1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1996 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd July 24, 1996 32.Os 33.Dt VOP_READDIR 9 34.Sh NAME 35.Nm VOP_READDIR 36.Nd read contents of a directory 37.Sh SYNOPSIS 38.In sys/param.h 39.In sys/dirent.h 40.In sys/vnode.h 41.Ft int 42.Fn VOP_READDIR "struct vnode *vp" "struct uio *uio" "struct ucred *cred" "int *eofflag" "int *ncookies" "u_long **cookies" 43.Sh DESCRIPTION 44Read directory entries. 45.Bl -tag -width ncookies 46.It Fa vp 47The vnode of the directory. 48.It Fa uio 49Where to read the directory contents. 50.It Fa cred 51The caller's credentials. 52.It Fa eofflag 53Return end of file status 54.Dv ( NULL 55if not wanted). 56.It Fa ncookies 57Number of directory cookies generated for NFS 58.Dv ( NULL 59if not wanted). 60.It Fa cookies 61Directory seek cookies generated for NFS 62.Dv ( NULL 63if not wanted). 64.El 65The directory contents are read into 66.Vt struct dirent 67structures. 68If the on-disc data structures differ from this then they 69should be translated. 70.Sh LOCKS 71The directory should be locked on entry and will still be locked on exit. 72.Sh RETURN VALUES 73Zero is returned on success, otherwise an error code is returned. 74.Pp 75If this is called from the NFS server, the extra arguments 76.Fa eofflag , 77.Fa ncookies 78and 79.Fa cookies 80are given. 81The value of 82.Fa *eofflag 83should be set to TRUE if the end of the directory is reached while 84reading. 85The directory seek cookies are returned to the NFS client and may be used 86later to restart a directory read part way through the directory. 87There should be one cookie returned per directory entry. 88The value of 89the cookie should be the offset within the directory where the on-disc 90version of the appropriate directory entry starts. 91Memory for the cookies should be allocated using: 92.Pp 93.Bd -literal 94 ...; 95 *ncookies = number of entries read; 96 *cookies = (u_int*)# 97 malloc(*ncookies * sizeof(u_int), M_TEMP, M_WAITOK); 98.Ed 99.Sh PSEUDOCODE 100.Bd -literal 101int 102vop_readdir(struct vnode *vp, struct uio *uio, struct ucred *cred, 103 int *eofflag, int *ncookies, u_int **cookies) 104{ 105 off_t off; 106 int error = 0; 107 108 /* 109 * Remember the original offset to use later in generating cookies. 110 */ 111 off = uio->uio_offset; 112 113 /* 114 * Read directory contents starting at uio->uio_offset into buffer 115 * pointed to by uio. 116 */ 117 ...; 118 119 if (!error && ncookies != NULL) { 120 struct dirent *dpStart; 121 struct dirent *dpEnd; 122 struct dirent *dp; 123 int count; 124 u_int *cookiebuf; 125 u_int *cookiep; 126 127 if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1) 128 panic("vop_readdir: unexpected uio from NFS server"); 129 130 /* 131 * Parse the stuff just read into the uio. 132 */ 133 dpStart = (struct dirent *) 134 ((char *)uio->uio_iov->iov_base - (uio->uio_offset - off)); 135 dpEnd = (struct dirent *) uio->uio_iov->iov_base; 136 137 /* 138 * Count number of entries. 139 */ 140 for (dp = dpStart, count = 0; 141 dp < dpEnd; 142 dp = (struct dirent *)((caddr_t) dp + dp->d_reclen)) 143 count++; 144 145 cookiebuf = (u_int *) malloc(count * sizeof(u_int), M_TEMP, M_WAITOK); 146 for (dp = dpStart; cookiep = cookiebuf; 147 dp < dpEnd; 148 dp = (struct dirent *)((caddr_t) dp + dp->d_reclen)) { 149 off += dp->d_reclen; 150 *cookiep++ = (u_int) off; 151 } 152 *ncookies = count; 153 *cookies = cookiebuf; 154 } 155 156 if (eofflag && uio->uio_offset is past the end of the directory) { 157 *eofflag = TRUE; 158 } 159 160 return error; 161} 162.Ed 163.Sh ERRORS 164.Bl -tag -width Er 165.It Bq Er EINVAL 166An attempt was made to read from an illegal offset in the directory. 167.It Bq Er EIO 168A read error occurred while reading the directory. 169.El 170.Sh SEE ALSO 171.Xr vnode 9 172.Sh AUTHORS 173This manual page was written by 174.An Doug Rabson . 175