____semctl50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) semid;
                syscallarg(int) semnum;
                syscallarg(int) cmd;
                syscallarg(union __semun *) arg;
        } */
        struct semid_ds sembuf;
        int cmd, error;
        void *pass_arg;
        union __semun karg;

        RUN_ONCE(&exithook_control, seminit_exithook);

        cmd = SCARG(uap, cmd);

        pass_arg = get_semctl_arg(cmd, &sembuf, &karg);

        if (pass_arg) {
                error = copyin(SCARG(uap, arg), &karg, sizeof(karg));
                if (error)
                        return error;
                if (cmd == IPC_SET) {
                        error = copyin(karg.buf, &sembuf, sizeof(sembuf));
                        if (error)
                                return (error);
                }
        }

        error = semctl1(l, SCARG(uap, semid), SCARG(uap, semnum), cmd,
            pass_arg, retval);

        if (error == 0 && cmd == IPC_STAT)
                error = copyout(&sembuf, karg.buf, sizeof(sembuf));

        return (error);
}

int
semctl1(struct lwp *l, int semid, int semnum, int cmd, void *v,
    register_t *retval)
{
        kauth_cred_t cred = l->l_cred;
        union __semun *arg = v;
        struct semid_ds *sembuf = v, *semaptr;
        int i, error, ix;

        SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n",
            semid, semnum, cmd, v));

        mutex_enter(&semlock);

        ix = IPCID_TO_IX(semid);
        if (ix < 0 || ix >= seminfo.semmni) {
                mutex_exit(&semlock);
                return (EINVAL);
        }

        semaptr = &sema[ix];
        if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
            semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) {
                mutex_exit(&semlock);
                return (EINVAL);
        }

        switch (cmd) {
        case IPC_RMID:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0)
                        break;
                semaptr->sem_perm.cuid = kauth_cred_geteuid(cred);
                semaptr->sem_perm.uid = kauth_cred_geteuid(cred);
                semtot -= semaptr->sem_nsems;
                for (i = semaptr->_sem_base - sem; i < semtot; i++)
                        sem[i] = sem[i + semaptr->sem_nsems];
                for (i = 0; i < seminfo.semmni; i++) {
                        if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
                            sema[i]._sem_base > semaptr->_sem_base)
                                sema[i]._sem_base -= semaptr->sem_nsems;
                }
                semaptr->sem_perm.mode = 0;
                semundo_clear(ix, -1);
                cv_broadcast(&semcv[ix]);
                break;

        case IPC_SET:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
                        break;
                KASSERT(sembuf != NULL);
                semaptr->sem_perm.uid = sembuf->sem_perm.uid;
                semaptr->sem_perm.gid = sembuf->sem_perm.gid;
                semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
                    (sembuf->sem_perm.mode & 0777);
                semaptr->sem_ctime = time_second;
                break;

        case IPC_STAT:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
                        break;
                KASSERT(sembuf != NULL);
                memset(sembuf, 0, sizeof *sembuf);
                sembuf->sem_perm = semaptr->sem_perm;
                sembuf->sem_perm.mode &= 0777;
                sembuf->sem_nsems = semaptr->sem_nsems;
                sembuf->sem_otime = semaptr->sem_otime;
                sembuf->sem_ctime = semaptr->sem_ctime;
                break;

        case GETNCNT:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
                        break;
                if (semnum < 0 || semnum >= semaptr->sem_nsems) {
                        error = EINVAL;
                        break;
                }
                *retval = semaptr->_sem_base[semnum].semncnt;
                break;

        case GETPID:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
                        break;
                if (semnum < 0 || semnum >= semaptr->sem_nsems) {
                        error = EINVAL;
                        break;
                }
                *retval = semaptr->_sem_base[semnum].sempid;
                break;

        case GETVAL:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
                        break;
                if (semnum < 0 || semnum >= semaptr->sem_nsems) {
                        error = EINVAL;
                        break;
                }
                *retval = semaptr->_sem_base[semnum].semval;
                break;

        case GETALL:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
                        break;
                KASSERT(arg != NULL);
                for (i = 0; i < semaptr->sem_nsems; i++) {
                        error = copyout(&semaptr->_sem_base[i].semval,
                            &arg->array[i], sizeof(arg->array[i]));
                        if (error != 0)
                                break;
                }
                break;

        case GETZCNT:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
                        break;
                if (semnum < 0 || semnum >= semaptr->sem_nsems) {
                        error = EINVAL;
                        break;
                }
                *retval = semaptr->_sem_base[semnum].semzcnt;
                break;

        case SETVAL:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
                        break;
                if (semnum < 0 || semnum >= semaptr->sem_nsems) {
                        error = EINVAL;
                        break;
                }
                KASSERT(arg != NULL);
                if ((unsigned int)arg->val > seminfo.semvmx) {
                        error = ERANGE;
                        break;
                }
                semaptr->_sem_base[semnum].semval = arg->val;
                semundo_clear(ix, semnum);
                cv_broadcast(&semcv[ix]);
                break;

        case SETALL:
                if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
                        break;
                KASSERT(arg != NULL);
                for (i = 0; i < semaptr->sem_nsems; i++) {
                        unsigned short semval;
                        error = copyin(&arg->array[i], &semval,
                            sizeof(arg->array[i]));
                        if (error != 0)
                                break;
                        if ((unsigned int)semval > seminfo.semvmx) {
                                error = ERANGE;
                                break;
                        }
                        semaptr->_sem_base[i].semval = semval;
                }
                semundo_clear(ix, -1);
                cv_broadcast(&semcv[ix]);
                break;

        default:
                error = EINVAL;
                break;
        }

        mutex_exit(&semlock);
        return (error);
}

int
sys_semget(struct lwp *l, const struct sys_semget_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(key_t) key;
                syscallarg(int) nsems;
                syscallarg(int) semflg;
        } */
        int semid, error = 0;
        int key = SCARG(uap, key);
        int nsems = SCARG(uap, nsems);
        int semflg = SCARG(uap, semflg);
        kauth_cred_t cred = l->l_cred;

        RUN_ONCE(&exithook_control, seminit_exithook);

        SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));

        mutex_enter(&semlock);

        if (key != IPC_PRIVATE) {
                for (semid = 0; semid < seminfo.semmni; semid++) {
                        if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
                            sema[semid].sem_perm._key == key)
                                break;
                }
                if (semid < seminfo.semmni) {
                        SEM_PRINTF(("found public key\n"));
                        if ((error = ipcperm(cred, &sema[semid].sem_perm,
                            semflg & 0700)))
                                goto out;
                        if (nsems > 0 && sema[semid].sem_nsems < nsems) {
                                SEM_PRINTF(("too small\n"));
                                error = EINVAL;
                                goto out;
                        }
                        if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
                                SEM_PRINTF(("not exclusive\n"));
                                error = EEXIST;
                                goto out;
                        }
                        goto found;
                }
        }

        SEM_PRINTF(("need to allocate the semid_ds\n"));
        if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
                if (nsems <= 0 || nsems > seminfo.semmsl) {
                        SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
                            seminfo.semmsl));
                        error = EINVAL;
                        goto out;
                }
                if (nsems > seminfo.semmns - semtot) {
                        SEM_PRINTF(("not enough semaphores left "
                            "(need %d, got %d)\n",
                            nsems, seminfo.semmns - semtot));
                        error = ENOSPC;
                        goto out;
                }
                for (semid = 0; semid < seminfo.semmni; semid++) {
                        if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
                                break;
                }
                if (semid == seminfo.semmni) {
                        SEM_PRINTF(("no more semid_ds's available\n"));
                        error = ENOSPC;
                        goto out;
                }
                SEM_PRINTF(("semid %d is available\n", semid));
                sema[semid].sem_perm._key = key;
                sema[semid].sem_perm.cuid = kauth_cred_geteuid(cred);
                sema[semid].sem_perm.uid = kauth_cred_geteuid(cred);
                sema[semid].sem_perm.cgid = kauth_cred_getegid(cred);
                sema[semid].sem_perm.gid = kauth_cred_getegid(cred);
                sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
                sema[semid].sem_perm._seq =
                    (sema[semid].sem_perm._seq + 1) & 0x7fff;
                sema[semid].sem_nsems = nsems;
                sema[semid].sem_otime = 0;
                sema[semid].sem_ctime = time_second;
                sema[semid]._sem_base = &sem[semtot];
                semtot += nsems;
                memset(sema[semid]._sem_base, 0,
                    sizeof(sema[semid]._sem_base[0]) * nsems);
                SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base,
                    &sem[semtot]));
        } else {
                SEM_PRINTF(("didn't find it and wasn't asked to create it\n"));
                error = ENOENT;
                goto out;
        }

 found:
        *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
 out:
        mutex_exit(&semlock);
        return (error);
}

#define SMALL_SOPS 8

void
do_semop_init(void)
{

        RUN_ONCE(&exithook_control, seminit_exithook);
}

/* all pointers already in kernel space */
int
do_semop1(struct lwp *l, int usemid, struct sembuf *sops,
    size_t nsops, struct timespec *timeout, register_t *retval)
{
        struct proc *p = l->l_proc;
        int semid, seq;
        struct semid_ds *semaptr;
        struct sembuf *sopptr = NULL;
        struct __sem *semptr = NULL;
        struct sem_undo *suptr = NULL;
        kauth_cred_t cred = l->l_cred;
        int timo = 0;
        int i, error;
        int do_wakeup, do_undos;

        RUN_ONCE(&exithook_control, seminit_exithook);

        SEM_PRINTF(("do_semop1(%d, %p, %zu)\n", usemid, sops, nsops));

        if (__predict_false((p->p_flag & PK_SYSVSEM) == 0)) {
                mutex_enter(p->p_lock);
                p->p_flag |= PK_SYSVSEM;
                mutex_exit(p->p_lock);
        }

restart:
        mutex_enter(&semlock);
        /* In case of reallocation, we will wait for completion */
        while (__predict_false(sem_realloc_state))
                cv_wait(&sem_realloc_cv, &semlock);

        semid = IPCID_TO_IX(usemid);    /* Convert back to zero origin */
        if (semid < 0 || semid >= seminfo.semmni) {
                error = EINVAL;
                goto out;
        }

        if (timeout) {
                error = ts2timo(CLOCK_MONOTONIC, TIMER_RELTIME, timeout,
                    &timo, NULL);
                if (error)
                        return error;
        }

        semaptr = &sema[semid];
        seq = IPCID_TO_SEQ(usemid);
        if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
            semaptr->sem_perm._seq != seq) {
                error = EINVAL;
                goto out;
        }

        if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) {
                SEM_PRINTF(("error = %d from ipaccess\n", error));
                goto out;
        }

        for (i = 0; i < nsops; i++)
                if (sops[i].sem_num >= semaptr->sem_nsems) {
                        error = EFBIG;
                        goto out;
                }
        /*
         * Loop trying to satisfy the vector of requests.
         * If we reach a point where we must wait, any requests already
         * performed are rolled back and we go to sleep until some other
         * process wakes us up.  At this point, we start all over again.
         *
         * This ensures that from the perspective of other tasks, a set
         * of requests is atomic (never partially satisfied).
         */
        do_undos = 0;

        for (;;) {
                do_wakeup = 0;

                for (i = 0; i < nsops; i++) {
                        sopptr = &sops[i];
                        semptr = &semaptr->_sem_base[sopptr->sem_num];

                        SEM_PRINTF(("semop:  semaptr=%p, sem_base=%p, "
                            "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n",
                            semaptr, semaptr->_sem_base, semptr,
                            sopptr->sem_num, semptr->semval, sopptr->sem_op,
                            (sopptr->sem_flg & IPC_NOWAIT) ?
                            "nowait" : "wait"));

                        if (sopptr->sem_op < 0) {
                                if ((int)(semptr->semval +
                                    sopptr->sem_op) < 0) {
                                        SEM_PRINTF(("semop:  "
                                            "can't do it now\n"));
                                        break;
                                } else {
                                        semptr->semval += sopptr->sem_op;
                                        if (semptr->semval == 0 &&
                                            semptr->semzcnt > 0)
                                                do_wakeup = 1;
                                }
                                if (sopptr->sem_flg & SEM_UNDO)
                                        do_undos = 1;
                        } else if (sopptr->sem_op == 0) {
                                if (semptr->semval > 0) {
                                        SEM_PRINTF(("semop:  not zero now\n"));
                                        break;
                                }
                        } else {
                                if (semptr->semncnt > 0)
                                        do_wakeup = 1;
                                semptr->semval += sopptr->sem_op;
                                if (sopptr->sem_flg & SEM_UNDO)
                                        do_undos = 1;
                        }
                }

                /*
                 * Did we get through the entire vector?
                 */
                if (i >= nsops)
                        goto done;

                /*
                 * No ... rollback anything that we've already done
                 */
                SEM_PRINTF(("semop:  rollback 0 through %d\n", i - 1));
                while (i-- > 0)
                        semaptr->_sem_base[sops[i].sem_num].semval -=
                            sops[i].sem_op;

                /*
                 * If the request that we couldn't satisfy has the
                 * NOWAIT flag set then return with EAGAIN.
                 */
                if (sopptr->sem_flg & IPC_NOWAIT) {
                        error = EAGAIN;
                        goto out;
                }

                if (sopptr->sem_op == 0)
                        semptr->semzcnt++;
                else
                        semptr->semncnt++;

                sem_waiters++;
                SEM_PRINTF(("semop:  good night!\n"));
                error = cv_timedwait_sig(&semcv[semid], &semlock, timo);
                SEM_PRINTF(("semop:  good morning (error=%d)!\n", error));
                sem_waiters--;

                /* Notify reallocator, if it is waiting */
                cv_broadcast(&sem_realloc_cv);

                /*
                 * Make sure that the semaphore still exists
                 */
                if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
                    semaptr->sem_perm._seq != seq) {
                        error = EIDRM;
                        goto out;
                }

                /*
                 * The semaphore is still alive.  Readjust the count of
                 * waiting processes.
                 */
                semptr = &semaptr->_sem_base[sopptr->sem_num];
                if (sopptr->sem_op == 0)
                        semptr->semzcnt--;
                else
                        semptr->semncnt--;

                /* In case of such state, restart the call */
                if (sem_realloc_state) {
                        mutex_exit(&semlock);
                        goto restart;
                }

                /* Is it really morning, or was our sleep interrupted? */
                if (error != 0) {
                        if (error == ERESTART)
                                error = EINTR;  // Simplify to just EINTR
                        else if (error == EWOULDBLOCK)
                                error = EAGAIN;  // Convert timeout to EAGAIN
                        goto out;
                }
                SEM_PRINTF(("semop:  good morning!\n"));
        }
done:
        /*
         * Process any SEM_UNDO requests.
         */
        if (do_undos) {
                for (i = 0; i < nsops; i++) {
                        /*
                         * We only need to deal with SEM_UNDO's for non-zero
                         * op's.
                         */
                        int adjval;

                        if ((sops[i].sem_flg & SEM_UNDO) == 0)
                                continue;
                        adjval = sops[i].sem_op;
                        if (adjval == 0)
                                continue;
                        error = semundo_adjust(p, &suptr, semid,
                            sops[i].sem_num, -adjval);
                        if (error == 0)
                                continue;

                        /*
                         * Oh-Oh!  We ran out of either sem_undo's or undo's.
                         * Rollback the adjustments to this point and then
                         * rollback the semaphore ups and down so we can return
                         * with an error with all structures restored.  We
                         * rollback the undo's in the exact reverse order that
                         * we applied them.  This guarantees that we won't run
                         * out of space as we roll things back out.
                         */
                        while (i-- > 0) {
                                if ((sops[i].sem_flg & SEM_UNDO) == 0)
                                        continue;
                                adjval = sops[i].sem_op;
                                if (adjval == 0)
                                        continue;
                                if (semundo_adjust(p, &suptr, semid,
                                    sops[i].sem_num, adjval) != 0)
                                        panic("semop - can't undo undos");
                        }

                        for (i = 0; i < nsops; i++)
                                semaptr->_sem_base[sops[i].sem_num].semval -=
                                    sops[i].sem_op;

                        SEM_PRINTF(("error = %d from semundo_adjust\n",
                            error));
                        goto out;
                } /* loop through the sops */
        } /* if (do_undos) */

        /* We're definitely done - set the sempid's */
        for (i = 0; i < nsops; i++) {
                sopptr = &sops[i];
                semptr = &semaptr->_sem_base[sopptr->sem_num];
                semptr->sempid = p->p_pid;
        }

        /* Update sem_otime */
        semaptr->sem_otime = time_second;

        /* Do a wakeup if any semaphore was up'd. */
        if (do_wakeup) {
                SEM_PRINTF(("semop:  doing wakeup\n"));
                cv_broadcast(&semcv[semid]);
                SEM_PRINTF(("semop:  back from wakeup\n"));
        }
        SEM_PRINTF(("semop:  done\n"));
        *retval = 0;

out:
        mutex_exit(&semlock);
        return error;
}

int
do_semop(struct lwp *l, int usemid, struct sembuf *usops,
    size_t nsops, void *utimeout, register_t *retval,
    int (*timeout_copyin)(const void *, void *, size_t))
{
        struct sembuf small_sops[SMALL_SOPS];
        struct sembuf *sops;
        struct timespec timeout;
        int error;

        do_semop_init();

        SEM_PRINTF(("do_semop(%d, %p, %zu)\n", usemid, usops, nsops));

        if (nsops <= SMALL_SOPS) {
                sops = small_sops;
        } else if (seminfo.semopm > 0 && nsops <= (size_t)seminfo.semopm) {
                sops = kmem_alloc(nsops * sizeof(*sops), KM_SLEEP);
        } else {
                SEM_PRINTF(("too many sops (max=%d, nsops=%zu)\n",
                    seminfo.semopm, nsops));
                return (E2BIG);
        }

        error = copyin(usops, sops, nsops * sizeof(sops[0]));
        if (error) {
                SEM_PRINTF(("error = %d from copyin(%p, %p, %zu)\n", error,
                    usops, &sops, nsops * sizeof(sops[0])));
                if (sops != small_sops)
                        kmem_free(sops, nsops * sizeof(*sops));
                return error;
        }

        if (utimeout) {
                error = (*timeout_copyin)(utimeout, &timeout, sizeof(timeout));
                if (error) {
                        SEM_PRINTF(("error = %d from copyin(%p, %p, %zu)\n",
                            error, utimeout, &timeout, sizeof(timeout)));
                        return error;
                }
        }

        error = do_semop1(l, usemid, sops, nsops, utimeout ? &timeout : NULL,
            retval);

        if (sops != small_sops)
                kmem_free(sops, nsops * sizeof(*sops));

        return error;
}

int
sys_semtimedop(struct lwp *l, const struct sys_semtimedop_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) semid;
                syscallarg(struct sembuf *) sops;
                syscallarg(size_t) nsops;
                syscallarg(struct timespec) timeout;
        } */
        int semid = SCARG(uap, semid);
        struct sembuf *sops = SCARG(uap, sops);
        size_t nsops = SCARG(uap, nsops);
        struct timespec *utimeout = SCARG(uap, timeout);

        return do_semop(l, semid, sops, nsops, utimeout, retval, copyin);
}

int
sys_semop(struct lwp *l, const struct sys_semop_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) semid;
                syscallarg(struct sembuf *) sops;
                syscallarg(size_t) nsops;
        } */
        int semid = SCARG(uap, semid);
        struct sembuf *sops = SCARG(uap, sops);
        size_t nsops = SCARG(uap, nsops);

        return do_semop(l, semid, sops, nsops, NULL, retval, copyin);
}

/*
 * Go through the undo structures for this process and apply the
 * adjustments to semaphores.
 */
/*ARGSUSED*/
void
semexit(struct proc *p, void *v)
{
        struct sem_undo *suptr;
        struct sem_undo **supptr;

        if ((p->p_flag & PK_SYSVSEM) == 0)
                return;

        mutex_enter(&semlock);

        /*
         * Go through the chain of undo vectors looking for one
         * associated with this process.
         */

        for (supptr = &semu_list; (suptr = *supptr) != NULL;
            supptr = &suptr->un_next) {
                if (suptr->un_proc == p)
                        break;
        }

        /*
         * If there is no undo vector, skip to the end.
         */

        if (suptr == NULL) {
                mutex_exit(&semlock);
                return;
        }

        /*
         * We now have an undo vector for this process.
         */

        SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p,
            suptr->un_cnt));

        /*
         * If there are any active undo elements then process them.
         */
        if (suptr->un_cnt > 0) {
                int ix;

                for (ix = 0; ix < suptr->un_cnt; ix++) {
                        int semid = suptr->un_ent[ix].un_id;
                        int semnum = suptr->un_ent[ix].un_num;
                        int adjval = suptr->un_ent[ix].un_adjval;
                        struct semid_ds *semaptr;

                        semaptr = &sema[semid];
                        if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
                                if (semnum >= semaptr->sem_nsems)
                                        panic("semexit - semnum out of range");

                        SEM_PRINTF(("semexit:  %p id=%d num=%d(adj=%d) ; "
                            "sem=%d\n",
                            suptr->un_proc, suptr->un_ent[ix].un_id,
                            suptr->un_ent[ix].un_num,
                            suptr->un_ent[ix].un_adjval,
                            semaptr->_sem_base[semnum].semval));

                        if (adjval < 0 &&
                            semaptr->_sem_base[semnum].semval < -adjval)
                                semaptr->_sem_base[semnum].semval = 0;
                        else
                                semaptr->_sem_base[semnum].semval += adjval;

                        cv_broadcast(&semcv[semid]);
                        SEM_PRINTF(("semexit:  back from wakeup\n"));
                }
        }

        /*
         * Deallocate the undo vector.
         */
        SEM_PRINTF(("removing vector\n"));
        suptr->un_proc = NULL;
        *supptr = suptr->un_next;
        mutex_exit(&semlock);
}

/*
 * Sysctl initialization and nodes.
 */

static int
sysctl_ipc_semmni(SYSCTLFN_ARGS)
{
        int newsize, error;
        struct sysctlnode node;
        node = *rnode;
        node.sysctl_data = &newsize;

        newsize = seminfo.semmni;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return error;

        return semrealloc(newsize, seminfo.semmns, seminfo.semmnu);
}

static int
sysctl_ipc_semmns(SYSCTLFN_ARGS)
{
        int newsize, error;
        struct sysctlnode node;
        node = *rnode;
        node.sysctl_data = &newsize;

        newsize = seminfo.semmns;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return error;

        return semrealloc(seminfo.semmni, newsize, seminfo.semmnu);
}

static int
sysctl_ipc_semmnu(SYSCTLFN_ARGS)
{
        int newsize, error;
        struct sysctlnode node;
        node = *rnode;
        node.sysctl_data = &newsize;

        newsize = seminfo.semmnu;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return error;

        return semrealloc(seminfo.semmni, seminfo.semmns, newsize);
}

SYSCTL_SETUP(sysctl_ipc_sem_setup, "sysctl kern.ipc subtree setup")
{
        const struct sysctlnode *node = NULL;

        sysctl_createv(clog, 0, NULL, &node,
            CTLFLAG_PERMANENT,
            CTLTYPE_NODE, "ipc",
            SYSCTL_DESCR("SysV IPC options"),
            NULL, 0, NULL, 0,
            CTL_KERN, KERN_SYSVIPC, CTL_EOL);

        if (node == NULL)
                return;

        sysctl_createv(clog, 0, &node, NULL,
            CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
            CTLTYPE_INT, "semmni",
            SYSCTL_DESCR("Max number of number of semaphore identifiers"),
            sysctl_ipc_semmni, 0, &seminfo.semmni, 0,
            CTL_CREATE, CTL_EOL);
        sysctl_createv(clog, 0, &node, NULL,
            CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
            CTLTYPE_INT, "semmns",
            SYSCTL_DESCR("Max number of number of semaphores in system"),
            sysctl_ipc_semmns, 0, &seminfo.semmns, 0,
            CTL_CREATE, CTL_EOL);
        sysctl_createv(clog, 0, &node, NULL,
            CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
            CTLTYPE_INT, "semmnu",
            SYSCTL_DESCR("Max number of undo structures in system"),
            sysctl_ipc_semmnu, 0, &seminfo.semmnu, 0,
            CTL_CREATE, CTL_EOL);
}