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175 lines
4.8 KiB
Groff
175 lines
4.8 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 1996 Doug Rabson
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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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 DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 24, 1996
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.Os
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.Dt VOP_READDIR 9
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.Sh NAME
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.Nm VOP_READDIR
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.Nd read contents of a directory
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/dirent.h
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.In sys/vnode.h
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.Ft int
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.Fn VOP_READDIR "struct vnode *vp" "struct uio *uio" "struct ucred *cred" "int *eofflag" "int *ncookies" "u_long **cookies"
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.Sh DESCRIPTION
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Read directory entries.
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.Bl -tag -width ncookies
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.It Fa vp
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The vnode of the directory.
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.It Fa uio
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Where to read the directory contents.
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.It Fa cred
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The caller's credentials.
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.It Fa eofflag
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Return end of file status
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.Dv ( NULL
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if not wanted).
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.It Fa ncookies
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Number of directory cookies generated for NFS
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.Dv ( NULL
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if not wanted).
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.It Fa cookies
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Directory seek cookies generated for NFS
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.Dv ( NULL
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if not wanted).
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.El
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The directory contents are read into
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.Vt struct dirent
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structures.
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If the on-disc data structures differ from this then they
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should be translated.
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.Sh LOCKS
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The directory should be locked on entry and will still be locked on exit.
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.Sh RETURN VALUES
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Zero is returned on success, otherwise an error code is returned.
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.Pp
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If this is called from the NFS server, the extra arguments
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.Fa eofflag ,
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.Fa ncookies
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and
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.Fa cookies
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are given.
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The value of
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.Fa *eofflag
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should be set to TRUE if the end of the directory is reached while
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reading.
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The directory seek cookies are returned to the NFS client and may be used
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later to restart a directory read part way through the directory.
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There should be one cookie returned per directory entry.
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The value of
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the cookie should be the offset within the directory where the on-disc
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version of the appropriate directory entry starts.
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Memory for the cookies should be allocated using:
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.Pp
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.Bd -literal
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...;
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*ncookies = number of entries read;
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*cookies = (u_int*)#
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malloc(*ncookies * sizeof(u_int), M_TEMP, M_WAITOK);
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.Ed
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.Sh PSEUDOCODE
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.Bd -literal
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int
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vop_readdir(struct vnode *vp, struct uio *uio, struct ucred *cred,
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int *eofflag, int *ncookies, u_int **cookies)
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{
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off_t off;
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int error = 0;
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/*
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* Remember the original offset to use later in generating cookies.
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*/
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off = uio->uio_offset;
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/*
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* Read directory contents starting at uio->uio_offset into buffer
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* pointed to by uio.
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*/
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...;
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if (!error && ncookies != NULL) {
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struct dirent *dpStart;
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struct dirent *dpEnd;
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struct dirent *dp;
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int count;
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u_int *cookiebuf;
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u_int *cookiep;
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if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1)
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panic("vop_readdir: unexpected uio from NFS server");
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/*
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* Parse the stuff just read into the uio.
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*/
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dpStart = (struct dirent *)
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((char *)uio->uio_iov->iov_base - (uio->uio_offset - off));
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dpEnd = (struct dirent *) uio->uio_iov->iov_base;
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/*
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* Count number of entries.
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*/
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for (dp = dpStart, count = 0;
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dp < dpEnd;
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dp = (struct dirent *)((caddr_t) dp + dp->d_reclen))
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count++;
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cookiebuf = (u_int *) malloc(count * sizeof(u_int), M_TEMP, M_WAITOK);
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for (dp = dpStart; cookiep = cookiebuf;
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dp < dpEnd;
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dp = (struct dirent *)((caddr_t) dp + dp->d_reclen)) {
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off += dp->d_reclen;
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*cookiep++ = (u_int) off;
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}
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*ncookies = count;
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*cookies = cookiebuf;
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}
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if (eofflag && uio->uio_offset is past the end of the directory) {
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*eofflag = TRUE;
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}
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return error;
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}
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.Ed
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EINVAL
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An attempt was made to read from an illegal offset in the directory.
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.It Bq Er EIO
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A read error occurred while reading the directory.
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.El
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.Sh SEE ALSO
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.Xr vnode 9
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.Sh AUTHORS
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This manual page was written by
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.An Doug Rabson .
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