1012 lines
23 KiB
C
1012 lines
23 KiB
C
/*-
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* Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org>
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* Copyright (c) 2003-2005 SPARTA, Inc.
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* Copyright (c) 2005 Robert N. M. Watson
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* All rights reserved.
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*
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* This software was developed for the FreeBSD Project in part by Network
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* Associates Laboratories, the Security Research Division of Network
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* Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
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* as part of the DARPA CHATS research program.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_mac.h"
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#include "opt_posix.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/eventhandler.h>
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#include <sys/kernel.h>
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#include <sys/ksem.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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#include <sys/posix4.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/module.h>
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#include <sys/condvar.h>
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#include <sys/sem.h>
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#include <sys/uio.h>
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#include <sys/semaphore.h>
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#include <sys/syscall.h>
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#include <sys/stat.h>
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#include <sys/sysent.h>
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#include <sys/sysctl.h>
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#include <sys/time.h>
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#include <sys/malloc.h>
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#include <sys/fcntl.h>
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#include <sys/_semaphore.h>
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#include <security/mac/mac_framework.h>
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static int sem_count_proc(struct proc *p);
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static struct ksem *sem_lookup_byname(const char *name);
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static int sem_create(struct thread *td, const char *name,
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struct ksem **ksret, mode_t mode, unsigned int value);
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static void sem_free(struct ksem *ksnew);
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static int sem_perm(struct thread *td, struct ksem *ks);
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static void sem_enter(struct proc *p, struct ksem *ks);
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static int sem_leave(struct proc *p, struct ksem *ks);
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static void sem_exechook(void *arg, struct proc *p, struct image_params *imgp);
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static void sem_exithook(void *arg, struct proc *p);
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static void sem_forkhook(void *arg, struct proc *p1, struct proc *p2,
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int flags);
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static int sem_hasopen(struct thread *td, struct ksem *ks);
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static int kern_sem_close(struct thread *td, semid_t id);
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static int kern_sem_post(struct thread *td, semid_t id);
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static int kern_sem_wait(struct thread *td, semid_t id, int tryflag,
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struct timespec *abstime);
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static int kern_sem_init(struct thread *td, int dir, unsigned int value,
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semid_t *idp);
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static int kern_sem_open(struct thread *td, int dir, const char *name,
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int oflag, mode_t mode, unsigned int value, semid_t *idp);
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static int kern_sem_unlink(struct thread *td, const char *name);
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#ifndef SEM_MAX
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#define SEM_MAX 30
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#endif
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#define SEM_MAX_NAMELEN 14
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#define SEM_TO_ID(x) ((intptr_t)(x))
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#define ID_TO_SEM(x) id_to_sem(x)
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/*
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* available semaphores go here, this includes sem_init and any semaphores
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* created via sem_open that have not yet been unlinked.
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*/
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LIST_HEAD(, ksem) ksem_head = LIST_HEAD_INITIALIZER(&ksem_head);
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/*
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* semaphores still in use but have been sem_unlink()'d go here.
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*/
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LIST_HEAD(, ksem) ksem_deadhead = LIST_HEAD_INITIALIZER(&ksem_deadhead);
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static struct mtx sem_lock;
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static MALLOC_DEFINE(M_SEM, "sems", "semaphore data");
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static int nsems = 0;
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SYSCTL_DECL(_p1003_1b);
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SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, "");
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static eventhandler_tag sem_exit_tag, sem_exec_tag, sem_fork_tag;
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#ifdef SEM_DEBUG
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#define DP(x) printf x
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#else
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#define DP(x)
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#endif
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static __inline
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void
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sem_ref(struct ksem *ks)
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{
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mtx_assert(&sem_lock, MA_OWNED);
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ks->ks_ref++;
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DP(("sem_ref: ks = %p, ref = %d\n", ks, ks->ks_ref));
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}
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static __inline
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void
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sem_rel(struct ksem *ks)
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{
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mtx_assert(&sem_lock, MA_OWNED);
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DP(("sem_rel: ks = %p, ref = %d\n", ks, ks->ks_ref - 1));
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if (--ks->ks_ref == 0)
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sem_free(ks);
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}
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static __inline struct ksem *id_to_sem(semid_t id);
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static __inline
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struct ksem *
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id_to_sem(semid_t id)
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{
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struct ksem *ks;
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mtx_assert(&sem_lock, MA_OWNED);
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DP(("id_to_sem: id = %0x,%p\n", id, (struct ksem *)id));
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LIST_FOREACH(ks, &ksem_head, ks_entry) {
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DP(("id_to_sem: ks = %p\n", ks));
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if (ks == (struct ksem *)id)
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return (ks);
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}
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return (NULL);
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}
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static struct ksem *
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sem_lookup_byname(const char *name)
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{
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struct ksem *ks;
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mtx_assert(&sem_lock, MA_OWNED);
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LIST_FOREACH(ks, &ksem_head, ks_entry)
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if (ks->ks_name != NULL && strcmp(ks->ks_name, name) == 0)
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return (ks);
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return (NULL);
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}
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static int
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sem_create(struct thread *td, const char *name, struct ksem **ksret,
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mode_t mode, unsigned int value)
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{
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struct ksem *ret;
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struct proc *p;
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struct ucred *uc;
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size_t len;
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int error;
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DP(("sem_create\n"));
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p = td->td_proc;
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uc = td->td_ucred;
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if (value > SEM_VALUE_MAX)
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return (EINVAL);
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ret = malloc(sizeof(*ret), M_SEM, M_WAITOK | M_ZERO);
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if (name != NULL) {
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len = strlen(name);
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if (len > SEM_MAX_NAMELEN) {
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free(ret, M_SEM);
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return (ENAMETOOLONG);
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}
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/* name must start with a '/' but not contain one. */
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if (*name != '/' || len < 2 || index(name + 1, '/') != NULL) {
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free(ret, M_SEM);
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return (EINVAL);
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}
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ret->ks_name = malloc(len + 1, M_SEM, M_WAITOK);
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strcpy(ret->ks_name, name);
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} else {
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ret->ks_name = NULL;
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}
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ret->ks_mode = mode;
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ret->ks_value = value;
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ret->ks_ref = 1;
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ret->ks_waiters = 0;
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ret->ks_uid = uc->cr_uid;
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ret->ks_gid = uc->cr_gid;
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ret->ks_onlist = 0;
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cv_init(&ret->ks_cv, "sem");
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LIST_INIT(&ret->ks_users);
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#ifdef MAC
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mac_posixsem_init(ret);
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mac_posixsem_create(uc, ret);
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#endif
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if (name != NULL)
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sem_enter(td->td_proc, ret);
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*ksret = ret;
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mtx_lock(&sem_lock);
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if (nsems >= p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX)) {
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sem_leave(td->td_proc, ret);
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sem_free(ret);
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error = ENFILE;
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} else {
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nsems++;
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error = 0;
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}
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mtx_unlock(&sem_lock);
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return (error);
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}
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#ifndef _SYS_SYSPROTO_H_
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struct ksem_init_args {
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unsigned int value;
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semid_t *idp;
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};
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int ksem_init(struct thread *td, struct ksem_init_args *uap);
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#endif
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int
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ksem_init(struct thread *td, struct ksem_init_args *uap)
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{
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int error;
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error = kern_sem_init(td, UIO_USERSPACE, uap->value, uap->idp);
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return (error);
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}
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static int
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kern_sem_init(struct thread *td, int dir, unsigned int value, semid_t *idp)
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{
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struct ksem *ks;
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semid_t id;
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int error;
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error = sem_create(td, NULL, &ks, S_IRWXU | S_IRWXG, value);
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if (error)
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return (error);
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id = SEM_TO_ID(ks);
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if (dir == UIO_USERSPACE) {
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error = copyout(&id, idp, sizeof(id));
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if (error) {
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mtx_lock(&sem_lock);
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sem_rel(ks);
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mtx_unlock(&sem_lock);
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return (error);
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}
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} else {
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*idp = id;
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}
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mtx_lock(&sem_lock);
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LIST_INSERT_HEAD(&ksem_head, ks, ks_entry);
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ks->ks_onlist = 1;
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mtx_unlock(&sem_lock);
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return (error);
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}
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#ifndef _SYS_SYSPROTO_H_
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struct ksem_open_args {
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char *name;
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int oflag;
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mode_t mode;
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unsigned int value;
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semid_t *idp;
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};
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int ksem_open(struct thread *td, struct ksem_open_args *uap);
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#endif
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int
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ksem_open(struct thread *td, struct ksem_open_args *uap)
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{
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char name[SEM_MAX_NAMELEN + 1];
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size_t done;
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int error;
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error = copyinstr(uap->name, name, SEM_MAX_NAMELEN + 1, &done);
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if (error)
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return (error);
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DP((">>> sem_open start\n"));
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error = kern_sem_open(td, UIO_USERSPACE,
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name, uap->oflag, uap->mode, uap->value, uap->idp);
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DP(("<<< sem_open end\n"));
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return (error);
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}
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static int
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kern_sem_open(struct thread *td, int dir, const char *name, int oflag,
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mode_t mode, unsigned int value, semid_t *idp)
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{
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struct ksem *ksnew, *ks;
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int error;
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semid_t id;
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ksnew = NULL;
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mtx_lock(&sem_lock);
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ks = sem_lookup_byname(name);
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/*
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* If we found it but O_EXCL is set, error.
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*/
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if (ks != NULL && (oflag & O_EXCL) != 0) {
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mtx_unlock(&sem_lock);
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return (EEXIST);
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}
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/*
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* If we didn't find it...
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*/
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if (ks == NULL) {
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/*
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* didn't ask for creation? error.
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*/
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if ((oflag & O_CREAT) == 0) {
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mtx_unlock(&sem_lock);
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return (ENOENT);
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}
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/*
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* We may block during creation, so drop the lock.
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*/
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mtx_unlock(&sem_lock);
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error = sem_create(td, name, &ksnew, mode, value);
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if (error != 0)
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return (error);
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id = SEM_TO_ID(ksnew);
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if (dir == UIO_USERSPACE) {
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DP(("about to copyout! %d to %p\n", id, idp));
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error = copyout(&id, idp, sizeof(id));
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if (error) {
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mtx_lock(&sem_lock);
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sem_leave(td->td_proc, ksnew);
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sem_rel(ksnew);
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mtx_unlock(&sem_lock);
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return (error);
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}
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} else {
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DP(("about to set! %d to %p\n", id, idp));
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*idp = id;
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}
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/*
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* We need to make sure we haven't lost a race while
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* allocating during creation.
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*/
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mtx_lock(&sem_lock);
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ks = sem_lookup_byname(name);
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if (ks != NULL) {
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/* we lost... */
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sem_leave(td->td_proc, ksnew);
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sem_rel(ksnew);
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/* we lost and we can't loose... */
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if ((oflag & O_EXCL) != 0) {
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mtx_unlock(&sem_lock);
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return (EEXIST);
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}
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} else {
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DP(("sem_create: about to add to list...\n"));
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LIST_INSERT_HEAD(&ksem_head, ksnew, ks_entry);
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DP(("sem_create: setting list bit...\n"));
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ksnew->ks_onlist = 1;
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DP(("sem_create: done, about to unlock...\n"));
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}
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} else {
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#ifdef MAC
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error = mac_posixsem_check_open(td->td_ucred, ks);
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if (error)
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goto err_open;
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#endif
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/*
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* if we aren't the creator, then enforce permissions.
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*/
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error = sem_perm(td, ks);
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if (error)
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goto err_open;
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sem_ref(ks);
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mtx_unlock(&sem_lock);
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id = SEM_TO_ID(ks);
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if (dir == UIO_USERSPACE) {
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error = copyout(&id, idp, sizeof(id));
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if (error) {
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mtx_lock(&sem_lock);
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sem_rel(ks);
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mtx_unlock(&sem_lock);
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return (error);
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}
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} else {
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*idp = id;
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}
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sem_enter(td->td_proc, ks);
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mtx_lock(&sem_lock);
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sem_rel(ks);
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}
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err_open:
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mtx_unlock(&sem_lock);
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return (error);
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}
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static int
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sem_perm(struct thread *td, struct ksem *ks)
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{
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struct ucred *uc;
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/*
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* XXXRW: This permission routine appears to be incorrect. If the
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* user matches, we shouldn't go on to the group if the user
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* permissions don't allow the action? Not changed for now. To fix,
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* change from a series of if (); if (); to if () else if () else...
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*/
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uc = td->td_ucred;
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DP(("sem_perm: uc(%d,%d) ks(%d,%d,%o)\n",
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uc->cr_uid, uc->cr_gid,
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ks->ks_uid, ks->ks_gid, ks->ks_mode));
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if ((uc->cr_uid == ks->ks_uid) && (ks->ks_mode & S_IWUSR) != 0)
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return (0);
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if ((uc->cr_gid == ks->ks_gid) && (ks->ks_mode & S_IWGRP) != 0)
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return (0);
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if ((ks->ks_mode & S_IWOTH) != 0)
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return (0);
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return (priv_check(td, PRIV_SEM_WRITE));
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}
|
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|
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static void
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sem_free(struct ksem *ks)
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{
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|
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#ifdef MAC
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mac_posixsem_destroy(ks);
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#endif
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nsems--;
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if (ks->ks_onlist)
|
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LIST_REMOVE(ks, ks_entry);
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|
if (ks->ks_name != NULL)
|
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free(ks->ks_name, M_SEM);
|
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cv_destroy(&ks->ks_cv);
|
|
free(ks, M_SEM);
|
|
}
|
|
|
|
static __inline struct kuser *sem_getuser(struct proc *p, struct ksem *ks);
|
|
|
|
static __inline struct kuser *
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sem_getuser(struct proc *p, struct ksem *ks)
|
|
{
|
|
struct kuser *k;
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|
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LIST_FOREACH(k, &ks->ks_users, ku_next)
|
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if (k->ku_pid == p->p_pid)
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return (k);
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return (NULL);
|
|
}
|
|
|
|
static int
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sem_hasopen(struct thread *td, struct ksem *ks)
|
|
{
|
|
|
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return ((ks->ks_name == NULL && sem_perm(td, ks) == 0)
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|| sem_getuser(td->td_proc, ks) != NULL);
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}
|
|
|
|
static int
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sem_leave(struct proc *p, struct ksem *ks)
|
|
{
|
|
struct kuser *k;
|
|
|
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DP(("sem_leave: ks = %p\n", ks));
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k = sem_getuser(p, ks);
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|
DP(("sem_leave: ks = %p, k = %p\n", ks, k));
|
|
if (k != NULL) {
|
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LIST_REMOVE(k, ku_next);
|
|
sem_rel(ks);
|
|
DP(("sem_leave: about to free k\n"));
|
|
free(k, M_SEM);
|
|
DP(("sem_leave: returning\n"));
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|
return (0);
|
|
}
|
|
return (EINVAL);
|
|
}
|
|
|
|
static void
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|
sem_enter(p, ks)
|
|
struct proc *p;
|
|
struct ksem *ks;
|
|
{
|
|
struct kuser *ku, *k;
|
|
|
|
ku = malloc(sizeof(*ku), M_SEM, M_WAITOK);
|
|
ku->ku_pid = p->p_pid;
|
|
mtx_lock(&sem_lock);
|
|
k = sem_getuser(p, ks);
|
|
if (k != NULL) {
|
|
mtx_unlock(&sem_lock);
|
|
free(ku, M_TEMP);
|
|
return;
|
|
}
|
|
LIST_INSERT_HEAD(&ks->ks_users, ku, ku_next);
|
|
sem_ref(ks);
|
|
mtx_unlock(&sem_lock);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_unlink_args {
|
|
char *name;
|
|
};
|
|
int ksem_unlink(struct thread *td, struct ksem_unlink_args *uap);
|
|
#endif
|
|
int
|
|
ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
|
|
{
|
|
char name[SEM_MAX_NAMELEN + 1];
|
|
size_t done;
|
|
int error;
|
|
|
|
error = copyinstr(uap->name, name, SEM_MAX_NAMELEN + 1, &done);
|
|
return (error ? error :
|
|
kern_sem_unlink(td, name));
|
|
}
|
|
|
|
static int
|
|
kern_sem_unlink(struct thread *td, const char *name)
|
|
{
|
|
struct ksem *ks;
|
|
int error;
|
|
|
|
mtx_lock(&sem_lock);
|
|
ks = sem_lookup_byname(name);
|
|
if (ks != NULL) {
|
|
#ifdef MAC
|
|
error = mac_posixsem_check_unlink(td->td_ucred, ks);
|
|
if (error) {
|
|
mtx_unlock(&sem_lock);
|
|
return (error);
|
|
}
|
|
#endif
|
|
error = sem_perm(td, ks);
|
|
} else
|
|
error = ENOENT;
|
|
DP(("sem_unlink: '%s' ks = %p, error = %d\n", name, ks, error));
|
|
if (error == 0) {
|
|
LIST_REMOVE(ks, ks_entry);
|
|
LIST_INSERT_HEAD(&ksem_deadhead, ks, ks_entry);
|
|
sem_rel(ks);
|
|
}
|
|
mtx_unlock(&sem_lock);
|
|
return (error);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_close_args {
|
|
semid_t id;
|
|
};
|
|
int ksem_close(struct thread *td, struct ksem_close_args *uap);
|
|
#endif
|
|
int
|
|
ksem_close(struct thread *td, struct ksem_close_args *uap)
|
|
{
|
|
|
|
return (kern_sem_close(td, uap->id));
|
|
}
|
|
|
|
static int
|
|
kern_sem_close(struct thread *td, semid_t id)
|
|
{
|
|
struct ksem *ks;
|
|
int error;
|
|
|
|
error = EINVAL;
|
|
mtx_lock(&sem_lock);
|
|
ks = ID_TO_SEM(id);
|
|
/* this is not a valid operation for unnamed sems */
|
|
if (ks != NULL && ks->ks_name != NULL)
|
|
error = sem_leave(td->td_proc, ks);
|
|
mtx_unlock(&sem_lock);
|
|
return (error);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_post_args {
|
|
semid_t id;
|
|
};
|
|
int ksem_post(struct thread *td, struct ksem_post_args *uap);
|
|
#endif
|
|
int
|
|
ksem_post(struct thread *td, struct ksem_post_args *uap)
|
|
{
|
|
|
|
return (kern_sem_post(td, uap->id));
|
|
}
|
|
|
|
static int
|
|
kern_sem_post(struct thread *td, semid_t id)
|
|
{
|
|
struct ksem *ks;
|
|
int error;
|
|
|
|
mtx_lock(&sem_lock);
|
|
ks = ID_TO_SEM(id);
|
|
if (ks == NULL || !sem_hasopen(td, ks)) {
|
|
error = EINVAL;
|
|
goto err;
|
|
}
|
|
#ifdef MAC
|
|
error = mac_posixsem_check_post(td->td_ucred, ks);
|
|
if (error)
|
|
goto err;
|
|
#endif
|
|
if (ks->ks_value == SEM_VALUE_MAX) {
|
|
error = EOVERFLOW;
|
|
goto err;
|
|
}
|
|
++ks->ks_value;
|
|
if (ks->ks_waiters > 0)
|
|
cv_signal(&ks->ks_cv);
|
|
error = 0;
|
|
err:
|
|
mtx_unlock(&sem_lock);
|
|
return (error);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_wait_args {
|
|
semid_t id;
|
|
};
|
|
int ksem_wait(struct thread *td, struct ksem_wait_args *uap);
|
|
#endif
|
|
int
|
|
ksem_wait(struct thread *td, struct ksem_wait_args *uap)
|
|
{
|
|
|
|
return (kern_sem_wait(td, uap->id, 0, NULL));
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_timedwait_args {
|
|
semid_t id;
|
|
const struct timespec *abstime;
|
|
};
|
|
int ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap);
|
|
#endif
|
|
int
|
|
ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
|
|
{
|
|
struct timespec abstime;
|
|
struct timespec *ts;
|
|
int error;
|
|
|
|
/* We allow a null timespec (wait forever). */
|
|
if (uap->abstime == NULL)
|
|
ts = NULL;
|
|
else {
|
|
error = copyin(uap->abstime, &abstime, sizeof(abstime));
|
|
if (error != 0)
|
|
return (error);
|
|
if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
|
|
return (EINVAL);
|
|
ts = &abstime;
|
|
}
|
|
return (kern_sem_wait(td, uap->id, 0, ts));
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_trywait_args {
|
|
semid_t id;
|
|
};
|
|
int ksem_trywait(struct thread *td, struct ksem_trywait_args *uap);
|
|
#endif
|
|
int
|
|
ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
|
|
{
|
|
|
|
return (kern_sem_wait(td, uap->id, 1, NULL));
|
|
}
|
|
|
|
static int
|
|
kern_sem_wait(struct thread *td, semid_t id, int tryflag,
|
|
struct timespec *abstime)
|
|
{
|
|
struct timespec ts1, ts2;
|
|
struct timeval tv;
|
|
struct ksem *ks;
|
|
int error;
|
|
|
|
DP((">>> kern_sem_wait entered!\n"));
|
|
mtx_lock(&sem_lock);
|
|
ks = ID_TO_SEM(id);
|
|
if (ks == NULL) {
|
|
DP(("kern_sem_wait ks == NULL\n"));
|
|
error = EINVAL;
|
|
goto err;
|
|
}
|
|
sem_ref(ks);
|
|
if (!sem_hasopen(td, ks)) {
|
|
DP(("kern_sem_wait hasopen failed\n"));
|
|
error = EINVAL;
|
|
goto err;
|
|
}
|
|
#ifdef MAC
|
|
error = mac_posixsem_check_wait(td->td_ucred, ks);
|
|
if (error) {
|
|
DP(("kern_sem_wait mac failed\n"));
|
|
goto err;
|
|
}
|
|
#endif
|
|
DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
|
|
if (ks->ks_value == 0) {
|
|
ks->ks_waiters++;
|
|
if (tryflag != 0)
|
|
error = EAGAIN;
|
|
else if (abstime == NULL)
|
|
error = cv_wait_sig(&ks->ks_cv, &sem_lock);
|
|
else {
|
|
for (;;) {
|
|
ts1 = *abstime;
|
|
getnanotime(&ts2);
|
|
timespecsub(&ts1, &ts2);
|
|
TIMESPEC_TO_TIMEVAL(&tv, &ts1);
|
|
if (tv.tv_sec < 0) {
|
|
error = ETIMEDOUT;
|
|
break;
|
|
}
|
|
error = cv_timedwait_sig(&ks->ks_cv,
|
|
&sem_lock, tvtohz(&tv));
|
|
if (error != EWOULDBLOCK)
|
|
break;
|
|
}
|
|
}
|
|
ks->ks_waiters--;
|
|
if (error)
|
|
goto err;
|
|
}
|
|
ks->ks_value--;
|
|
error = 0;
|
|
err:
|
|
if (ks != NULL)
|
|
sem_rel(ks);
|
|
mtx_unlock(&sem_lock);
|
|
DP(("<<< kern_sem_wait leaving, error = %d\n", error));
|
|
return (error);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_getvalue_args {
|
|
semid_t id;
|
|
int *val;
|
|
};
|
|
int ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap);
|
|
#endif
|
|
int
|
|
ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
|
|
{
|
|
struct ksem *ks;
|
|
int error, val;
|
|
|
|
mtx_lock(&sem_lock);
|
|
ks = ID_TO_SEM(uap->id);
|
|
if (ks == NULL || !sem_hasopen(td, ks)) {
|
|
mtx_unlock(&sem_lock);
|
|
return (EINVAL);
|
|
}
|
|
#ifdef MAC
|
|
error = mac_posixsem_check_getvalue(td->td_ucred, ks);
|
|
if (error) {
|
|
mtx_unlock(&sem_lock);
|
|
return (error);
|
|
}
|
|
#endif
|
|
val = ks->ks_value;
|
|
mtx_unlock(&sem_lock);
|
|
error = copyout(&val, uap->val, sizeof(val));
|
|
return (error);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct ksem_destroy_args {
|
|
semid_t id;
|
|
};
|
|
int ksem_destroy(struct thread *td, struct ksem_destroy_args *uap);
|
|
#endif
|
|
int
|
|
ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
|
|
{
|
|
struct ksem *ks;
|
|
int error;
|
|
|
|
mtx_lock(&sem_lock);
|
|
ks = ID_TO_SEM(uap->id);
|
|
if (ks == NULL || !sem_hasopen(td, ks) ||
|
|
ks->ks_name != NULL) {
|
|
error = EINVAL;
|
|
goto err;
|
|
}
|
|
#ifdef MAC
|
|
error = mac_posixsem_check_destroy(td->td_ucred, ks);
|
|
if (error)
|
|
goto err;
|
|
#endif
|
|
if (ks->ks_waiters != 0) {
|
|
error = EBUSY;
|
|
goto err;
|
|
}
|
|
sem_rel(ks);
|
|
error = 0;
|
|
err:
|
|
mtx_unlock(&sem_lock);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Count the number of kusers associated with a proc, so as to guess at how
|
|
* many to allocate when forking.
|
|
*/
|
|
static int
|
|
sem_count_proc(struct proc *p)
|
|
{
|
|
struct ksem *ks;
|
|
struct kuser *ku;
|
|
int count;
|
|
|
|
mtx_assert(&sem_lock, MA_OWNED);
|
|
|
|
count = 0;
|
|
LIST_FOREACH(ks, &ksem_head, ks_entry) {
|
|
LIST_FOREACH(ku, &ks->ks_users, ku_next) {
|
|
if (ku->ku_pid == p->p_pid)
|
|
count++;
|
|
}
|
|
}
|
|
LIST_FOREACH(ks, &ksem_deadhead, ks_entry) {
|
|
LIST_FOREACH(ku, &ks->ks_users, ku_next) {
|
|
if (ku->ku_pid == p->p_pid)
|
|
count++;
|
|
}
|
|
}
|
|
return (count);
|
|
}
|
|
|
|
/*
|
|
* When a process forks, the child process must gain a reference to each open
|
|
* semaphore in the parent process, whether it is unlinked or not. This
|
|
* requires allocating a kuser structure for each semaphore reference in the
|
|
* new process. Because the set of semaphores in the parent can change while
|
|
* the fork is in progress, we have to handle races -- first we attempt to
|
|
* allocate enough storage to acquire references to each of the semaphores,
|
|
* then we enter the semaphores and release the temporary references.
|
|
*/
|
|
static void
|
|
sem_forkhook(void *arg, struct proc *p1, struct proc *p2, int flags)
|
|
{
|
|
struct ksem *ks, **sem_array;
|
|
int count, i, new_count;
|
|
struct kuser *ku;
|
|
|
|
mtx_lock(&sem_lock);
|
|
count = sem_count_proc(p1);
|
|
if (count == 0) {
|
|
mtx_unlock(&sem_lock);
|
|
return;
|
|
}
|
|
race_lost:
|
|
mtx_assert(&sem_lock, MA_OWNED);
|
|
mtx_unlock(&sem_lock);
|
|
sem_array = malloc(sizeof(struct ksem *) * count, M_TEMP, M_WAITOK);
|
|
mtx_lock(&sem_lock);
|
|
new_count = sem_count_proc(p1);
|
|
if (count < new_count) {
|
|
/* Lost race, repeat and allocate more storage. */
|
|
free(sem_array, M_TEMP);
|
|
count = new_count;
|
|
goto race_lost;
|
|
}
|
|
/*
|
|
* Given an array capable of storing an adequate number of semaphore
|
|
* references, now walk the list of semaphores and acquire a new
|
|
* reference for any semaphore opened by p1.
|
|
*/
|
|
count = new_count;
|
|
i = 0;
|
|
LIST_FOREACH(ks, &ksem_head, ks_entry) {
|
|
LIST_FOREACH(ku, &ks->ks_users, ku_next) {
|
|
if (ku->ku_pid == p1->p_pid) {
|
|
sem_ref(ks);
|
|
sem_array[i] = ks;
|
|
i++;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
LIST_FOREACH(ks, &ksem_deadhead, ks_entry) {
|
|
LIST_FOREACH(ku, &ks->ks_users, ku_next) {
|
|
if (ku->ku_pid == p1->p_pid) {
|
|
sem_ref(ks);
|
|
sem_array[i] = ks;
|
|
i++;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
mtx_unlock(&sem_lock);
|
|
KASSERT(i == count, ("sem_forkhook: i != count (%d, %d)", i, count));
|
|
/*
|
|
* Now cause p2 to enter each of the referenced semaphores, then
|
|
* release our temporary reference. This is pretty inefficient.
|
|
* Finally, free our temporary array.
|
|
*/
|
|
for (i = 0; i < count; i++) {
|
|
sem_enter(p2, sem_array[i]);
|
|
mtx_lock(&sem_lock);
|
|
sem_rel(sem_array[i]);
|
|
mtx_unlock(&sem_lock);
|
|
}
|
|
free(sem_array, M_TEMP);
|
|
}
|
|
|
|
static void
|
|
sem_exechook(void *arg, struct proc *p, struct image_params *imgp __unused)
|
|
{
|
|
sem_exithook(arg, p);
|
|
}
|
|
|
|
static void
|
|
sem_exithook(void *arg, struct proc *p)
|
|
{
|
|
struct ksem *ks, *ksnext;
|
|
|
|
mtx_lock(&sem_lock);
|
|
ks = LIST_FIRST(&ksem_head);
|
|
while (ks != NULL) {
|
|
ksnext = LIST_NEXT(ks, ks_entry);
|
|
sem_leave(p, ks);
|
|
ks = ksnext;
|
|
}
|
|
ks = LIST_FIRST(&ksem_deadhead);
|
|
while (ks != NULL) {
|
|
ksnext = LIST_NEXT(ks, ks_entry);
|
|
sem_leave(p, ks);
|
|
ks = ksnext;
|
|
}
|
|
mtx_unlock(&sem_lock);
|
|
}
|
|
|
|
static int
|
|
sem_modload(struct module *module, int cmd, void *arg)
|
|
{
|
|
int error = 0;
|
|
|
|
switch (cmd) {
|
|
case MOD_LOAD:
|
|
mtx_init(&sem_lock, "sem", "semaphore", MTX_DEF);
|
|
p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
|
|
p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
|
|
sem_exit_tag = EVENTHANDLER_REGISTER(process_exit, sem_exithook,
|
|
NULL, EVENTHANDLER_PRI_ANY);
|
|
sem_exec_tag = EVENTHANDLER_REGISTER(process_exec, sem_exechook,
|
|
NULL, EVENTHANDLER_PRI_ANY);
|
|
sem_fork_tag = EVENTHANDLER_REGISTER(process_fork, sem_forkhook, NULL, EVENTHANDLER_PRI_ANY);
|
|
break;
|
|
case MOD_UNLOAD:
|
|
if (nsems != 0) {
|
|
error = EOPNOTSUPP;
|
|
break;
|
|
}
|
|
EVENTHANDLER_DEREGISTER(process_exit, sem_exit_tag);
|
|
EVENTHANDLER_DEREGISTER(process_exec, sem_exec_tag);
|
|
EVENTHANDLER_DEREGISTER(process_fork, sem_fork_tag);
|
|
mtx_destroy(&sem_lock);
|
|
break;
|
|
case MOD_SHUTDOWN:
|
|
break;
|
|
default:
|
|
error = EINVAL;
|
|
break;
|
|
}
|
|
return (error);
|
|
}
|
|
|
|
static moduledata_t sem_mod = {
|
|
"sem",
|
|
&sem_modload,
|
|
NULL
|
|
};
|
|
|
|
SYSCALL_MODULE_HELPER(ksem_init);
|
|
SYSCALL_MODULE_HELPER(ksem_open);
|
|
SYSCALL_MODULE_HELPER(ksem_unlink);
|
|
SYSCALL_MODULE_HELPER(ksem_close);
|
|
SYSCALL_MODULE_HELPER(ksem_post);
|
|
SYSCALL_MODULE_HELPER(ksem_wait);
|
|
SYSCALL_MODULE_HELPER(ksem_timedwait);
|
|
SYSCALL_MODULE_HELPER(ksem_trywait);
|
|
SYSCALL_MODULE_HELPER(ksem_getvalue);
|
|
SYSCALL_MODULE_HELPER(ksem_destroy);
|
|
|
|
DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
|
|
MODULE_VERSION(sem, 1);
|