137 lines
3.3 KiB
C
137 lines
3.3 KiB
C
/* $NetBSD: vfs_cwd.c,v 1.11 2023/09/23 18:21:11 ad Exp $ */
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/*-
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* Copyright (c) 2008, 2020, 2023 The NetBSD Foundation, Inc.
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* All rights reserved.
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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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Current working directory.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: vfs_cwd.c,v 1.11 2023/09/23 18:21:11 ad Exp $");
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#include <sys/param.h>
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#include <sys/atomic.h>
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#include <sys/filedesc.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/kmem.h>
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/*
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* Create an initial cwdinfo structure, using the same current and root
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* directories as curproc.
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*/
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struct cwdinfo *
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cwdinit(void)
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{
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struct cwdinfo *cwdi;
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struct cwdinfo *copy;
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cwdi = kmem_alloc(sizeof(*cwdi), KM_SLEEP);
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KASSERT(ALIGNED_POINTER(cwdi, COHERENCY_UNIT));
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rw_init(&cwdi->cwdi_lock);
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copy = curproc->p_cwdi;
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rw_enter(©->cwdi_lock, RW_READER);
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cwdi->cwdi_cdir = copy->cwdi_cdir;
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if (cwdi->cwdi_cdir)
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vref(cwdi->cwdi_cdir);
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cwdi->cwdi_rdir = copy->cwdi_rdir;
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if (cwdi->cwdi_rdir)
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vref(cwdi->cwdi_rdir);
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cwdi->cwdi_edir = copy->cwdi_edir;
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if (cwdi->cwdi_edir)
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vref(cwdi->cwdi_edir);
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rw_exit(©->cwdi_lock);
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cwdi->cwdi_cmask = copy->cwdi_cmask;
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cwdi->cwdi_refcnt = 1;
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return (cwdi);
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}
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/*
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* Make p2 share p1's cwdinfo.
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*/
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void
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cwdshare(struct proc *p2)
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{
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struct cwdinfo *cwdi;
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cwdi = curproc->p_cwdi;
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atomic_inc_uint(&cwdi->cwdi_refcnt);
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p2->p_cwdi = cwdi;
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}
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/*
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* Make sure proc has only one reference to its cwdi, creating
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* a new one if necessary.
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*/
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void
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cwdunshare(struct proc *p)
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{
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struct cwdinfo *cwdi = p->p_cwdi;
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if (cwdi->cwdi_refcnt > 1) {
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cwdi = cwdinit();
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cwdfree(p->p_cwdi);
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p->p_cwdi = cwdi;
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}
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}
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/*
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* Release a cwdinfo structure.
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*/
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void
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cwdfree(struct cwdinfo *cwdi)
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{
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membar_release();
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if (atomic_dec_uint_nv(&cwdi->cwdi_refcnt) > 0)
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return;
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membar_acquire();
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vrele(cwdi->cwdi_cdir);
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rw_destroy(&cwdi->cwdi_lock);
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if (cwdi->cwdi_rdir)
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vrele(cwdi->cwdi_rdir);
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if (cwdi->cwdi_edir)
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vrele(cwdi->cwdi_edir);
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kmem_free(cwdi, sizeof(*cwdi));
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}
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void
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cwdexec(struct proc *p)
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{
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cwdunshare(p);
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if (p->p_cwdi->cwdi_edir) {
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vrele(p->p_cwdi->cwdi_edir);
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}
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}
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