478 lines
11 KiB
C
478 lines
11 KiB
C
/* $OpenBSD: linux_getcwd.c,v 1.2 2001/05/16 12:50:21 ho Exp $ */
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/* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */
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/*-
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* Copyright (c) 1999 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Bill Sommerfeld.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_compat.h"
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#include "opt_mac.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/namei.h>
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#include <sys/filedesc.h>
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#include <sys/kernel.h>
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <sys/syscallsubr.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/proc.h>
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#include <sys/uio.h>
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#include <sys/malloc.h>
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#include <sys/dirent.h>
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#include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */
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#ifdef COMPAT_LINUX32
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#include <machine/../linux32/linux.h>
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#include <machine/../linux32/linux32_proto.h>
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#else
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#include <machine/../linux/linux.h>
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#include <machine/../linux/linux_proto.h>
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#endif
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#include <compat/linux/linux_util.h>
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#include <security/mac/mac_framework.h>
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static int
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linux_getcwd_scandir(struct vnode **, struct vnode **,
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char **, char *, struct thread *);
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static int
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linux_getcwd_common(struct vnode *, struct vnode *,
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char **, char *, int, int, struct thread *);
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#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
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/*
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* Vnode variable naming conventions in this file:
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*
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* rvp: the current root we're aiming towards.
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* lvp, *lvpp: the "lower" vnode
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* uvp, *uvpp: the "upper" vnode.
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*
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* Since all the vnodes we're dealing with are directories, and the
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* lookups are going *up* in the filesystem rather than *down*, the
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* usual "pvp" (parent) or "dvp" (directory) naming conventions are
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* too confusing.
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*/
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/*
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* XXX Will infinite loop in certain cases if a directory read reliably
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* returns EINVAL on last block.
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* XXX is EINVAL the right thing to return if a directory is malformed?
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*/
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/*
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* XXX Untested vs. mount -o union; probably does the wrong thing.
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*/
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/*
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* Find parent vnode of *lvpp, return in *uvpp
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*
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* If we care about the name, scan it looking for name of directory
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* entry pointing at lvp.
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*
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* Place the name in the buffer which starts at bufp, immediately
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* before *bpp, and move bpp backwards to point at the start of it.
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*
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* On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed
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* On exit, *uvpp is either NULL or is a locked vnode reference.
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*/
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static int
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linux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td)
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struct vnode **lvpp;
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struct vnode **uvpp;
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char **bpp;
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char *bufp;
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struct thread *td;
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{
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int error = 0;
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int eofflag;
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off_t off;
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int tries;
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struct uio uio;
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struct iovec iov;
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char *dirbuf = NULL;
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int dirbuflen;
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ino_t fileno;
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struct vattr va;
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struct vnode *uvp = NULL;
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struct vnode *lvp = *lvpp;
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struct componentname cn;
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int len, reclen;
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tries = 0;
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/*
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* If we want the filename, get some info we need while the
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* current directory is still locked.
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*/
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if (bufp != NULL) {
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error = VOP_GETATTR(lvp, &va, td->td_ucred);
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if (error) {
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vput(lvp);
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*lvpp = NULL;
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*uvpp = NULL;
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return error;
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}
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}
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/*
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* Ok, we have to do it the hard way..
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* Next, get parent vnode using lookup of ..
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*/
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cn.cn_nameiop = LOOKUP;
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cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY;
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cn.cn_thread = td;
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cn.cn_cred = td->td_ucred;
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cn.cn_pnbuf = NULL;
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cn.cn_nameptr = "..";
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cn.cn_namelen = 2;
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cn.cn_consume = 0;
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cn.cn_lkflags = LK_SHARED;
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/*
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* At this point, lvp is locked and will be unlocked by the lookup.
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* On successful return, *uvpp will be locked
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*/
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#ifdef MAC
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error = mac_vnode_check_lookup(td->td_ucred, lvp, &cn);
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if (error == 0)
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#endif
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error = VOP_LOOKUP(lvp, uvpp, &cn);
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if (error) {
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vput(lvp);
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*lvpp = NULL;
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*uvpp = NULL;
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return error;
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}
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uvp = *uvpp;
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/* If we don't care about the pathname, we're done */
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if (bufp == NULL) {
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vput(lvp);
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*lvpp = NULL;
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return 0;
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}
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fileno = va.va_fileid;
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dirbuflen = DIRBLKSIZ;
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if (dirbuflen < va.va_blocksize)
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dirbuflen = va.va_blocksize;
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dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
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#if 0
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unionread:
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#endif
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off = 0;
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do {
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/* call VOP_READDIR of parent */
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iov.iov_base = dirbuf;
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iov.iov_len = dirbuflen;
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uio.uio_iov = &iov;
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uio.uio_iovcnt = 1;
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uio.uio_offset = off;
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uio.uio_resid = dirbuflen;
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uio.uio_segflg = UIO_SYSSPACE;
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uio.uio_rw = UIO_READ;
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uio.uio_td = td;
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eofflag = 0;
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#ifdef MAC
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error = mac_vnode_check_readdir(td->td_ucred, uvp);
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if (error == 0)
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#endif /* MAC */
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error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag,
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0, 0);
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off = uio.uio_offset;
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/*
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* Try again if NFS tosses its cookies.
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* XXX this can still loop forever if the directory is busted
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* such that the second or subsequent page of it always
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* returns EINVAL
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*/
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if ((error == EINVAL) && (tries < 3)) {
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off = 0;
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tries++;
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continue; /* once more, with feeling */
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}
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if (!error) {
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char *cpos;
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struct dirent *dp;
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cpos = dirbuf;
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tries = 0;
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/* scan directory page looking for matching vnode */
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for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) {
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dp = (struct dirent *) cpos;
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reclen = dp->d_reclen;
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/* check for malformed directory.. */
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if (reclen < DIRENT_MINSIZE) {
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error = EINVAL;
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goto out;
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}
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/*
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* XXX should perhaps do VOP_LOOKUP to
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* check that we got back to the right place,
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* but getting the locking games for that
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* right would be heinous.
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*/
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if ((dp->d_type != DT_WHT) &&
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(dp->d_fileno == fileno)) {
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char *bp = *bpp;
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bp -= dp->d_namlen;
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if (bp <= bufp) {
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error = ERANGE;
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goto out;
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}
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bcopy(dp->d_name, bp, dp->d_namlen);
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error = 0;
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*bpp = bp;
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goto out;
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}
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cpos += reclen;
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}
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}
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} while (!eofflag);
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error = ENOENT;
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out:
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vput(lvp);
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*lvpp = NULL;
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free(dirbuf, M_TEMP);
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return error;
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}
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/*
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* common routine shared by sys___getcwd() and linux_vn_isunder()
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*/
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#define GETCWD_CHECK_ACCESS 0x0001
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static int
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linux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td)
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struct vnode *lvp;
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struct vnode *rvp;
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char **bpp;
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char *bufp;
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int limit;
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int flags;
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struct thread *td;
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{
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struct filedesc *fdp = td->td_proc->p_fd;
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struct vnode *uvp = NULL;
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char *bp = NULL;
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int error;
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accmode_t accmode = VEXEC;
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if (rvp == NULL) {
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rvp = fdp->fd_rdir;
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if (rvp == NULL)
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rvp = rootvnode;
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}
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VREF(rvp);
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VREF(lvp);
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/*
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* Error handling invariant:
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* Before a `goto out':
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* lvp is either NULL, or locked and held.
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* uvp is either NULL, or locked and held.
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*/
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error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY);
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if (error != 0)
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panic("vn_lock LK_RETRY returned error %d", error);
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if (bufp)
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bp = *bpp;
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/*
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* this loop will terminate when one of the following happens:
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* - we hit the root
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* - getdirentries or lookup fails
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* - we run out of space in the buffer.
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*/
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if (lvp == rvp) {
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if (bp)
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*(--bp) = '/';
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goto out;
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}
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do {
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if (lvp->v_type != VDIR) {
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error = ENOTDIR;
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goto out;
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}
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/*
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* access check here is optional, depending on
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* whether or not caller cares.
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*/
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if (flags & GETCWD_CHECK_ACCESS) {
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error = VOP_ACCESS(lvp, accmode, td->td_ucred, td);
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if (error)
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goto out;
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accmode = VEXEC|VREAD;
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}
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/*
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* step up if we're a covered vnode..
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*/
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while (lvp->v_vflag & VV_ROOT) {
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struct vnode *tvp;
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if (lvp == rvp)
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goto out;
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tvp = lvp;
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lvp = lvp->v_mount->mnt_vnodecovered;
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vput(tvp);
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/*
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* hodie natus est radici frater
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*/
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if (lvp == NULL) {
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error = ENOENT;
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goto out;
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}
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VREF(lvp);
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error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY);
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if (error != 0)
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panic("vn_lock LK_RETRY returned %d", error);
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}
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error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td);
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if (error)
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goto out;
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#ifdef DIAGNOSTIC
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if (lvp != NULL)
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panic("getcwd: oops, forgot to null lvp");
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if (bufp && (bp <= bufp)) {
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panic("getcwd: oops, went back too far");
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}
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#endif
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if (bp)
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*(--bp) = '/';
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lvp = uvp;
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uvp = NULL;
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limit--;
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} while ((lvp != rvp) && (limit > 0));
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out:
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if (bpp)
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*bpp = bp;
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if (uvp)
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vput(uvp);
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if (lvp)
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vput(lvp);
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vrele(rvp);
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return error;
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}
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/*
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* Find pathname of process's current directory.
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*
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* Use vfs vnode-to-name reverse cache; if that fails, fall back
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* to reading directory contents.
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*/
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int
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linux_getcwd(struct thread *td, struct linux_getcwd_args *args)
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{
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caddr_t bp, bend, path;
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int error, len, lenused;
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#ifdef DEBUG
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if (ldebug(getcwd))
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printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize);
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#endif
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len = args->bufsize;
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if (len > MAXPATHLEN*4)
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len = MAXPATHLEN*4;
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else if (len < 2)
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return ERANGE;
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path = (char *)malloc(len, M_TEMP, M_WAITOK);
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error = kern___getcwd(td, path, UIO_SYSSPACE, len);
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if (!error) {
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lenused = strlen(path) + 1;
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if (lenused <= args->bufsize) {
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td->td_retval[0] = lenused;
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error = copyout(path, args->buf, lenused);
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}
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else
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error = ERANGE;
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} else {
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bp = &path[len];
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bend = bp;
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*(--bp) = '\0';
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/*
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* 5th argument here is "max number of vnodes to traverse".
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* Since each entry takes up at least 2 bytes in the output buffer,
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* limit it to N/2 vnodes for an N byte buffer.
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*/
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mtx_lock(&Giant);
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error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL,
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&bp, path, len/2, GETCWD_CHECK_ACCESS, td);
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mtx_unlock(&Giant);
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if (error)
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goto out;
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lenused = bend - bp;
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td->td_retval[0] = lenused;
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/* put the result into user buffer */
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error = copyout(bp, args->buf, lenused);
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}
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out:
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free(path, M_TEMP);
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return (error);
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}
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